Recycled newspaper fibers as reinforcing fillers in thermoplastics. Part I, Analysis of tensile and impact properties in polypropylene

Treesearch

A. R. Sanadi; R. A. Young; C. Clemons; R. M. Rowell

1994-01-01

Recycled newspaper fibers (ONP) are potentially outstanding nonabrasive reinforcing fibers with high specific properties. In this study, a high energy thermokinetic mixer was used to mix these fibers in a polypropylene (PP) matrix, and the blends were then injection molded in order to observe the tensile and impact strengths of the composites. A 40% (weight) of ONP in...

Date palm biochar-polymer composites: An investigation of electrical, mechanical, thermal and rheological characteristics.

PubMed

Poulose, Anesh Manjaly; Elnour, Ahmed Yagoub; Anis, Arfat; Shaikh, Hamid; Al-Zahrani, S M; George, Justin; Al-Wabel, Mohammad I; Usman, Adel R; Ok, Yong Sik; Tsang, Daniel C W; Sarmah, Ajit K

2018-04-01

The application of biochar (BC) as a filler in polymers can be viewed as a sustainable approach that incorporates pyrolysed waste based value-added material and simultaneously mitigate bio-waste in a smart way. The overarching aim of this work was to investigate the electrical, mechanical, thermal and rheological properties of biocomposite developed by utilizing date palm waste-derived BC for the reinforcing of polypropylene (PP) matrix. Date palm waste derived BC prepared at (700 and 900°C) were blended at different proportions with polypropylene and the resultant composites (BC/PP) were characterized using an array of techniques (scanning electron microscope, energy-dispersive X-ray spectroscopy and Fourier transform infra-red spectroscopy). Additionally the thermal, mechanical, electrical and rheological properties of the BC/PP composites were evaluated at different loading of BC content (from 0 to15% w/w). The mechanical properties of BC/PP composites showed an improvement in the tensile modulus while that of electrical characterization revealed an enhanced electrical conductivity with increased BC loading. Although the BC incorporation into the PP matrix has significantly reduced the total crystallinity of the resulted composites, however; a positive effect on the crystallization temperature (T c ) was observed. The rheological characterization of BC/PP composites revealed that the addition of BC had minimal effect on the storage modulus (G') compared to the neat (PP). Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and Characterization of Extruded Composites Based on Polypropylene and Chitosan Compatibilized with Polypropylene-Graft-Maleic Anhydride.

PubMed

Carrasco-Guigón, Fernando Javier; Rodríguez-Félix, Dora Evelia; Castillo-Ortega, María Mónica; Santacruz-Ortega, Hisila C; Burruel-Ibarra, Silvia E; Encinas-Encinas, Jose Carmelo; Plascencia-Jatomea, Maribel; Herrera-Franco, Pedro Jesus; Madera-Santana, Tomas Jesus

2017-01-25

The preparation of composites of synthetic and natural polymers represent an interesting option to combine properties; in this manner, polypropylene and chitosan extruded films using a different proportion of components and polypropylene-graft-maleic anhydride (PPgMA) as compatibilizer were prepared. The effect of the content of the biopolymer in the polypropylene (PP) matrix, the addition of compatibilizer, and the particle size on the properties of the composites was analyzed using characterization by fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), tensile strength, and contact angle, finding that in general, the addition of the compatibilizer and reducing the particle size of the chitosan, favored the physicochemical and morphological properties of the films.

Study on the Effect of Surface Energy of Polypropylene/Polyamide12 polymer Hybrid Matrix Reinforced with Virgin and Recycled Carbon Fiber

NASA Astrophysics Data System (ADS)

Sena Maia, Bruno

The presented work is focused on characterization of thermal treated recycled and virgin carbon fibers. Their thermal performances, chemical surface composition and its influence on interfacial adhesion phenomena on PP/PA12 hybrid matrix were compared using TGA, FTIR and XPS analysis. Additionally, differences between hybrid matrix structural performances of PP/PA12 using both surface modifiers PMPPIC and MAPP were investigated. Final mechanical properties improvements between 8% up to 17% were reached by addition of PMPPIC in PP/PA12 hybrid matrix. For PP/PA12 matrix reinforcement using virgin and recycled carbon fibers, impact energy was improved up to 98% compared with MAPP modified matrix leading to a novel composite with good energy absorption. Finally, wettability studies and surface free energy analysis of all materials studied support the effect of the addition of PMPPIC, MAPP and carbon fibers in final composite surface thermodynamics bringing important data correlation between interfacial adhesion mechanisms and final composite performance.

Distribution of Oil in a PP/EPDM Thermoplastic Elastomer

NASA Astrophysics Data System (ADS)

Kikuchi, Yutaka; Okada, Tetsuo; Inoue, Takashi

Distribution of oil in a commercial PP(polypropylene)/EPDM(ethylene-propyrene-diene rubber) thermoplastic elastomer was analyzed by light scattering. It was shown that the oil preferentially stays in EPDM particles at low temperatures and it migrates to PP matrix at high temperatures. That is, the oil is expected to play a dual role; softener at ambient temperature and plasticizer at processing temperature. The temperature dependence of oil distribution was nicely interpreted by a thermodynamic discussion.

Preparation and Characterization of Extruded Composites Based on Polypropylene and Chitosan Compatibilized with Polypropylene-Graft-Maleic Anhydride

PubMed Central

Carrasco-Guigón, Fernando Javier; Rodríguez-Félix, Dora Evelia; Castillo-Ortega, María Mónica; Santacruz-Ortega, Hisila C.; Burruel-Ibarra, Silvia E.; Encinas-Encinas, Jose Carmelo; Plascencia-Jatomea, Maribel; Herrera-Franco, Pedro Jesus; Madera-Santana, Tomas Jesus

2017-01-01

The preparation of composites of synthetic and natural polymers represent an interesting option to combine properties; in this manner, polypropylene and chitosan extruded films using a different proportion of components and polypropylene-graft-maleic anhydride (PPgMA) as compatibilizer were prepared. The effect of the content of the biopolymer in the polypropylene (PP) matrix, the addition of compatibilizer, and the particle size on the properties of the composites was analyzed using characterization by fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), tensile strength, and contact angle, finding that in general, the addition of the compatibilizer and reducing the particle size of the chitosan, favored the physicochemical and morphological properties of the films. PMID:28772464

The Compatibility Effect Of Coupling Agent On Rheological-Morphological Relationship Of Banana Fibre Reinforced Polypropylene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, S. Y.; Shamsudin, Z.

The rheological properties of banana fibre reinforced polypropylene (PP/BF) composites at different composition were analysed using Shimadzu capillary rheometer. The effect of coupling agent concentration on the rheological properties was studied and followed by drawing a relationship of rheological-morphological properties of PP/BF composites. It was found that all composite system exhibits pseudoplasticity and incorporation of treated fibres consequents enhanced viscosity due to improved interfacial adhesion at fibre-matrix interface. However, it was observed that PP/BF composite with 2 wt% silane concentration does not yield further enhancement in the rheological properties when compared to that of 1 wt%. Composites with 1 wt%more » silane concentration were found to yield most promising compatibility effect with well-oriented and uniformly dispersed fibre morphology.« less

Reactive compatibilization in polymer alloys, recyclates and composites

NASA Astrophysics Data System (ADS)

Czvikovszky, T.; Hargitai, H.; Rácz, I.; Csukat, G.

1999-05-01

The efficiency of all composite materials depends on the fiber-matrix interface and its ability to transfer stress from the matrix to the fiber. Radiation treatment is a possible way to bind together the main components of the composite. In our earlier work we applied acrylic oligomer-treated fibers irradiated with low energy electron beam to reinforce recycled polypropylene. In the present work the interaction between the matrix and fibers - PAN and glass fibers - was investigated by ESCA (Electron Spectroscopy for Chemical Analysis). On the other hand, the conventional way of compatibilization - the effect of using maleic anhydride grafted PP as a coupling agent - was examined in flax fiber-PP composites.

Some Exploitation Properties of Wood Plastic Hybrid Composites Based on Polypropylene and Plywood Production Waste

NASA Astrophysics Data System (ADS)

Kajaks, Janis; Kalnins, Karlis; Uzulis, Sandris; Matvejs, Juris

2015-12-01

During the last 20-30 years many researchers have paid attention to the studies of properties of thewood polymer composites (WPC). A lot of works are closely related to investigations of exploitation properties of wood fibres or wood flour containing polyolefine composites [1, 2]. The most useful from wide selection of polyolefines are polypropylenes, but timber industry waste materials comprising lignocellulose fibres are often used as reinforcement of WPC [3-12]. Plywood industry is not an exception - part of waste materials (by-products) are used for heat energy, i.e. burned. In this work we have approbated reinforcing of polypropylene (PP) with one of the plywood industry by-products, such as birch plywood sawdust (PSWD),which containswood fibre fractions with different length [13]. The main fraction (50%) includes fibres with length l = 0.5 - 1 mm. Our previous study [13] has confirmed that PSWD is a promising filler for PP reinforcing. Addition of PSWD up to 40-50 wt.% has increased WPC tensile and flexural modulus, but decreased deformation ability of PP matrix, impact strength, water resistance and fluidity of composite melts. It was shown [13] that modification of the composites with interfacial modifier - coupling agent maleated polypropylene (MAPP content up to 5-7 wt.%) considerably improved all the abovementioned properties. SEM investigations also confirmed positive action of coupling agent on strengthening of adhesion interaction between components wood and PP matrix. Another way how to make better properties of the WPC is to form hybridcomposites [1, 14-24]. Very popular WPC modifiers are nanoparticle additions like organonanoclays, which increase WPC physical-mechanical properties - microhardness, water resistance and diminish barrier properties and combustibility [1, 2, 14-17, 19, 20]. The goal of this study was to investigate organonanoclays influence on plywood production industry by-product birch plywood sawdust (PSWD) containing polypropylenewood hybrid composites (WPHC) physical-mechanical and other exploitation properties.

Effects of Surface Modification on the Mechanical Properties of Flax/β-Polypropylene Composites

PubMed Central

Wu, Chang-Mou; Lai, Wen-You; Wang, Chen-Yu

2016-01-01

The effects of surface treatment of flax fibers featuring vinyltrimethoxy silane (VTMO) and maleic anhydride-polypropylene (MAPP) on the mechanical properties of flax/PP composites were investigated. α-polypropylene (α-PP) and β-polypropylene (β-PP) were used as matrices for measuring the mechanical properties of the flax fiber/polypropylene (flax/PP) composites. Flax/PP composites composed of double-covered uncommingled yarn (DCUY) were prepared using a film-stacking technique. The influence of surface treatment on the tensile, flexural, impact, and water uptake properties of Flax/PP composites were investigated. MAPP treatment was suitable for flax/PP composites in terms of superior tensile and impact properties. VTMO treatment showed superior flexural properties and less influence on the impact properties after moisture absorption. PMID:28773439

Comparison of polypropylene mesh and porcine-derived, cross-linked urinary bladder matrix materials implanted in the rabbit vagina and abdomen.

PubMed

Fan, Xuemei; Wang, Yanzhou; Wang, Yu; Xu, Huicheng

2014-05-01

Our aim was to compare histological and biomechanical effects of polypropylene (PP) mesh and porcine-derived, cross-linked urinary bladder matrix (cUBM) graft materials using a rabbit vaginal and abdominal model. Forty rabbits were implanted with PP mesh (n = 20) or cUBM (n = 20) in the vagina and abdomen. Two grafts (PP or cUBM) of the same type were placed into each site, so each rabbit had four grafts. Grafts were harvested 12 weeks later and processed for histologic analysis and biomechanical testing. There were high rates of two types of grafts missing in the vagina. Vaginal PP was associated with erosion reaction (67%), whereas abdominal PP and cUBM showed no sign of erosion. All patches adhered to rectus abdominis or vaginal mucosa and shrank to varying degrees, especially for PP grafts. Compared with vaginal PP, vaginal cUBM induced milder chronic inflammation response, had lower scores (P = 0.000) for inflammation response, and showed higher scores for neovascularization (P = 0.000) and fibroblastic proliferation (P = 0.002). In the abdomen, both histopathological parameters were insignificantly different (P > 0.05) between cUBM and PP. The mechanical properties of UBM did not deteriorate following implantation, whereas the ultimate tensile strength and elastic modulus of vaginal PP increased. PP had higher scores for tensile and break strength than did cUBM (P < 0.05). The cUBM has good biocompatibility, high ability to integrate with the vagina, and maintains mechanical properties in vivo. It may be a promising material for pelvic floor reconstruction.

Evaluation of foaming polypropylene modified with ramified polymer

NASA Astrophysics Data System (ADS)

Demori, Renan; de Azeredo, Ana Paula; Liberman, Susana A.; Mauler, Raquel S.

2015-05-01

Polypropylene foams have great industrial interest because of balanced physical and mechanical properties, recyclability as well as low material cost. During the foaming process, the elongational forces applied to produce the expanded polymer are strong enough to rupture cell walls. As a result, final foam has a high amount of coalesced as well as opened cells which decreases mechanical and also physical properties. To increase melt strength and also avoid the coalescence effect, one of the current solution is blend PP with ramified polymers as well as branched polypropylene (LCBPP) or ethylene-octene copolymer (POE). In this research to provide extensional properties and achieve uniform cellular structures of expanded PP, 20 phr of LCBPP or POE was added into PP matrix. The blend of PP with ramified polymers was prepared by twin-screw extrusion. Injection molding process was used to produce PP foams using azodicarbonamide (ACA) as chemical blowing agent. The morphological results of the expanded PP displayed a non-uniform geometrical cell, apparent density of 0.48 g/cm3 and cell density of 13.9.104 cell/cm3. Otherwise, the expanded PP blended with LCBPP or POE displayed a homogeneous cell structure and increased the amount of smaller cells (50-100 μm of size). The apparent density slightly increased with addition of LCBPP or POE, 0.64 and 0.57 g/cm3, respectively. Thus, the cell density reduced to 65% in PP/LCBPP 100/20 and 75% in the sample PP/POE 100/20 compared to expanded PP. The thermo-mechanical properties (DMTA) of PP showed specific stiffness of 159 MPa.cm-3.g-1, while the sample PP/LCBPP 100/20 increased the stiffness values of 10%. Otherwise, the expanded PP/POE 100/20 decreased the specific stiffness values at -30%, in relation to expanded PP. In summary, blending PP with ramified polymers showed increasing of the homogenous cellular structure as well as the amount of smaller cells in the expanded material.

Thermal Conductivity Performance of Polypropylene Composites Filled with Polydopamine-Functionalized Hexagonal Boron Nitride.

PubMed

Chen, Lin; Xu, Hong-Fei; He, Shao-Jian; Du, Yi-Hang; Yu, Nan-Jie; Du, Xiao-Ze; Lin, Jun; Nazarenko, Sergei

2017-01-01

Mussel-inspired approach was attempted to non-covalently functionalize the surfaces of boron nitride (BN) with self-polymerized dopamine coatings in order to reduce the interfacial thermal barrier and enhance the thermal conductivity of BN-containing composites. Compared to the polypropylene (PP) composites filled with pristine BN at the same filler content, thermal conductivity was much higher for those filled with both functionalized BN (f-BN) and maleic anhydride grafted PP (PP-g-ma) due to the improved filler dispersion and better interfacial filler-matrix compatibility, which facilitated the development of more thermal paths. Theoretical models were also applied to predict the composite thermal conductivity in which the Nielsen model was found to fit well with the experimental results, and the estimated effective aspect ratio of fillers well corresponded to the degree of filler aggregation as observed in the morphological study.

Thermal Conductivity Performance of Polypropylene Composites Filled with Polydopamine-Functionalized Hexagonal Boron Nitride

PubMed Central

Xu, Hong-Fei; He, Shao-Jian; Du, Yi-Hang; Yu, Nan-Jie; Du, Xiao-Ze; Lin, Jun; Nazarenko, Sergei

2017-01-01

Mussel-inspired approach was attempted to non-covalently functionalize the surfaces of boron nitride (BN) with self-polymerized dopamine coatings in order to reduce the interfacial thermal barrier and enhance the thermal conductivity of BN-containing composites. Compared to the polypropylene (PP) composites filled with pristine BN at the same filler content, thermal conductivity was much higher for those filled with both functionalized BN (f-BN) and maleic anhydride grafted PP (PP-g-ma) due to the improved filler dispersion and better interfacial filler-matrix compatibility, which facilitated the development of more thermal paths. Theoretical models were also applied to predict the composite thermal conductivity in which the Nielsen model was found to fit well with the experimental results, and the estimated effective aspect ratio of fillers well corresponded to the degree of filler aggregation as observed in the morphological study. PMID:28107466

Biocomposites from co-polypropylene and distillers' grains

NASA Astrophysics Data System (ADS)

Zarrinbakhsh, Nima; Mohanty, Amar K.; Misra, Manjusri

2015-05-01

In the present work, we have explored the polymeric composites of distillers' grains with co-polypropylene (co-PP). The effect of maleated-PP compatibilizer on mechanical, thermomechanical and physical properties was evaluated. The composite materials were produced by melt extrusion in a micro-compounder followed by injection molding in a micro-injection machine. The composites were characterized for their tensile, flexural and impact properties. Also, melt flow index and heat deflection temperature were measured. The results showed more than 30 % improvement in modulus when comparing the compatibilized biocomposite with neat co-PP. Also, the strength of the compatibilized biocomposite measured in tensile and flexural tests was comparable to or even better than that of the neat matrix. On the other hand, the reduced flexibility and toughness as a result of compatibilization were in an acceptable range. The biocomposites showed more rigidity at elevated temperatures. The produced distillers' grain biocomposites showed promises for industrial applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanadi, A.R.; Caulfield, D.F.; Jacobson, R.E.

Kenaf (Hibiscus Cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In our experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the non-polar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50 % by volume (39 % by volume) of kenaf-PP composites compares favorablymore » with a 40 % by weight of glass fiber-PP injection molded composites, These results suggest that kenaf fibers are a viable alternative to inorganic/mineral based reinforcing fibers as long as the right processing conditions are used and for applications where the higher water absorption is not critical.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanadi, A.R.; Caulfield, D.F.; Jacobson, R.E.

Kenaf (Hibiscus cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In these experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the nonpolar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50% by weight (39% by volume) of kenaf-PP composite compare favorably with amore » 40% by weight of glass fiber-PP injection-molded composite. These results suggest that kenaf fibers are a viable alternative to inorganic/mineral-based reinforcing fibers as long as the right processing conditions are used and they are used in applications where the higher water absorption is not critical.« less

Fabrication of borassus fruit lignocellulose fiber/PP composites and comparison with jute, sisal and coir fibers.

PubMed

Sudhakara, P; Jagadeesh, Dani; Wang, YiQi; Prasad, C Venkata; Devi, A P Kamala; Balakrishnan, G; Kim, B S; Song, J I

2013-10-15

Novel composites based on borassus fruit fine fiber (BFF) and polypropylene (PP) were fabricated with variable fiber composition (5, 10, 15 and 20 wt%) by injection molding. Maleated PP (MAPP) was also used as compatibilizer at 5 wt% for effective fiber-matrix adhesion. FTIR analysis confirms the evidence of a chemical bonding between the fiber and polymeric matrix through esterification in presence of MAPP. The tensile and flexural properties were found to increase with 15 and 10 wt% fiber loadings respectively, and decreased thereafter. Coir, jute and sisal fiber composites were also fabricated with 15 wt% fiber loading under the same conditions as used for BFF/PP composites. It was found that the mechanical properties of BFF (15 wt%)/PP composites were equivalent to jute/PP, sisal/PP and superior to coir/PP composites. Jute/PP and sisal/PP composites showed higher water absorption than BFF/PP and coir/PP composites. These results have demonstrated that the BFF/PP composites can also be an alternative material for composites applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

Novel polypropylene/inorganic fullerene-like WS2 nanocomposites containing a β-nucleating agent: isothermal crystallization and melting behavior.

PubMed

Naffakh, Mohammed; Marco, Carlos; Ellis, Gary

2012-02-16

The isothermal crystallization and subsequent melting behavior of isotactic polypropylene (iPP) nucleated with different nucleating agents (NAs) are investigated. Tungsten disulfide (IF-WS(2)) and N,N'-dicyclohexyl-2,6-naphthalene (NJ) and dual-additive mixtures are introduced into an iPP matrix to generate new materials that exhibit variable α- and β-polymorphism. As shown in previous work, small amounts of IF-WS(2) or NJ have a nucleating effect during the crystallization of iPP. However, the isothermal crystallization and melting behavior of iPP nucleated by dual α(IF-WS(2))/β(NJ) additive systems are dependent on both the NA composition balance and the crystallization temperature. In particular, our results demonstrate that it is possible to obtain any α-phase to β-phase content ratio by controlling the composition of NAs under appropriate isothermal crystallization conditions. The nucleating behavior of the additives can be illustrated by competitive nucleation, and the correlation between crystallization and melting temperatures and relative α- and β-crystals content in iPP in the nanocomposites is discussed.

Nano-Charged Polypropylene Application: Realistic Perspectives for Enhancing Durability

PubMed Central

Naddeo, Carlo; Vertuccio, Luigi; Barra, Giuseppina; Guadagno, Liberata

2017-01-01

Isotactic polypropylene/multi-walled carbon nanotube (iPP/MWCNTs) films have been exposed to accelerated weathering in a UV device for increasing times. The effect of UV irradiation on the structural and chemical changes has been investigated. The resistance to accelerated photooxidation of (iPP/MWCNTs) films has been compared to the photooxidation behaviour of unfilled polypropylene films with the same structural organization. The chemical and structural modifications resulting from photooxidation have been followed using infrared spectroscopy, calorimetric and diffractometric analysis. MWCNTs embedded in the polymeric matrix are able to strongly contrast the degradation mechanisms and the structural and morphological rearrangements caused by the UV treatment on the unfilled polymer. MWCNTs determine an induction period (IP) before the increase of the carbonyl and hydroxyl groups. The extent of the IP is strictly correlated to the amount of MWCNTs. The low electrical percolation threshold (EPT) and the electrical conductivity of the nanocomposites, together with their excellent thermal and photooxidative stability, make them promising candidates to fulfill many industrial requirements. PMID:28805728

Morphology and crystalline-phase-dependent electrical insulating properties in tailored polypropylene for HVDC cables

NASA Astrophysics Data System (ADS)

Zha, Jun-Wei; Yan, Hong-Da; Li, Wei-Kang; Dang, Zhi-Min

2016-11-01

Polypropylene (PP) has become one promising material to potentially replace the cross-link polyethylene used for high voltage direct current cables. Besides the isotactic polypropylene, the block polypropylene (b-PP) and random polypropylene (r-PP) can be synthesized through the copolymerization of ethylene and propylene molecules. In this letter, the effect of morphology and crystalline phases on the insulating electrical properties of PP was investigated. It was found that the introduction of polyethylene monomer resulted in the formation of β and γ phases in b-PP and r-PP. The results from the characteristic trap energy levels indicated that the β and γ phases could induce deep electron traps which enable to capture the carriers. And the space charge accumulation was obviously suppressed. Besides, the decreased electrical conductivity was observed in b-PP and r-PP. It is attributed to the existence of deep traps which can effectively reduce the carrier mobility and density in materials.

Study of EPDM/PP polymeric blends: mechanical behavior and effects of compatibilization

NASA Astrophysics Data System (ADS)

Bouchart, Vanessa; Bhatnagar, N.; Brieu, Mathias; Ghosh, A. K.; Kondo, Djimedo

2008-09-01

A blend of Ethylene Propylene Diene Monomer (EPDM) rubber reinforced by polypropylene (PP) particles has been processed and its hyperelastic behavior has been characterized under cyclic uni-axial tensile tests. The experimental results show a significant effect of the fraction of polypropylene particles (10%, 25% and 30% by weight). Moreover, from another series of tests conducted on materials containing compatibilizers at different mass concentration, it is observed that the introduction of a compatibilizer increases the rigidity of the blends and affects notably their macroscopic behavior. These observations are interpreted as a consequence of the modification at microlevel of adherence between particles and matrix phases. The use of a nonlinear micromechanical model allows us to confirm this interpretation. To cite this article: V. Bouchart et al., C. R. Mecanique 336 (2008).

Styrene-butadiene-styrene copolymer compatibilized carbon black/polypropylene/polystyrene composites with tunable morphology, electrical conduction and rheological stabilities.

PubMed

Song, Yihu; Xu, Chunfeng; Zheng, Qiang

2014-04-21

We report a facile kinetic strategy in combination with styrene-butadiene-styrene (SBS) copolymer compatibilizers for preparing carbon black (CB) filled immiscible polypropylene (PP)/polystyrene (PS) (1/1) blends with finely tuned morphologies and show the important role of location and migration of CB nanoparticles in determining the electrical conductivity and rheological behaviour of the composites. A novel method of mixing a SBS/CB (5/3) masterbatch with the polymers allowed producing composites with CB aggregates dispersed partially in the unfavorable PP phase and partially in the PP side of the interface to exhibit diverse phase connectivity and electrical conductivity depending on the compounding sequences. A cocontinuous morphology with CB enrichment along the interface was formed in the composite prepared by mixing the SBS/CB masterbatch with the premixed PP/PS blend, giving rise to a highest electrical conductivity and dynamic moduli at low frequencies. On the other hand, mixing the masterbatch with one and then with another polymer yielded droplet (PS)-in-matrix (filled PP) composites. The composites underwent phase coalescence and CB redistribution accompanied by marked dynamic electrical conduction and modulus percolations as a function of time during thermal annealing at 180 °C. The composites with the initial droplet-in-matrix morphology progressed anomalously into the cocontinuous morphology, reflecting a common mechanism being fairly nonspecific for understanding the processing of filled multicomponent composites with tailored performances of general concern.

Microstructure and Properties of Polypropylene/Carbon Nanotube Nanocomposites

PubMed Central

Bikiaris, Dimitrios

2010-01-01

In the last few years, great attention has been paid to the preparation of polypropylene (PP) nanocomposites using carbon nanotubes (CNTs) due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. This is due to the unique combination of structural, mechanical, electrical, and thermal transport properties of CNTs. However, it is well-known that the properties of polymer-based nanocomposites strongly depend on the dispersion of nanofillers and almost all the discussed properties of PP/CNTs nanocomposites are strongly related to their microstructure. PP/CNTs nanocomposites were, mainly, prepared by melt mixing and in situ polymerization. Young’s modulus, tensile strength and storage modulus of the PP/CNTs nanocomposites can be increased with increasing CNTs content due to the reinforcement effect of CNTs inside the polymer matrix. However, above a certain CNTs content the mechanical properties are reduced due to the CNTs agglomeration. The microstructure of nanocomposites has been studied mainly by SEM and TEM techniques. Furthermore, it was found that CNTs can act as nucleating agents promoting the crystallization rates of PP and the addition of CNTs enhances all other physical properties of PP. The aim of this paper is to provide a comprehensive review of the existing literature related to PP/CNTs nanocomposite preparation methods and properties studies.

Comparative studies of Titanium Dioxide and Zinc Oxide as a potential filler in Polypropylene reinforced rice husk composite

NASA Astrophysics Data System (ADS)

Awang, M.; Mohd, W. R. Wan

2018-04-01

Arising global environmental issues have triggered the search of new products and processes that are compatible with the environment while maintaining novel properties of materials. In this work, green composites containing rice husk (RH), polypropylene (PP), and incorporated with two different fillers namely titanium dioxide (TiO2) and zinc oxide (ZnO) were prepared using an internal mixer and were injected into desired specimen by using an injection molding method. Mechanical properties of the composite were studied using Instron universal testing machine with load cell of 30kN capacity. Morphological of tensile fractured surface of composites was observed using scanning electron microscopy (SEM). The results show that the composites with the addition of TiO2 gave an excellent mechanical properties than the composites filled with ZnO. Furthermore, morphological image of PP/RH/TiO2 also shows a good interaction occurred between polymer matrix and RH particles as compared to that of PP/RH/ZnO.

Morphological, rheological and mechanical characterization of polypropylene nanocomposite blends.

PubMed

Rosales, C; Contreras, V; Matos, M; Perera, R; Villarreal, N; García-López, D; Pastor, J M

2008-04-01

In the present work, the effectiveness of styrene/ethylene-butylene/styrene rubbers grafted with maleic anhydride (MA) and a metallocene polyethylene (mPE) as toughening materials in binary and ternary blends with polypropylene and its nanocomposite as continuous phases was evaluated in terms of transmission electron microscopy (TEM), scanning electron microscopy (SEM), oscillatory shear flow and dynamic mechanical thermal analysis (DMA). The flexural modulus and heat distortion temperature values were determined as well. A metallocene polyethylene and a polyamide-6 were used as dispersed phases in these binary and ternary blends produced via melt blending in a corotating twin-screw extruder. Results showed that the compatibilized blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the matrix phase and no significant changes in shear viscosity, melt elasticity, flexural or storage moduli and heat distortion temperature values were observed between them. However, the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene phase exhibited better toughness, lower shear viscosity, flexural modulus, and heat distortion temperature values than that prepared with polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the PP and to the type of morphology developed in the different blends.

Synthesis of highly efficient flame retardant polypropylene nanocomposites with surfactant intercalated layered double hydroxides.

PubMed

Qiu, Lei; Gao, Yanshan; Zhang, Cheng; Yan, Qinghua; O'Hare, Dermot; Wang, Qiang

2018-02-27

The thermal and flame retardant performances of polypropylene (PP) nanocomposites with sodium dodecyl sulfate (DDS) and stearic acid intercalated layered double hydroxides (DDS-LDHs and stearic-LDHs) were investigated in this study. The DDS- and stearic-LDHs were treated using the aqueous miscible organic solvent treatment (AMOST) method to give highly dispersed platelets in PP composites. The incorporation of AMO-DDS- and stearic-LDHs improved the thermal stability and flame retardancy of the PP matrix significantly. The T 0.5 (temperature at 50% weight loss) of PP/AMO-stearic-LDH (20 wt%) nanocomposites dramatically increased by 80 °C compared to that of neat PP. The flame retardant performance was dependent on both surfactants and the loading of LDHs. The AMO-stearic-LDHs showed better flame retardant properties than the AMO-DDS-LDHs, especially when the LDH loading was higher than ca. 7 wt%. In addition, stearic-LDHs with different solvothermal times including 5, 10, 24 and 72 h were studied. It was found that the nanocomposites with LDHs solvothermally treated for 10 h showed the best thermal stability. The PP/stearic-LDH (24 h) nanocomposites with 20 wt% LDH loading possessed a better flame retardant performance, with PHRR reduction reaching 70%.

Composites of multi-walled carbon nanotubes with polypropylene and thermoplastic olefin blends prepared by melt compounding

NASA Astrophysics Data System (ADS)

Petrie, Kyle G.

Composites of multi-walled carbon nanotubes (MWCNTs) with polypropylene (PP) and thermoplastic olefins (TPOs) were prepared by melt compounding. Two non-covalent functionalization methods were employed to improve nanotube dispersion and the resulting composite properties are reported. The first functionalization approach involved partial coating of the surface of the nanotubes with a hyperbranched polyethylene (HBPE). MWCNT functionalization with HBPE was only moderately successful in breaking up the large aggregates that formed upon melt mixing with PP. In spite of the formation of large aggregates, the samples were conductive above a percolation threshold of 7.3 wt%. MWCNT functionalization did not disrupt the electrical conductivity of the nanotubes. The composite strength was improved with addition of nanotubes, but ductility was severely compromised because of the existence of aggregates. The second method involved PP matrix functionalization with aromatic moieties capable of pi-pi interaction with MWCNT sidewalls. Various microscopy techniques revealed the addition of only 25 wt% of PP-g-pyridine (Py) to the neat PP was capable of drastically reducing nanotube aggregate size and amount. Raman spectroscopy confirmed improved polymer/nanotube interaction with the PP-g-Py matrix. Electrical percolation threshold was obtained at a MWCNT loading of approximately 1.2 wt%. Electrical conductivity on the order of 10 -2 S/m was achieved, suggesting possible use in semi-conducting applications. Composite strength was improved upon addition of MWCNTs. The matrix functionalization with Py resulted in a significant improvement in composite ductility when filled with MWCNTs in comparison to its maleic anhydride (MA) counterpart. Preliminary investigations suggest that the use of alternating current (AC) electric fields may be effective in aligning nanotubes in PP to reduce the filler loading required for electrical percolation. Composites containing MWCNT within PP/ethylene-octene copolymer (EOC) blends were prepared. Microscopy revealed that MWCNTs localized preferentially in the EOC phase. This was explained by the tendency of the system to minimize interfacial energy when the MWCNTs reside in the thermodynamically preferential phase. A kinetic approach, which involved pre-mixing the MWCNTs with PP and adding the EOC phase subsequently was attempted to monitor the migration of MWCNTs. MWCNTs began to migrate after two minutes of melt mixing with the EOC. The PP-g-Py matrix functionalization appears to slightly delay the migration. A reduction in electrical percolation threshold to 0.5 wt% MWCNTs was achieved with a co-continuous blend morphology, consisting of a 50/50 by weight ratio of PP and EOC.

Effect of compatibilizing agents on the interface and mechanical behaviour of polypropylene/hemp bast fiber biocomposites

NASA Astrophysics Data System (ADS)

Boruvka, M.; Lenfeld, P.; Brdlik, P.; Behalek, L.

2015-07-01

During the last years automotive industry has given a lot of attention to the biobased polymers that are sustainable and eco-friendly. Nevertheless fully green composites are currently too expensive for most applications. A viable solution and logical starting point at this material revolution lies in reinforced synthetic thermoplastics based on plant derived biodegradable fibers. Plant fibers (PF's) have potential to reduce weight of composite vehicle parts up to 40% compared with the main automotive composites filler, glass fibers (GF's). Production of GF's composites is much more energy intensive and polluting compared with growing, harvesting and preparing of PF's. The main disadvantage of PF's lies in combination of non-polar hydrophobic polymer matrix and polar hydrophilic fibers. This combination creates poor interface with low adhesion of both components. That implies poor wettability of fibres by polymer matrix and low mechanical properties of biocomposites. Therefore specific compatibilizing agents (Struktol SA1012, Fusabond P353, Smart + Luperox) were used in order to enhance compatibility between reinforcement and matrix. In this paper sets of biocomposite compounds were prepared by twin screw extrusion considering different type and weight percentage (wt. %) of compatibilizing agents, hemp bast fibres (HBF's) within ratio 20 (wt. %) and polypropylene (PP) THERMOFIL PP E020M matrix. Resulting compounds were than injection molded and tested samples were characterized by means of scanning electron microscopy (SEM) and mechanical testing.

Phase separation of DMDBS from iPP, and controlled crystalline orientation

NASA Astrophysics Data System (ADS)

Sreenivas, K.; Kumaraswamy, Guruswamy; Basargekar, R. S.

2012-02-01

We report an unexpected dependence of DMDBS phase separation temperature on the molecular weight of the matrix isotactic polypropylene (iPP). DMDBS crystallizes out at lower temperatures for iPP with decreasing molecular weight (and correspondingly lower tacticity). This molecular weight dependence is unique to iPP, and is not observed for either syndiotactic PP or for random ethylene-PP copolymers. We show that thermodynamic Flory-type arguments are unable to rationalize the observed results. We also results on extrusion film casting of iPP containing DMDBS and show that flow-alignment of DMDBS networks template the orientation of PP crystals. The modulus and yield strength increase on addition of DMDBS, relative to the neat iPP. Tensile modulus and yield stress of drawn films increase with the degree of orientation, and we are able to achieve a substantial increase even at relatively low draw ratios.

Extrudable polymer-polymer composites based on ultra-high molecular weight polyethylene

NASA Astrophysics Data System (ADS)

Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Buslovich, D. G.; Dontsov, Yu. V.

2017-12-01

Mechanical and tribotechnical characteristics of polymer-polymeric composites of UHMWPE are studied with the aim of developing extrudable, wear-resistant, self-lubricant polymer mixtures for Additive Manufacturing (AM). The motivation of the study is their further application as feedstocks for 3D printing. Blends of UHMWPE with graft- and block copolymers of low-density polyethylene (HDPE-g-VTMS, HDPE-g-SMA, HDPE-b-EVA), polypropylene (PP), block copolymers of polypropylene and polyamide with linear low density polyethylene (PP-b-LLDPE, PA-b-LLDPE), as well as cross-linked polyethylene (PEX-b), are examined. The choice of compatible polymer components for an ultra- high molecular weight matrix for increasing processability (extrudability) is motivated by the search for commercially available and efficient additives aimed at developing wear-resistant extrudable polymer composites for additive manufacturing. The extrudability, mechanical properties and wear resistance of UHMWPE-based polymer-polymeric composites under sliding friction with different velocities and loads are studied.

Chemical cross-linking of polypropylenes towards new shape memory polymers.

PubMed

Raidt, Thomas; Hoeher, Robin; Katzenberg, Frank; Tiller, Joerg C

2015-04-01

In this work, syndiotactic polypropylene (sPP) as well as isotactic polypropylene (iPP) are cross-linked to gain a shape memory effect. Both prepared PP networks exhibit maximum strains of 700%, stored strains of up to 680%, and recoveries of nearly 100%. While x-iPP is stable for many cycles, x-sPP ruptures after the first shape-memory cycle. It is shown by wide-angle X-ray scattering (WAXS) experiments that cross-linked iPP exhibits homoepitaxy in the temporary, stretched shape but in contrast to previous reports it contains a higher amount of daughter than mother crystals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of fibre treatment using fluorosilane on Sansevieria Trifasciata/Polypropylene composite

NASA Astrophysics Data System (ADS)

Aref, Yanzur Mohd; Baharum, Azizah

2018-04-01

Recently, there is an increasing interest in the development of wood-plastic composites (WPC) due to their advantages such as wide availability, low cost, environment friendliness and sustainability. However, some major factors limiting the large scales production of WPC including the tendency of natural fibres to absorb water and the poor compatibility between fibre and matrix. In this study, we investigated the effectiveness of natural fibre treatment using fluorosilane in imparting hydrophobicity to the polypropylene (PP) matrix composite reinforced with Sansevieria Trifasciata (ST) fibres. ST fibres are subjected to silane treatment with 1H,1H,2H,2H-perfluorooctyltriethoxsysilane (POTS) at 1, 3 and 5% for a period of 2 hours. Influence of POTS treatment on the physical and mechanical properties of composites was studied to determine the optimum condition of silane treatment. The water contact angle (WCA) of WPC increased after POTS treatment where the highest value of 115° was shown by 3% POTS treated ST/PP composite. Based on mechanical properties results, incorporation of POTS treated ST fibre improves the mechanical properties with the enhancement of flexural and impact strength. The treatment with 3% POTS revealed statistically higher flexural strength and modulus compared to 1 and 5%. The water absorption test of ST/PP composites also gives the best result for 3% POTS treatment with 20.90% water uptake.

Rheological and mechanical properties of polypropylene prepared with multi-walled carbon nanotube masterbatch.

PubMed

Shim, Young-Sun; Park, Soo-Jin

2012-07-01

In this study, the effects of polypropylene-grafted maleic-anhydride-treated multi-walled carbon nanotubes (PP-MWNTs) on the viscoelastic behaviors and mechanical properties of a polypropylene-(PP)-based composite system were examined. The PP-MWNT/PP composites were prepared via melt mixing with a 3:1 ratio of PP-g-MA and acid-treated MWNTs at 220 degrees C. The surface characteristics of the PP-MWNTs were confirmed via Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The viscoelastic behavior and mechanical properties of the PP-MWNT/PP composites were confirmed using a rheometer and an ultimate testing machine (UTM). The storage and loss moduli increased with increasing PP-MWNT content. The critical intensity stress factor (K(IC)) of the PP-MWNT/PP composites at high filler loading was also higher than that of the MWNT/PP composites. In conclusion, the viscoelastic behavior and mechanical properties of MWNT/PP can be improved by grafting MWNTs to PP-g-MA.

Mechanical and morphological properties of polypropylene/nano α-Al2O3 composites.

PubMed

Mirjalili, F; Chuah, L; Salahi, E

2014-01-01

A nanocomposite containing polypropylene (PP) and nano α-Al2O3 particles was prepared using a Haake internal mixer. Mechanical tests, such as tensile and flexural tests, showed that mechanical properties of the composite were enhanced by addition of nano α-Al2O3 particles and dispersant agent to the polymer. Tensile strength was approximately ∼ 16% higher than pure PP by increasing the nano α-Al2O3 loading from 1 to 4 wt% into the PP matrix. The results of flexural analysis indicated that the maximum values of flexural strength and flexural modulus for nanocomposite without dispersant were 50.5 and 1954 MPa and for nanocomposite with dispersant were 55.88 MPa and 2818 MPa, respectively. However, higher concentration of nano α-Al2O3 loading resulted in reduction of those mechanical properties that could be due to agglomeration of nano α-Al2O3 particles. Transmission and scanning electron microscopic observations of the nanocomposites also showed that fracture surface became rougher by increasing the content of filler loading from 1 to 4% wt.

Environmental aging and degradation of multiwalled carbon nanotube reinforced polypropylene

EPA Science Inventory

The degradation of polypropylene (PP) and PP-multiwalled carbon nanotube (PP-MWCNT) panels during environmental weathering resulted in an increased degree of crystallinity, making them brittle, and creating surface cracks. The degradation led to a breakdown of the panels and incr...

Improving amphiphilic polypropylenes by grafting poly(vinylpyrrolidone) and poly(ethylene glycol) methacrylate segments on a polypropylene microporous membrane

NASA Astrophysics Data System (ADS)

Chen, Huirong; Ma, Wenzhong; Xia, Yanping; Gu, Yi; Cao, Zheng; Liu, Chunlin; Yang, Haicun; Tao, Shengxi; Geng, Haoran; Tao, Guoliang; Matsuyama, Hideto

2017-10-01

An amphiphilic polypropylene-g-poly[vinylpyrrolidone-co-poly(ethylene glycol) methacrylate] (PP-g-(NVP-co-PEGMA)) modifier was prepared by melt grafting polymerization using N-vinyl pyrrolidone (NVP) as the grafting monomer and poly(ethylene glycol) (PEGMA) as the comonomer. Fourier transform infrared (FTIR) spectroscopy and elemental analysis showed that the hydrophilic branched chains (NVP-g-PEGMA) were successfully grafted to polypropylene (PP) macromolecular chains. The largest NVP grafting degree for PP-g-(NVP-co-PEGMA) (up to 20.4%) was obtained when the mass ratio of PP/NVP/PEGMA was 100/30/15. Hydrophilic PP microporous membranes were prepared by stretching cast films of PP/PP-g-(NVP-co-PEGMA) blends. The membrane thermostability (including the modifier) was better than that of the pure PP membrane with a similar surface pore structure. The porosity of the modified membranes was only slightly lower than that of the pure PP membranes. Contact angle measurements were used to examine the hydrophilicity of the membranes. The water contact angle of the membranes decreased when PP-g-(NVP-co-PEGMA) was added, and the minimum contact angle was 64.5°. Therefore, this work provides a good application for stretched hydrophilic PP membrane fabrication.

Mixing of Isotactic and Syndiotactic Polypropylenes in the Melt

DOE Office of Scientific and Technical Information (OSTI.GOV)

CLANCY,THOMAS C.; PUTZ,MATHIAS; WEINHOLD,JEFFREY D.

2000-07-14

The miscibility of polypropylene (PP) melts in which the chains differ only in stereochemical composition has been investigated by two different procedures. One approach used detailed local information from a Monte Carlo simulation of a single chain, and the other approach takes this information from a rotational isomeric state model devised decades ago, for another purpose. The first approach uses PRISM theory to deduce the intermolecular packing in the polymer blend, while the second approach uses a Monte Carlo simulation of a coarse-grained representation of independent chains, expressed on a high-coordination lattice. Both approaches find a positive energy change uponmore » mixing isotactic PP (iPP) and syndiotactic polypropylene (sPP) chains in the melt. This conclusion is qualitatively consistent with observations published recently by Muelhaupt and coworkers. The size of the energy chain on mixing is smaller in the MC/PRISM approach than in the RIS/MC simulation, with the smaller energy change being in better agreement with the experiment. The RIS/MC simulation finds no demixing for iPP and atactic polypropylene (aPP) in the melt, consistent with several experimental observations in the literature. The demixing of the iPP/sPP blend may arise from attractive interactions in the sPP melt that are disrupted when the sPP chains are diluted with aPP or iPP chains.« less

Dispersion and reaggregation of nanoparticles in the polypropylene copolymer foamed by supercritical carbon dioxide.

PubMed

Oh, Kyunghwan; Seo, Youngwook P; Hong, Soon Man; Takahara, Atsushi; Lee, Kyoung Hwan; Seo, Yongsok

2013-07-14

For the preparation of nanocomposites, we conducted environmentally benign foaming processing on polypropylene (PP) copolymer/clay nanocomposites via a batch process in an autoclave. We investigated the dispersion and the exfoliation of the nanoclay particles. Full exfoliation was achieved by the foamability of the matrix PP copolymer using supercritical carbon dioxide (sc CO2) and subcritical carbon dioxide (sub CO2). More and smaller cells were observed when the clay was blended as heterogeneous nuclei and sc CO2 was used. Small angle X-ray scattering showed that highly dispersed states (exfoliation) of the clay particles were obtained by the foaming process. Since the clay particles provided more nucleating sites for the foaming of the polymer, a well dispersed (or fully exfoliated) nanocomposite exhibited a higher cell density and a smaller cell size at the same clay particle concentration. Expansion of the adsorbed CO2 facilitated the exfoliation of the clay platelets; thus, sc CO2 at lower temperature was more efficient for uniform foaming-cell production. Fully dispersed clay platelets were, however, re-aggregated when subjected to a further melting processing. The reprocessed nanocomposites still had some exfoliated platelets as well as some aggregated intercalates. The dual role of the nanoclay particles as foaming nucleus and a crystallization nucleus was confirmed by cell growth observation and nonisothermal crystallization kinetics analysis. A low foaming temperature and a high saturation pressure were more favorable for obtaining a uniform foam. The PP copolymer was found to be foamed more easily than polypropylene. A small amount of other olefin moieties in the backbone of the polymer facilitated better foamability than the neat polypropylene.

The upcycling of post-industrial PP/PET waste streams through in-situ microfibrillar preparation

NASA Astrophysics Data System (ADS)

Delva, Laurens; Ragaert, Kim; Cardon, Ludwig

2015-12-01

Post-industrial plastic waste streams can be re-used as secondary material streams for polymer processing by extrusion or injection moulding. One of the major commercially available waste stream contains polypropylene (PP) contaminated with polyesters (mostly polyethylene tereftalate - PET). An important practical hurdle for the direct implementation of this waste stream is the immiscibility of PP and PET in the melt, which leads to segregation within the polymer structure and adversely affects the reproducibility and mechanical properties of the manufactured parts. It has been indicated in literature that the creation of PET microfibrils in the PP matrix could undo these drawbacks and upcycle the PP/PET combination. Within the current research, a commercially available virgin PP/PET was evaluated for the microfibrillar preparation. The mechanical (tensile and impact) properties, thermal properties and morphology of the composites were characterized at different stages of the microfibrillar preparation.

Glass Fiber Reinforced Polypropylene Mechanical Properties Enhancement by Adhesion Improvement

PubMed Central

Etcheverry, Mariana; Barbosa, Silvia E.

2012-01-01

Glass fibers (GF) are the reinforcement agent most used in polypropylene (PP) based composites, as they have good balance between properties and costs. However, their final properties are mainly determined by the strength and stability of the polymer-fiber interphase. Fibers do not act as an effective reinforcing material when the adhesion is weak. Also, the adhesion between phases can be easily degraded in aggressive environmental conditions such as high temperatures and/or elevated moisture, and by the stress fields to which the material may be exposed. Many efforts have been done to improve polymer-glass fiber adhesion by compatibility enhancement. The most used techniques include modifications in glass surface, polymer matrix and/or both. However, the results obtained do not show a good costs/properties improvement relationship. The aim of this work is to perform an accurate analysis regarding methods for GF/PP adhesion improvement and to propose a new route based on PP in-situ polymerization onto fibers. This route involves the modification of fibers with an aluminum alkyl and hydroxy-α-olefin and from there to enable the growth of the PP chains using direct metallocenic copolymerization. The adhesion improvements were further proved by fragmentation test, as well as by mechanical properties measurements. The strength and toughness increases three times and the interfacial strength duplicates in PP/GF composites prepared with in-situ polymerized fibers. PMID:28817025

Highest recorded electrical conductivity and microstructure in polypropylene-carbon nanotubes composites and the effect of carbon nanofibers addition

NASA Astrophysics Data System (ADS)

Ramírez-Herrera, C. A.; Pérez-González, J.; Solorza-Feria, O.; Romero-Partida, N.; Flores-Vela, A.; Cabañas-Moreno, J. G.

2018-04-01

In the last decade, numerous investigations have been devoted to the preparation of polypropylene-multiwalled carbon nanotubes (PP/MWCNT) nanocomposites having enhanced properties, and in particular, high electrical conductivities (> 1 S cm-1). The present work establishes that the highest electrical conductivity in PP/MWCNT nanocomposites is limited by the amount of nanofiller content which can be incorporated in the polymer matrix, namely, about 20 wt%. This concentration of MWCNT in PP leads to a maximum electrical conductivity slightly lower than 8 S cm-1, but only by assuring an adequate combination of dispersion and spatial distribution of the carbon nanotubes. The realization of such an optimal microstructure depends on the characteristics of the production process of the PP/MWCNT nanocomposites; in our experiments, involving composite fabrication by melt mixing and hot pressing, a second re-processing cycle is shown to increase the electrical conductivity values by up to two orders of magnitude, depending on the MWCNT content of the nanocomposite. A modest increase of the highest electrical conductivity obtained in nanocomposites with 21.5 wt% MWCNT content has been produced by the combined use of carbon nanofibers (CNF) and MWCNT, so that the total nanofiller content was increased to 30 wt% in the nanocomposite with PP—15 wt% MWCNT—15 wt%CNF.

Effectiveness of the ZeroFly® storage bag fabric against stored-product insects

USDA-ARS?s Scientific Manuscript database

The ZeroFly® Storage Bag is a polypropylene bag (PP) which has deltamethrin incorporated in its fibers, and represents a novel approach to reducing stored-product insect pest-related postharvest losses. Fabric samples from ZeroFly bags, polypropylene (PP) bags, jute bags, malathion-treated PP bags, ...

Tissue response to collagen containing polypropylene meshes in an ovine vaginal repair model.

PubMed

Darzi, Saeedeh; Urbankova, Iva; Su, Kai; White, Jacinta; Lo, Camden; Alexander, David; Werkmeister, Jerome A; Gargett, Caroline E; Deprest, Jan

2016-07-15

Pelvic Organ Prolapse (POP) is the herniation of pelvic organs into the vagina. Despite broad acceptance of mesh use in POP surgical repair, the complication rate is unacceptable. We hypothesized that collagen-containing polypropylene (PP) mesh types could modulate mesh-tissue integration and reduce long-term inflammation, thereby reducing mesh-associated complications. This study compared the long-term tissue response to an unmodified PP mesh and two collagen containing meshes in an ovine model which has similar pelvic anatomy and vaginal size to human. Three commercially available macroporous PP meshes, uncoated PP mesh (Avaulta Solo) (PP), the same textile PP mesh layered with a sheet of cross-linked porcine acellular matrix (Avaulta Plus) (PP-ACM) and a different yet also macroporous PP (Sofradim) mesh coated with solubilized atelocollagen (Ugytex) (PP-sCOL) were implanted in the ovine vagina and tissue explanted after 60 and 180days. The macrophage phenotype and response to implanted meshes, and vascularity were quantified by immunostaining and morphometry. We quantified changes in extracellular matrix composition biochemically and collagen organisation and percentage area around the interface of the mesh implants by Sirius Red birefringence and morphometry. PP-ACM induced a more sustained inflammatory response, indicated by similar CD45(+) leukocytes but reduced CD163(+) M2 macrophages at 60days (P<0.05). PP-sCOL increased Von Willebrand Factor (vWF)-immunoreactive vessel profiles after 60days. At the micro-molecular level, collagen birefringence quantification revealed significantly fewer mature collagen fibrils (red, thick fibrils) at the mesh-tissue interface than control tissue for all mesh types (P<0.001) but still significantly greater than the proportion of immature (green thin fibrils) at 60days (P<0.05). The proportion of mature collagen fibrils increased with time around the mesh filaments, particularly those containing collagen. The total collagen percent area at the mesh interface was greatest around the PP-ACM mesh at 60days (P<0.05). By 180days the total mature and immature collagen fibres at the interface of the mesh filaments resembled that of native tissue. In particular, these results suggest that both meshes containing collagen evoke different types of tissue responses at different times during the healing response yet both ultimately lead to physiological tissue formation approaching that of normal tissue. Pelvic organ prolapse (POP) is the descent of the pelvic organs to the vagina. POP affects more than 25% of all women and the lifetime risk of undergoing POP surgery is 19%. Although synthetic polypropylene (PP) meshes have improved the outcome of the surgical treatment for POP, there was an unacceptable rate of adverse events including mesh exposure and contracture. It is hypothesized that coating the PP meshes with collagen would provide a protective effect by preventing severe mesh adhesions to the wound, resulting in a better controlled initial inflammatory response, and diminished risk of exposure. In this study we assessed the effect of two collagen-containing PP meshes on the long-term vaginal tissue response using new techniques to quantify these tissue responses. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mechanical and Morphological Properties of Polypropylene/Nano α-Al2O3 Composites

PubMed Central

Mirjalili, F.; Chuah, L.; Salahi, E.

2014-01-01

A nanocomposite containing polypropylene (PP) and nano α-Al2O3 particles was prepared using a Haake internal mixer. Mechanical tests, such as tensile and flexural tests, showed that mechanical properties of the composite were enhanced by addition of nano α-Al2O3 particles and dispersant agent to the polymer. Tensile strength was approximately ∼16% higher than pure PP by increasing the nano α-Al2O3 loading from 1 to 4 wt% into the PP matrix. The results of flexural analysis indicated that the maximum values of flexural strength and flexural modulus for nanocomposite without dispersant were 50.5 and 1954 MPa and for nanocomposite with dispersant were 55.88 MPa and 2818 MPa, respectively. However, higher concentration of nano α-Al2O3 loading resulted in reduction of those mechanical properties that could be due to agglomeration of nano α-Al2O3 particles. Transmission and scanning electron microscopic observations of the nanocomposites also showed that fracture surface became rougher by increasing the content of filler loading from 1 to 4% wt. PMID:24688421

Instrumented impact testing of kenaf fiber reinforced polypropylene composites: effects of temperature and composition

Treesearch

Craig Merrill Clemons; Anand R. Sanadi

2007-01-01

An instrumented Izod test was used to investigate the effects of fiber content, coupling agent, and temperature on the impact performance of kenaf fiber reinforced polypropylene (PP). Composites containing 0-60% (by weight) kenaf fiber and 0 or 2% maleated polypropylene (MAPP) and PP/wood flour composites were tested at room temperature and between -50 °C and +...

High impact strength polymers having novel nano-structures produced via reactive extrusion

NASA Astrophysics Data System (ADS)

Tortorella, Nathan Fraser

A major focus of scientists and engineers over the last century has been to increase the impact strength and therefore reduce the brittleness of materials. By altering and adding energy absorption mechanisms, brittle failure can be averted. Isotactic polypropylene (PP) is the focus of this dissertation because it is an extremely low cost, high volume, versatile plastic but behaves in a brittle manner at or below room temperature or in a notched state. Early work on impact modification of polypropylene focused on blending energy-absorbing low density elastomers and rubbers. These binary blends all had a common problem---an increase in impact strength was paralleled by a significant decrease in both elastic modulus and yield stress. Reactive extrusion processing has allowed the in-situ compatibilization of isotactic polypropylene and metallocene-catalyzed ethylene-octene copolymers (EOCs). This process involves combining both the comonomer and vector fluid approaches to grafting polyolefins. Styrene monomer and a multifunctional acrylate monomer undergo peroxide-induced copolymerization and grafting in the presence of both PP and EOC. This results in a phase separated alloy with an impact strength over 13 times that of pure polypropylene and double that of the physical blend. There is also a significant improvement in stress-strain performance when comparing the alloys to physical blend counterparts. Many researchers have categorized the necessary components to toughening polypropylene as pertaining to the amorphous phase. The alloys described in this dissertation meet the criteria put forth by these researchers, namely low density, crystallinity, and modulus of the elastomer phase, sub-micron particle diameter, close inter-particle distance, and a high degree of entanglements of both the PP matrix phase and EOC minor phase. But many people neglect to study the crystalline state of impact modified PP in conjunction with the amorphous phase. This work shows that the typical 10-100 mum diameter spherulitic structures found in pure PP are not present in the alloys. In fact, the spherulites are less than a micron in diameter, are uniformly distributed throughout the sample, and crystallize at much higher temperatures. SEM images, when coupled with DSC and XRD, reveal the presence of a high number of small lamellar crystals composed of a unique highly dense cross-hatched structure. Thus, impact strength and stiffness can be simultaneously improved by controlling the size and cross-hatch density of the lamellar crystals and applying phase transformation toughening concepts.

Nanoindentation of the interphase region of a wood-reinforced polypropylene composite

Treesearch

Joseph E. Jakes; John C. Hermanson; Donald S. Stone

2007-01-01

The interphase region of a wood-reinforced polypropylene (PP) composite was investigated with nanoindentation techniques capable of separating intrinsic properties of PP in the interphase region from the effect of elastic discontinuity caused by the nearby wood cell wall. From data collected in this experiment, no differences in hardness or Young’s modulus for PP were...

Coir fiber reinforced polypropylene composite panel for automotive interior applications

Treesearch

Nadir Ayrilmis; Songklod Jarusombuti; Vallayuth Fueangvivat; Piyawade Bauchongkol; Robert H. White

2011-01-01

In this study, physical, mechanical, and flammability properties of coconut fiber reinforced polypropylene (PP) composite panels were evaluated. Four levels of the coir fiber content (40, 50, 60, and 70 % based on the composition by weight) were mixed with the PP powder and a coupling agent, 3 wt % maleic anhydride grafted PP (MAPP) powder. The water resistance and the...

Application of Analytic Hierarchy Process (AHP) in the analysis of the fuel efficiency in the automobile industry with the utilization of Natural Fiber Polymer Composites (NFPC)

NASA Astrophysics Data System (ADS)

Jayamani, E.; Perera, D. S.; Soon, K. H.; Bakri, M. K. B.

2017-04-01

A systematic method of material analysis aiming for fuel efficiency improvement with the utilization of natural fiber reinforced polymer matrix composites in the automobile industry is proposed. A multi-factor based decision criteria with Analytical Hierarchy Process (AHP) was used and executed through MATLAB to achieve improved fuel efficiency through the weight reduction of vehicular components by effective comparison between two engine hood designs. The reduction was simulated by utilizing natural fiber polymer composites with thermoplastic polypropylene (PP) as the matrix polymer and benchmarked against a synthetic based composite component. Results showed that PP with 35% of flax fiber loading achieved a 0.4% improvement in fuel efficiency, and it was the highest among the 27 candidate fibers.

Dispersion of carbon nanotubes in melt compounded polypropylene based composites investigated by THz spectroscopy.

PubMed

Casini, R; Papari, G; Andreone, A; Marrazzo, D; Patti, A; Russo, P

2015-07-13

We investigate the use of Terahertz (THz) Time Domain Spectroscopy (TDS) as a tool for the measurement of the index dispersion of multi-walled carbon nanotubes (MWCNT) in polypropylene (PP) based composites. Samples containing 0.5% by volume concentration of non-functionalized and functionalized carbon nanotubes are prepared by melt compounding technology. Results indicate that the THz response of the investigated nanocomposites is strongly dependent on the kind of nanotube functionalization, which in turn impacts on the level of dispersion inside the polymer matrix. We show that specific dielectric parameters such as the refractive index and the absorption coefficient measured by THz spectroscopy can be both correlated to the index of dispersion as estimated using conventional optical microscopy.

Plant growth responses to polypropylene--biocontainers

USDA-ARS?s Scientific Manuscript database

The influence of bio-fillers incorporated into polypropylene (PP) on the growth of plants was evaluated. Biocontainers were created by injection molding of PP with 25-40% by weight of Osage orange tree, Paulownia tree, coffee tree wood or dried distillers grain and 5% by weight of maleated polypropy...

Texturing of polypropylene (PP) with nanosecond lasers

NASA Astrophysics Data System (ADS)

Riveiro, A.; Soto, R.; del Val, J.; Comesaña, R.; Boutinguiza, M.; Quintero, F.; Lusquiños, F.; Pou, J.

2016-06-01

Polypropylene (PP) is a biocompatible and biostable polymer, showing good mechanical properties that has been recently introduced in the biomedical field for bone repairing applications; however, its poor surface properties due to its low surface energy limit their use in biomedical applications. In this work, we have studied the topographical modification of polypropylene (PP) laser textured with Nd:YVO4 nanosecond lasers emitting at λ = 1064 nm, 532 nm, and 355 nm. First, optical response of this material under these laser wavelengths was determined. The application of an absorbing coating was also studied. The influence of the laser processing parameters on the surface modification of PP was investigated by means of statistically designed experiments. Processing maps to tailor the roughness, and wettability, the main parameters affecting cell adhesion characteristics of implants, were also determined. Microhardness measurements were performed to discern the impact of laser treatment on the final mechanical properties of PP.

Effect of polypropylene maleic anhydride (PPMAH) on mechanical and morphological properties of polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr)/empty fruit bunch (EFB) composites

NASA Astrophysics Data System (ADS)

Othman, Nurul Syazwani; Santiagoo, Ragunathan; Abdillahi, Khalid Mohamed; Ismail, Hanafi

2017-07-01

The fabrication of polypropylene (PP)/ recycled acrylonitrile butadiene rubber (NBRr)/ empty fruit bunch (EFB) composites were investigated. The effects of polypropylene maleic anhydride (PPMAH) as a compatibilizer on the mechanical and morphological properties of PP/NBRr/EFB composites were studied. Composites were prepared through melt mixing using heated two roll mill at 180 °C for 9 minutes and rotor speed of 15 rpm. NBRr loading were varied from 0 to 60 phr and PPMAH was fixed for 5 phr. The composites were moulded into a 1 mm thin sheet using hot press machine and then cut into dumbbell shape. The mechanical and morphological properties of composites were examined using universal tensile machine (UTM) and scanning electron microscope (SEM), respectively. Tensile strength and Young's modulus of PP/NBRr/EFB composites decreased with increasing NBRr loading, whilst increasing the elongation at break. However, PPMAH compatibilized composites have resulted 27% to 40% and 25% to 42% higher tensile strength and Young's modulus, respectively, higher compared to uncompatibilized composites. This was due to the better adhesion between PP/NBRr matrices and EFB filler with the presence of maleic anhydride moieties. From the morphological study, the micrograph of PPMAH compatibilized composites has proved the well bonded and good attachments of EFB filler with PP/NBRr matrices which results better tensile strength to the PP/NBRr/EFB composites.

Studies on thermal decomposition behaviors of polypropylene using molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Huang, Jinbao; He, Chao; Tong, Hong; Pan, Guiying

2017-11-01

Polypropylene (PP) is one of the main components of waste plastics. In order to understand the mechanism of PP thermal decomposition, the pyrolysis behaviour of PP has been simulated from 300 to 1000 K in periodic boundary conditions by molecular dynamic method, based on AMBER force field. The simulation results show that the pyrolysis process of PP can mostly be divided into three stages: low temperature pyrolysis stage, intermediate temperature stage and high temperature pyrolysis stage. PP pyrolysis is typical of random main-chain scission, and the possible formation mechanism of major pyrolysis products was analyzed.

Polypropylene/glass fiber hierarchical composites incorporating inorganic fullerene-like nanoparticles for advanced technological applications.

PubMed

Díez-Pascual, Ana M; Naffakh, Mohammed

2013-10-09

Novel isotactic polypropylene (iPP)/glass fiber (GF) laminates reinforced with inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles as environmentally friendly fillers have been successfully fabricated by simple melt-blending and fiber impregnation in a hot-press without the addition of any compatibilizer. The influence of IF-WS2 concentration on the morphology, viscosity. and thermal and mechanical behavior of the hierarchical composites has been investigated. Results revealed an unprecedented 62 °C increase in the degradation temperature of iPP/GF upon addition of only 4.0 wt % IF-WS2. The coexistence of both micro- and nanoscale fillers resulted in synergistic effects on enhancing the stiffness, strength, crystallinity, thermal stability, glass transition (Tg) and heat distortion temperature (HDT) of the matrix. The approach used in this work is an efficient, versatile, scalable and economic strategy to improve the mechanical and thermal behavior of GF-reinforced thermoplastics with a view to extend their use in advanced technological applications. This new type of composite materials shows great potential to improve the efficiency and sustainability of many forms of transport.

Interfacial enhancement of polypropylene composites modified with sorbitol derivatives and siloxane-silsesquioxane resin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobrzyńska-Mizera, Monika, E-mail: monika.dobrzynska-mizera@doctorate.put.poznan.pl; Sterzyński, Tomasz; Dutkiewicz, Michał

Composites based on polypropylene (iPP) modified with a sorbitol derivative (NX8000) and siloxane-silsesquioxane resin (SiOPh) containing maleated polypropylene (MAPP) as compatibilizer were prepared by melt extrusion. Calorimetric investigations were carried out using differential scanning calorimetry (DSC), whereas the morphological and mechanical properties were investigated by scanning electron microscopy (SEM) and static tensile tests. DSC measurements revealed no influence of SiOPh and a slight effect of MAPP addition on the crystallization kinetics of polypropylene. Additionally, the introduction of MAPP into the iPP+NX8000+SiOPh composites increased plastic properties of the samples. All the above was attributed to the compatibilizing effect of MAPP whichmore » improved interfacial adhesion between iPP, NX8000 and SiOPh. This phenomenon was also confirmed by the SEM images illustrating more homogenous distribution of the filler in the compatibilized samples.« less

Interfacial enhancement of polypropylene composites modified with sorbitol derivatives and siloxane-silsesquioxane resin

NASA Astrophysics Data System (ADS)

Dobrzyńska-Mizera, Monika; Dutkiewicz, Michał; Sterzyński, Tomasz; Di Lorenzo, Maria Laura

2015-12-01

Composites based on polypropylene (iPP) modified with a sorbitol derivative (NX8000) and siloxane-silsesquioxane resin (SiOPh) containing maleated polypropylene (MAPP) as compatibilizer were prepared by melt extrusion. Calorimetric investigations were carried out using differential scanning calorimetry (DSC), whereas the morphological and mechanical properties were investigated by scanning electron microscopy (SEM) and static tensile tests. DSC measurements revealed no influence of SiOPh and a slight effect of MAPP addition on the crystallization kinetics of polypropylene. Additionally, the introduction of MAPP into the iPP+NX8000+SiOPh composites increased plastic properties of the samples. All the above was attributed to the compatibilizing effect of MAPP which improved interfacial adhesion between iPP, NX8000 and SiOPh. This phenomenon was also confirmed by the SEM images illustrating more homogenous distribution of the filler in the compatibilized samples.

Effect of coupling agent on durian skin fibre nanocomposite reinforced polypropylene

NASA Astrophysics Data System (ADS)

Siti Nur E'zzati, M. A.; Anuar, H.; Siti Munirah Salimah, A. R.

2018-01-01

This paper reports on the development of a composite-based natural fiber to reduce the reliance on petroleum-based product in order to amplify environmental awareness. The production of Durian Skin Nanofiber (DSNF) was conducted using biological fermentation method via rhizopus oryzae in order to obtain the nano dimension of the particle size. Polypropylene (PP) and DSNF were produced using Haake internal mixer via melt blending technique. The significant effect of maleic anhydride grafted polypropylene (MAPP) on the properties of PP/DSNF nanocomposite was investigated to study its mechanical properties which are tensile strength and thermal stability using thermogravimetric (TGA) and differential scanning analysis (DSC). The tensile property of PP nanocomposites increased from 33 MPa to 38 MPa with the presence of MAPP. The addition of MAPP also increased the thermal stability of PP/DSNF nanocomposite where the char residue increased by 52%. Besides that, the thermal degradation of PP/DSNF and PP/DSNF-MAPP were higher than PP where they exerted higher amount of weight loss at an elevated temperature. The percentage of crystallinity, %Xc, of PP nanocomposites improved with the addition of MAPP by 35% based on the differential scanning calorimetry (DSC) result. The SEM analysis showed that the PP/DSNF-MAPP exerts ductile fracture while PP/DSNF exerts brittle fracture.

Maleated polypropylene film and wood fiber handsheet laminates

Treesearch

Sangyeob Lee; Todd F. Shupe; Leslie H. Groom; Chung Y. Hse

2008-01-01

The grafting effect of maleic anhydride (MA) as an interfacial bonding agent and its influence on the tensile strength properties of thermomechanical pulp handsheet-isotactic polypropylene (iPP) film laminates was studied. For the MA treated with benzoyl peroxide (BPO) as an initiator, tensile strength properties increased 76% with PP film over untreated laminates. The...

[The Use of FTIR Coupled with Partial Least Square for Quantitative Analysis of the Main Composition of Bamboo/Polypropylene Composites].

PubMed

Lao, Wan-li; He, Yu-chan; Li, Gai-yun; Zhou, Qun

2016-01-01

The biomass to plastic ratio in wood plastic composites (WPCs) greatly affects the physical and mechanical properties and price. Fast and accurate evaluation of the biomass to plastic ratio is important for the further development of WPCs. Quantitative analysis of the WPC main composition currently relies primarily on thermo-analytical methods. However, these methods have some inherent disadvantages, including time-consuming, high analytical errors and sophisticated, which severely limits the applications of these techniques. Therefore, in this study, Fourier Transform Infrared (FTIR) spectroscopy in combination with partial least square (PLS) has been used for rapid prediction of bamboo and polypropylene (PP) content in bamboo/PP composites. The bamboo powders were used as filler after being dried at 105 degrees C for 24 h. PP was used as matrix materials, and some chemical regents were used as additives. Then 42 WPC samples with different ratios of bamboo and PP were prepared by the methods of extrusion. FTIR spectral data of 42 WPC samples were collected by means of KBr pellets technique. The model for bamboo and PP content prediction was developed by PLS-2 and full cross validation. Results of internal cross validation showed that the first derivative spectra in the range of 1 800-800 cm(-1) corrected by standard normal variate (SNV) yielded the optimal model. For both bamboo and PP calibration, the coefficients of determination (R2) were 0.955. The standard errors of calibration (SEC) were 1.872 for bamboo content and 1.848 for PP content, respectively. For both bamboo and PP validation, the R2 values were 0.950. The standard errors of cross validation (SECV) were 1.927 for bamboo content and 1.950 for PP content, respectively. And the ratios of performance to deviation (RPD) were 4.45 for both biomass and PP examinations. The results of external validation showed that the relative prediction deviations for both biomass and PP contents were lower than ± 6%. FTIR combined with PLS can be used for rapid and accurate determination of bamboo and PP content in bamboo/PP composites.

Flexural creep behaviour of jute polypropylene composites

NASA Astrophysics Data System (ADS)

Chandekar, Harichandra; Chaudhari, Vikas

2016-09-01

Present study is about the flexural creep behaviour of jute fabric reinforced polypropylene (Jute-PP) composites. The PP sheet and alkali treated jute fabric is stacked alternately and hot pressed in compression molding machine to get Jute-PP composite laminate. The flexural creep study is carried out on dynamic mechanical analyzer. The creep behaviour of the composite is modeled using four-parameter Burgers model. Short-term accelerated creep testing is conducted which is later used to predict long term creep behaviour. The feasibility of the construction of a master curve using the time-temperature superposition (TTS) principle to predict long term creep behavior of unreinforced PP and Jute-PP composite is investigated.

Bostrycin, a novel coupling agent for protein immobilization and prevention of biomaterial-centered infection produced by Nigrospora sp. No. 407.

PubMed

Yang, Wen-Jen; Yang, Chih-Sheng; Huang, Chen-Ji; Chen, Ko-Shao; Lin, Shuen-Fuh

2012-05-10

Bostrycin, a red antibacterial agent with tetrahydroanthraquinone structure, has been isolated from Nigrospora sp. No. 407. This study investigated the potential antibacterial and multifunctional properties of matrixes through immobilization of bostrycin on their surface for immobilization of protein and prevention of bacterial growth. Bostrycin was immobilized on nonwoven polypropylene (PP) fabric by a technique using glutaraldehyde and polyethyleneimine for the activation of the surface. Glucose oxidase immobilized on bostrycin-treated nonwoven PP fabric showed high activity. The immobilization process improved thermal stability of the enzymes. During repeated assay for 30 cycles, the enzyme activity dropped to only 70% of the initial activity. Both bostrycin-treated nonwoven PP fabric sample and subsequently immobilized glucose oxidase sample on the surface also still exhibited a bacteriostatic effect. This is the first study to show that bostrycin is a promising coupling agent for surface modification on matrix and its potential applications in protein immobilization and biomaterial-centered infection. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

Investigating interfacial phenomena in polypropylene/glass fiber composites

NASA Astrophysics Data System (ADS)

Toke, Jeffrey Michael

The adhesion in polypropylene (PP)/glass composites is low due to the non-polar, non-reactive characteristics of PP. When maleated PP (mPP) is added to the matrix, adhesion is improved. Understanding the mechanisms of this phenomenon is critical in maximizing the adhesion in PP/glass composites. The strength of adhesion in PP/glass composites was investigated using glass bead composites. A Near-IR spectroscopic technique was used to evaluate the chemical reactions in the interphase. Twelve different commercial grades of maleated PP (mPP) were tested. The range of maleic anydride (MAH) content was from 0.3 weight percent (wt%) to 2.4 wt%, with one sample at 10 wt%. These mPPs were blended with a commercial PP from Huntsman, P4C5Z-027 (PP), a 20 MFI (melt flow index) polymer with minimal additives, in concentrations ranging from 0 to 20 wt%. Bead composites of non-coated (NON) and gamma-APS-coated beads (APS) were made to compare the strength of the interphase in the composite systems. The bead volume fraction used was 25 volume percent (vol%). Three polymers with different MAH content and different viscosities were tested at 1, 5, 10 and 20 wt%. All of the mPPs were tested at 5 wt%. In general, the mPP composites all exhibited higher strength compared to the PP. Pukanszky's model for tensile strength was applied that included the strength of the unfilled matrix and the volume percent of the beads in a single factor, B. Comparison of all of the polymers at 5 wt% showed that there were four groupings of the mPPs. The polymers with MAH content greater than 1.5 wt% showed the strongest adhesion with B values of ˜2.5. All of these polymers had viscosities less than 100 Pa-s (180°C, 1 Hz angular frequency). The next group of polymers, with B ˜ 2, had MAH contents ranging from 0.8 to 1.2 wt%, with viscosities ranging from the 21 Pa-s to greater than 2300 Pa-s (180°C, 1 Hz angular frequency). The following group, with B ˜ 0.9, had anhydride concentrations of 0.6 and 0.7 wt%, and viscosities of 127 and 3800 Pa-s, respectively. Finally, there were several polymers with B ˜ 0.6 that were not significantly different than the unmodified PP. Viscosity and anhydride concentration showed competing effects in the mPP samples. Overall, increasing the concentration of anhydride increased adhesion, but viscosity is reduced in high MAH content mPPs. When the anhydride content was below 1.5 wt%, increased viscosity showed greater adhesion. (Abstract shortened by UMI.)

Surface modification of polypropylene mesh devices with cyclodextrin via cold plasma for hernia repair: Characterization and antibacterial properties

NASA Astrophysics Data System (ADS)

Sanbhal, Noor; Mao, Ying; Sun, Gang; Xu, Rui Fang; Zhang, Qian; Wang, Lu

2018-05-01

Light weight polypropylene (PP) mesh is the most widely used implant among all other synthetic meshes for hernia repair. However, infection is the complication associated to all synthetic meshes after hernia repair. Thus, to manage mesh related infection; antibacterial drug is generally loaded to surgical implants to supply drug locally in mesh implanted site. Nevertheless, PP mesh restricts the loading of antibacterial drug at operated area due to its low wettability. The aim of this study was to introduce a novel antimicrobial PP mesh modified with β-cyclodextrine (CD) and loaded with antimicrobial agent for infection prevention. A cold oxygen plasma treatment was able to activate the surfaces of polypropylene fibers, and then CD was incorporated onto the surfaces of PP fibers. Afterward, triclosan, as a model antibacterial agent, was loaded into CD cavity to provide desired antibacterial functions. The modified polypropylene mesh samples CD-Tric-1, CD-Tric-3 exhibited excellent inhibition zone and continuous antibacterial efficacy against E. coli and S. aureus up to 6 and 7 days respectively. Results of AFM, SEM, FTIR and antibacterial tests evidenced that oxygen plasma process is necessary to increase chemical connection between CD molecules and PP fibers. The samples were also characterized by using EDX, XRD, TGA, DSC and water contact angle.

Prototyping the Use of Dispersion Models to Predict Ground Concentrations During Burning of Deployed Military Waste

DTIC Science & Technology

2012-03-22

Fabric 3.85% Polypropylene (PP) (Class 5 plastics, soda cups, yogurt boxes, syrup bottles, prescription bottles) 1.32% Yard waste 5.67% PVC (Class 3...plastics, milk jugs) 1.23% Cardboard 31.33% Polypropylene (PP) (Class 5 plastics, soda cups, yogurt boxes, syrup bottles, prescription bottles) 0.62

Thermosets as compatibilizers at the isotactic polypropylene film and thermomechanical pulp fiber interphase

Treesearch

Sangyeob Lee; Todd F. Shupe; Chung Y. Hse

2008-01-01

The objective of this study was to improve interfacial adhesion properties at the interface of thermomechanical pulp (TMP) fiber and isotactic polypropylene (iPP) using thermoset adhesives such as phenol formaldehyde (PF) and urea formaldehyde (UF). This study also attempted to achieve fiber-to-fiber adhesion using thermoset adhesives before the molten iPP would flow...

A study on flexural and water absorption of surface modified rice husk flour/E-glass/polypropylene hybrid composite

NASA Astrophysics Data System (ADS)

Rassiah, K.; Sin, T. W.; Ismail, M. Z.

2016-10-01

This work is to study the effects of rice husk (RH)/E-Glass (EG)/polypropylene (PP) hybrid composites in terms of flexural and water absorption properties. The tests conducted are the flexural test and also the water absorption test using two types of water: distilled and sea water. The hybrid composites are prepared with various ratios of fibre weight fractions and the rice husk is treated using 2% Sodium Hydroxide (NaOH) to improve interaction and adhesion between the non-polar matrix and the polar lignocellulosic fibres. It was found that the content of rice husk/E-Glass fillers affected the structural integrity and flexural properties of hybrid composites. In addition, a higher ratio of rice husk contributes to higher water absorption in the hybrid composites.

Extended Investigation on the Delicate Correlations Between Thermal Behavior and Physical Characteristics of Multi-component Blends

NASA Astrophysics Data System (ADS)

Shokoohi, Shirin

2015-11-01

Polypropylene (PP)/polyamide6 (PA6)/ethylene propylene diene rubber (EPDM) (70/15/15) ternary polymer blends compatibilized with maleic anhydride-grafted EPDM (EPDM-g-MA) were prepared under various processing parameters (barrel temperature, screw speed, and blending sequence). Thermal studies on the prepared blend samples were carried out using differential scanning calorimetry and dynamic mechanical thermal analysis. According to the results, heterogeneous nucleation phenomenon was observed due to the solidification of the PA6 particles dispersed within the PP melt leading to a significant increase in the crystallinity degree and exotherm crystallization peak temperature of PP compared to the pure homopolymer. This was suppressed in the samples with core-shell morphology due to the reduced PP/PA6 interfacial contact. Fractionated crystallization was observed when PA6 droplets dispersed too fine within the matrix (in this case bar{d}_M˜ 0.3 \\upmu {m}). Scanning electron microscopy micrographs were consistent with the melting and crystallization behavior of the blend samples.

Processing-property relationships of polypropylene/ciprofloxacin fibers

NASA Astrophysics Data System (ADS)

Botta, L.; Scaffaro, R.

2015-12-01

In this work we prepared polypropylene (PP) fibers incorporating an antibiotic, i.e. ciprofloxacin (CFX), by melt spinning. In particular, PP has been compounded with CFX at different concentrations by using a counter-rotating twin screw compounder. The PP/CFX fibers have been spun by using a capillary rheometer operating under a constant extrusion speed. The effect of "online" hot drawing during the melt spinning or of an "offline" cold drawing on the properties of PP/CFX fibers were evaluated. In particular, the influence of the drawing conditions on the mechanical properties and the release kinetics were studied. Moreover, the rheological behavior in non-isothermal elongation flow has been assessed.

Morphological and Mechanical Properties of Polypropylene[PP]/Poly(Ethylene Vinyl Acetate)[EVA] Blends. I. Homopolymer PP/Eva Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramirez-Vargas, E.

2000-10-01

Morphological and mechanical properties of polypropylene [PP]/poly(ethylene vinyl acetate) [EVA] blends have been studied. Infrared results using thin films first indicated a transition toward compatibility between both components at concentrations above 40% EVA. The transition was verified with different experimental techniques and it was associated to morphological changes and mechanical properties. The PP/EVA blends were mechanically evaluated in terms of impact and tensile strength to determine the influence of blending on the performance properties of these materials. Agreement was found between the transition and the enhancement of both elongation at break and impact strength.

Application of Glass Fiber Waste Polypropylene Aggregate in Lightweight Concrete – thermal properties

NASA Astrophysics Data System (ADS)

Citek, D.; Rehacek, S.; Pavlik, Z.; Kolisko, J.; Dobias, D.; Pavlikova, M.

2018-03-01

Actual paper focus on thermal properties of a sustainable lightweight concrete incorporating high volume of waste polypropylene aggregate as partial substitution of natural aggregate. In presented experiments a glass fiber reinforced polypropylene (GFPP) which is a by-product of PP tubes production, partially substituted fine natural silica aggregate in 10, 20, 30, 40 and 50 mass %. Results were compared with a reference concrete mix without plastic waste in order to quantify the effect of GFPP use on concrete properties. Main material physical parameters were studied (bulk density, matrix density without air content, and particle size distribution). Especially a thermal transport and storage properties of GFPP were examined in dependence on compaction time. For the developed lightweight concrete, thermal properties were accessed using transient impulse technique, where the measurement was done in dependence on moisture content (from the fully water saturated state to dry state). It was found that the tested lightweight concrete should be prospective construction material possessing improved thermal insulation function and the reuse of waste plastics in concrete composition was beneficial both from the environmental and financial point of view.

Effect of wet-dry cycling on the decay properties of aspen fiber high-density polypropylene composites.

Treesearch

Rebecca E. Ibach; Roger M. Rowell; Sandra E. Lange; Rebecca L. Schumann

2002-01-01

Aspen fiber-polypropylene composites were prepared with various levels of fiber (0,30%, 40%, 50%, and 60%), polypropylene (PP) (100%, 98%, 70%, 68%, 60%, 58%, 50%, 48%, 40%, and 38%), and the compatibilizer maleated polypropylene (MAPP) (0 and 2%). Specimens were either subjected to 10 cycles of 1 week room temperature water soaking-oven drying or 2-hr. boiling...

Kenaf Bast Fibers—Part II: Inorganic Nanoparticle Impregnation for Polymer Composites

DOE PAGES

Shi, Jinshu; Shi, Sheldon Q.; Barnes, H. Michael; ...

2011-01-01

The objective of this study was to investigate an inorganic nanoparticle impregnation (INI) technique to improve the compatibility between kenaf bast fibers and polyolefin matrices. The Scanning Electron Microscopy (SEM) was used to examine the surface morphology of the INI-treated fibers showing that the CaCO 3 nanoparticle crystals grew onto the fiber surface. Energy-dispersive X-ray spectroscopy (EDS) was used to verify the CaCO 3 nanoparticle deposits on the fiber surface. The tension tests of the individual fiber were conducted, and the results showed that the tensile strength of the fibers increased significantly (more than 20%) after the INI treatments. Polymermore » composites were fabricated using the INI-treated fiber as reinforcement and polypropylene (PP) as the matrix. The results showed that the INI treatments improved the compatibility between kenaf fibers and PP matrix. The tensile modulus and tensile strength of the composites reinforced with INI-treated fibers increased by 25.9% and 10.4%, respectively, compared to those reinforced with untreated kenaf fibers.« less

Recent Development of Flax Fibres and Their Reinforced Composites Based on Different Polymeric Matrices

PubMed Central

Zhu, Jinchun; Zhu, Huijun; Njuguna, James; Abhyankar, Hrushikesh

2013-01-01

This work describes flax fibre reinforced polymeric composites with recent developments. The properties of flax fibres, as well as advanced fibre treatments such as mercerization, silane treatment, acylation, peroxide treatment and coatings for the enhancement of flax/matrix incompatibility are presented. The characteristic properties and characterizations of flax composites on various polymers including polypropylene (PP) and polylactic acid, epoxy, bio-epoxy and bio-phenolic resin are discussed. A brief overview is also given on the recent nanotechnology applied in flax composites. PMID:28788383

The effect of modified ijuk fibers to crystallinity of polypropylene composite

NASA Astrophysics Data System (ADS)

Prabowo, I.; Nur Pratama, J.; Chalid, M.

2017-07-01

Nowadays, plastics becomes concern associated with its degradation and environmental issues. It has led studies to develop an environmental-friendly material. To minimize the impact of those problems, recently the usage of natural fibers as a filler are introduced because of biodegradability and availability. The promising natural fiber is “ijuk” fiber from Arenga pinnata plant as a filler and polypropylene (PP) polymer as a matrix. Unfortunately, the natural fibers and polymers have the different properties on which polymers are polar while natural fibers are non-polar so that reducing the compatibility and resulting the poor crystallinity. To enhance the compatibility and crystallinity, ijuk fibers were prepared by multistage treatments including alkalinization with 5 and 10% sodium hydroxide (NaOH), oxidation with 3 and 6% sodium hypochlorite (NaClO) and hydrolysis with 20% sulphuric acid (H2SO4) in sequences. The purposes of multistage treatments are to remove the components such as lignin, wax, hemicellulose, to cause an oxidative fragmentation of remaining lignin and to annihilate the amorphous parts respectively. Fourier-Transform Infrared (FTIR) confirms the compatibility meanwhile Differential Scanning Calorimetry (DSC) reveals the crystallinity and Scanning Electron Microscope (SEM) displays surface morphology of polypropylene. The experiments were revealing that the effects of “ijuk” fibers by the multistage treatments of 5 and 10% NaOH resulting the crystallinity of polypropylene around 31.2 and 27.64% respectively compared to the crystallinity before adding the “ijuk” fibers for 16.8%. It indicates that the entire treatments increasing the compatibility and crystallinity of polypropylene. In addition, the use of 5% NaOH offers the better crystallinity than non-treated polypropylene. The experiments conclude that by adding alkalinized “ijuk” fibers of multistage treatments can increase the compatibility and crystallinity of polypropylene.

Upcycling of polypropylene waste by surface modification using radiation-induced grafting

NASA Astrophysics Data System (ADS)

Hassan, Muhammad Inaam ul; Taimur, Shaista; Yasin, Tariq

2017-11-01

In this work, upcycling of polypropylene waste into amidoxime functionalized polypropylene adsorbent was studied using radiation-induced grafting technique. Polypropylene waste (PPw) was resulted from accelerated thermal ageing of polypropylene (PP). Bulk grafting of acrylonitrile (AN) onto PPw was achieved by simultaneous radiation grafting method using gamma rays. Degree of grafting of AN on PPw is affected by absorbed dose and dose rate. The acrylonitrile groups of grafted PPw were chemically converted into amidoxime functionality. Both the acrylonitrile-grafted PP waste and its amidoxime product were investigated by FTIR, XRD, SEM-EDX and TGA techniques. The prepared amidoxime adsorbent with amidoxime group density of 8.06 mmol/g was used for removal of copper ions from aqueous solutions. The effects of various physicochemical conditions such as: solution pH, adsorbent content, initial metal ion concentration and time on adsorption were studied to maximize adsorption of metal ion. Pseudo-first-order, pseudo-second-order and intra-particle diffusion models were applied to study the kinetics of adsorption. Maximum Langmuir adsorption capacity of 208.3 mg/g at pH 5.0 with optimum contact time of 120 min was observed. Utilization of PP waste and its comparable adsorption capacity with existing radiation grafted polymer-based adsorbents provide a new, cheap and cost effective system.

Migration Study of Butylated Hydroxytoluene and Irganox 1010 from Polypropylene Treated with Severe Processing Conditions.

PubMed

Kang, Kyungmo; Chang, Yoonjee; Choi, Jae Chun; Park, Se-Jong; Han, Jaejoon

2018-04-01

Safety concerns have emerged over the increased use of polypropylene (PP) in food-packaging markets. Some antioxidants in PP can migrate to foods and cause undesirable effects in humans. In this study, migration behaviors of butylated hydroxytoluene (BHT) and Irganox 1010 (I-1010) in PP sheets were determined according to the US FDA migration test conditions. In particular, we tested the effects of severe conditions of food processing and storage, such as autoclave heating (sterilization at about 121 °C), microwave radiation (700 W), and deep freezing (-30 °C) on migration of antioxidants. Migrant concentrations were higher in 95% ethanol as lipid food simulant, because of the hydrophobic nature of both PP and antioxidants. Autoclave heating treatment increased migrant concentrations compared with other processing conditions. Moreover, increased migrant concentrations by deep freezing condition were attributed to the brittleness of PP at freezing temperature. Regardless of processing conditions, BHT which has a lower molecular weight, migrated faster than I-1010. The antioxidants with hydrophobic nature such as butylated hydroxytoluene (BHT) and Irganox 1010 (I-1010) in polypropylene sheets would be migrated to foods, which is an important issue for industrial production food packaging materials. Migration behavior was promoted by severe processing conditions such as autoclave heating, microwave radiation, freezing, and especially autoclave heating treatment led the highest migration among them. Therefore, control of chemical additive migration from polypropylene food packaging is needed for safe food processing. © 2018 Institute of Food Technologists®.

Effect of Sericin on Mechanical Behavior of Composite Material Reinforced by Silk Woven Fabric

NASA Astrophysics Data System (ADS)

Kimura, Teruo; Ino, Haruhiro; Hanada, Koji; Katori, Sigetaka

Recent, attention has been given to shift from glass fibers and carbon fibers to natural fibers for FRP composites for the goal of protecting the environment. This paper concerned with the application of silk fabric for composite materials. Polypropylene (PP) was used for the matrix material and the silk fabric composites were molded using a compression molding method. Especially, the effect of sericin on mechanical behaviors of composite materials was discussed. Good adhesion between silk and PP was obtained by removing the sericin existing around the fibroin. The tensile modulus of composite decreased with decreasing the sericin because of the flexibility of silk fibers without sericin. In particular, the higher Izod impact value was obtained for the composites containing the silk fibers without sericin.

Analysis and optimization of machining parameters of laser cutting for polypropylene composite

NASA Astrophysics Data System (ADS)

Deepa, A.; Padmanabhan, K.; Kuppan, P.

2017-11-01

Present works explains about machining of self-reinforced Polypropylene composite fabricated using hot compaction method. The objective of the experiment is to find optimum machining parameters for Polypropylene (PP). Laser power and Machining speed were the parameters considered in response to tensile test and Flexure test. Taguchi method is used for experimentation. Grey Relational Analysis (GRA) is used for multiple process parameter optimization. ANOVA (Analysis of Variance) is used to find impact for process parameter. Polypropylene has got the great application in various fields like, it is used in the form of foam in model aircraft and other radio-controlled vehicles, thin sheets (∼2-20μm) used as a dielectric, PP is also used in piping system, it is also been used in hernia and pelvic organ repair or protect new herrnis in the same location.

Storing of Extracts in Polypropylene Microcentrifuge Tubes Yields Contaminant Peak During Ultra-flow Liquid Chromatographic Analysis.

PubMed

Kshirsagar, Parthraj R; Hegde, Harsha; Pai, Sandeep R

2016-05-01

This study was designed to understand the effect of storage in polypropylene microcentrifuge tubes and glass vials during ultra-flow liquid chromatographic (UFLC) analysis. One ml of methanol was placed in polypropylene microcentrifuge tubes (PP material, Autoclavable) and glass vials (Borosilicate) separately for 1, 2, 4, 8, 10, 20, 40, and 80 days intervals stored at -4°C. Contaminant peak was detected in methanol stored in polypropylene microcentrifuge tubes using UFLC analysis. The contaminant peak detected was prominent, sharp detectable at 9.176 ± 0.138 min on a Waters 250-4.6 mm, 4 μ, Nova-Pak C18 column with mobile phase consisting of methanol:water (70:30). It was evident from the study that long-term storage of biological samples prepared using methanol in polypropylene microcentrifuge tubes produce contaminant peak. Further, this may mislead in future reporting an unnatural compound by researchers. Long-term storage of biological samples prepared using methanol in polypropylene microcentrifuge tubes produce contaminant peakContamination peak with higher area under the curve (609993) was obtained in ultra-flow liquid chromatographic run for methanol stored in PP microcentrifuge tubesContamination peak was detected at retention time 9.113 min with a lambda max of 220.38 nm and 300 mAU intensity on the given chromatographic conditionsGlass vials serve better option over PP microcentrifuge tubes for storing biological samples. Abbreviations used: UFLC: Ultra Flow Liquid Chromatography; LC: Liquid Chromatography; MS: Mass spectrometry; AUC: Area Under Curve.

Structure development in melt processing isotactic polypropylene, polypropylene blends/compounds and dynamically vulcanized polyolefin TPEs

NASA Astrophysics Data System (ADS)

Yu, Yishan

The influence of various fillers, nucleating agents and ethylene propylene diene terpolymer (EPDM) additive on crystalline modification (alpha-, beta- and smectic forms) and crystalline orientation of polypropylene in die extrudates, melt spun filaments, thick rods, blow molded bottles and injection molded parts of isotactic polypropylene (PP), its blends/compounds and dynamically vulcanized polypropylene thermoplastic elastomers (TPEs) were experimentally studied under a range of cooling and processing conditions. The phenomena of crystallization, polymorphism and orientation in processing of both thin and thick samples (filaments, rods, bottles and injection molded parts) were simulated through transport laws incorporating polymer crystallization kinetics. Continuous cooling transformation (CCT) curves for the various material systems investigated were developed under quiescent and uniaxial stress conditions. We applied experimental data on polymorphism of thin sections to predict crystalline structure variation in thick parts. The predictions were consistent with experiments. For filaments, the polypropylene crystalline orientation-spinline stress relationship is generally similar for the neat PP, blends/compounds and TPEs. However, the blends and TPEs have much lower birefringence apparently due to a lack of orientation in the rubber phase. It was shown that the polypropylene contribution to the birefringence for the neat PP and its blends is the same at the same spinline stress. For bottles, the inflation pressures used have little effect on orientation of either polypropylene crystals or disc-shaped talc filler. The talc discs are highly oriented parallel to the bottle surface. For the bottles without talc, the orientation of polypropylene crystallographic axes are low. The polypropylene crystallographic b-axes in the talc filled bottles are more highly oriented. For injection molded parts, it was found that a low orientation layer exists between the part surface and an intermediate highly oriented layer in the parts of neat PP and its blends/compounds. The thickness of this layer increases as the injection pressure decreases. This layer was not formed in the TPE parts. This would seem to be associated with the TPEs exhibiting a yield stress in shear flow and not exhibiting fountain flow in mold filling. For all parts studied, the orientation characteristics of polypropylene crystallographic axes in the highly oriented layer are similar from sample to sample. The strong orientation of the c-axis parallel to the machine direction and the b-axis perpendicular to the machine direction are observed in the highly oriented layer. The talc discs in both the highly oriented layer and the intermediate position are highly oriented parallel to the part face due to melt flow. At intermediate position in the talc-filled parts, the polypropylene crystallographic (040) planes prefer to align themselves parallel to the part surface but are not so well oriented when the talc is absent.

Interfacial properties of aluminum/glass-fiberreinforced polypropylene sandwich composites

NASA Astrophysics Data System (ADS)

Baştürk, S. B.; Guruşçu, A.; Tanoğlu, M.

2013-07-01

Aluminum/glass-fiber-reinforced polypropylene (Al/GFPP) laminates were manufactured by using various surface pretreatment techniques. Adhesion at the composite/metal interface was achieved by a surface pretreatment of Al sheets with amino-based silane coupling agents, incorporation of a polyolefin-based adhesive film and modification with a PP-based film containing 20 wt.% of maleic-anhydride-modified polypropylene (PP-g-MA). In order to increase the effect of bonding between components of the laminates, the combination of silane treatment and the addition of the PP-based film was also investigated. The mechanical properties (shear, peel, and bending strengths) of adhesively bonded Al/GFPP laminates were examined to evaluate the effects of the surface treatments mentioned. It was revealed that the adhesion in the laminated Al/GFPP systems could be improved by the treatment of aluminum surface with an amino-based silane coupling agent. Judging from the results of peel and bending strength, with incorporation of polyolefin-based films, adhesion in the Al/GFPP laminates increased significantly. The modification of Al/GFPP interfaces with a PP-g-MA/PP layer led to the highest improvement in their adhesion properties. The combination of surface modification with silane and addition of PP-based films did not yield the high bending strength desired. This may be due to the insufficient bonding between silane groups and PP-based films.

Supercritical CO2 foaming of radiation crosslinked polypropylene/high-density polyethylene blend: Cell structure and tensile property

NASA Astrophysics Data System (ADS)

Yang, Chenguang; Xing, Zhe; Zhang, Mingxing; Zhao, Quan; Wang, Mouhua; Wu, Guozhong

2017-12-01

A blend of isotactic polypropylene (PP) with high-density polyethylene (HDPE) in different PP/HDPE ratios was irradiated by γ-ray to induce cross-linking and then foamed using supercritical carbon dioxide (scCO2) as a blowing agent. Radiation effect on the melting point and crystallinity were analyzed in detail. The average cell diameter and cell density were compared for PP/HDPE foams prepared under different conditions. The optimum absorbed dose for the scCO2 foaming of PP/HDPE in terms of foaming ability and cell structure was 20 kGy. Tensile measurements showed that the elongation at break and tensile strength at break of the crosslinked PP/HDPE foams were higher than the non-crosslinked ones. Of particular interest was the increase in the foaming temperature window from 4 ℃ for pristine PP to 8-12 ℃ for the radiation crosslinked PP/HDPE blends. This implies much easier handling of scCO2 foaming of crosslinked PP with the addition of HDPE.

Rutherford Backscattering Spectrometry studies of 100 keV nitrogen ion implanted polypropylene polymer

NASA Astrophysics Data System (ADS)

Chawla, Mahak; Aggarwal, Sanjeev; Sharma, Annu

2017-09-01

The effect of nitrogen ion implantation on the structure and composition in polypropylene (PP) polymer has been studied. Implantation was carried out using 100 keV N+ ions at different fluences of 1 × 1015, 1 × 1016 and 1 × 1017 ions cm-2 with beam current density of ∼0.65 μA cm-2. Surface morphological changes in the pre- and post-implanted PP specimens have been studied using Rutherford Backscattering Spectrometry (RBS) and UV-Visible Spectroscopy. The spatial distribution of implantation induced modification in the form of carbonization and dehydrogenation in the near surface region of PP matrix, the projected range, retained dose of implanted nitrogen, the various elements present in the implanted layers and their differential cross-sections have been analyzed using RBS spectra. RUMP simulation yielded an increase in the concentration of carbon near the surface from 33 at.% (virgin) to 42 at.% at fluence of 1 × 1017 N+ cm-2. Further, optical absorption has been found to increase with a shift in the absorption edge from UV towards visible region with increasing fluence. UV-Vis absorption spectra also indicate a drastic decrease in optical energy gap from 4.12 eV (virgin) to 0.25 eV (1 × 1017 N+ cm-2) indicating towards the formation of carbonaceous network in the implanted region. All these changes observed using UV-Visible have been further correlated with the outcomes of the RBS characterization.

Novel polypropylene biocomposites reinforced with carbon nanotubes and hydroxyapatite nanorods for bone replacements.

PubMed

Liao, Cheng Zhu; Li, Kai; Wong, Hoi Man; Tong, Wing Yin; Yeung, Kelvin Wai Kwok; Tjong, Sie Chin

2013-04-01

Multi-walled carbon nanotubes (MWNTs) of 0.1 and 0.3 wt.% and hydoxyapatite nanorods (nHAs) of 8-20 wt.% were incorporated into polypropylene (PP) to form biocomposites using melt-compounding and injection molding techniques. The structural, mechanical, thermal and in vitro cell responses of the PP/MWNT-nHA hybrids were investigated. Tensile and impact tests demonstrated that the MWNT additions are beneficial in enhancing the stiffness, tensile strength and impact toughness of the PP/nHA nanocomposites. According to thermal analysis, the nHA and MWNT fillers were found to be very effective to improve dimensional and thermal stability of PP. The results of osteoblast cell cultivation and dimethyl thiazolyl diphenyl tetrazolium (MTT) tests showed that the PP/MWNT-nHA nanocomposites are biocompatible. Such novel PP/MWNT-nHA hybrids are considered to be potential biomaterials for making orthopedic bone implants. Copyright © 2012 Elsevier B.V. All rights reserved.

Properties of lightweight cement-based composites containing waste polypropylene

NASA Astrophysics Data System (ADS)

Záleská, Martina; Pavlíková, Milena; Pavlík, Zbyšek

2016-07-01

Improvement of buildings thermal stability represents an increasingly important trend of the construction industry. This work aims to study the possible use of two types of waste polypropylene (PP) for the development of lightweight cement-based composites with enhanced thermal insulation function. Crushed PP waste originating from the PP tubes production is used for the partial replacement of silica sand by 10, 20, 30, 40 and 50 mass%, whereas a reference mixture without plastic waste is studied as well. First, basic physical and thermal properties of granular PP random copolymer (PPR) and glass fiber reinforced PP (PPGF) aggregate are studied. For the developed composite mixtures, basic physical, mechanical, heat transport and storage properties are accessed. The obtained results show that the composites with incorporated PP aggregate exhibit an improved thermal insulation properties and acceptable mechanical resistivity. This new composite materials with enhanced thermal insulation function are found to be promising materials for buildings subsoil or floor structures.

Influence of PP-g-MA compatibilizer characteristics on mechanical properties of glass fiber reinforced polypropylene composites

NASA Astrophysics Data System (ADS)

Guan, Zhuo

Glass fiber (GF) reinforced polypropylene (PP) has become a common composite material used for various applications. Previous reports indicated that grafting ratio and molecular weight (MW) of znaleic anhydride grafted polypropylene (PP-g-MA) are the two most significant factors affecting the mechanical properties of PP/PP-g-MA/GF composites, but the combined effect of these two factors remains controversial. The study of the importance of MA grafting ratio and MW is continued in this work using PPIPP-g MA/GF composites containing various grades and concentrations of PP-g MA compatibilizer. First, MFR and FT1R analyses were performed to characterize the physical and chemical properties- of each PP-g-MA resin. Then, premixed PP and PP-g-MA blend were compounded with GF via twin screw extrusion, with the compounds injection molded into tensile, flexural and Izod impact specimens (all ASTM standard) for mechanical properties testing. Generally speaking, at a given GF content, higher compatibilizer concentrations led to higher tensile, flexural and notched Izod impact strength up to an optimum MA concentrations above which these properties tended to level off PP-g-MA resins with higher grafting ratio were more efficient compatibilizers as indicated by improved tensile, flexural and impact properties at lower PP-g-MA contents. In addition, MW was expected to affect properties as well, with too high and too 16w MW values leading to reduced reinforcement. While the optimum MW values for tensile and impact strength were still not clear based on present results, the estimated optimum weight average MW for maximum flexural strength was 90,000 +/- 1,400 g/mol.

Research on mechanical properties of carbon fiber /polyamide reinforced PP composites

NASA Astrophysics Data System (ADS)

Chen, Xinghui; Yu, Qiang; Liu, Lixia; Ji, Wenhua; Yang, Li; Fan, Dongli

2017-10-01

The polyamide composites reinforced by carbon fiber/polypropylene are produced by injection molding processing. The flow abilities and mechanical properties of the CF/PA/PP composite materials are studied by the fusion index instrument and the universal testing machine. The results show that with the content of carbon fiber/polyamide increase, the impact breaking strength and the tensile property of the composite materials increase, which is instructive to the actual injection production of polypropylene products.

Effect of Surface-Modified TiO2 Nanoparticles on the Anti-Ultraviolet Aging Performance of Foamed Wheat Straw Fiber/Polypropylene Composites

PubMed Central

Xuan, Lihui; Han, Guangping; Wang, Dong; Cheng, Wanli; Gao, Xun; Chen, Feng; Li, Qingde

2017-01-01

Surface modification and characterization of titanium dioxide (TiO2) nanoparticles and their roles in thermal, mechanical, and accelerated aging behavior of foamed wheat straw fiber/polypropylene (PP) composites are investigated. To improve the dispersion of nanoparticles and increase the possible interactions between wheat straw fiber and the PP matrix, the surface of the TiO2 nanoparticles was modified with ethenyltrimethoxy silane (A171), a silane coupling agent. The grafting of A171 on the TiO2 nanoparticles’ surface was characterized by Fourier transform infrared spectroscopy (FTIR). The wheat straw fibers treated with A171 and modified TiO2 nanoparticles were characterized by FTIR and thermogravimetric analysis (TGA). FTIR spectra confirmed that the organic functional groups of A171 were successfully grafted onto the TiO2 nanoparticles and wheat straw fibers, and the modified TiO2 nanoparticles were adsorbed onto the wheat straw fibers. Thermogravimetric analysis showed that a higher thermal stability of the wheat straw fiber was obtained with the modified TiO2 nanoparticles. The flexural, tensile, and impact properties were improved. A higher ultraviolet (UV) stability of the samples treated with modified TiO2 nanoparticles was exhibited by the study of the color change and loss in mechanical properties. PMID:28772816

Polypropylene Biocomposites with Boron Nitride and Nanohydroxyapatite Reinforcements

PubMed Central

Chan, Kai Wang; Wong, Hoi Man; Yeung, Kelvin Wai Kwok; Tjong, Sie Chin

2015-01-01

In this study, we develop binary polypropylene (PP) composites with hexagonal boron nitride (hBN) nanoplatelets and ternary hybrids reinforced with hBN and nanohydroxyapatite (nHA). Filler hybridization is a sound approach to make novel nanocomposites with useful biological and mechanical properties. Tensile test, osteoblastic cell culture and dimethyl thiazolyl diphenyl tetrazolium (MTT) assay were employed to investigate the mechanical performance, bioactivity and biocompatibility of binary PP/hBN and ternary PP/hBN-nHA composites. The purpose is to prepare biocomposite nanomaterials with good mechanical properties and biocompatibility for replacing conventional polymer composites reinforced with large hydroxyapatite microparticles at a high loading of 40 vol%. Tensile test reveals that the elastic modulus of PP composites increases, while tensile elongation decreases with increasing hBN content. Hybridization of hBN with nHA further enhances elastic modulus of PP. The cell culture and MTT assay show that osteoblastic cells attach and proliferate on binary PP/hBN and ternary PP/hBN-20%nHA nanocomposites. PMID:28787984

Kenaf/PP and EFB/PP: Effect of fibre loading on the mechanical properties of polypropylene composites

NASA Astrophysics Data System (ADS)

Anuar, N. I. S.; Zakaria, S.; Harun, J.; Wang, C.

2017-07-01

Kenaf and empty fruit bunch (EFB) fibre which are the important natural fibres in Malaysia were studied as nonwoven polymer composites. The effect of fibre loading on kenaf polypropylene and EFB polypropylene nonwoven composite was studied at different mixture ratio. Kenaf polypropylene nonwoven composite (KPNC) and EFB polypropylene nonwoven composite (EPNC) were prepared by carding and needle-punching techniques, followed by a compression moulding at 6 mm thickness. This study was conducted to identify the optimum fibre loading of nonwoven polypropylene composite and their effect on the mechanical strength. The study was designed at 40%, 50%, 60% and 70% of fibre content in nonwoven mat and composite. The tensile strength, flexural strength and compression strength were tested to evaluate the composite mechanical properties. It was found that the mechanical properties for both kenaf and EFB nonwoven composites were influenced by the fibre content. KPNC showed higher mechanical strength than EPNC. The highest flexural strength was obtained at 60% KPNC and the lowest value was showed by 40% EPNC. The tensile and flexural strength for both KPNC and EPNC decreased after the fibre loading of 60%.

Flexural properties untreated and treated kenaf fiber reinforced polypropylene composites

NASA Astrophysics Data System (ADS)

Husin, Muhammad Muslimin; Mustapa, Mohammad Sukri; Wahab, Md Saidin; Arifin, Ahmad Mubarak Tajul; Masirin, Mohd Idrus Mohd; Jais, Farhana Hazwanee

2017-05-01

Today natural fiber polymer composites are being extensively used as alternatives in producing furniture to fulfill society demand instead of saving cost and environmentally friendly. The objective of this search is to investigate the untreated fine and rough kenaf fiber (KF) as well as treated KF reinforced with polypropylene (PP) on the flexural strength. Flexural strengths of pure PP, 10%, and 20% of untreated fine and rough KF by weight to PP have been recorded. In addition, flexural strengths of treated KF soaked with 5% and 10% of Sodium Hydroxide (NaOH) have also been recorded. KF reinforced PP (PP/KF) untreated and treated composites were melt blended and then injection molded to observe their flexural strengths by measuring their threshold. Three point bending test was apply to determine the flexural stress of the composites. The result show treated fine KF produce better flexural performance at 20% PP/KF. Scanning Electron Microscopy (SEM) is used to observe the morphological surface PP/KF. Overall 5% NaOH with 20% PP/KF (Fine KF) show good interfacial bonding PP/KF and best result with flexural stress value 30.25MPa.

Thermal properties of light-weight concrete with waste polypropylene aggregate

NASA Astrophysics Data System (ADS)

Záleská, Martina; Pokorný, Jaroslav; Pavlíková, Milena; Pavlík, Zbyšek

2017-07-01

Thermal properties of a sustainable light-weight concrete incorporating high volume of waste polypropylene as partial substitution of natural aggregate were studied in the paper. Glass fiber reinforced polypropylene (GFPP), a by-product of PP tubes production, partially substituted fine natural silica aggregate in 10, 20, 30, 40, and 50 mass%. In order to quantify the effect of GFPP use on concrete properties, a reference concrete mix without plastic waste was studied as well. For the applied GFPP, bulk density, matrix density, and particle size distribution were measured. Specific attention was paid to thermal transport and storage properties of GFPP that were examined in dependence on compaction time. For the developed light-weight concrete, thermal properties were accessed using transient impulse technique, whereas the measurement was done in dependence on moisture content, from the dry state to fully water saturated state. Additionally, the investigated thermal properties were plotted as function of porosity. The tested light-weight concrete was found to be prospective construction material possessing improved thermal insulation function. Moreover, the reuse of waste plastics in concrete composition was beneficial both from the environmental and financial point of view considering plastics low biodegradability and safe disposal.

Water-wettable polypropylene fibers by facile surface treatment based on soy proteins.

PubMed

Salas, Carlos; Genzer, Jan; Lucia, Lucian A; Hubbe, Martin A; Rojas, Orlando J

2013-07-24

Modification of the wetting behavior of hydrophobic surfaces is essential in a variety of materials, including textiles and membranes that require control of fluid interactions, adhesion, transport processes, sensing, etc. This investigation examines the enhancement of wettability of an important class of textile materials, viz., polypropylene (PP) fibers, by surface adsorption of different proteins from soybeans, including soy flour, isolate,glycinin, and β-conglycinin. Detailed investigations of soy adsorption from aqueous solution (pH 7.4, 25 °C) on polypropylene thin films is carried out using quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). A significant amount of protein adsorbs onto the PP surfaces primarily due to hydrophobic interactions. We establish that adsorption of a cationic surfactant, dioctadecyldimethylammonium bromide (DODA) onto PP surfaces prior to the protein deposition dramatically enhances its adsorption. The adsorption of proteins from native (PBS buffer, pH 7.4, 25 °C) and denatured conditions (PBS buffer, pH 7.4, 95 °C) onto DODA-treated PP leads to a high coverage of the proteins on the PP surface as confirmed by a significant improvement in water wettability. A shift in the contact angle from 128° to completely wettable surfaces (≈0°) is observed and confirmed by imaging experiments conducted with fluorescence tags. Furthermore, the results from wicking tests indicate that hydrophobic PP nonwovens absorb a significant amount of water after protein treatment, i.e., the PP-modified surfaces become completely hydrophilic.

Co-pyrolysis of polypropylene waste with Brazilian heavy oil.

PubMed

Assumpção, Luiz C F N; Carbonell, Montserrat M; Marques, Mônica R C

2011-01-01

To evaluate the chemical recycling of plastic residues, co-pyrolysis of polypropylene (PP) waste with Brazilian crude oil was evaluated varying the temperature (400°C to 500°C) and the amount of PP fed to the reactor. The co-pyrolysis of plastic waste in an inert atmosphere provided around 80% of oil pyrolytic, and of these, half represent the fraction of diesel oil. This study can be used as a reference in chemical recycling of plastics, specially associated with plastics co-pyrolysis.

Pyrolysis of virgin and waste polypropylene and its mixtures with waste polyethylene and polystyrene.

PubMed

Kiran Ciliz, Nilgun; Ekinci, Ekrem; Snape, Colin E

2004-01-01

A comparison of waste and virgin polypropylene (PP) plastics under slow pyrolysis conditions is presented. Moreover, mixtures of waste PP with wastes of polyethylene (PE) and polystyrene (PS) were pyrolyzed under the same operating conditions. Not only the impact of waste on degradation products but also impacts of the variations in the mixing ratio were investigated. The thermogravimetric weight loss curves and their derivatives of virgin and waste PP showed differences due to the impurities which are dirt and food residues. The liquid yield distribution concerning the aliphatic, mono-aromatic and poly-aromatic compounds varies as the ratio of PP waste increases in the waste plastic mixtures. In addition to this, the alkene/alkane ratio of gas products shows variations depending on the mixing ratio of wastes.

Surface treated polypropylene (PP) fibres for reinforced concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

López-Buendía, Angel M., E-mail: buendia@uv.es; Romero-Sánchez, María Dolores; Climent, Verónica

Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in themore » mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.« less

Decoration of Silica Nanoparticles on Polypropylene Separator for Lithium-Sulfur Batteries.

PubMed

Li, Jing; Huang, Yudai; Zhang, Su; Jia, Wei; Wang, Xingchao; Guo, Yong; Jia, Dianzeng; Wang, Lishi

2017-03-01

A SiO 2 nanoparticle decorated polypropylene (PP) separator (PP-SiO 2 ) has been prepared by simply immersing the PP separator in the hydrolysis solution of tetraethyl orthosilicate (TEOS) with the assistance of Tween-80. After decoration, the thermal stability and the electrolyte wettability of the PP-SiO 2 separator are obviously improved. When the PP-SiO 2 separator is used for lithium-sulfur (Li-S) batteries, the cyclic stability and rate capability of the batteries are greatly enhanced. The capacity retention ratio of the Li-S battery configured with the PP-SiO 2 separator is 64% after 200 cycles at 0.2 C, which is much higher than that configured with the PP separator (45%). Moreover, the rate capacity of the Li-S batteries using the PP-SiO 2 separator reaches 956.3, 691.5, 621, and 567.6 mAh g -1 at the current density of 0.2, 0.5, 1, and 2 C, respectively. The reason could be ascribed to that the polar silica coating not only alleviates the shuttle effect but also facilitates Li-ion migration.

Morphology study of peroxide-induced dynamically vulcanized polypropylene/ethylene-propylene-diene monomer/zinc dimethacrylate blends during tensile deformation.

PubMed

Chen, Yukun; Xu, Chuanhui; Cao, Liming; Wang, Yanpeng; Fang, Liming

2013-06-27

Polypropylene (PP)/ethylene-propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blend (EPDM/PP ratio of 30/70) with remarkable extensibility was successfully prepared via peroxide dynamic vulcanization. The uniaxial tensile properties, crystallization behavior, structure, and morphology during stretching were investigated. The tensile process study showed that the PP/EPDM/ZDMA blend exhibited the rubbery-like behavior with an elongation beyond 600%. The ZDMA graft-product domain increased the compatibility and interfacial adhesion between rubber and PP phases, while it reduced the crystallinity of the PP phase. On the basis of TEM and SEM analyses, we found that the cross-linked rubber particles could be elongated and oriented along the tensile direction, whereas the ZDMA graft-product domain "encapsulated" rubber phase together, acting as a "bridge" between elongated rubber phases and the PP phase during uniaxial stretching. The stress could be effectively transferred from the PP phase to the numerous elongated rubber phases due to the excellent compatibility and interfacial adhesion between rubber and PP phases, resulting in the rubbery-like behavior.

Preparation and Compatibility Evaluation of Polypropylene/High Density Polyethylene Polyblends

PubMed Central

Lin, Jia-Horng; Pan, Yi-Jun; Liu, Chi-Fan; Huang, Chien-Lin; Hsieh, Chien-Teng; Chen, Chih-Kuang; Lin, Zheng-Ian; Lou, Ching-Wen

2015-01-01

This study proposes melt-blending polypropylene (PP) and high density polyethylene (HDPE) that have a similar melt flow index (MFI) to form PP/HDPE polyblends. The influence of the content of HDPE on the properties and compatibility of polyblends is examined by using a tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and X-ray diffraction (XRD). The SEM results show that PP and HDPE are incompatible polymers with PP being a continuous phase and HDPE being a dispersed phase. The FTIR results show that the combination of HDPE does not influence the chemical structure of PP, indicating that the polyblends are made of a physical blending. The DSC and XRD results show that PP and HDPE are not compatible, and the combination of HDPE is not correlated with the crystalline structure and stability of PP. The PLM results show that the combination of HDPE causes stacking and incompatibility between HDPE and PP spherulites, and PP thus has incomplete spherulite morphology and a smaller spherulite size. However, according to mechanical property test results, the combination of HDPE improves the impact strength of PP. PMID:28793750

Preparation and Compatibility Evaluation of Polypropylene/High Density Polyethylene Polyblends.

PubMed

Lin, Jia-Horng; Pan, Yi-Jun; Liu, Chi-Fan; Huang, Chien-Lin; Hsieh, Chien-Teng; Chen, Chih-Kuang; Lin, Zheng-Ian; Lou, Ching-Wen

2015-12-17

This study proposes melt-blending polypropylene (PP) and high density polyethylene (HDPE) that have a similar melt flow index (MFI) to form PP/HDPE polyblends. The influence of the content of HDPE on the properties and compatibility of polyblends is examined by using a tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and X-ray diffraction (XRD). The SEM results show that PP and HDPE are incompatible polymers with PP being a continuous phase and HDPE being a dispersed phase. The FTIR results show that the combination of HDPE does not influence the chemical structure of PP, indicating that the polyblends are made of a physical blending. The DSC and XRD results show that PP and HDPE are not compatible, and the combination of HDPE is not correlated with the crystalline structure and stability of PP. The PLM results show that the combination of HDPE causes stacking and incompatibility between HDPE and PP spherulites, and PP thus has incomplete spherulite morphology and a smaller spherulite size. However, according to mechanical property test results, the combination of HDPE improves the impact strength of PP.

Finite element investigation of temperature dependence of elastic properties of carbon nanotube reinforced polypropylene

NASA Astrophysics Data System (ADS)

Ahmadi, Masoud; Ansari, Reza; Rouhi, Saeed

2017-11-01

This paper aims to investigate the elastic modulus of the polypropylene matrix reinforced by carbon nanotubes at different temperatures. To this end, the finite element approach is employed. The nanotubes with different volume fractions and aspect ratios (the ratio of length to diameter) are embedded in the polymer matrix. Besides, random and regular algorithms are utilized to disperse carbon nanotubes in the matrix. It is seen that as the pure polypropylene, the elastic modulus of carbon nanotube reinforced polypropylene decreases by increasing the temperature. It is also observed that when the carbon nanotubes are dispersed parallelly and the load is applied along the nanotube directions, the largest improvement in the elastic modulus of the nanotube/polypropylene nanocomposites is obtained.

Growth kinetics and biodeterioration of polypropylene microplastics by Bacillus sp. and Rhodococcus sp. isolated from mangrove sediment.

PubMed

Auta, H S; Emenike, C U; Jayanthi, B; Fauziah, S H

2018-02-01

Interest in the biodegradation of microplastics is due to their ubiquitous distribution, availability, high persistence in the environment and deleterious impact on marine biota. The present study evaluates the growth response and mechanism of polypropylene (PP) degradation by Bacillus sp. strain 27 and Rhodococcus sp. strain 36 isolated from mangrove sediments upon exposure to PP microplastics. Both bacteria strains were able to utilise PP microplastic for growth as confirmed by the reduction of the polymer mass. The weight loss was 6.4% by Rhodococcus sp. strain 36 and 4.0% by Bacillus sp. strain 27 after 40days of incubation. PP biodegradation was further confirmed using Fourier-transform infrared spectroscopy and scanning electron microscopy analyses, which revealed structural and morphological changes in the PP microplastics with microbial treatment. These analyses showed that the isolates can colonise, modify and utilise PP microplastics as carbon source. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface grafting of styrene on polypropylene fibers by argon plasma and its adsorption-regeneration of BTX

NASA Astrophysics Data System (ADS)

Xu, J. J.; Guo, M. L.; Chen, Q. G.; Lian, Z. Y.; Wei, W. J.; Luo, Z. W.; Xie, G.; Chen, H. N.; Dong, K.

2017-08-01

Active macromolecular free radicals were generated on polypropylene (PP) fibers surfaces by argon (Ar) plasma irradiation, then, PP surface modified fibers (PP-g-St fibers) were prepared by in-situ grafting reaction of styrene monomers (St). Effects of reaction parameters on grafting percentage were studied and adsorption capacities of PP-g-St fibers for benzene, toluene and xylene (BTX) were evaluated. Afterwards, regeneration adsorption efficiencies after maximum adsorption were explored. The results indicated that the optimum input power, irradiation time and grafting reaction time are 90 W, 3 min and 3 h respectively and the grafting percentage of St reached 5.7 %. The adsorption capacities of PP-g-St fibers towards toluene and xylene emulsions and solutions in water increased by 336.89 % and 344.57 % respectively, compared to pristine PP fibers. In addition, regeneration adsorption efficiencies of modified fibers remained > 90 % after six cycles of regeneration-adsorption experiments, which showed excellent regeneration ability.

Histologic Inflammatory Response to Transvaginal Polypropylene Mesh: A Systematic Review.

PubMed

Thomas, Dominique; Demetres, Michelle; Anger, Jennifer T; Chughtai, Bilal

2018-01-01

To evaluate the inflammatory response following transvaginal implantation of polypropylene (PP) mesh. A comprehensive literature search was performed in the following databases from inception in April 2017: Ovid MEDLINE, Ovid EMBASE, and The Cochrane Library (Wiley). The studies retrieved were screened for eligibility against predefined inclusion and exclusion criteria. Twenty-three articles were included in this review. Following the implantation of PP mesh, there are immediate and local inflammatory responses. PP mesh elicits an inflammatory response that decreases over time; however, no studies documented a complete resolution. Further studies are needed to determine if there is a complete resolution of inflammation or if it persists. Copyright © 2017 Elsevier Inc. All rights reserved.

Influence of processing conditions on the morphology of expanded perlite/polypropylene composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattausch, H., E-mail: hannelore.mattausch@unileoben.ac.at, E-mail: stephan.laske@unileoben.ac.at; Laske, S., E-mail: hannelore.mattausch@unileoben.ac.at, E-mail: stephan.laske@unileoben.ac.at; Holzer, C., E-mail: clemens.holzer@unileoben.ac.at

Perlite is an oversaturated, volcanic, glassy rock, which has chemically bound water from 2 to 5 wt%. Upon heating, perlite can be expanded up to 20 times of its original volume. Important applications are in the field of building industry, in refrigeration engineering or the pharmaceutical industry. As mineral filler in polymers, expanded perlite can increase the thermal conductivity, the viscosity and the mechanical properties of polypropylene composites. But there are still many challenges that must be analyzed to reach the full potential of those composites. This research work focuses on the morphology of expanded perlite/polypropylene (PP) compounds and themore » interactions between filler and polymer. To achieve good performance a homogenous dispersion of the filler in the polymer matrix is needed because the enhancement of the material correlates strongly with the morphology of the composite. Therefore it is necessary to characterize the microstructure of these materials in order to establish adequate structure-process-property relationships. The expanded perlite/PP composites were compounded with a co-rotating twin screw extruder Theysohn TSK 30/40D. For producing the closed cell expanded perlite a new technology, the bublon process, was used. For the material characterization two particles sizes were chosen and the filler content was varied at 5, 10 and 15 wt%. For the analysis of the effects of the screw geometry, two setups have been chosen for the processing of the materials. The produced materials were analyzed by scanning electron microscope (SEM) and tensile testing. The results show a reinforcement effect of the filler and differences in the inner structure of expanded perlite and in the morphology.« less

Relationship between compatibilizer and yield strength of PLA/PP Blend

NASA Astrophysics Data System (ADS)

Jariyakulsith, Pattanun; Puajindanetr, Somchai

2018-01-01

The aim of this research is to study the relationship between compatibilizer and yield strength of polylactic acid (PLA) and polypropylene (PP) blend. The PLA is blended with PP (PLA/PP) at the ratios of 70/30, 50/50 and 30/70. In addition, (1) polypropylene grafted maleic anhydride (PP-g-MAH) as a compatibilizer at 0.3 and 0.7 part per hundred of PLA/PP resin (phr) and (2) dicumyl peroxide (DCP) being an initiator at 0.03 and 0.07 phr are added in each composition. Yield strength is characterized to study the interaction between compatibilizer, initiator and yield strength by using experimental design of multilevel full factorial. The results show that (1) the yield strength of PLA/PP blend are increased after addition of compatibilizer. Because the adding of PP-g-MAH and DCP resulted in improving compatibility between PLA and PP. (2) there are interaction between PP-g-MAH and DCP that have affected the final properties of PLA/PP blend. The highest yield strength of 27.68 MPa is provided at the ratio of 70/30 blend by using the 0.3 phr of PP-g-MAH and 0.03 phr of DCP. Linear regression model is fitted and follow the assumptions of normal distribution.

Plasma treatment of polypropylene fabric for improved dyeability with soluble textile dyestuff

NASA Astrophysics Data System (ADS)

Yaman, Necla; Özdoğan, Esen; Seventekin, Necdet; Ayhan, Hakan

2009-05-01

The impact of plasma treatment parameters on the surface morphology, physical-chemical, and dyeing properties of polypropylene (PP) using anionic and cationic dyestuffs were investigated in this study. Argon plasma treatment was used to activate PP fabric surfaces. Activated surfaces were grafted different compounds: 6-aminohexanoic acid (6-AHA), acrylic acid (AA), ethylendiamine (EDA), acryl amide (AAMID) and hexamethyldisiloxane (HMDS). Compounds were applied after the plasma treatment and the acid and basic dyeing result that was then observed, were quite encouraging in certain conditions. The possible formed oxidizing groups were emphasized by FTIR and ATR and the surface morphology of plasma treated PP fibers was also investigated with scanning electron microscopy (SEM). PP fabric could be dyed with acid and basic dyestuffs after only plasma treatment and plasma induced grafting, and fastnesses of the dyed samples were satisfactory.

Improved properties of recycled polypropylene by introducing the long chain branched structure through reactive extrusion.

PubMed

Li, Yingchun; Jia, Shuai; Du, Shuanli; Wang, Yafei; Lv, Lida; Zhang, Jianbin

2018-06-01

An approach originated from preparing long chain branched polypropylene (PP) was applied to modify the properties of recycled PP that involved reactive extrusion to introduce a branched chain structure onto recycled PP under the assistance of chemical reaction between maleic anhydride (MAH) monomer and glycidyl methacrylate (GMA) grafts. The results from Fourier transformed infrared spectroscopy (FTIR) indicated the reaction took place during melt mixing, and the intensity of ester increased with increasing amount of MAH. Several rheological plots including complex viscosity, storage modulus, loss modulus, loss tangent and Cole-Cole plot were used to investigate the rheological properties of recycled PP and modified PP with MAH, which indicated an additional longer relaxation time that was not shown in recycled PP. The effects of branched structure on melting and crystallization behaviors were also investigated, demonstrating the branched chains acted as nucleating agent. Moreover, the branched structure of modified samples gave rise to enhance mechanical properties, especially, the higher impact strength compared with recycled PP. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of modification of isotactic polypropylene by additives of polyamide 6/66 on structural characteristics of composites

NASA Astrophysics Data System (ADS)

Vorontsov, N. V.; Popov, A. A.; Margolin, A. L.

2017-12-01

Changes in the supramolecular structure of polymer composites based on isotactic polypropylene (PP) and polyamide 6/66 (PA) are studied depending on the PP : PA ratio. Temperatures and enthalpies of melting and crystallization of both PP and PA and their composites are determined depending on the composition of the mixtures. It was shown that the initial melting point of a composite does not change with increasing PA content in the blends. The crystallization temperature of the mixtures is shown to increase with the addition of PA and becomes much higher than the crystallization temperatures of both PP and PA. The observed effect can be due to a strong interaction between the PP and PA molecules, thus decreasing the molecular mobility and increasing the crystallization temperature. The crystallization and melting of PP-PA mixtures are found to proceed at the close temperatures, although the crystallization and melting temperatures of pure PP and pure PA differ widely. The melting and crystallization enthalpies decrease with increasing PA concentration in the mixtures, which indicates a decrease in the degree of crystallinity of the composite.

Catalytic copyrolysis of particle board and polypropylene over Al-MCM-48

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hannah; Choi, Suek Ju; Kim, Ji Man

Highlights: • Al-MCM-48 was used for catalytic copyrolysis of particle board and polypropylene. • Catalytic produced mainly hydrocarbons. • The hydrocarbons produced were mainly in the diesel range. - Abstract: Particle board and polypropylene (PP) at a mixing ratio of 1:1 were copyrolyzed over two Al-MCM-48 catalysts with Si/Al ratios of 20 and 80. The catalyst characteristics were examined by measuring the Brunauer-Emmett-Teller surface area, temperature programmed desorption of ammonia, and X-ray diffraction. The main pyrolysis products of particle board were oxygenates, acids, and phenolics, whereas a large quantity of hydrocarbons within the diesel fuel range was produced from copyrolysismore » with polypropylene. The catalytic copyrolysis of particle board and PP over the Al-MCM-48 catalysts produced bio-oil with a much larger hydrocarbon content than that from the catalytic pyrolysis of particle board only. The hydrocarbons produced were mainly in the diesel range, highlighting the potential for the production of high-quality fuel.« less

Radiation resistant polypropylene blended with mobilizer,. antioxidants and nucleating agent

NASA Astrophysics Data System (ADS)

Shamshad, A.; Basfar, A. A.

2000-03-01

Post-irradiation storage of medical disposables prepared from isotactic polypropylene renders them brittle due to degradation. To avoid this, isotactic polypropylene [(is)PP] was blended with a mobilizer, dioctyl pthallate (DOP), three antioxidants (hindered amines and a secondary antioxidant) and benzoic acid to obtain radiation-resistant, thermally-stable and transparent material. Different formulations prepared were subjected to gamma radiation to doses of 25 and 50 kGy. Tests of breakage on bending after ageing in an oven at 70°C up to 12 months have shown that the addition of DOP and the antioxidants imparts improved radiation and thermal stability as compared to (is)PP alone or its blend with DOP. All the formulations irradiated or otherwise demonstrated excellent colour stability even after accelerated ageing at 70°C for prolonged periods.

Environmental Particle Emissions due to Automated Drilling of Polypropylene Composites and Nanocomposites Reinforced with Talc, Montmorillonite and Wollastonite

NASA Astrophysics Data System (ADS)

Starost, K.; Frijns, E.; Laer, J. V.; Faisal, N.; Egizabal, A.; Elizextea, C.; Nelissen, I.; Blazquez, M.; Njuguna, J.

2017-05-01

In this study, the effect on nanoparticle emissions due to drilling on Polypropylene (PP) reinforced with 20% talc, 5% montmorillonite (MMT) and 5% Wollastonite (WO) is investigated. The study is the first to explore the nanoparticle release from WO and talc reinforced composites and compares the results to previously researched MMT. With 5% WO, equivalent tensile properties with a 10 % weight reduction were obtained relative to the reference 20% talc sample. The materials were fabricated through injection moulding. The nanorelease studies were undertaken using the controlled drilling methodology for nanoparticle exposure assessment developed within the European Commission funded SIRENA Life 11 ENV/ES/506 project. Measurements were taken using CPC and DMS50 equipment for real-time characterization and measurements. The particle number concentration (of particles <1000nm) and particle size distribution (4.87nm - 562.34nm) of the particles emitted during drilling were evaluated to investigate the effect of the silicate fillers on the particles released. The nano-filled samples exhibited a 33% decrease (MMT sample) or a 30% increase (WO sample) on the average particle number concentration released in comparison to the neat polypropylene sample. The size distribution data displayed a substantial percentage of the particles released from the PP, PP/WO and PP/MMT samples to be between 5-20nm, whereas the PP/talc sample emitted larger particle diameters.

Hydrophilic TiO2 porous spheres anchored on hydrophobic polypropylene membrane for wettability induced high photodegrading activities.

PubMed

Niu, Fang; Zhang, Le-Sheng; Chen, Chao-Qiu; Li, Wei; Li, Lin; Song, Wei-Guo; Jiang, Lei

2010-08-01

TiO(2) porous nanospheres on polypropylene (PP) films (TiO(2)/PP composite) are produced at ambient temperature. Particle/pore size match up is the key anchoring point to overcome the low affinity between hydrophilic materials and hydrophobic materials. With the hydrophilic TiO(2) catalyst evenly dispersed on a hydrophobic surface, the aqueous solution will selectively skip the substrate and wet the catalysts. Such a wettability-induced smart system maximizes the degrading activity of the TiO(2) catalyst. In photodegrading reactions, the resulting TiO(2)/PP composite film exhibits a 10 times higher activity in flow-type setup than the same TiO(2) catalyst in a traditional batch-type setup.

Plasma enhanced modification of TMP fiber and its effect on tensile strength of wood fiber/PP composite

Treesearch

Sangyeob Lee; Todd F. Shupe; Chung Y. Hse

2009-01-01

Plasma-assisted surface treatment on thermomechanical pulp (TMP) fiber and polypropylene (PP) film was investigated to obtain interfacial adhesion at the wood fiber and PP interface. A metal plate between electrodes prevented thermal damage to the TMP fiber handsheets and PP film. Oxygen-plasma treatment provided better surface activation on the TMP fiber and...

Melting processes of oligomeric α and β isotactic polypropylene crystals at ultrafast heating rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Xiaojing; He, Xuehao, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn; Jiang, Shichun, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn

The melting behaviors of α (stable) and β (metastable) isotactic polypropylene (iPP) crystals at ultrafast heating rates are simulated with atomistic molecular dynamics method. Quantitative information about the melting processes of α- and β-iPP crystals at atomistic level is achieved. The result shows that the melting process starts from the interfaces of lamellar crystal through random dislocation of iPP chains along the perpendicular direction of lamellar crystal structure. In the melting process, the lamellar crystal gradually expands but the corresponding thickness decreases. The analysis shows that the system expansion lags behind the crystallinity decreasing and the lagging extents for α-more » and β-iPP are significantly different. The apparent melting points of α- and β-iPP crystals rise with the increase of the heating rate and lamellar crystal thickness. The apparent melting point of α-iPP crystal is always higher than that of β-iPP at differently heating rates. Applying the Gibbs-Thomson rule and the scaling property of the melting kinetics, the equilibrium melting points of perfect α- and β-iPP crystals are finally predicted and it shows a good agreement with experimental result.« less

Spinnability and Characteristics of Polyvinylidene Fluoride (PVDF)-based Bicomponent Fibers with a Carbon Nanotube (CNT) Modified Polypropylene Core for Piezoelectric Applications

PubMed Central

Glauß, Benjamin; Steinmann, Wilhelm; Walter, Stephan; Beckers, Markus; Seide, Gunnar; Gries, Thomas; Roth, Georg

2013-01-01

This research explains the melt spinning of bicomponent fibers, consisting of a conductive polypropylene (PP) core and a piezoelectric sheath (polyvinylidene fluoride). Previously analyzed piezoelectric capabilities of polyvinylidene fluoride (PVDF) are to be exploited in sensor filaments. The PP compound contains a 10 wt % carbon nanotubes (CNTs) and 2 wt % sodium stearate (NaSt). The sodium stearate is added to lower the viscosity of the melt. The compound constitutes the fiber core that is conductive due to a percolation CNT network. The PVDF sheath’s piezoelectric effect is based on the formation of an all-trans conformation β phase, caused by draw-winding of the fibers. The core and sheath materials, as well as the bicomponent fibers, are characterized through different analytical methods. These include wide-angle X-ray diffraction (WAXD) to analyze crucial parameters for the development of a crystalline β phase. The distribution of CNTs in the polymer matrix, which affects the conductivity of the core, was investigated by transmission electron microscopy (TEM). Thermal characterization is carried out by conventional differential scanning calorimetry (DSC). Optical microscopy is used to determine the fibers’ diameter regularity (core and sheath). The materials’ viscosity is determined by rheometry. Eventually, an LCR tester is used to determine the core’s specific resistance. PMID:28811400

Ziegler-Natta Catalyst Based on MgCl₂/Clay/ID/TiCl₄ for the Synthesis of Spherical Particles of Polypropylene Nanocomposites.

PubMed

Cardoso, Renata da Silva; Oliveira, Jaqueline da Silva; Ramis, Luciana Bortolin; Marques, Maria de Fátima V

2018-07-01

In the present work, we have designed MgCl2/clay/internal donor (ID)/TiCl4 based bisupported Ziegler-Natta catalysts containing varying amounts of organoclay (montmorillonite) in order to synthesize spherical particles of polypropylene/clay nanocomposites (PCN). The organoclay was introduced into the catalyst support formulation and PCN was obtained using the in situ polymerization technique. Decreasing the reaction time, it was possible to obtain nanocomposites with high concentrations of clay (masterbatches). Micrographs of SEM confirmed the spherical morphology of the catalysts. In addition, XRD patterns show that the active sites for polymerization were inserted in the clay galleries. The catalytic performance was evaluated in slurry propylene polymerization using triethylaluminium as cocatalyst and silane as external electron donor at 70 °C, 4 bar, and different reaction times. The PCNs obtained containing different clay amounts were characterized by X-ray diffraction, thermal analyses, transmission electronic microscopy, and extractables in heptane. The results revealed that the synthesized PP/clay particles were also spherical showing that the morphological control is possible even using catalysts containing high amounts of clay. The PCN presented high degradation temperature (459 °C). The XRD peak related to the clay interlamellar distance has shifted to lower angles, and TEM images confirmed the formation of exfoliated/intercalated clay on the PP matrix and absence of microparticles of clay.

Fabrication and characterization of jute fabrics reinforced polypropylene-based composites: effects of ionizing radiation and disaccharide (sucrose)

NASA Astrophysics Data System (ADS)

Sahadat Hossain, Md.; Uddin, Muhammad B.; Razzak, Md.; Sarwaruddin Chowdhury, A. M.; Khan, Ruhul A.

2017-12-01

Composites were prepared successfully by compression molding technique using jute fabrics (reinforcing agent) and polypropylene (matrix). Jute fabrics were treated with disaccharide (sucrose) solution and composites were fabricated with the treated fabric and polypropylene. The fiber content of the prepared composites was 40% by weight. It was found that the sucrose (2% solution) decreased the tensile strength (TS) and elongation at break about 6% and 37%, respectively, but tensile modulus and impact strength improved about 27% and 32%, respectively. When gamma radiation was applied through the untreated and treated composites the mechanical properties were improved much higher in non-treated Jute/PP-based composites than that of sucrose treated composites. For 5.0 kGy gamma dose the highest mechanical properties were observed for non-treated composites. At 5.0 kGy gamma dose the improvement of TS was 14% and 2% for non-treated and sucrose treated composites, respectively. The water uptake property of the sucrose treated composites was performed up to 10 days and composites absorbed 18% water. The functional groups of the both composites were analyzed by Fourier transform infrared spectroscopy machine. The scanning electron microscopic images of the both composites were taken for the surface and fiber adhesion analysis.

Variation and Grey GM(1, 1) Prediction of Melting Peak Temperature of Polypropylene During Ultraviolet Radiation Aging

NASA Astrophysics Data System (ADS)

Chen, K.; Y Zhang, T.; Zhang, F.; Zhang, Z. R.

2017-12-01

Grey system theory regards uncertain system in which information is known partly and unknown partly as research object, extracts useful information from part known, and thereby revealing the potential variation rule of the system. In order to research the applicability of data-driven modelling method in melting peak temperature (T m) fitting and prediction of polypropylene (PP) during ultraviolet radiation aging, the T m of homo-polypropylene after different ultraviolet radiation exposure time investigated by differential scanning calorimeter was fitted and predicted by grey GM(1, 1) model based on grey system theory. The results show that the T m of PP declines with the prolong of aging time, and fitting and prediction equation obtained by grey GM(1, 1) model is T m = 166.567472exp(-0.00012t). Fitting effect of the above equation is excellent and the maximum relative error between prediction value and actual value of T m is 0.32%. Grey system theory needs less original data, has high prediction accuracy, and can be used to predict aging behaviour of PP.

Evaluation of Environmental Aging of Polypropylene Irradiated Versus Pristine

NASA Astrophysics Data System (ADS)

Romano, Rebeca S. Grecco; Oliani, Washington Luiz; Parra, Duclerc Fernandes; Lugao, Ademar Benevolo

Polypropylene (PP) is the most common thermoplastic resin of the plastic market due to its very interesting physical, chemical and processing properties at very low market price, however after its use the resin does not degrade in the environment or it degrades at very low rate. This study has the objective of comparing the environmental exposure of PP irradiated with 20 kGy and pristine PP. Dumbbell samples were manufactured by injection molding and exposed to the environment during 90 days; another one set was subjected to gamma irradiation at 20 kGy total dose and exposed at the same conditions too. The samples were characterized by mechanical testing, visual inspection, infrared spectroscopy (IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The irradiated samples, after environmental aging, showed oxidation and presence of cracks in samples of the PP 20 kGy.

A study on the tensile properties of silicone rubber/polypropylene fibers/silica hybrid nanocomposites.

PubMed

Ziraki, Sahar; Zebarjad, Seyed Mojtaba; Hadianfard, Mohammad Jafar

2016-04-01

Metacarpophalangeal joint implants have been usually made of silicone rubber. In the current study, silica nano particles and polypropylene fibers were added to silicone rubber to improve silicone properties. The effect of the addition of silica nano particles and polypropylene fibers on the tensile behavior of the resultant composites were investigated. Composite samples with different content of PP fibers and Silica nano particles (i. e. 0, 1 and 2wt%) as well as the hybrid composite of silicone rubber with 1wt% SiO2 and 1wt% PP fiber were prepared. Tensile tests were done at constant cross head speed. To study the body fluid effect on the mechanical properties of silicone rubber composites, samples soaked in simulated body fluid (SBF) at 37°C were also tested. The morphology of the samples were studied by scanning electron microscope. Results of analysis revealed that an increase in PP fibers and silica nano particles content to 2wt%, increases the tensile strength of silicone rubber of about 75% and 42% respectively. It was found out that the strength of the samples decreases after being soaked in simulated body fluid, though composites with PP fibers as the reinforcement showed less property degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel polypropylene/inorganic fullerene-like WS2 nanocomposites containing a β-nucleating agent: dynamic crystallization and melting behavior.

PubMed

Naffakh, Mohammed; Marco, Carlos; Ellis, Gary

2011-09-22

The dynamic crystallization and melting behavior of isotactic polypropylene-tungsten disulfide (iPP/IF-WS(2)) nanocomposites incorporating a β-nucleating agent is investigated by X-ray diffraction and differential scanning calorimetry. A conventional melt-processing strategy is employed to generate new materials that exhibit variable α and β polymorphism under the appropriate kinetic conditions. The results show that when the dual additive system is employed the nucleation ability on isotactic polypropylene not only depends on the nucleation efficiency (NE) and relative content of the individual α and β-nucleating agents, but also on the cooling rates employed. The nucleating behavior of the additives is explained by competitive nucleation, and the correlation between crystallization and melting temperatures and relative content of α and β-crystals of iPP in the nanocomposites is discussed.

Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joshi, Ujjwal Man, E-mail: umjoshi@gmail.com; Subedi, Deepak Prasad, E-mail: deepaksubedi2001@yahoo.com

Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H{sub 2}O), glycerol (C{sub 3}H{sub 8}O{sub 3}) and diiodomethane (CH{sub 2}I{sub 2}) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase inmore » surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.« less

Radiation-grafting of vinyl monomers separately onto polypropylene monofilament sutures

NASA Astrophysics Data System (ADS)

López-Saucedo, Felipe; Alvarez-Lorenzo, Carmen; Concheiro, Angel; Bucio, Emilio

2017-03-01

N-isopropylacrylamide (NIPAAm), 2-hydroxyethylmethacrylate (HEMA) and N-vinylimidazole (NVIm) were grafted separately onto polypropylene (PP) monofilament sutures. These grafted copolymers have properties with potential application in the synthesis of new medical devices. Co-60 gamma radiation was employed with dose rate of 9.2 kGyh-1 in synthesis of copolymers with different grafting percentages: PP-g-PNIPAAm from 11% to 175%, PP-g-PHEMA from 6% to 130%, and PP-g-PNVIm from 10% to 17%. Both NIPAAm and HEMA were grafted applying the pre-irradiation method under different reaction conditions: dose, temperature, monomer concentration and reaction time; NVIm was grafted by simultaneous method with doses from 20 up to 60 kGy. Grafted polymers were characterized by FTIR-ATR, TGA and DSC; and their swelling in water was recorded. Modified suture PP-g-PNIPAAm had thermo-responsive properties while PP-g-PNVIm exhibited pH-sensitive swelling. Overall, the implemented grafting strategies provided a hydrophilic surface layer that did not cause detrimental effects on mechanical properties and cytocompatibility of the sutures.

Introduction of anticoagulation group to polypropylene film by radiation grafting and its blood compatibility

NASA Astrophysics Data System (ADS)

Mao, Chun; Zhang, Can; Qiu, Yongzhi; Zhu, Aiping; Shen, Jian; Lin, Sicong

2004-04-01

Based on in vitro tests for an improvement of the blood compatibility of polypropylene (PP) films by grafting O-butyrylchitosan (OBCS), we prepared a novel biocompatible film. The immobilization was accomplished by irradiating with ultraviolet light, OBCS being coated on the film surface to photolyze azide groups, thus cross-linking OBCS and PP together. The grafted sample films were verified by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA) and the water contact angle measurements. The blood compatibility of the OBCS-grafted PP films was evaluated by platelet rich plasma (PRP) contacting experiments and protein adsorption experiments using blank PP film as the control. It demonstrated that blood compatibility of the OBCS-grafted surfaces is better than that of the blank PP. The suitable modifications could be carried out to tailor PP biomaterial to meet the specific needs of different biomedical applications. These results suggest that the photocrosslinkable chitosan developed here has the potential of serving as a new biomaterial in medical use.

Extracellular matrix regenerative graft attenuates the negative impact of polypropylene prolapse mesh on vagina in rhesus macaque.

PubMed

Liang, Rui; Knight, Katrina; Barone, William; Powers, Robert W; Nolfi, Alexis; Palcsey, Stacy; Abramowitch, Steven; Moalli, Pamela A

2017-02-01

The use of wide pore lightweight polypropylene mesh to improve anatomical outcomes in the surgical repair of prolapse has been hampered by mesh complications. One of the prototype prolapse meshes has been found to negatively impact the vagina by inducing a decrease in smooth muscle volume and contractility and the degradation of key structural proteins (collagen and elastin), resulting in vaginal degeneration. Recently, bioscaffolds derived from extracellular matrix have been used to mediate tissue regeneration and have been widely adopted in tissue engineering applications. Here we aimed to: (1) define whether augmentation of a polypropylene prolapse mesh with an extracellular matrix regenerative graft in a primate sacrocolpopexy model could mitigate the degenerative changes; and (2) determine the impact of the extracellular matrix graft on vagina when implanted alone. A polypropylene-extracellular matrix composite graft (n = 9) and a 6-layered extracellular matrix graft alone (n = 8) were implanted in 17 middle-aged parous rhesus macaques via sacrocolpopexy and compared to historical data obtained from sham (n = 12) and the polypropylene mesh (n = 12) implanted by the same method. Vaginal function was measured in passive (ball-burst test) and active (smooth muscle contractility) mechanical tests. Vaginal histomorphologic/biochemical assessments included hematoxylin-eosin and trichrome staining, immunofluorescent labeling of α-smooth muscle actin and apoptotic cells, measurement of total collagen, collagen subtypes (ratio III/I), mature elastin, and sulfated glycosaminoglycans. Statistical analyses included 1-way analysis of variance, Kruskal-Wallis, and appropriate post-hoc tests. The host inflammatory response in the composite mesh-implanted vagina was reduced compared to that following implantation with the polypropylene mesh alone. The increase in apoptotic cells observed with the polypropylene mesh was blunted in the composite (overall P < .001). Passive mechanical testing showed inferior parameters for both polypropylene mesh alone and the composite compared to sham whereas the contractility and thickness of smooth muscle layer in the composite were improved with a value similar to sham, which was distinct from the decreases observed with polypropylene mesh alone. Biochemically, the composite had similar mature elastin content, sulfated glycosaminoglycan content, and collagen subtype III/I ratio but lower total collagen content when compared to sham (P = .011). Multilayered extracellular matrix graft alone showed overall comparable values to sham in aspects of the biomechanical, histomorphologic, or biochemical endpoints of the vagina. The increased collagen subtype ratio III/I with the extracellular matrix graft alone (P = .033 compared to sham) is consistent with an ongoing active remodeling response. Mesh augmentation with a regenerative extracellular matrix graft attenuated the negative impact of polypropylene mesh on the vagina. Application of the extracellular matrix graft alone had no measurable negative effects suggesting that the benefits of this extracellular matrix graft occur when used without a permanent material. Future studies will focus on understanding mechanisms. Copyright © 2016. Published by Elsevier Inc.

Extracellular matrix regenerative graft attenuates the negative impact of polypropylene prolapse mesh on vagina in rhesus macaque

PubMed Central

Liang, Rui; Knight, Katrina; Barone, William; Powers, Robert W.; Nolfi, Alexis; Palcsey, Stacy; Abramowitch, Steven; Moalli, Pamela A.

2016-01-01

BACKGROUND The use of wide pore lightweight polypropylene mesh to improve anatomical outcomes in the surgical repair of prolapse has been hampered by mesh complications. One of the prototype prolapse meshes has been found to negatively impact the vagina by inducing a decrease in smooth muscle volume and contractility and the degradation of key structural proteins (collagen and elastin), resulting in vaginal degeneration. Recently, bioscaffolds derived from extracellular matrix have been used to mediate tissue regeneration and have been widely adopted in tissue engineering applications. OBJECTIVE Here we aimed to: (1) define whether augmentation of a polypropylene prolapse mesh with an extracellular matrix regenerative graft in a primate sacrocolpopexy model could mitigate the degenerative changes; and (2) determine the impact of the extracellular matrix graft on vagina when implanted alone. STUDY DESIGN A polypropylene-extracellular matrix composite graft (n = 9) and a 6-layered extracellular matrix graft alone (n = 8) were implanted in 17 middle-aged parous rhesus macaques via sacrocolpopexy and compared to historical data obtained from sham (n = 12) and the polypropylene mesh (n = 12) implanted by the same method. Vaginal function was measured in passive (ball-burst test) and active (smooth muscle contractility) mechanical tests. Vaginal histomorphologic/ biochemical assessments included hematoxylin-eosin and trichrome staining, immunofluorescent labeling of α-smooth muscle actin and apoptotic cells, measurement of total collagen, collagen subtypes (ratio III/ I), mature elastin, and sulfated glycosaminoglycans. Statistical analyses included 1-way analysis of variance, Kruskal-Wallis, and appropriate posthoc tests. RESULTS The host inflammatory response in the composite mesh-implanted vagina was reduced compared to that following implantation with the polypropylene mesh alone. The increase in apoptotic cells observed with the polypropylene mesh was blunted in the composite (overall P < .001). Passive mechanical testing showed inferior parameters for both polypropylene mesh alone and the composite compared to sham whereas the contractility and thickness of smooth muscle layer in the composite were improved with a value similar to sham, which was distinct from the decreases observed with polypropylene mesh alone. Biochemically, the composite had similar mature elastin content, sulfated glycosaminoglycan content, and collagen subtype III/I ratio but lower total collagen content when compared to sham (P = .011). Multilayered extracellular matrix graft alone showed overall comparable values to sham in aspects of the biomechanical, histomorphologic, or biochemical end-points of the vagina. The increased collagen subtype ratio III/I with the extracellular matrix graft alone (P = .033 compared to sham) is consistent with an ongoing active remodeling response. CONCLUSION Mesh augmentation with a regenerative extracellular matrix graft attenuated the negative impact of polypropylene mesh on the vagina. Application of the extracellular matrix graft alone had no measurable negative effects suggesting that the benefits of this extra-cellular matrix graft occur when used without a permanent material. Future studies will focus on understanding mechanisms. PMID:27615441

Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

NASA Astrophysics Data System (ADS)

Liu, Wenyong; Luo, Yuting; Sun, Linyu; Wu, Ruomei; Jiang, Haiyun; Liu, Yuejun

2013-01-01

We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low surface free energy, the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

E-beam sterilizable thermoplastics elastomers for healthcare devices: Mechanical, morphology, and in vivo studies.

PubMed

Balaji, Ananad Bellam; Ratnam, Chantara Thevy; Khalid, Mohammad; Walvekar, Rashmi

2018-03-01

The effect of electron beam radiation on ethylene-propylene diene terpolymer/polypropylene blends is studied as an attempt to develop radiation sterilizable polypropylene/ethylene-propylene diene terpolymer blends suitable for medical devices. The polypropylene/ethylene-propylene diene terpolymer blends with mixing ratios of 80/20, 50/50, 20/80 were prepared in an internal mixer at 165°C and a rotor speed of 50 rpm/min followed by compression molding. The blends and the individual components were radiated using 3.0 MeV electron beam accelerator at doses ranging from 0 to 100 kGy in air and room temperature. All the samples were tested for tensile strength, elongation at break, hardness, impact strength, and morphological properties. After exposing to 25 and 100 kGy radiation doses, 50% PP blend was selected for in vivo studies. Results revealed that radiation-induced crosslinking is dominating in EPDM dominant blends, while radiation-induced degradation is prevailing in PP dominant blends. The 20% PP blend was found to be most compatible for 20-60 kGy radiation sterilization. The retention in impact strength with enhanced tensile strength of 20% PP blend at 20-60 kGy believed to be associated with increased compatibility between PP and EPDM along with the radiation-induced crosslinking. The scanning electron micrographs of the fracture surfaces of the PP/EPDM blends showed evidences consistent with the above contentation. The in vivo studies provide an instinct that the radiated blends are safe to be used for healthcare devices.

Impact and hardness optimisation of composite materials inspired by the babassu nut (Orbignya speciosa).

PubMed

Staufenberg, Gerrit; Graupner, Nina; Müssig, Jörg

2015-08-20

The babassu nut is the fruit of the babassu palm Orbignya speciosa. The combination of hardness and impact strength is difficult to acquire for artificial materials, making the babassu nut a promising source for biomimetic inspiration. Unnotched Charpy impact tests, Shore D hardness tests and scanning electron microscopy were used for mechanical and microscopical analysis of the pericarp. Four major principles were found for a biomimetic approach: a hard core ((1); endocarp) is embedded in a soft outer layer of high impact strength ((2); epicarp) and is reinforced with fibres of variable fineness (3), some of which are oriented radial to the core (4). Biomimetic fibre-reinforced composites were produced using abstracted mechanisms of the babassu nut based on regenerated cellulose fibres (lyocell, L) with two different fineness values as reinforcement embedded in a polylactide (PLA) core matrix and polypropylene (PP) based outer layers. The biomimetic fibre composite reaches a significantly higher impact strength that is 1.6 times higher than the reference sample produced from a PLA/PP/L-blend. At the same time the hardness is slightly increased compared to PP/L.

Flexure and impact properties of glass fiber reinforced nylon 6-polypropylene composites

NASA Astrophysics Data System (ADS)

Kusaseh, N. M.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Azhari, A.; Iqbal, A. K. M. A.

2018-03-01

In recent years, polymer composites are rapidly developing and replacing the metals or alloys in numerous engineering applications. These polymer composites are the topic of interests in industrial applications such as automotive and aerospace industries. In the present research study, glass fiber (GF) reinforced nylon 6 (PA6)-polypropylene (PP) composite specimens were prepared successfully using injection molding process. Test specimens of five different compositions such as, 70%PA6+30%PP, 65%PA6+30%PP+5%GF, 60%PA6+30%PP+10%GF, 55%PA6+30%PP+15%GF and 50%PA6+30%PP+20%GF were prepared. In the experiments, flexure and impact tests were carried out. The obtained results revealed that flexure and impact properties of the polymer composites were significantly influenced by the glass fiber content. Results showed that flexural strength is low for pure polymer blend and flexural strength of GF reinforced composite increases gradually with the increase in glass fiber content. Test results also revealed that the impact strength of 70%PA6+30%PP is the highest and 55%PA6+30%PP+15%GF composite shows moderate impact strength. On the other hand, 50%PA6+30%PP+20%GF composite shows low toughness or reduced impact strength.

3D printing of polypropylene using the fused filament fabrication technique

NASA Astrophysics Data System (ADS)

Silva, A. F.; Carneiro, O. S.; Gomes, R.

2017-10-01

This work addresses the potential of polypropylene, neat (PP) and reinforced with short glass fibers (GRPP), as a candidate for the Fused Filament Fabrication (FFF)-based 3D printing technique. The entire production chain was evaluated, i.e., starting with PP and GRPP pellets, filaments were produced by extrusion and test samples were printed in different process conditions (different layers' thicknesses, deposition orientation and infill) with the in-house produced filaments. This strategy enabled a true comparison between parts printed (FFF) with parts manufactured by compression molding (CM), using exactly the same grade of raw material.

Effect of Micro Porous Shape on Mechanical Properties in Polypropylene Syntactic Foams

NASA Astrophysics Data System (ADS)

Mae, Hiroyuki; Omiya, Masaki; Kishimoto, Kikuo

The objective is to characterize the effect of the microstructure of the micro pores inside the matrix on the mechanical properties of the thermoplastic syntactic polypropylene (PP) foams at the intermediate and high strain rates. Tensile tests are conducted at the nominal strain rates from 3 x 10-1 to 102 s-1. In addition, the dart impact tests are conducted at the impact velocities of 0.1, 1 and 10 m/s. Then, the constitutive law with craze evolution is modified by introducing the relative density, the stress concentration coefficient and the volume fraction of cell edge, and then applied to the dart impact test mode for simulating the macroscopic load displacement history of the dart impact process. Moreover, the microstructural finite element analysis is conducted to characterize the local stress states in the microstructure. In the tensile loading, the elastic modulus is not influenced by the shape of the micro pores in the PP matrix while the yield stress and the strain energy up to failure are relatively influenced by the shape of micro pores. The microstructural finite element analysis shows that the magnitudes of the localized stresses at the edges and the ligaments of the elliptical-shape micro pores are larger than those at the spherical micro pores, leading to the early yielding and the small material ductility. In the case of the dart impact loading, the microstructure of pores has strong effect on the absorbed energy. This is because the elliptical-shape micro pores are very sensitive to the shear deformation, which is revealed by the microstructural finite element analysis. The modified constitutive law with the stress concentration coefficient and the volume fraction of the cell edges successfully predicts the load-displacement curve of the dart impact loading in the spherical micro-porous PP foam. It is concluded that the micro porous shape has strong effect on the material ductility especially in the dart impact test, leading to the possibility to control the material ductility by the shape of the micro pores in the polymeric foams.

Morphology Evolution of Polypropylene in Immiscible Polymer Blends for Fabrication of Nanofibers

USDA-ARS?s Scientific Manuscript database

Immiscible blends of cellulose acetate butyrate (CAB) and isotactic polypropylenes (iPPs) with different melting index were extruded through a two-strand rod die. The extrudates were hot-drawn at the die exit at different draw ratios by controlling the drawing speed. The morphologies of iPP fibers e...

Facile preparation in two steps of highly hydrophobic coatings on polypropylene surface

NASA Astrophysics Data System (ADS)

Petcu, Cristian; Nistor, Cristina Lavinia; Purcar, Violeta; Cinteză, Ludmila Otilia; Spătaru, Cătălin-Ilie; Ghiurea, Marius; Ianchiş, Raluca; Anastasescu, Mihai; Stoica, Mihai

2015-08-01

Monolayer and bilayer coatings deposited on polypropylene (PP) surface were prepared by sol-gel process at room temperature. Monolayer coatings were produced from sol-gel acidic solutions, containing tetraethylorthosilicate (TEOS) and different co-precursors such as phenyltriethoxysilane (PhTES), octylmethyldimethoxysilane (OMDMS) and dodecyltriethoxysilane (DOTES). Bilayer coatings consist of one layer prepared in a similar way described for monolayer coatings, followed by a second layer, obtained from fluorinated silica nanoparticles dispersion. The fluorinated group has been confirmed by the presence of Csbnd F bonds along with network Sisbnd Osbnd Si vibrational mode. Water contact angle values registered for bilayer-coated polypropylene are higher, comparing with the reference (pristine PP) and with the monolayer-coated substrate, and varies as a function of the hydrophobic functional groups of the silica co-precursors: phenyl < octyl < dodecyl. The fluorooctyl functions lead to a significant decrease in the surface energy values for bilayer coating, with very small values of polar component.

Zinc Oxide-Enhanced Piezoelectret Polypropylene Microfiber for Mechanical Energy Harvesting.

PubMed

Zhu, Jianxiong; Zhu, Yali; Song, Weixing; Wang, Hui; Gao, Min; Cho, Minkyu; Park, Inkyu

2018-06-13

This paper reports zinc oxide (ZnO)-coated piezoelectret polypropylene (PP) microfibers with a structure of two opposite arc-shaped braces for enhanced mechanical energy harvesting. The ZnO film was coated onto PP microfibers via magnetron sputtering to form a ZnO/PP compound structure. Triboelectric Nanogenerator (TENG) based on ZnO/PP microfiber compound film was carefully designed with two opposite arc-shaped braces. The results of this study demonstrated that the mechanical energy collection efficiency of TENG based on piezoelectret PP microfiber was greatly enhanced by the coated ZnO and high-voltage corona charging method. We found that, with the step-increased distance of traveling for the movable carbon black electrode, an electrical power with an approximately quadratic function of distance was generated by this mechanical-electrical energy conversion, because more PP microfibers were connected to the electrode. Further, with a full contact condition, the peak of the generated voltage, current, and charges based on the ZnO/PP microfibers by this mechanical-electrical energy conversion with 1 m/s 2 reached 120 V, 3 μA, and 49 nC, respectively. Moreover, a finger-tapping test was used to demonstrate that the ZnO/PP microfiber TENG is capable of lighting eight light-emitting diodes.

Tensile Properties and Deflection Temperature of Polypropylene/Sumberejo Kenaf Fiber Composites with Fiber Content Variation

NASA Astrophysics Data System (ADS)

Ollivia, S. L.; Juwono, A. L.; Roseno, Seto

2017-05-01

The use of synthetic fibers as reinforcement in composites has disadvantage which are unsustainable and an adverse impact on the environment. An alternative reinforcement for composites is natural fiber. Polypropylene and Sumberejo kenaf fibers were used respectively as the matrix and reinforcement. The aim of this research was to obtain the optimum tensile properties and deflection temperature with the variation of kenaf fiber fractions. Polypropylene/kenaf fiber composites were fabricated by hot press method. The kenaf fiber was soaked in NaOH solution before being used as the reinforcement and polypropylene was extruded before being used as the matrix. The weight fractions were varied to produce composites and pristine polypropylene samples were also prepared for comparison. The optimum tensile strength, modulus and deflection temperature were found in the composites with the 40 wt% kenaf fiber fraction with an increase up to 80% and 170% compared to the pristine polypropylene with the values of (60.3 ± 4,3) MPa and (159.1 ± 1,8) °C respectively. The Scanning Electron Microscope observation results in the fracture surface of the composites with the 40 wt% fiber fraction showed a relatively good bonding interface between fibers and the matrix and the failure modes were fiber breakage and matrix failures.

The Study on the Mechanical Properties of Multi-walled Carbon Nanotube/Polypropylene Fibers

NASA Astrophysics Data System (ADS)

Youssefi, Mostafa; Safaie, Banafsheh

2018-06-01

Polypropylene (PP) is an important semicrystalline polymer with various applications. Polypropylene fibers containing 1 wt% of multi-walled carbon nanotube was spun using a conventional melt spinning apparatus. The produced fibers were drawn with varying levels of draw ratio. The mechanical properties of the composites were studied. Tensile strength and modulus of the composite fibers were increased with the increase in draw ratio. Molecular orientation and helical content of the composite fibers were increased after drawing. To conclude, tensile properties and molecular orientation of the composite fibers were higher than those of neat polypropylene fibers with the same draw ratio.

The Study on the Mechanical Properties of Multi-walled Carbon Nanotube/Polypropylene Fibers

NASA Astrophysics Data System (ADS)

Youssefi, Mostafa; Safaie, Banafsheh

2018-01-01

Polypropylene (PP) is an important semicrystalline polymer with various applications. Polypropylene fibers containing 1 wt% of multi-walled carbon nanotube was spun using a conventional melt spinning apparatus. The produced fibers were drawn with varying levels of draw ratio. The mechanical properties of the composites were studied. Tensile strength and modulus of the composite fibers were increased with the increase in draw ratio. Molecular orientation and helical content of the composite fibers were increased after drawing. To conclude, tensile properties and molecular orientation of the composite fibers were higher than those of neat polypropylene fibers with the same draw ratio.

Chapter 1.4: Spatially Resolved Characterization of CNC-Polypropylene composite by Confocal Raman Microscopy

Treesearch

Umesh Agarwal; Ronald Sabo; Richard Reiner; Craig Clemons; Alan Rudie

2013-01-01

Raman spectroscopy was used to analyze cellulose nanocrystal (CNC)-polypropylene (PP) composites and to investigate the spatial distribution of CNCs in extruded composite filaments. Three composites were made from two forms of nanocellulose (CNCs from wood pulp and the nanoscale fraction of microcrystalline cellulose), and two of the three composites...

Spatially Resolved Characterization of Cellulose Nanocrystal-Polypropylene Composite by Confocal Raman Microscopy

Treesearch

Umesh P. Agarwal; Ronald Sabo; Richard S. Reiner; Craig M. Clemons; Alan W. Rudie

2012-01-01

Raman spectroscopy was used to analyze cellulose nanocrystal (CNC)–polypropylene (PP) composites and to investigate the spatial distribution of CNCs in extruded composite filaments. Three composites were made from two forms of nanocellulose (CNCs from wood pulp and the nanoscale fraction of microcrystalline cellulose) and two of the three composites investigated used...

Transcrystalline interphases in natural fiber-PP composites: effect of coupling agent

Treesearch

A.R. Sanadi; D.F. Caulfield

2000-01-01

The interest in lignocellulosic fiber composites has been growing in recent years because of their high specific properties. In this work, a new technique was used to prepare specimen to observe the transcrystalline zones in kenaf fiber-polypropylene composites. A maleated polypropylene (MAPP) coupling agent was used to improve the stress-transfer efficiency in the...

Evaluation of the mechanical and thermal properties of coffee tree wood flour - polypropylene composites

USDA-ARS?s Scientific Manuscript database

Columbian coffee trees are subject to frequent replacement plantings due to disease and local climate changes which makes them an ideal source of wood fibers for wood plastic composites (WPC). Composites of polypropylene (PP) consisting of 25% and 40% by weight of coffee wood flour (CF) and 0% or 5%...

Development of advanced antimicrobial and sterilized plasma polypropylene grafted muga (Antheraea assama) silk as suture biomaterial.

PubMed

Gogoi, Dolly; Choudhury, Arup Jyoti; Chutia, Joyanti; Pal, Arup Ratan; Khan, Mojibur; Choudhury, Manash; Pathak, Pallabi; Das, Gouranga; Patil, Dinkar S

2014-04-01

Surface modification of silk fibroin (SF) materials using environmentally friendly and non-hazardous process to tailor them for specific application as biomaterials has drawn a great deal of interest in the field of biomedical research. To further explore this area of research, in this report, polypropylene (PP) grafted muga (Antheraea assama) SF (PP-AASF) suture is developed using plasma treatment and plasma graft polymerization process. For this purpose, AASF is first sterilized in argon (Ar) plasma treatment followed by grafting PP onto its surface. AASF is a non-mulberry variety having superior qualities to mulberry SF and is still unexplored in the context of suture biomaterial. AASF, Ar plasma treated AASF (AASFAr) and PP-AASF are subjected to various characterization techniques for better comparison and the results are attempted to correlate with their observed properties. Excellent mechanical strength, hydrophobicity, antibacterial behavior, and remarkable wound healing activity of PP-AASF over AASF and AASFAr make it a promising candidate for application as sterilized suture biomaterial. Copyright © 2013 Wiley Periodicals, Inc.

Robust Polypropylene Fabrics Super-Repelling Various Liquids: A Simple, Rapid and Scalable Fabrication Method by Solvent Swelling.

PubMed

Zhu, Tang; Cai, Chao; Duan, Chunting; Zhai, Shuai; Liang, Songmiao; Jin, Yan; Zhao, Ning; Xu, Jian

2015-07-01

A simple, rapid (10 s) and scalable method to fabricate superhydrophobic polypropylene (PP) fabrics is developed by swelling the fabrics in cyclohexane/heptane mixture at 80 °C. The recrystallization of the swollen macromolecules on the fiber surface contributes to the formation of submicron protuberances, which increase the surface roughness dramatically and result in superhydrophobic behavior. The superhydrophobic PP fabrics possess excellent repellency to blood, urine, milk, coffee, and other common liquids, and show good durability and robustness, such as remarkable resistances to water penetration, abrasion, acidic/alkaline solution, and boiling water. The excellent comprehensive performance of the superhydrophobic PP fabrics indicates their potential applications as oil/water separation materials, protective garments, diaper pads, or other medical and health supplies. This simple, fast and low cost method operating at a relatively low temperature is superior to other reported techniques for fabricating superhydrophobic PP materials as far as large scale manufacturing is considered. Moreover, the proposed method is applicable for preparing superhydrophobic PP films and sheets as well.

Selective aminolysis of acetylated lignin: Toward simultaneously improving thermal-oxidative stability and maintaining mechanical properties of polypropylene.

PubMed

Ye, Dezhan; Kong, Jinfeng; Gu, Shaojin; Zhou, Yingshan; Huang, Caoxing; Xu, Weilin; Zhang, Xi

2018-03-01

Even with outstanding radical capturing ability, the utilization of lignin as a natural antioxidant in polypropylene (PP) still has been pended. Usually, the compatibility of its blends is improved based on the reaction of hydroxyl content, thus leading to the decreasing content of phenolic hydroxyl (Ph-OH) group and inferior thermal-oxidative stability of lignin blends. Here, the selective aminolysis of acetylated Kraft lignin (pyr-KL) was investigated, which structures were characterized using FTIR, 31 P-NMR and GPC. The Ph-OH group of acetylated KL could be released by the addition of pyrrolidine; however the aliphatic hydroxyl group is still blocked. With the control of reaction conditions, the highest oxidation induction time of pyr-KL/PP (0.5wt% loading) reaches up to 22.6min, almost 2.6 times than that of pure PP. More importantly, the mechanical properties of PP were also maintained under the loading of pyr-KL, which is much better than that of curde KL/PP. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of polypropylene/Mg–Al layered double hydroxides nanocomposites through wet pan-milling: non-isothermal crystallization behaviour

PubMed Central

Zheng, Yilei

2018-01-01

Differential scanning calorimeter was used to extensively investigate the non-isothermal crystallization of polypropylene (PP)/layered double hydroxides (LDHs) nanocomposites prepared through wet solid-state shear milling. The corresponding crystallization kinetics was further investigated by using Ozawa, modified Avrami and combined Avrami–Ozawa method, respectively. The results showed that the Ozawa method could not well describe the crystallization kinetics of pure PP and its nanocomposites. Comparatively, the modified Avrami method as well as the combined Avrami–Ozawa method gives the satisfactory results. Under the effect of pan-milling, the produced LDH nano intercalated/exfoliated particles exhibit the inhibitive effect on the PP nucleation but more remarkable promotion effect on the spherulite growth, leading to enhancement in the overall crystallization rate. This is reflected in increase of the calculated fold surface free energy σe and also the supercooling degree ΔT required for crystallization nucleation. In addition, the polarized optical microscopy observation also verifies the higher spherulite growth rate of PP/LDHs nanocomposites than that of pure PP. PMID:29410819

Spinning, structure and properties of PP/CNTs and PP/carbon black composite fibers

NASA Astrophysics Data System (ADS)

Marcincin, A.; Hricova, M.; Ujhelyiova, A.

2014-08-01

In this paper, the effect of the compatibilisers-dispersants and other nanofillers on melt spinning of the polypropylene (PP) composites, containing carbon nanotubes (CNTs), and carbon black pigment (CBP) has been investigated. Further, the structure and selected properties of composite fibers, such as mechanical and electrical have been studied. The results revealed, that percolation threshold for PP/CBP composite fibres was situated within the concentration of 15 - 20 wt%, what is several times higher than for PP/CNTs fibers.

Influence of injection temperatures and fiberglass compositions on mechanical properties of polypropylene

NASA Astrophysics Data System (ADS)

Keey, Tony Tiew Chun; Azuddin, M.

2017-06-01

Injection molding process appears to be one of the most suitable mass and cost efficiency manufacturing processes for polymeric parts nowadays due to its high efficiency of large scale production. When down-scaling the products and components, the limits of conventional injection molding process are reached. These constraints had initiated the development of conventional injection molding process into a new era of micro injection molding technology. In this study, fiberglass reinforced polypropylenes (PP) with various glass fiber percentage materials were used. The study start with fabrication of micro tensile specimens at three different injection temperature, 260°C, 270°C and 280°C for different percentage by weight of fiberglass reinforced PP. Then evaluate the effects of various injection temperatures on the tensile properties of micro tensile specimens. Different percentage by weight of fiberglass reinforced PP were tested as well and it was found that 20% fiberglass reinforced PP possessed the greatest percentage increase of tensile strength with increasing temperatures.

Non-cross-linked porcine acellular dermal matrices for abdominal wall reconstruction.

PubMed

Burns, Nadja K; Jaffari, Mona V; Rios, Carmen N; Mathur, Anshu B; Butler, Charles E

2010-01-01

Non-cross-linked porcine acellular dermal matrices have been used clinically for abdominal wall repair; however, their biologic and mechanical properties and propensity to form visceral adhesions have not been studied. The authors hypothesized that their use would result in fewer, weaker visceral adhesions than polypropylene mesh when used to repair ventral hernias and form a strong interface with the surrounding musculofascia. Thirty-four guinea pigs underwent inlay repair of surgically created ventral hernias using polypropylene mesh, porcine acellular dermal matrix, or a composite of the two. The animals were killed at 4 weeks, and the adhesion tenacity grade and surface area of the repair site involved by adhesions were measured. Sections of the repair sites, including the implant-musculofascia interface, underwent histologic analysis and uniaxial mechanical testing. The incidence of bowel adhesions to the repair site was significantly lower with the dermal matrix (8 percent, p < 0.01) and the matrix/mesh combination (0 percent, p < 0.001) than with polypropylene mesh alone (70 percent). The repairs made with the matrix or the matrix/mesh combination, compared with the polypropylene mesh repairs, had significantly lower mean adhesion surface areas [12.8 percent (p < 0.001), 9.2 percent (p < 0.001), and 79.9 percent] and grades [0.6 (p < 0.001), 0.6 (p < 0.001), and 2.9]. The dermal matrix underwent robust cellular and vascular infiltration. The ultimate tensile strength at the implant-musculofascia interface was similar in all groups. Porcine acellular dermal matrix becomes incorporated into the host tissue and causes fewer adhesions to repair sites than does polypropylene mesh, with similar implant-musculofascia interface strength. It also inhibits adhesions to adjacent dermal matrix in the combination repairs. It has distinct advantages over polypropylene mesh for complex abdominal wall repairs, particularly when material placement directly over bowel is unavoidable.

Polypropylenes foam consisting of thermally expandable microcapsule as blowing agent

NASA Astrophysics Data System (ADS)

Jeoung, Sun Kyung; Hwang, Ye Jin; Lee, Hyun Wook; Kwak, Sung Bok; Han, In-Soo; Ha, Jin Uk

2016-03-01

The structure of thermally expandable microcapsule (TEMs) is consisted of a thermoplastic shell which is filled with liquid hydrocarbon at core. The shell of TEMs becomes soft when the temperature is higher than boiling temperature of liquid hydrocarbon. The shell of TEMs is expanded under the high temperature because the inner pressure of TEMs is increased by vaporization of hydrocarbon core. Therefore, the TEMs are applicable for blowing agents and light weight fillers. In this research, we fabricated the polypropylene (PP) foam by using the TEMs and chemical blowing agents and compared to their physical properties. The density of the specimen was decreased when the contents of chemical blowing agents and TEMs were increased. In addition, the mechanical properties (i.e. tensile strength and impact strength) of specimens were deteriorated with increasing amount of chemical blowing agents and TEMs. However, PP foam produced with TEMs showed higher impact strength than the one with the chemical blowing agent. In order to clarify the dependence of impact strength of PP foam as the blowing agent, the morphology difference of the PP foams was investigated. Expanding properties of PP foams produced with TEMs was changed with TEMs content of PP foams. Processing conditions also influenced the mechanical properties of PP foam containing TEMs.

Effects of Polypropylene Orientation on Mechanical and Heat Seal Properties of Polymer-Aluminum-Polymer Composite Films for Pouch Lithium-Ion Batteries.

PubMed

Zeng, Fangxinyu; Chen, Jinyao; Yang, Feng; Kang, Jian; Cao, Ya; Xiang, Ming

2018-01-16

In this study, polyamide-aluminum foil-polypropylene (PA-Al-PP) composite films with different orientation status of the PP layer were prepared, and their morphology, tensile, peeling and heat seal behavior were studied. The comparative study of tensile and fracture behaviors of single-layer film of PA, Al and PP, as well as the composite films of PA-Al, PP-Al and PA-Al-PP revealed that in PA-Al-PP composite film, the PA layer with the highest tensile strength can share the tensile stress from the Al layer during stretching, while the PP layer with the lowest tensile strength can prevent further development of the small cracks on boundary of the Al layer during stretching. Moreover, the study of heat seal behavior suggested that both the orientation status and the heat seal conditions were important factors in determining the heat seal strength ( HSS ) and failure behavior of the sample. Four failure types were observed, and a clear correspondence between HSS and failure types was found. The results also elucidated that for the composite film, only in the cases where the tensile stress was efficiently released by each layer during HSS measurement could the composite film exhibit desired high HSS that was even higher than its tensile strength.

Effect of cyclical thermal to mechanical properties of Hybrid Laminate Composites (HLC) with skin recycle polypropylene/natural fiber/halloysite and core PP/KF composites

NASA Astrophysics Data System (ADS)

Sri Suharty, Neng; Ismail, Hanafi; Suci Handayani, Desi; Diharjo, Kuncoro; Rachman Wibowo, Fajar; Arnita Wuri, Margaretha

2016-02-01

This research has successfully synthesized six hybrid laminate composites (HLC). These HLC consist of two layers skin composites and one layer of core PP/KF composites. There are sticked with epoxy adhesive by using cold press method. In this research 6 types of skin are used, namely the rPP (recycled polypropylene, HC1); rPP/DVB/PP-g-AA/KF (HC2); rPP/DVB/PP-g-AA/Hall (HC3); rPP/DVB/PP-g-AA/Hall+ZB (HC4); rPP/DVB/PP-g-AA/KF/Hall (HC5) and rPP/DVB/PP-g-AA/KF/Hall+ZB (HC6) composites. The mechanical properties assessment tensile strength (TS) of various HLC before and after cyclical thermal (CT) was done by ASTM D638. While testing the flame retardant: such as time to ignition (TTI) and burning rate (BR) was done by ASTM D635. Heat stability of HLC can be recognized by conducting the CT treatment. It is to determine the effect of fluctuating heat loads on mechanical properties of HLC materials. The TS result of five HLCs (HC2, HC3, HC4, HC5 and HC6) before CT treatment were higher than HC1 (blank HLC). Those five HLC are also able to increase the TTI and reduce the BR compared to HC1. The CT treatment conditions performed at 45 oC as much as 125 times. After CT treatment, the TS values only slightly decline compared to before CT treatment.

Study on structure and hydrophobicity of PP/EVA co-blending membrane: Quenching rate

NASA Astrophysics Data System (ADS)

Tang, Na; Li, Zhao; Hua, Xinxin

2017-03-01

Isotactic polypropylene (iPP)/ethylene vinyl acetate (EVA) co-blending hydrophobic microporous membranes for vacuum membrane distillation (VMD) were prepared via thermally induced phase separation (TIPS). In the process of preparation, quenching rate has a great influence on the membrane morphology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Causa, Andrea; Acierno, Domenico; Filippone, Giovanni

We prepare and characterize multiphase systems in which small amounts of recycled polymer, namely polyethylene terephtalate (PET) ground from waste bottles, are dispersed in a co-continuous blend of high-density polyethylene (HDPE) and polypropylene (PP). Some of such ternary systems are also filled with plate-like clay nanoparticles with different polarities, in order to assess their influence on the morphology and mechanical behaviour of the blends. On the basis of preliminary wettability considerations and inspections by means of scanning electron microscopy (SEM), the PET is found to preferentially locate within the PP phase. Such a positioning is desirable in order to minimizemore » the presence of multiple interfaces, which is one of the major issues in the recycling process of co-mingles plastics. By means of SEM, dynamic-mechanical analysis and tensile tests we show that the addition of a filler with low polarity, which locates at the PET-matrix interface, has relevant implications on the structure and properties of the ternary systems, refining their morphology at the micro-scale and enhancing their high-temperature mechanical behaviour.« less

Barrier properties of PE, PP and EVA (nano)composites - The influence of filler type and concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merinska, D.; Kalendova, A.; Tesarikova, A.

2014-05-15

Nanocomposite materials with layered clay used as nanofiller and polyethylene (PE), polypropylene (PP) and copolymer ethylene and vinyl acetate matrix (EVA, the content of VA component 19 wt. %) were prepared by compounding the individual components in Brabender kneader. The MMT Na+ and four types of commercial products such as Nanofil N 5 and N3000, Cloisite 93A and 30B were used as nanofillers. Next to the clays microprecipitated CaHCO{sub 3}, nanosilica and Halloysite tubes were used. The quantity of all the above-mentioned (nano)fillers was 1, 3 and 5 wt. % in relation to the content of montmorillonite. The aim wasmore » to evaluate the influence of (nano)filler type and concentration on nanocomposite barrier properties. The morphology of nanocomposite samples was examined by means of XRD analysis illustrated by transmission electronic microscopy TEM. Furthermore, permeability for O{sub 2} and CO{sub 2} were observed.« less

Sirolimus-coated, poly(L-lactic acid)-modified polypropylene mesh with minimal intra-peritoneal adhesion formation in a rat model.

PubMed

Lu, S; Hu, W; Zhang, Z; Ji, Z; Zhang, T

2018-05-18

This study evaluated the manufacturing method and anti-adhesion properties of a new composite mesh in the rat model, which was made from sirolimus (SRL) grafts on a poly(L-lactic acid) (PLLA)-modified polypropylene (PP) hernia mesh. PLLA was first grafted onto argon-plasma-treated native PP mesh through catalysis of stannous chloride. SRL was grafted onto the surface of PP-PLLA meshes using catalysis of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 4-dimethylaminopyridine (DMAP) in a CH 2 Cl 2 solvent. Sprague-Dawley female rats received either SRL-coated meshes, PP-PLLA meshes, or native PP meshes to repair abdominal wall defects. At different intervals, rats were euthanized by a lethal dose of chloral hydrate and adhesion area and tenacity were evaluated. Sections of the mesh with adjacent tissues were assessed histologically. Attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy indicated the existence of a C=O group absorption peak (1724.1 cm -1 ), and scanning electron microscope morphological analysis indicated that the surface of the PP mesh was covered with SRL. Compared to the native PP meshes and PP-PLLA meshes, SRL-coated meshes demonstrated the greatest ability to decrease the formation of adhesions (P < 0.05) and inflammation. The SRL-coated composite mesh showed minimal formation of intra-abdominal adhesions in a rat model of abdominal wall defect repair.

Experimental investigation on flexure and impact properties of injection molded polypropylene-nylon 6-glass fiber polymer composites

NASA Astrophysics Data System (ADS)

Nuruzzaman, D. M.; Kusaseh, N. M.; Chowdhury, M. A.; Rahman, N. A. N. A.; Oumer, A. N.; Fatchurrohman, N.; Iqbal, A. K. M. A.; Ismail, N. M.

2018-04-01

In this research study, glass fiber (GF) reinforced polypropylene (PP)-nylon 6 (PA6) polymer blend composites were prepared using injection molding process. Specimens of four different compositions such as 80%PP+20%PA6, 80%PP+18%PA6+2%GF, 80%PP+16%PA6+4%GF and 80%PP+14%PA6+6%GF were prepared. In the injection molding process, suitable process parameters were selected depending on the type of composite specimen in producing defects free dog bone shaped specimens. Flexure and impact tests were carried out according to ASTM standard. The important flexure properties such as flexural modulus, flexural yield strength, flexural strength and flexural strain were investigated. The obtained results revealed that flexural modulus of 80%PP+20%PA6 polymer blend is the lowest and the polymer blend composite shows steadily improved modulus as the glass fiber content is increased. Results also showed that flexural strength of pure polymer blend is the lowest but it improves gradually when the glass fiber content is increased. Impact test results revealed that impact strength of 80%PP+20%PA6 polymer blend is the highest whereas all the composites show reduced impact strength or toughness. It is noticed that 80%PP+14%PA6+6%GF composite exhibits the lowest impact strength.

Thermal Degradation and Combustion Behavior of Polypropylene/MWCNT Composites

NASA Astrophysics Data System (ADS)

Zaikov, G. E.; Rakhimkulov, A. D.; Lomakin, S. M.; Dubnikova, I. L.; Shchegolikhin, A. N.; Davidov, E. Ya.

2010-06-01

Studies of thermal and fire-resistant properties of the polypropylene/multi-walled carbon nanotube composites (PP/MWCNT) prepared by means of melt intercalation are discussed. The sets of the data acquired with the aid of non-isothermal TG experiments have been treated by the model kinetic analysis. The thermal-oxidative degradation behavior of PP/MWCNT and stabilizing effect caused by addition of MWCNT has been investigated by means of TGA and EPR spectroscopy. The results of cone calorimetric tests lead to the conclusion that char formation plays a key role in the mechanism of flame retardation for nanocomposites. This could be explained by the specific antioxidant properties and high thermal conductivity of MWCNT which determine high-performance carbonization during thermal degradation process. Comparative analysis of the flammability characteristics for PP-clay/MWCNT nanocomposites was provided in order to emphasize the specific behavior of the nanocomposites under high-temperature tests.

Influence of different components in a TPV PP/EPDM based with low hardness

NASA Astrophysics Data System (ADS)

Gheller, J.; Jacobi, M. M.

2014-05-01

Thermoplastic vulcanizates (TPVs) are a class of polymeric material obtained by dynamic vulcanization of an elastomer in a melted thermoplastic matrix. This work intend to evaluate different variables in the production of low hardness TPVs made of polypropylene (PP) and ethylene propylene rubber (EPDM), as well the optimization of the variables looking for TPVs with improved performance. In the Study I the influence of PP crystallinity were evaluated, in the Study II the effects of different amounts of dicumyl peroxide (DCP) were evaluated and in the Study III the amount of the phenolic resin were evaluated. This extended abstract presents, in a more detailed way, the results considering the curative phenolic resin content (Study III). The others results and discussions are briefly described in the results and discussions section. The compounds were obtained in a closed mixing chamber and their processability properties, swelling, hardness and tensile strength were evaluated. With the results obtained were possible to evaluate the influence of different ingredients in the TPVs properties. The results were discussed and presented looking for a better understanding of the influence of this variable in the final product, as well the correlation between then.

[Quantification of Wood Flour and Polypropylene in Chinese Fir/Polypropylene Composites by FTIR].

PubMed

Lao, Wan-li; Li, Gai-yun; Zhou, Qun; Qin, Te-fu

2015-06-01

The ratio of wood and plastic in Wood Plastic Composites (WPCss) influences quality and price, but traditional thermochemical methods cannot rapidly and accurately quantify the ratio of wood/PP in WPCss. This paper was addressed to investigate the feasibility of quantifying the wood flour content and plastic content in WPCss by Fourier Transform Infrared (FTIR) spectroscopy. With Chinese fir, polypropylene (PP) and other additives as raw materials, 13 WPCs samples with different wood flour contents, ranging from 9.8% to 61.5%, were prepared by modifying wood flour, mixing materials and extrusion pelletizing. The samples were analyzed by FTIR with the KBr pellets technique. The absorption peaks of WPCss at 1059, 1 033 and 1 740 cm(-1) are considered as characteristic of Chinese fir, and the absorption peaks at 1 377, 2 839 and 841 cm(-1) are typical of PP by comparing the spectra of WPCss with that of Chinese fir, PP and other additives. The relationship between the wood flour content, PP content in WPCss and their characteristic IR peaks height ratio was established. The results show that there is a strong linear correlation between the wood flour content in WPCss and I1 059/l 1 377/I1 033, /I1377, R2 are 0.992 and 0.993 respectively; there is a high linear correlation between the PP content in WPCss and I1 377/I1 740, I2 839 /I1 740 R2 are 0.985 and 0.981, respectively. Quantitative methods of the wood flour content and PP content in WPCss by FTIR were developed, the predictive equations of the wood flour content in WPCss are y = 53.297x-9. 107 and y = 55.922x-10.238, the predictive equations of the PP content in WPCss are y = 6.828 5x+5.403 6 and y = 8.719 7x+3.295 8. The results of the accuracy test and precision test show that the method has strong repeatability and high accuracy. The average prediction relative deviations of the wood flour content and PP content in WPCss are about 5%. The prediction accuracy has been improved remarkably, compared to thermochemical methods. More importantly, FTIR is more easy-handing. This experiment may provide a simple, rapid and accurate method for quantification of wood flour and PP in Chinese fir/PP composites.

Microcrystalline-cellulose and polypropylene based composite: A simple, selective and effective material for microwavable packaging.

PubMed

Ummartyotin, S; Pechyen, C

2016-05-20

Cellulose based composite was successfully designed as active packaging with additional feature of microwavable properties. Small amount of cellulose with 10 μm in diameter was integrated into polypropylene matrix. The use of maleic anhydride was employed as coupling agent. Thermal and mechanical properties of cellulose based composite were superior depending on polypropylene matrix. Crystallization temperature and compressive strength were estimated to be 130 °C and 5.5 MPa. The crystal formation and its percentage were therefore estimated to be 50% and it can be predicted on the feasibility of microwavable packaging. Morphological properties of cellulose based composite presented the good distribution and excellent uniformity. It was remarkable to note that cellulose derived from cotton can be prepared as composite with polypropylene matrix. It can be used as packaging for microwave application. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Effect of Mechanical Performance on PP Fiber to Polymer Mortar

NASA Astrophysics Data System (ADS)

Xie, Xinying; Kang, Xinnan; Jin, Yujie; Cai, Jingwei

2018-03-01

It introduces the purpose of of adding Polypropylene fiber. The paper The production process and test method of epoxy resin mortar with PP fiber are developed. The influence of PP fiber on mechanical properties of polymer mortar was studied in this paper, including the influence of PP fiber content on flexural strength, the ratio of flexural and compressive strength and so on. The experimental results are compared and analyzed. The reason is found, the conclusion of research is acquired.

Polypropylene/hydrophobic-silica-aerogel-composite separator induced enhanced safety and low polarization for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Feng, Guanhua; Li, Zihe; Mi, Liwei; Zheng, Jinyun; Feng, Xiangming; Chen, Weihua

2018-02-01

Separator as an important part of lithium-ion batteries, allowing the ion to transfer and preventing the direct contact of anode with cathode, determines the safety of the batteries. In this work, a kind of polypropylene/hydrophobic silica-aerogel-composite (SAC) separator is fabricated through combining hydrophobic silica aerogel and polypropylene (PP) separator. The rationally designed SAC effectively increases the thermal stability of the separator with slightly growing weight (the area retention rate is 30% higher than that of the PP separator after being heated for 30 min at 160 °C). In addition, the hydrophobic silica aerogel layer in SAC significantly improves the wettability of PP separator to electrolyte owning to the introduced hydrophobic functional groups of -Si(CH3)3 and porous structure, and the contact angles of SAC separator to several common organic electrolytes (EC/DMC, DMC/DOL, Diglyme) are close to 0°. Electrochemical tests show that the prepared SAC separator can decrease the polarization of Li-ion batteries and leads to improved power performance and cycle stability. And the SAC separator is firm with neglectable abscission after folding 200 times. This work provides a new way to improve the safety and simultaneously reduce the polarization of the batteries, implying promising application potential in power batteries.

Effect of cellulose nanocrystals (CNCs) on crystallinity, mechanical and rheological properties of polypropylene/CNCs nanocomposites

NASA Astrophysics Data System (ADS)

Bagheriasl, D.; Carreau, P. J.; Dubois, C.; Riedl, B.

2015-05-01

Rheological and mechanical properties of polypropylene (PP)/CNCs nanocomposites were compared with those of nanocomposites containing poly(ethylene-co-vinyl alcohol) as a compatibilizer. The nanocomposites were prepared by a Brabender internal mixer at CNC contents of 5 wt%. The compression molded nanocomposite dog-bones and disks were characterized regarding their tensile and dynamic rheological behavior, respectively. The complex viscosity of the nanocomposites samples containing the compatibilizer were increased, slightly, compared to the non-compatibilized nanocomposite samples. Moreover, an overshoot in the transient start-up viscosity of the compatibilized nanocomposite was observed. The Young modulus of the nanocomposite samples containing the compatibilizer were increased up to ca. 37% compared to the neat PP. The elongation at break was decreased in all PP/CNC nanocomposite samples, but less for the nanocomposite samples containing the compatibilizer. The crystalline content of the PP in the nanocomposites and also the crystallization temperature were increased after compatibilization. These results could be ascribed to the efficiency of the poly(ethylene-co-vinyl alcohol) as a compatibilizer that favors a better dispersion and wetting of the hydrophilic CNCs within the hydrophobic PP.

Characterization of Mechanical Properties of PP/HMSPP Blends with Natural and Synthetic Polymers Subjected to Gamma-Irradiation

NASA Astrophysics Data System (ADS)

Cardoso, E. C. L.; Scagliusi, S. R.; Lugão, A. B.

Hydrocarbon polymers, as PP, made from cheap petrochemical feedstock are important in many branches of industry. However, they have an undesirable influence on the environment and cause problems due to waste deposition and utilization. Polymeric materials composites account for an estimated from 20 to 30% of total volume of solid waste disposed. Thus, there is a tendency to substitute such polymers by those ones that undergo biodegradable processes. Polypropylene (PP) is a commodity, with high melting point, high chemical resistance, low density, with a balance between physical and mechanical properties and easy processing at low cost. Nevertheless, PP shows limitations for some special applications in automotive industry and civil construction. In order to minimize this deficiency, related to rheological behavior of polymer melt, especially referring to viscosity in processing temperature, a 50% mixture with HMSPP (High melt Strength Polypropylene) was used. PP/HMSPP was blended with 10, 15, 30 and 50% of natural (sugarcane bagasse) and synthetic polymers (PHB and PLA) aiming to partially biodegradable materials. The admixtures were subjected to gamma-irradiation at 50, 100, 150 and 200 kGy and then further assessed by mechanical tests in order to evaluate their degradability.

Effect of carboxylic acids as compatibilizer agent on mechanical properties of thermoplastic starch and polypropylene blends.

PubMed

Martins, Andréa Bercini; Santana, Ruth Marlene Campomanes

2016-01-01

In this work, polypropylene/thermoplastic starch (PP/TPS) blends were prepared as an alternative material to use in disposable packaging, reducing the negative polymeric environmental impact. Unfortunately, this material displays morphological characteristics typical of immiscible polymer blends and a compatibilizer agent is needed. Three different carboxyl acids: myristic (C14), palmitic (C16) and stearic acids (C18) were used as natural compatibilizer agent (NCA). The effects of NCA on the mechanical, physical, thermal and morphological properties of PP/TPS blends were investigated and compared against PP/TPS with and without PP-grafted maleic anhydride (PPgMA). When compared to PP/TPS, blends with C18, PPgMA and C14 presented an improvement of 25, 22 and 17% in tensile strength at break and of 180, 194 and 259% in elongation at break, respectively. The highest increase, 54%, in the impact strength was achieved with C14 incorporation. Improvements could be seen, through scanning electron microscopy (SEM) images, in the compatibility between the immiscible components by acids incorporation. These results showed that carboxylic acids, specifically C14, could be used as compatibilizer agent and could substitute PPgMA. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of cellulose nanocrystals (CNC) particle morphology on dispersion and rheological and mechanical properties of polypropylene/CNC nanocomposites.

PubMed

Khoshkava, Vahid; Kamal, Musa R

2014-06-11

Polypropylene (PP) nanocomposites containing spray-dried cellulose nanocrystals (CNC), freeze-dried CNC, and spray-freeze-dried CNC (CNCSFD) were prepared via melt mixing in an internal batch mixer. Polarized light, scanning electron, and atomic force microscopy showed significantly better dispersion of CNCSFD in PP/CNC nanocomposites compared with the spray-dried and freeze-dried CNCs. Rheological measurements, including linear and nonlinear viscoelastic tests, were performed on PP/CNC samples. The microscopy results were supported by small-amplitude oscillatory shear tests, which showed substantial rises in the magnitudes of key rheological parameters of PP samples containing CNCSFD. Steady-shear results revealed a strong shear thinning behavior of PP samples containing CNCSFD. Moreover, PP melts containing CNCSFD exhibited a yield stress. The magnitude of the yield stress and the degree of shear thinning behavior increased with CNCSFD concentration. It was found that CNCSFD agglomerates with a weblike structure were more effective in modifying the rheological properties. This effect was attributed to better dispersion of the agglomerates with the weblike structure. Dynamic mechanical analysis showed considerable improvement in the modulus of samples containing CNCSFD agglomerates. The percolation mechanical model with modified volume percolation threshold and filler network strength values and the Halpin-Kardos model were used to fit the experimental results.

Effect of Multiwalled Carbon Nanotubes on the Mechanical Properties of Carbon Fiber-Reinforced Polyamide-6/Polypropylene Composites for Lightweight Automotive Parts.

PubMed

Nguyen-Tran, Huu-Duc; Hoang, Van-Tho; Do, Van-Ta; Chun, Doo-Man; Yum, Young-Jin

2018-03-15

The development of lightweight automotive parts is an important issue for improving the efficiency of vehicles. Polymer composites have been widely applied to reduce weight and improve mechanical properties by mixing polymers with carbon fibers, glass fibers, and carbon nanotubes. Polypropylene (PP) has been added to carbon fiber-reinforced nylon-6 (CF/PA6) composite to achieve further weight reduction and water resistance. However, the mechanical properties were reduced by the addition of PP. In this research, multiwalled carbon nanotubes (CNTs) were added to compensate for the reduced mechanical properties experienced when adding PP. Tensile testing and bending tests were carried out to evaluate the mechanical properties. A small amount of CNTs improved the mechanical properties of carbon fiber-reinforced PA6/PP composites. For example, the density of CF/PA6 was reduced from 1.214 to 1.131 g/cm³ (6.8%) by adding 30 wt % PP, and the tensile strength of 30 wt % PP composite was improved from 168 to 173 MPa (3.0%) by adding 0.5 wt % CNTs with small increase of density (1.135 g/cm³). The developed composite will be widely used for lightweight automotive parts with improved mechanical properties.

Effect of Multiwalled Carbon Nanotubes on the Mechanical Properties of Carbon Fiber-Reinforced Polyamide-6/Polypropylene Composites for Lightweight Automotive Parts

PubMed Central

Nguyen-Tran, Huu-Duc; Do, Van-Ta; Yum, Young-Jin

2018-01-01

The development of lightweight automotive parts is an important issue for improving the efficiency of vehicles. Polymer composites have been widely applied to reduce weight and improve mechanical properties by mixing polymers with carbon fibers, glass fibers, and carbon nanotubes. Polypropylene (PP) has been added to carbon fiber-reinforced nylon-6 (CF/PA6) composite to achieve further weight reduction and water resistance. However, the mechanical properties were reduced by the addition of PP. In this research, multiwalled carbon nanotubes (CNTs) were added to compensate for the reduced mechanical properties experienced when adding PP. Tensile testing and bending tests were carried out to evaluate the mechanical properties. A small amount of CNTs improved the mechanical properties of carbon fiber-reinforced PA6/PP composites. For example, the density of CF/PA6 was reduced from 1.214 to 1.131 g/cm3 (6.8%) by adding 30 wt % PP, and the tensile strength of 30 wt % PP composite was improved from 168 to 173 MPa (3.0%) by adding 0.5 wt % CNTs with small increase of density (1.135 g/cm3). The developed composite will be widely used for lightweight automotive parts with improved mechanical properties. PMID:29543754

Effects of Polypropylene Orientation on Mechanical and Heat Seal Properties of Polymer-Aluminum-Polymer Composite Films for Pouch Lithium-Ion Batteries

PubMed Central

Chen, Jinyao; Yang, Feng; Kang, Jian; Cao, Ya; Xiang, Ming

2018-01-01

In this study, polyamide-aluminum foil-polypropylene (PA-Al-PP) composite films with different orientation status of the PP layer were prepared, and their morphology, tensile, peeling and heat seal behavior were studied. The comparative study of tensile and fracture behaviors of single-layer film of PA, Al and PP, as well as the composite films of PA-Al, PP-Al and PA-Al-PP revealed that in PA-Al-PP composite film, the PA layer with the highest tensile strength can share the tensile stress from the Al layer during stretching, while the PP layer with the lowest tensile strength can prevent further development of the small cracks on boundary of the Al layer during stretching. Moreover, the study of heat seal behavior suggested that both the orientation status and the heat seal conditions were important factors in determining the heat seal strength (HSS) and failure behavior of the sample. Four failure types were observed, and a clear correspondence between HSS and failure types was found. The results also elucidated that for the composite film, only in the cases where the tensile stress was efficiently released by each layer during HSS measurement could the composite film exhibit desired high HSS that was even higher than its tensile strength. PMID:29337881

Ethylcellulose-coated polyolefin separators for lithium-ion batteries with improved safety performance.

PubMed

Xiong, Ming; Tang, Haolin; Wang, Yadong; Pan, Mu

2014-01-30

With the widely use in portable electronic devices and electric vehicles, the safety of lithium-ion battery has raised serious concerns, in which the thermal stability of separator plays an essential role in preventing thermal runaway reactions. The novelty of this work is to coat commercialized polyethylene (PE) separator and trilayer polypropylene/polyethylene/polypropylene (PP/PE/PP) separator with ethylcellulose (EC), a thermally stable and renewable biomass. The formation of the EC layer with high porosity is through a simple dipping and extracting process. The effects of the EC layer on thermal shrinkage, electrolyte wettability and cell performance are investigated. After coating, the thermal shrinkage of PE separator at shutdown and meltdown point is reduced from 20% to 9% and 42% to 23% respectively, while the drop of OCV under increasing temperature is also postponed from 130°C to 160°C. The electrolyte wettability of pristine trilayer PP/PE/PP separator is greatly improved, leading to increased capacity retention from 28% to 99% of the cell. Copyright © 2013 Elsevier Ltd. All rights reserved.

Liquid-State and Solid-State Properties of Nanotube/Polypropylene Nanocomposites Elaborated via a Simple Procedure

PubMed Central

Huegun, Arrate; Fernández, Mercedes; Peña, Juanjo; Muñoz, María Eugenia; Santamaría, Antxon

2013-01-01

Non-modified Multiwalled Carbon Nanotubes (MWCNT) and polypropylene (PP) in absence of compatibilizer have been chosen to elaborate MWCNT/PP nanocomposites using a simple melt-mixing dispersing method. Calorimetry results indicate little effect of MWCNTs on crystallinity of PP, revealing not much interaction between nanotubes and PP chains, which is compatible with the employed manufacturing procedure. In any case, a hindering of polymer chains motion by MWCNTs is observed in the molten state, using oscillatory flow experiments, and a rheological percolation threshold is determined. The percolation limit is not noticed by Pressure-Volume-Temperature (PVT) measurements in the melt, because this technique rather detects local motions. Keeping the nanocomposites in the molten state provokes an electrical conductivity increase of several orders of magnitude, but on ulterior crystallization, the conductivity decreases, probably due to a reduction of the ionic conductivity. For a concentration of 2% MWCNTs, in the limit of percolation, the conductivity decreases considerably more, because percolation network constituted in the molten state is unstable and is destroyed during crystallization. PMID:28348329

Influence of electron beam irradiation on mechanical and thermal properties of polypropylene/polyamide blend

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, Shigeya, E-mail: shi-nakamura@hitachi-chem.co.jp; Tokumitsu, Katsuhisa

The effects of electron beam irradiation on the mechanical and thermal properties of polypropylene (PP) and polyamide6 (PA6) blends-with talc 20 wt% as filler, SEBS-g-MAH as compatibilizer, and triallyl isocyanurate as crosslinking agent-were investigated. Although the tensile and flexural moduli and strengths of the PP/PA6 blends with talc, SEBS-g-MAH, and TAIC could be increased by the application of electron beam irradiation, the impact strength was decreased. Ddifferential scanning calorimetryer measurements showed that the melting temperatures of all PP/PA6 blends were decreased with increases in the electron beam irradiationdose. From dynamic mechanical analyzer results, a storage modulus curve in the plateaumore » region was observed only in the PP/PA6 blends with talc, SEBS-g-MAH, and TAIC; the storage modulus increased with increasing electron beam irradiation dose, indicating that the three-dimensional network developed gradually in the more amorphous PA6. As a result, the most significant improvement observed in heat distortion tests under high load (1.8 MPa) occurred at 200 kGy.« less

Enhancement of visible-light photoactivity by polypropylene coated plasmonic Au/TiO2 for dye degradation in water solution

NASA Astrophysics Data System (ADS)

D'Amato, C. A.; Giovannetti, R.; Zannotti, M.; Rommozzi, E.; Ferraro, S.; Seghetti, C.; Minicucci, M.; Gunnella, R.; Di Cicco, A.

2018-05-01

A new approach to obtain a heterogeneous photocatalytic material with gold nanoparticles and TiO2 semiconductor was performed exploiting the reducing ability of acetylacetone, a chemical present in the TiO2 paste formulation. Gold/TiO2 heterogeneous catalyst supported on polypropylene [PP@Au-TiO2]A was prepared; composition, structure and morphology of this new material were defined by using UV-Vis spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD), X-ray Fluorescence (XRF), Raman Spectroscopy, Photoluminescence and Diffuse Reflectance Spectroscopy. The new material was tested in the photocatalytic degradation of Alizarin Red S in water solution, as target pollutant, under visible light and correlated with structural and spectroscopic characterizations. [PP@Au-TiO2]A showed higher photocatalytic activity respect to pure [PP@TiO2]A with an improvement of photodegradation kinetic. The best performance was obtained using [PP@Au-TiO2]A sample with 0.006 wt.% of Au and the photocatalytic improvement was correlated with the band gap energy decrease of photocatalyst.

Functional behaviour of polypropylene/ZnO soluble starch nanocomposites

NASA Astrophysics Data System (ADS)

Chandramouleeswaran, Subramani; Mhaske, S. T.; Kathe, A. A.; Varadarajan, P. V.; Prasad, Virendra; Vigneshwaran, Nadanathangam

2007-09-01

ZnO-polypropylene nanocomposites (nano-PP) were prepared using nanoparticles of ZnO stabilized by soluble starch (nano-ZnO) as filler in PP by the melt mixing process. X-ray diffraction (XRD) and other spectroscopic analysis—ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) and photoluminescence—revealed the presence and characteristics of nano-ZnO in the composites. The presence of ZnO imparts whiteness, while starch increased the yellowing of polymers. The nanocomposites were analyzed for changes in optical, mechanical, electrical and rheological properties, as influenced by the increasing concentration of nano-ZnO. The mechanical properties were marginally increased and the dielectric strength of the nano-PP increased to a notable level. By monitoring the evolution of the carbonyl absorption bands from FTIR analysis, the efficacy of nano-ZnO in the reduction of photo-degradation due to UV irradiation was demonstrated. The excellent antibacterial activity exhibited by nano-ZnO impregnated PP against two human pathogenic bacteria, Staphylococcus aureus and Klebsiella pneumoniae, makes it a suitable candidate for food packaging applications.

Processing and characterization of unidirectional thermoplastic nanocomposites

NASA Astrophysics Data System (ADS)

Narasimhan, Kameshwaran

The manufacture of continuous fibre-reinforced thermoplastic nanocomposites is discussed for the case of E-Glass reinforced polypropylene (PP) matrix and for E-Glass reinforced Polyamide-6 (Nylon-6), with and without dispersed nanoclay (montmorillonite) platelets. The E-Glass/PP nanocomposite was manufactured using pultrusion, whereas the E-Glass/Nylon-6 nanocomposite was manufactured using compression molding. Mechanical characterization of nanocomposites were performed and compared with traditional microcomposites. Compressive as well as shear strength of nanocomposites was improved by improving the yield strength of the surrounding matrix through the dispersion of nanoclay. Significant improvements were achieved in compressive strength and shear strength with relatively low nanoclay loadings. Initially, polypropylene with and without nanoclay were melt intercalated using a single-screw extruder and the pultruded nanocomposite was fabricated using extruded pre-impregnated (pre-preg) tapes. Compression tests were performed as mandated by ASTM guidelines. SEM and TEM characterization revealed presence of nanoclay in an intercalated and partially exfoliated morphology. Mechanical tests confirmed significant improvements in compressive strength (˜122% at 10% nanoclay loading) and shear strength (˜60% at 3% nanoclay loading) in modified pultruded E-Glass/PP nanocomposites in comparison with baseline properties. Uniaxial tensile tests showed a small increase in tensile strength (˜3.4%) with 3% nanoclay loading. Subsequently, E-Glass/Nylon-6 nanocomposite panels were manufactured by compression molding. Compression tests were performed according to IITRI guidelines, whereas short beam shear and uni-axial tensile tests were performed according to ASTM standards. Mechanical tests confirmed strength enhancement with nanoclay addition, with a significant improvement in compressive strength (50% at 4% nanoclay loading) and shear strength (˜36% at 4% nanoclay loading) when compared with the baseline E-Glass/Nylon-6. Uni-axial tensile tests resulted in a small increase in tensile strength (˜3.2%) with 4% nanoclay loading. Also, hygrothermal aging (50°C and 100% RH) of baseline and nanoclay modified (4%) E-Glass/Nylon-6 was studied. It was observed that the moisture diffusion process followed Fickian diffusion. E-Glass/Nylon-6 modified with 4% nanoclay loading showed improved barrier performance with a significant reduction (˜30%) in moisture uptake compared to baseline E-Glass/Nylon-6 composites. Significant improvement in mechanical properties was also observed in hygrothermally aged nanocomposite specimens when compared with the aged baseline composite.

Cryogenic performance of single polymer polypropylene composites

NASA Astrophysics Data System (ADS)

Atli-Veltin, Bilim

2018-03-01

The main objective of the experimental study detailed in this paper is to investigate the performance of fully recyclable, lightweight, low-cost, thermoplastic Polypropylene (PP) composite tapes at low temperatures. Coupons made of [±45] and [0/90] laminates are subjected to tensile and 3-point bending tests at room temperature as well as at -196 °C. In addition to that, cryogenic low velocity impact tests at 268 J and 777 J impact energies are performed on tubular structures. The results are indicating that the laminates made of PP tapes have sufficient ductility for cryogenic applications. Low velocity impact tests showed that the viscoelastic behavior of the material is preserved, even at such low temperatures and more than 72% of impact energy is absorbed by the material.

Development and mechanical characterization of a polypropylene (pp) composite with grinding sludge as fiber

NASA Astrophysics Data System (ADS)

Rodrigues, D. A.; Oliveira, A. S. M.; Specht, R. F.; Santana, R. M. C.

2014-05-01

The search for alternative materials that provide reduced costs in manufacturing processes, and the need of to recycle materials normally disposable, it has aroused great interest and much research, with regard to reduction of material consumption due to its high cost and scarcity. Within this focus, this work aims to characterize a thermoplastic composite, whose polymer matrix is polypropylene (PP), and as disperse phase "grinding sludge, GS" from the various machining processes for grinding. After drying and sieving the GS and its subsequent mixing with the thermoplastic resin to prepare the PP/GS composites formulated were 80/20, 70/30, 60/40 w/w. The composite was injected into an injection mold in the form specimen test. The specimens followed the ASTM D638 and ASTM D256 for tensile and impact respectively. Three processing parameters were varied: the content of GS, temperature and injection rate. Each of these variables has three levels: L (low), M (medium) and H (high), making all possible combinations, totaling 27 processing conditions. The experimental conditions followed a statistical design obtained with the software Statgraphics Centurion, where the effects of variables are studied according to their statistical significance. An analysis of MEV and EDS was performed to obtain the characteristics of the "grinding sludge" (geometry and composition). Despite having been sifted, the geometry of the GS was still very rough, with varied shapes and sizes, and even made up a small percentage of abrasive grains. The variable that most influenced the mechanical properties was the content of particulate GS. The values obtained for the maximum tensile strength not behaved in descending order as expected, this may be the effect of small amount of samples tested. The results of the mechanical properties showed that for the elasticity modulus increased with increasing of GS; the values of elongation and impact strength decreased with increasing of GS.

Influence of Interleaved Films on the Mechanical Properties of Carbon Fiber Fabric/Polypropylene Thermoplastic Composites

PubMed Central

Kim, Jong Won; Lee, Joon Seok

2016-01-01

A laminated composite was produced using a thermoplastic prepreg by inserting an interleaved film with the same type of matrix as the prepreg during the lay-up process to improve the low interlaminar properties, which is a known weakness of laminated composites. Carbon fiber fabric (CFF) and polypropylene (PP) were used to manufacture the thermoplastic prepregs. Eight prepregs were used to produce the laminated composites. Interleaved films with different thicknesses were inserted into each prepreg. The physical properties of the composite, such as thickness, density, fiber volume fraction (Vf), and void content (Vc), were examined. The tensile strength, flexural strength, interlaminar shear strength (ILSS), impact property, and scanning electron microscopy (SEM) were used to characterize the mechanical properties. Compared to the composite without any inserted interleaved film, as the thickness of the inserted interleaved resin film was increased, Vc decreased by 51.45%. At the same time, however, the tensile strength decreased by 8.75%. Flexural strength increased by 3.79% and flexural modulus decreased by 15.02%. Interlaminar shear strength increased by 11.05% and impact strength increased by 15.38%. Fracture toughness of the laminated composite was improved due to insertion of interleaved film. PMID:28773467

Influence of Interleaved Films on the Mechanical Properties of Carbon Fiber Fabric/Polypropylene Thermoplastic Composites.

PubMed

Kim, Jong Won; Lee, Joon Seok

2016-05-06

A laminated composite was produced using a thermoplastic prepreg by inserting an interleaved film with the same type of matrix as the prepreg during the lay-up process to improve the low interlaminar properties, which is a known weakness of laminated composites. Carbon fiber fabric (CFF) and polypropylene (PP) were used to manufacture the thermoplastic prepregs. Eight prepregs were used to produce the laminated composites. Interleaved films with different thicknesses were inserted into each prepreg. The physical properties of the composite, such as thickness, density, fiber volume fraction ( V f ), and void content ( V c ), were examined. The tensile strength, flexural strength, interlaminar shear strength (ILSS), impact property, and scanning electron microscopy (SEM) were used to characterize the mechanical properties. Compared to the composite without any inserted interleaved film, as the thickness of the inserted interleaved resin film was increased, V c decreased by 51.45%. At the same time, however, the tensile strength decreased by 8.75%. Flexural strength increased by 3.79% and flexural modulus decreased by 15.02%. Interlaminar shear strength increased by 11.05% and impact strength increased by 15.38%. Fracture toughness of the laminated composite was improved due to insertion of interleaved film.

Effect of polyamide 6 on the morphology and electrical conductivity of carbon black-filled polypropylene composites

NASA Astrophysics Data System (ADS)

Zhang, Xuewei; Liu, Jiang; Wang, Yi; Wu, Wei

2017-12-01

Carbon black (CB)-filled polypropylene (PP) with surface resistivity between 106 and 109 Ω sq-1 is the ideal antistatic plastic material in the electronics and electric industry. However, a large amount of CB may have an adverse effect on the mechanical properties and processing performance of the material, thus an improved ternary system is developed. Blends of CB-filled PP and polyamide 6 (PA6) have been prepared by melt blending in order to obtain electrically conductive polymer composites with a low electrical percolation threshold based on the concept of double percolation. The morphological developments of these composites were studied by scanning electron microscopy. The results showed that CB particles were selectively dispersed in PA6 phases due to the good interaction and interfacial adhesion between CB and PA6. At the same CB loadings, the surface resistivity of PP/PA6/CB composite was smaller than that of PP/CB composite system, which indicated the better conductivity in the former composite. The increasing amount of PA6 in the composites changed the morphology from a typical sea-island morphology to a co-continuous morphology. What is more, with 8 wt% of CB and PP/PA6 phase ratio of 70/30 in which the PP and PA6 phases formed a co-continuous structure, the electrical conductivity of the composite peaked at 2.01 × 105 Ω sq-1.

Chemiluminescence and reactivity of the composites based on blends of polypropylene and polyamide

NASA Astrophysics Data System (ADS)

Vorontsov, N. V.; Popov, A. A.; Margolin, A. L.

2017-12-01

The effect of the composition of blends based on isotactic polypropylene (PP) and aliphatic polyamide 6/66-4 (PA) on the rate of photo-oxidation of their mixtures in air at room temperature has been studied. The decay of photoinduced chemiluminescence was studied to determine the kinetics of peroxyl radical termination in composites and the rate constants of this process depending on the composition of the mixtures. In the presence of PA, the rate of photo-oxidation of mixtures is much higher than the rates of photo-oxidation of separately taken components, PP and PA. Thus, the kinetics of photo-oxidation of mixtures differs from the simple sum of photo-oxidation kinetics of PP and PA, which should be expected in the absence of chemical and physical interaction of the components of the mixture. A decrease in the rate constants due to PA additives indicates a decrease in the mobility of molecules in the composites and explains the observed increase in photo-oxidation of mixtures.

Effect of atmospheric oxidative plasma treatments on polypropylenic fibers surface: Characterization and reaction mechanisms

NASA Astrophysics Data System (ADS)

Nisticò, Roberto; Magnacca, Giuliana; Faga, Maria Giulia; Gautier, Giovanna; D'Angelo, Domenico; Ciancio, Emanuele; Lamberti, Roberta; Martorana, Selanna

2013-08-01

Atmospheric pressure plasma-dielectric barrier discharge (APP-DBD, open chamber configuration) was used to functionalize polypropylene (PP) fibers surface in order to generate oxidized-reactive groups such as hydroperoxides, alcohols and carbonyl species (i.e. ketones and others). Such a species increased the surface polarity, without causing material degradation. Three different types of plasma mixture (He, He/O2, He/O2/H2O) under three different values of applied power (750, 1050, 1400 W) were investigated. The formed plasma species (O2+, O single atom and OH radical) and their distribution were monitored via optical emission spectrometry (OES) measurements, and the plasma effects on PP surface species formation were followed by X-ray photoemission spectroscopy (XPS). Results allowed to better understand the reaction pathways between plasma phase and PP fibers. In fact, two reaction mechanisms were proposed, the first one concerning the plasma phase reactions and the second one involving material surface modifications.

Impact fragmentation of polyurethane and polypropylene cylinder

NASA Astrophysics Data System (ADS)

Kishimura, Hiroaki; Noguchi, Daisuke; Preechasupanya, Worrayut; Matsumoto, Hitoshi

2013-11-01

The impact fragmentation of a bulk polyurethane elastomer (PU) and polypropylene (PP) cylinder have been investigated using a Cu plate projectile launched by a propellant gun at a velocity of 0.53-1.4 km/s. A projectile drills into a PU sample and forms a cavity in the sample. A small number of tiny fragments are formed. When the projectile smashes in at 1.4 km/s, the PU cylinder bursts and PU fragments form. On the other hand, a brittle fracture occurs on the PP cylinder. The mass of fragments from the PU sample generated at a lower impact velocity is distributed in the lognormal form, whereas the mass of fragments from the PU sample generated by a 1.4 km/s impact follows a power-law distribution. The fragment mass distribution of the PP sample generated at a lower impact velocity obeys the power-law form, whereas that generated at a higher impact velocity follows the lognormal form.

Characterization of carbon nanofibre-reinforced polypropylene foams.

PubMed

Antunes, M; Velasco, J I; Realinho, V; Arencón, D

2010-02-01

In this paper, carbon-nanofibre-reinforced polypropylene foams were prepared and characterized regarding their foaming behaviour, cellular structure and both thermo-mechanical as well as electrical properties. Polypropylene (PP) nanocomposites containing 5, 10 and 20 wt% of carbon nanofibres (CNF) and a chemical blowing agent were prepared by melt-mixing inside a twin-screw extruder and subsequently water-cooled and pelletized. The extruded nanocomposites were later foamed using a one-step compression-moulding process. The thermo-mechanical properties of the CNF-reinforced PP foams were studied, analyzing the influence of the carbon nanofibres on the cellular structure and subsequent thermo-mechanical behaviour of the foams. Carbon nanofibres not only seemed to act as nucleating agents, reducing the average cell size of the foams and increasing their cell density for similar expansion ratios, but also helped produce mechanically-improved foams, even reaching for the 20 wt% CNF-reinforced ones a specific modulus around 1.2 GPa x cm3/g for densities as low as 300 kg/m3. An increasingly higher electrical conductivity was assessed for both the solids as well as the foams with increasing the amount of carbon nanofibres.

A trilayer separator with dual function for high performance lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Song, Rensheng; Fang, Ruopian; Wen, Lei; Shi, Ying; Wang, Shaogang; Li, Feng

2016-01-01

In this article, we propose a trilayer graphene/polypropylene/Al2O3 (GPA) separator with dual function for high performance lithium-sulfur (Li-S) batteries. Graphene is coated on one side of polypropylene (PP) separator, which functions as a conductive layer and an electrolyte reservoir that allows for rapid electron and ion transport. Then Al2O3 particles are coated on the other side to further enhance thermal stability and safety of the graphene coated polypropylene (GCP) separator, which are touched with lithium metal anode in the Li-S battery. The GPA separator shows good thermal stability after heating at 157 °C for 10 min while both GCP and PP separators showing an obvious shrinkage about 10%. The initial discharge specific capacity of Li-S coin cell with a GPA separator could reach 1067.7 mAh g-1 at 0.2C. After 100 discharge/charge cycles, it can still deliver a reversible capacity of as high as 804.4 mAh g-1 with 75% capacity retention. The pouch cells further confirm that the trilayer design has great promise towards practical applications.

A preclinical evaluation of polypropylene/polylacticacid hybrid meshes for fascial defect repair using a rat abdominal hernia model

PubMed Central

Le Teuff, Isabelle; Huberlant, Stephanie; Carteron, Patrick; Letouzey, Vincent; de Tayrac, Renaud

2017-01-01

Objectives Synthetic mesh surgery for both abdominal and urogenital hernia repair is often unsatisfactory in the long-term due to postoperative complications. We hypothesized that a semi-degradable mesh hybrid may provide more appropriate biocompatibility with comparable mechanical properties. The aim was to compare its in vivo biocompatibility with a commercial polypropylene (PP) mesh. Methods 72 rats were randomly allocated to either our new composite mesh (monofilament PP mesh knitted with polylactic-acid-fibers (PLA)) or to a commercially available PP mesh that was used as a control. 15, 90, and 180 days after implantation into the rat abdomen mesh tissue complexes were analysed for erosion, contraction, foreign body reaction, tissue integration and biomechanical properties. Results No differences were seen in regard to clinical parameters including erosion, contraction or infection rates between the two groups. Biomechanical properties including breaking load, stiffness and deformation did not show any significant differences between the different materials at any timepoint. Macrophage staining did not reveal any significant differences between the two groups or between timepoints either. In regard to collagen I there was significantly less collagen I in the PP group compared to the PP/ PLA group at day 180. Collagen III did not show any significant differences at any timepoint between the two groups. Conclusion A PP/PLA hybrid mesh, leaving a low amount of PP after PLA degradation seems to have comparable biomechanical properties like PP at 180 days due to enhanced collagen production without significant differences in erosion, contraction, herniation or infection rates. PMID:28598983

One-Piece Leak-Proof Battery

DOEpatents

Verhoog, Roelof

1999-03-23

The casing of a leak-proof one-piece battery is made of a material comprising a mixture of at least a matrix based on polypropylene and an alloy of a polyamide and a polypropylene. The ratio of the matrix to the alloy is in the range 0.5 to 6 by weight. The alloy forms elongate arborescent inclusions in the matrix such that, on average, the largest dimension of a segment of the arborescence is at least twenty times the smallest dimension of the segment.

Properties of flat-pressed wood plastic composites containing fire retardants

Treesearch

Nadir Ayrilmis; Jan. T. Benthien; Heiko Thoemen; Robert H. White

2011-01-01

This study investigated physical, mechanical, and fire properties of the flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) [5 or 15% by weight (wt)] at 50 wt % of the wood flour (WF). The WPC panels were made from dry-blended WF, polypropylene (PP) with maleic anhydride grafted PP (2 wt %), and FR powder formulations using a...

Field evaluation of the long-lasting treated storage bag, deltamethrin-incorporated (ZeroFly® Storage Bag) as a barrier to insect pest infestation

USDA-ARS?s Scientific Manuscript database

The deltamethrin-incorporated polypropylene (PP) bag, ZeroFly® Storage Bag, is a new technology to reduce postharvest losses caused by stored-product insect pests. ZeroFly bags filled with untreated maize were compared to PP bags filled with maize treated with Betallic Super (80 g pirimiphos-methyl ...

Influence of residual stress on the adhesion and surface morphology of PECVD-coated polypropylene

NASA Astrophysics Data System (ADS)

Jaritz, Montgomery; Hopmann, Christian; Behm, Henrik; Kirchheim, Dennis; Wilski, Stefan; Grochla, Dario; Banko, Lars; Ludwig, Alfred; Böke, Marc; Winter, Jörg; Bahre, Hendrik; Dahlmann, Rainer

2017-11-01

The properties of plasma-enhanced chemical vapour deposition (PECVD) coatings on polymer materials depend to some extent on the surface and material properties of the substrate. Here, isotactic polypropylene (PP) substrates are coated with silicon oxide (SiO x ) films. Plasmas for the deposition of SiO x are energetic and oxidative due to the high amount of oxygen in the gas mixture. Residual stress measurements using single Si cantilever stress sensors showed that these coatings contain high compressive stress. To investigate the influence of the plasma and the coatings, residual stress, silicon organic (SiOCH) coatings with different thicknesses between the PP and the SiO x coating are used as a means to protect the substrate from the oxidative SiO x coating process. Pull-off tests are performed to analyse differences in the adhesion of these coating systems. It could be shown that the adhesion of the PECVD coatings on PP depends on the coatings’ residual stress. In a PP/SiOCH/SiO x -multilayer system the residual stress can be significantly reduced by increasing the thickness of the SiOCH coating, resulting in enhanced adhesion.

A simple model for heterogeneous nucleation of isotactic polypropylene

NASA Astrophysics Data System (ADS)

Howard, Michael; Milner, Scott

2013-03-01

Flow-induced crystallization (FIC) is of interest because of its relevance to processes such as injection molding. It has been suggested that flow increases the homogeneous nucleation rate by reducing the melt state entropy. However, commercial polypropylene (iPP) exhibits quiescent nucleation rates that are much too high to be consistent with homogeneous nucleation in carefully purified samples. This suggests that heterogeneous nucleation is dominant for typical samples used in FIC experiments. We describe a simple model for heterogeneous nucleation of iPP, in terms of a cylindrical nucleus on a flat surface with the critical size and barrier set by the contact angle. Analysis of quiescent crystallization data with this model gives reasonable values for the contact angle. We have also employed atomistic simulations of iPP crystals to determine surface energies with vacuum and with Hamaker-matched substrates, and find values consistent with the contact angles inferred from heterogeneous nucleation experiments. In future work, these results combined with calculations from melt rheology of entropy reduction due to flow can be used to estimate the heterogeneous nucleation barrier reduction due to flow, and hence the increase in nucleation rate due to FIC for commecial iPP.

Dynamic fracture toughness of cellulose-fiber-reinforced polypropylene : preliminary investigation of microstructural effects

Treesearch

Craig M. Clemons; Daniel F. Caulfield; A. Jeffrey Giacomin

1999-10-01

In this study, the microstructure of injection-molded polypropylene reinforced with cellulose fiber was investigated. Scanning electron microscopy of the fracture surfaces and X-ray diffraction were used to investigate fiber orientation. The polypropylene matrix was removed by solvent extraction, and the lengths of the residual fibers were optically determined. Fiber...

Influence of non-covalent modification of multiwalled carbon nanotubes on the crystallization behaviour of binary blends of polypropylene and polyamide 6.

PubMed

Mukhopadhyay, Nabaneeta; Panwar, Ajay S; Kumar, Gulshan; Samajdar, I; Bhattacharyya, Arup R

2015-02-14

Blends of polypropylene (PP) and polyamide 6 (PA6) with multiwalled carbon nanotubes (MWNTs) were prepared using different processing strategies in a twin-screw micro-compounder. The effect of MWNTs on the crystallization behaviour of the PP phase and the PA6 phase of the blend has been investigated through non-isothermal crystallization studies by differential scanning calorimetric analysis. Furthermore, the effect of the addition of the compatibilizer (PP-g-MA) and the modification of MWNTs (m-MWNTs) with a non-covalent organic modifier (Li-salt of 6 amino hexanoic acid, Li-AHA) has also been studied in context to the crystallization behaviour of the PP and PA6 phase in the blend. The crystallization studies have indicated a significant increase in bulk crystallization temperature of the PP phase in the blend in the presence of MWNTs. Moreover, the formation of 'trans-lamellar crystalline' structure consisting of PA6 'trans-crystalline lamellae' on MWNTs surface was facilitated in the case of blends prepared via 'protocol 2' as compared to the corresponding blends prepared via 'protocol 1'. Wide angle X-ray diffraction analysis has showed the existence of a β-polymorph of the PP phase due to incorporation of the PA6 phase in the blend. Addition of MWNTs in the blends has facilitated further β-crystalline structure formation of the PP phase. In the presence of m-MWNTs, a higher β-fraction was observed in the PP phase as compared to the blend with pristine MWNTs. Addition of PP-g-MA has suppressed the β-phase formation in the PP phase in the blend. X-ray bulk texture analysis revealed that incorporation of PA6 as well as pristine/modified MWNTs has influenced the extent of orientation of the PP chains towards specific crystalline planes in various blend compositions of PP and PA6.

Genome Regions Associated with Functional Performance of Soybean Stem Fibers in Polypropylene Thermoplastic Composites

PubMed Central

Reinprecht, Yarmilla; Arif, Muhammad; Simon, Leonardo C.; Pauls, K. Peter

2015-01-01

Plant fibers can be used to produce composite materials for automobile parts, thus reducing plastic used in their manufacture, overall vehicle weight and fuel consumption when they replace mineral fillers and glass fibers. Soybean stem residues are, potentially, significant sources of inexpensive, renewable and biodegradable natural fibers, but are not curretly used for biocomposite production due to the functional properties of their fibers in composites being unknown. The current study was initiated to investigate the effects of plant genotype on the performance characteristics of soybean stem fibers when incorporated into a polypropylene (PP) matrix using a selective phenotyping approach. Fibers from 50 lines of a recombinant inbred line population (169 RILs) grown in different environments were incorporated into PP at 20% (wt/wt) by extrusion. Test samples were injection molded and characterized for their mechanical properties. The performance of stem fibers in the composites was significantly affected by genotype and environment. Fibers from different genotypes had significantly different chemical compositions, thus composites prepared with these fibers displayed different physical properties. This study demonstrates that thermoplastic composites with soybean stem-derived fibers have mechanical properties that are equivalent or better than wheat straw fiber composites currently being used for manufacturing interior automotive parts. The addition of soybean stem residues improved flexural, tensile and impact properties of the composites. Furthermore, by linkage and in silico mapping we identified genomic regions to which quantitative trait loci (QTL) for compositional and functional properties of soybean stem fibers in thermoplastic composites, as well as genes for cell wall synthesis, were co-localized. These results may lead to the development of high value uses for soybean stem residue. PMID:26167917

In situ reactive compatibilization of polypropylene/ethylene-propylene-diene monomer thermoplastic vulcanizate by zinc dimethacrylate via peroxide-induced dynamic vulcanization.

PubMed

Chen, Yukun; Xu, Chuanhui; Liang, Xingquan; Cao, Liming

2013-09-12

This work demonstrates an approach of in situ reactive compatibilization between polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) by using zinc dimethacrylate (ZDMA) as a compatibilizer and, simultaneously, as a very strong reinforcing agent. With the incorporation of 7phr ZDMA in the PP/EPDM (30/70, w/w) thermoplastic vulcanizate (TPV), the tensile strength, tear strength, elongation at break, and hardness of PP/EPDM/ZDMA TPV were increased from 5.3 MPa, 31.3 kN/m, 222%, and 78 up to 11.2 MPa, 64.2 kN/m, 396%, and 83, respectively. This tremendous reinforcing as well as the compatibilization effect of the ZDMA was understood by polymerization of ZDMA and ZDMA reacted with EPDM and PP during peroxide-induced dynamic vulcanization. A peculiar phase structure that rubber particles were surrounded and "bonded" by a thick transition zone that contained numerous of nanoparticles with dimensions of about 20-30 nm was observed from transmission electron microscopy. Scanning electron microscopy results confirmed that incorporation of ZDMA reduced the size of the cross-linked EPDM particles. Moreover, we found that the compatibilized TPV showed a higher tan δ peak temperature for EPDM phase and a lower tan δ peak temperature for PP phase. The suggested method for in situ reactive compatibilization of PP and EPDM offers routes to the design of new TPV-based technical products for diversified applications.

Effect of polyamide 6 on the morphology and electrical conductivity of carbon black-filled polypropylene composites

PubMed Central

Zhang, Xuewei; Liu, Jiang; Wang, Yi

2017-01-01

Carbon black (CB)-filled polypropylene (PP) with surface resistivity between 106 and 109 Ω sq−1 is the ideal antistatic plastic material in the electronics and electric industry. However, a large amount of CB may have an adverse effect on the mechanical properties and processing performance of the material, thus an improved ternary system is developed. Blends of CB-filled PP and polyamide 6 (PA6) have been prepared by melt blending in order to obtain electrically conductive polymer composites with a low electrical percolation threshold based on the concept of double percolation. The morphological developments of these composites were studied by scanning electron microscopy. The results showed that CB particles were selectively dispersed in PA6 phases due to the good interaction and interfacial adhesion between CB and PA6. At the same CB loadings, the surface resistivity of PP/PA6/CB composite was smaller than that of PP/CB composite system, which indicated the better conductivity in the former composite. The increasing amount of PA6 in the composites changed the morphology from a typical sea–island morphology to a co-continuous morphology. What is more, with 8 wt% of CB and PP/PA6 phase ratio of 70/30 in which the PP and PA6 phases formed a co-continuous structure, the electrical conductivity of the composite peaked at 2.01 × 105 Ω sq−1. PMID:29308223

Effects of fire retardants on physical, mechanical, and fire properties of flat-pressed WPCs

Treesearch

Nadir Ayrilmis; Jan T. Benthien; Heiko Thoemen; Robert H. White

2012-01-01

Physical, mechanical, and fire properties of the flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (10% by weight) at different levels of wood flour (WF) content, 40, 50, or 60 wt%, were investigated. The WPC panels were made from dry-blended WF, polypropylene (PP), and fire retardant (FR) powders with maleic anhydride-grafted PP (2...

Evaluation of the effect of organic pro-degradant concentration in polypropylene exposed to the natural ageing

NASA Astrophysics Data System (ADS)

Montagna, L. S.; Catto, A. L.; Rossini, K.; Forte, M. M. C.; Santana, R. M. C.

2014-05-01

The production and consumption of plastics in the last decade has recorded a remarkable increase in the scientific and industrial interest in environmentally degradable polymer (EDPs). Polymers wastes are deposited improperly, such as dumps, landfills, rivers and seas, causing a serious problem by the accumulation in the environment. The abiotic processes, like the photodegradation, are the most efficient occurring in the open environmental, where the polymers undergo degradation from the action of sunlight that result from direct exposure to solar radiation, however depend of the type of chemical ageing, which is the principal component of climatic ageing. The subject of this work is to study the influence of concentration of organic pro-degradant (1, 2 and 3 % w/w) in the polypropylene (PP) exposed in natural ageing. PP samples with and without the additive were processed in plates square form, obtained by thermal compression molding (TCM) using a press at 200°C under 2 tons for 5 min, and then were exposed at natural ageing during 120 days. The presence of organic additive influenced on PP degradability, this fact was assessed by changes in the thermal and morphology properties of the samples after 120 days of natural ageing. Scanning Electronic Microscopy (SEM) results of the morphological surface of the modified PP samples showed greater degradation photochemical oxidative when compared to neat PP, due to increase of rugosity and formation of microvoids. PP samples with different pro-degradant concentration under natural ageing presented a degree of crystallinity, obtained by Differential Scanning Calorimeter (DSC) increases in comparing the neat PP.

Facile synthesis of flexible macroporous polypropylene sponges for separation of oil and water

PubMed Central

Wang, Guowei; Uyama, Hiroshi

2016-01-01

Oil spill disasters always occur accidentally, accompanied by the release of plenty of crude oil that could spread quickly over a wide area, creating enormous damage to the fragile marine ecological system. Therefore, the facile large-scale synthesis of hydrophobic three-dimensional (3-D) porous sorbents from low cost raw materials is in urgent demand. In this study, we report the facile template-free synthesis of polypropylene (PP) sponge by using a thermally-induced phase separation (TIPS) technique. The obtained sponge showed macroporous structure, excellent mechanical property, high hydrophobicity, and superoleophilicity. Oil could be separated from an oil/water mixture by simple immersing the sponge into the mixture and subsequent squeezing the sponge. All of these features make this sponge the most promising oil sorbent that will replace commercial non-woven PP fabrics. PMID:26880297

Electromagnetic absorption behaviour of ferrite loaded three phase carbon fabric composites

NASA Astrophysics Data System (ADS)

Jagatheesan, Krishnasamy; Ramasamy, Alagirusamy; Das, Apurba; Basu, Ananjan

2018-02-01

This article investigates the electromagnetic absorption behaviours of carbon helical yarn fabric reinforced composites and manganese-zinc (Mn-Zn) ferrite particles loaded 3 phase fabric composites. A carbon helical yarn having stainless steel core was prepared and made into single jersey knitted fabric. The composite was prepared by sandwiching a fabric with polypropylene films and thermal pressed. The absorption values of helical yarn fabric composite was observed to be less in the C band region (4-8 GHz). For improving the absorption coefficients of composite, Mn-Zn ferrite particles were dispersed in the polypropylene (PP) composite. The ferrite loaded PP composites exhibited better permittivity and permeability values, hence the absorption loss of the composite was improved. The helical yarn fabric reinforced with Mn-Zn ferrite/PP composite showed larger absorption coefficients than virgin PP/fabric composite. The change in thermal stability and particle size distribution in the Mn-Zn ferrite/PP composite was also analyzed. At higher ferrite concentration, bimodal particle distribution was observed which increased the conductivity and shielding effectiveness (SE) of the composite. In addition, complex permittivity value was also increased for higher incident frequency (4-8 GHz). As the ferrite content increases, the dielectric loss and magnetic permeability of PP/ferrite increases due to increased magnetic loss. Hence, ferrite loaded PP composite showed the total SE of -14.2 dB with the absorption coefficients of 0.717. The S1C7 fabric composite having ferrite dispersion showed the better absorption loss and lower reflection coefficient of 14.2 dB and 0.345 respectively compared to virgin PP/helical yarn fabric composite. The increasing ferrite content (45 wt%) improved the absorption loss and total SE. Though, ferrite based fabric composite exhibits moderate absorptive shielding, it can be used as shielding panels in the electronic industries.

Effect of pH and polypropylene beads in hybrid water treatment process of alumina ceramic microfiltration and PP beads with air back-flushing and UV irradiation.

PubMed

Park, Jin Yong; Song, Seunghwa

2017-07-07

For advanced water treatment, effects of pH and pure polypropylene (PP) beads packing concentration on membrane fouling and treatment efficiency were observed in a hybrid process of alumina ceramic microfiltration (MF; pore size 0.1 μm) and pure PP beads. Instead of natural organic matters and fine inorganic particles in natural water source, a quantity of humic acid (HA) and kaolin was dissolved in distilled water. The synthetic feed flowed inside the MF membrane, and the permeated water contacted the PP beads fluidized in the gap of the membrane and the acryl module case with outside UV irradiation. Periodic air back-flushing was performed to control membrane fouling during 10 s per 10 min. The membrane fouling resistance (R f ) was the maximum at 30 g/L of PP bead concentration. Finally, the maximum total permeated volume (V T ) was acquired at 5 g/L of PP beads, because flux maintained higher all through the operation. The treatment efficiency of turbidity was almost constant, independent of PP bead concentration; however, that of dissolved organic materials (DOM) showed the maximal at 50 g/L of PP beads. The R f increased as increasing feed pH from 5 to 9; however, the maximum V T was acquired at pH 6. It means that the membrane fouling could be inhibited at low acid condition. The treatment efficiency of turbidity increased a little, and that of DOM increased from 73.6 to 75.7% as increasing pH from 5 to 9.

Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

PubMed

Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

2013-03-01

The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

Antimicrobial polymers - The antibacterial effect of photoactivated nano titanium dioxide polymer composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huppmann, T., E-mail: teresa.huppmann@tum.de; Leonhardt, S., E-mail: stefan.leonhardt@mytum.de, E-mail: erhard.krampe@tum.de; Krampe, E., E-mail: stefan.leonhardt@mytum.de, E-mail: erhard.krampe@tum.de

To obtain a polymer with antimicrobial properties for medical and sanitary applications nanoscale titanium dioxide (TiO{sub 2}) particles have been incorporated into a medical grade polypropylene (PP) matrix with various filler contents (0 wt %, 2 wt %, 10 wt % and 15 wt %). The standard application of TiO{sub 2} for antimicrobial efficacy is to deposit a thin TiO{sub 2} coating on the surface. In contrast to the common way of applying a coating, TiO{sub 2} particles were applied into the bulk polymer. With this design we want to ensure antimicrobial properties even after application of impact effects thatmore » could lead to surface defects. The filler material (Aeroxide® TiO{sub 2} P25, Evonik) was applied via melt compounding and the compounding parameters were optimized with respect to nanoscale titanium dioxide. In a next step the effect of UV-irradiation on the compounds concerning their photocatalytic activity, which is related to the titanium dioxide amount, was investigated. The photocatalytic effect of TiO{sub 2}-PP-composites was analyzed by contact angle measurement, by methylene blue testing and by evaluation of inactivation potential for Escherichia coli (E.coli) bacteria. The dependence of antimicrobial activity on the filler content was evaluated, and on the basis of different titanium dioxide fractions adequate amounts of additives within the compounds were discussed. Specimens displayed a higher photocatalytic and also antimicrobial activity and lower contact angles with increasing titania content. The results suggest that the presence of titania embedded in the PP matrix leads to a surface change and a photocatalytic effect with bacteria killing result.« less

Melt-state rheology, solid-state mechanical properties and microstructure of polymer-clay nanocomposites

NASA Astrophysics Data System (ADS)

Somwangthanaroj, Anongnat

Polymer/clay nanocomposites have the potential usefulness in industrial applications such as automotive and packaging due to their strong, light-weight and inexpensive properties. However, to respond to needs of various applications it is crucial to understand the crystallization and rheological properties of these materials. Our initial hypothesis was that the processing conditions such as shear rate, shear strain and temperature affect the crystallization kinetics of intercalated polypropylene nanocomposites. Another hypothesis was that the compatibilizer, PP-MA, affects the role of the nucleating agent, sodium benzoate. The final hypothesis was that the rheological properties of nanocomposites depend on the degree of clay dispersion. By means of time-resolved small-angle light scattering, we were able to demonstrate that clay enhances the crystallization kinetics in nanocomposites and its result differs significantly from that of pure polypropylene. Characteristic crystallization times are extracted from the time evolution of integral measures of the angularly dependent parallel polarized and cross polarized light scattering intensity. Flow acceleration of crystallization kinetics has been observed for the polymer nanocomposites at applied strain rates for which flow has only modest effect on polypropylene crystallization. Furthermore, we were able to conclude that the addition of the nucleating agent sodium benzoate in the presence of polypropylene grafted maleic anhydride is not effective in accelerating crystallization. The rheological properties of two types of polypropylene/clay nanocomposites, with different degrees of clay dispersion have been measured in both linear and non-linear viscoelastic regime. In the linear viscoelastic regime, the storage and loss modulus of nanocomposites increases when clay loading increases. The storage and loss modulus of unsonicated nanocomposites are higher than the sonicated ones because the ultrasonic processing alters the structure of clay and polymer blend in sonicated nanocomposite. Non-linear rheology addresses the possible structure of particulate domains of clays in polymers. From this research, we demonstrated the possible effect of clay and compatibilizer on the crystallization kinetics and the effect of structure of clay and polymer matrix on rheological properties. To understand how clay enhances the mechanical properties, we still need to investigate where the clay actually resides and how the polymer crystallite forms.

Analysis of Nanodomain Composition in High-Impact Polypropylene by Atomic Force Microscopy-Infrared.

PubMed

Tang, Fuguang; Bao, Peite; Su, Zhaohui

2016-05-03

In this paper, compositions of nanodomains in a commercial high-impact polypropylene (HIPP) were investigated by an atomic force microscopy-infrared (AFM-IR) technique. An AFM-IR quantitative analysis method was established for the first time, which was then employed to analyze the polyethylene content in the nanoscopic domains of the rubber particles dispersed in the polypropylene matrix. It was found that the polyethylene content in the matrix was close to zero and was high in the rubbery intermediate layers, both as expected. However, the major component of the rigid cores of the rubber particles was found to be polypropylene rather than polyethylene, contrary to what was previously believed. The finding provides new insight into the complicated structure of HIPPs, and the AFM-IR quantitative method reported here offers a useful tool for assessing compositions of nanoscopic domains in complex polymeric systems.

Electromagnetic interference shielding effectiveness of polypropylene/conducting fiber composites

NASA Astrophysics Data System (ADS)

Lee, Pyoung-Chan; Kim, Bo-Ram; Jeoung, Sun Kyoung; Kim, Yeung Keun

2016-03-01

Electromagnetic released from the automotive electronic parts is harmful to human body. Electromagnetic interference (EMT) shielding refers to the reflection and/or adsorption of electromagnetic radiation by a material, which thereby acts as a shield against the penetration of the radiation through the shield. Polypropylene (PP)/conductive micro fiber composites containing various fiber contents and fiber length were injection-molded. The effect of fiber content and length on electrical properties of the composites was studied by electrical resistivity and EMT shielding measurements. The through-plane electrical conductivity and dielectric permittivity were obtained by measuring dielectric properties. The EMT shielding effectiveness (SE) was investigated by using S-parameter in the range of 100 ~ 1500 MHz. Reflection, absorption and multiple-reflection are the EMT attenuation mechanisms. From the measurement of S-Parameters, the absorption coefficient, reflection coefficient, and the shielding efficiency of the materials were calculated. The EMT SE of PP/conducing fiber composites is 40 dB over a wide frequency range up to 1.5 GHz, which is higher than that of PP/talc composite used automotive parts, viz. 0 dB.

Abiotic degradation of plastic films

NASA Astrophysics Data System (ADS)

Ángeles-López, Y. G.; Gutiérrez-Mayen, A. M.; Velasco-Pérez, M.; Beltrán-Villavicencio, M.; Vázquez-Morillas, A.; Cano-Blanco, M.

2017-01-01

Degradable plastics have been promoted as an option to mitigate the environmental impacts of plastic waste. However, there is no certainty about its degradability under different environmental conditions. The effect of accelerated weathering (AW), natural weathering (NW) and thermal oxidation (TO) on different plastics (high density polyethylene, HDPE; oxodegradable high density polyethylene, HDPE-oxo; compostable plastic, Ecovio ® metalized polypropylene, PP; and oxodegradable metalized polypropylene, PP-oxo) was studied. Plastics films were exposed to AW per 110 hours; to NW per 90 days; and to TO per 30 days. Plastic films exposed to AW and NW showed a general loss on mechanical properties. The highest reduction in elongation at break on AW occurred to HDPE-oxo (from 400.4% to 20.9%) and was higher than 90% for HDPE, HDPE-oxo, Ecovio ® and PP-oxo in NW. No substantial evidence of degradation was found on plastics exposed to TO. Oxo-plastics showed higher degradation rates than their conventional counterparts, and the compostable plastic was resistant to degradation in the studied abiotic conditions. This study shows that degradation of plastics in real life conditions will vary depending in both, their composition and the environment.

Surface functionalisation of polypropylene hernia-repair meshes by RF-activated plasma polymerisation of acrylic acid and silver nanoparticles

NASA Astrophysics Data System (ADS)

Nisticò, Roberto; Rosellini, Andrea; Rivolo, Paola; Faga, Maria Giulia; Lamberti, Roberta; Martorana, Selanna; Castellino, Micaela; Virga, Alessandro; Mandracci, Pietro; Malandrino, Mery; Magnacca, Giuliana

2015-02-01

Hernia diseases are among the most common and diffuse causes of surgical interventions. Unfortunately, still nowadays there are different phenomena which can cause the hernioplasty failure, for instance post-operative prostheses displacements and proliferation of bacteria in the surgical site. In order to limit these problems, commercial polypropylene (PP) and polypropylene/Teflon (PP/PTFE) bi-material meshes were surface functionalised to confer adhesive properties (and therefore reduce undesired displacements) using polyacrylic acid synthesized by plasma polymerisation (PPAA). A broad physico-chemical and morphological characterisation was carried out and adhesion properties were investigated by means of atomic force microscopy (AFM) used in force/distance (F/D) mode. Once biomedical devices surface was functionalised by PPAA coating, metallic silver nanoparticles (AgNPs) with antimicrobial properties were synthesised and loaded onto the polymeric prostheses. The effect of the PPAA, containing carboxylic functionalities, adhesive coating towards AgNPs loading capacity was verified by means of X-ray photoelectron spectroscopy (XPS). Preliminary measurement of the Ag loaded amount and release in water were also investigated via inductively coupled plasma atomic emission spectroscopy (ICP-AES). Promising results were obtained for the functionalised biomaterials, encouraging future in vitro and in vivo tests.

The Thermal Conductivity Measurements of Solid Samples by Heat Flux Differantial Scanning Calorimetry

NASA Astrophysics Data System (ADS)

Kök, M.; Aydoǧdu, Y.

2007-04-01

The thermal conductivity of polyvinylchloride (PVC), polysytrene (PS) and polypropylene (PP) were measured by heat flux DSC. Our results are in good agreement with the results observed by different methods.

Damage zone development and failure sequence in glass fibre mat-reinforced polypropylene under static loading conditions

NASA Astrophysics Data System (ADS)

Karger-Kocsis, J.; Fejes-Kozma, Zs.

1994-01-01

The size of the damage zone in glass mat-reinforced PP (GMT—PP) can well be estimated by locating the acoustic emission (AE) events monitored during loading. It was shown that the extension of this zone can be adequately approximated by a circle of about 30-mm diameter, the half of which penetrates into the free ligament of the specimen.

Polymer Grafted Nanoparticles for Designed Interfaces in Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Mohammadkhani, Mohammad

This dissertation presents the design, synthesis, and characterization of polymer nanocomposite interfaces and the property enhancement from this interface design. Through the use of reversible addition fragmentation chain transfer (RAFT) polymerization for the grafting of polymer chains to silica nanoparticles, the surface of silica nanoparticles can be manipulated to tune the properties of nanocomposites by controlling the interface between the particles and the polymer matrix. In the first part of this work, compatibility of 15 nm silica nanoparticles grafted with different alkyl methacrylates with linear low density polyethylene was investigated. SI-RAFT polymerization of hexyl, lauryl, and stearyl methacrylate on silica NPs was studied in detail and revealed living character for all these polymerizations. Composites of linear low density polyethylene filled with PHMA, PLMA, and PSMA-g-SiO2 NPs were prepared and analyzed to find the effects of side chain length on the dispersibility of particles throughout the matrix. PSMA brushes were the most "olefin-like" of the series and thus showed the highest compatibility with polyethylene. The effects of PSMA brush molecular weight and chain density on the dispersion of silica particles were investigated. Multiple characterizations such as DSC, WAXS, and SAXS were applied to study the interaction between PSMA-g-SiO2 NPs and the polyethylene matrix. In the next part, the compatibility of PSMA-g-SiO2 NPs with different molecular variables with isotactic polypropylene was investigated. Anthracene was used as a conjugated ligand to introduce to the surface of PSMA-g-SiO2 NPs to develop bimodal architecture on nanoparticles and use them in polypropylene dielectric nanocomposites. The dispersion of particles was investigated and showed that for both monomodal and bimodal particles where PSMA chains are medium density and relatively high molecular weight, they maintain an acceptable level of dispersion throughout of the matrix. Furthermore, the effects of anthracene surface modification and also level of dispersion towards improving the dielectric breakdown strength under AC and DC conditions were studied. Finally, the RAFT polymerizations of isoprene in solution and, for the first time, on the surface of silica particles using a high temperature stable trithiocarbonate RAFT agent were studied. The effects of different temperatures, initiators, and monomer feed ratios on the kinetics of the SI-RAFT polymerization were also investigated. Kinetic studies revealed that the rate of SI-RAFT polymerization increased with an increase in the density of grafted RAFT agent. Well-defined polyisoprene-grafted silica NPs (PIP-g-SiO2 NPs) were synthesized and mixed with a polyisoprene matrix to determine the compatibility and dispersion of these particles with the matrix. Hydrogenation of PIP-g-SiO2 NPs were performed using p-toluenesulfonyl hydrazide at high temperature to obtain hydrogenated (HPIP)-g-SiO2 NPs. A bimodal octadecylsilane (C18)-HPIP-g-SiO2 NPs sample was synthesized and mixed with isotactic PP matrix analyzed for the compatibility with polypropylene.

Co-pyrolysis of rice straw and polypropylene using fixed-bed pyrolyzer

NASA Astrophysics Data System (ADS)

Izzatie, N. I.; Basha, M. H.; Uemura, Y.; Mazlan, M. A.; Hashim, M. S. M.; Amin, N. A. M.; Hamid, M. F.

2016-11-01

The present work encompasses the impact of temperature (450, 500, 550, 600 °C) on the properties of pyrolysis oil and on other product yield for the co-pyrolysis of Polypropylene (PP) plastics and rice straw. Co-pyrolysis of PP plastic and rice straw were conducted in a fixed-bed drop type pyrolyzer under an inert condition to attain maximum oil yield. Physically, the pyrolysis oil is dark-brown in colour with free flowing and has a strong acrid smell. Copyrolysis between these typically obtained in maximum pyrolysis oil yields up to 69% by ratio 1:1 at a maximum temperature of 550 °C. From the maximum yield of pyrolysis oil, characterization of pyrolysis product and effect of biomass type of the composition were evaluated. Pyrolysis oil contains a high water content of 66.137 wt.%. Furfural, 2- methylnaphthalene, tetrahydrofuran (THF), toluene and acetaldehyde were the major organic compounds found in pyrolysis oil of rice straw mixed with PP. Bio-char collected from co-pyrolysis of rice straw mixed with PP plastic has high calorific value of 21.190 kJ/g and also carbon content with 59.02 wt.% and could contribute to high heating value. The non-condensable gases consist of hydrogen, carbon monoxide, and methane as the major gas components.

Novel PEPA-functionalized graphene oxide for fire safety enhancement of polypropylene

NASA Astrophysics Data System (ADS)

You Xu, Jia; Liu, Jie; Li, Kai Dan; Miao, Lei; Tanemura, Sakae

2015-04-01

Polypropylene (PP) is a general-purpose plastic, but some applications are constrained by its high flammability. Thus, flame retardant PP is urgently demanded. In this article, intumescent flame retardant PP (IFRPP) composites with enhanced fire safety were prepared using 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo [2.2.2] octane (PEPA) functionalized graphene oxide (PGO) as synergist. The PGO was prepared through a mild chemical reaction by the covalent attachment of a caged-structure organic compound, PEPA, onto GO nanosheets using toluene diisocynate (TDI) as the intermediary agent. The novel PEPA-functionalized graphene oxide not only improves the heat resistance of GO but also converts GO and PEPA from hydrophobic to hydrophilic materials, which leads to even distribution in PP. In our case, 7 wt% addition of PGO as one of the fillers for IFRPP composites significantly reduces its inflammability and fire hazards when compared with PEPA, by the improvement of first release rate peak (PHRR), total heat release, first smoke release rate peak (PSRR) and total smoke release, suggesting its great potential as the IFR synergist in industry. The reason is mainly attributed to the barrier effect of the unburned graphene sheets, which protects by the decomposition products of PEPA and TDI, promotes the formation of graphitized carbon and inhibits the heat and gas release.

Investigations into the mechanical and physical behavior of thermoplastic elastomers

NASA Astrophysics Data System (ADS)

Wright, Kathryn Janelle

This thesis describes investigations into the physical and mechanical characteristics of two commercial thermoplastic elastomer (TPE) systems. Both systems studied exhibit elastomeric behavior similar to more traditional crosslinked elastomers; however, in these TPEs non-conventional polymer architectures and morphologies are used to produce their elastomeric behavior. The two TPEs of interest are ethylene-propylene random copolymers and dynamically vulcanized blends of ethylene-propylene-diene monomer (EPDM) and isotactic polypropylene (iPP). Very few studies have examined the mechanical behavior of these materials in terms of their composition and morphology. As such, the primary goal of this research is to both qualitatively and quantitatively understand the influence of composition and morphology on mechanical behavior. In additional very little information is available that compares their performance with that of crosslinked elastomers. As a result, the secondary goal is to qualitatively compare the mechanical responses of these TPEs with that of their more traditional counterparts. The ethylene-propylene copolymers studied have very high comonomer contents and exhibit slow crystallization kinetics. Their morphology consists of nanoscale crystallites embedded in an amorphous rubbery matrix. These crystallites act as physical crosslinks that allow for elasticity. Slow crystallization causes subsequent changes in mechanical behavior that take place over days and even weeks. Physical responses (e.g., density, crystallization kinetics, and crystal structure) of five copolymer compositions are investigated. Mechanical responses (e.g., stiffness, ductility, yielding, and reversibility) are also examined. Finally, the influence of morphology on deformation is studied using in situ analytical techniques. The EPDM/iPP blends are dynamically vulcanized which produces a complex morphology consisting of chemically crosslinked EPDM domains embedded within a semicrystalline iPP matrix. Six compositions are investigated as a function of three parameters: major volume fraction, iPP molecular weight, and EPDM cure state. The influence of these parameters on morphology and resulting mechanical behavior is examined. This work culminates in the development of a morphological model to describe the steady-state reversibility of these EPDM/iPP blends. The model is then evaluated in terms of composition and cure state.

Tensile properties of wood flour/kenaf fiber polypropylene hybrid composites

Treesearch

Jamal Mirbagheri; Mehdi Tajvidi; John C. Hermanson; Ismaeil Ghasemi

2007-01-01

Hybrid composites of wood flour/kenaf fiber and polypropylene were prepared at a fixed fiber to plastic ratio of 40 : 60 and variable ratios of the two reinforcements namely 40 : 0, 30 : 10, 20 : 20, 10 : 30, and 0 : 40 by weight. Polypropylene was used as the polymer matrix, and 40–80 mesh kenaf fiber and 60–100 mesh wood flour were used as the...

An innovative recycling process to obtain pure polyethylene and polypropylene from household waste.

PubMed

Serranti, Silvia; Luciani, Valentina; Bonifazi, Giuseppe; Hu, Bin; Rem, Peter C

2015-01-01

An innovative recycling process, based on magnetic density separation (MDS) and hyperspectral imaging (HSI), to obtain high quality polypropylene and polyethylene as secondary raw materials, is presented. More in details, MDS was applied to two different polyolefin mixtures coming from household waste. The quality of the two separated PP and PE streams, in terms of purity, was evaluated by a classification procedure based on HSI working in the near infrared range (1000-1700 nm). The classification model was built using known PE and PP samples as training set. The results obtained by HSI were compared with those obtained by classical density analysis carried in laboratory on the same polymers. The results obtained by MDS and the quality assessment of the plastic products by HSI showed that the combined action of these two technologies is a valid solution that can be implemented at industrial level. Copyright © 2014 Elsevier Ltd. All rights reserved.

Catalytic co-pyrolysis of cellulose and polypropylene over all-silica mesoporous catalyst MCM-41 and Al-MCM-41.

PubMed

Chi, Yongchao; Xue, Junjie; Zhuo, Jiankun; Zhang, Dahu; Liu, Mi; Yao, Qiang

2018-08-15

Fast pyrolysis is one of the most economical and efficient technologies to convert biomass to bio-oil and valuable chemical products. Co-pyrolysis with hydrogen rich materials such as plastics over zeolite catalysts is one of the significant solutions to various problems of bio-oil such as high oxygen content, low heat value and high acid content. This paper studied pyrolysis of cellulose and polypropylene (PP) separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41. The pyrolysis over different heating rates (10K/min, 20K/min, 30K/min) was studied by Thermogravimetry Analysis (TGA) and kinetic parameters were obtained by Coats-Redfern method and isoconversion method. TG and DTG data shows that the two catalysts advance the pyrolysis reaction of PP significantly and reduce its peak temperature of DTG curve from 458°C to 341°C. The activation energy of pyrolysis of PP also has a remarkable reduction over the two catalysts. Py-GC/MS method was used to obtain the product distribution of pyrolysis of cellulose and PP separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41 at constant temperature of 650°C. Experiment results proved that co-pyrolysis with PP bring significant changes to the product distribution of cellulose. Oxygenated compounds such as furans are decreased, while yields of olefins and aromatics increase greatly. The yield of furans increases with the catalysis of MCM-41 as for the pyrolysis of cellulose and co-pyrolysis, while the yield of olefins and aromatics both experience significant growth over Al-MCM-41, which can be explained by the abundant acid centers in Al-MCM-41. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of the effect of organic pro-degradant concentration in polypropylene exposed to the natural ageing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montagna, L. S., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Catto, A. L., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Rossini, K., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br

The production and consumption of plastics in the last decade has recorded a remarkable increase in the scientific and industrial interest in environmentally degradable polymer (EDPs). Polymers wastes are deposited improperly, such as dumps, landfills, rivers and seas, causing a serious problem by the accumulation in the environment. The abiotic processes, like the photodegradation, are the most efficient occurring in the open environmental, where the polymers undergo degradation from the action of sunlight that result from direct exposure to solar radiation, however depend of the type of chemical ageing, which is the principal component of climatic ageing. The subject ofmore » this work is to study the influence of concentration of organic pro-degradant (1, 2 and 3 % w/w) in the polypropylene (PP) exposed in natural ageing. PP samples with and without the additive were processed in plates square form, obtained by thermal compression molding (TCM) using a press at 200°C under 2 tons for 5 min, and then were exposed at natural ageing during 120 days. The presence of organic additive influenced on PP degradability, this fact was assessed by changes in the thermal and morphology properties of the samples after 120 days of natural ageing. Scanning Electronic Microscopy (SEM) results of the morphological surface of the modified PP samples showed greater degradation photochemical oxidative when compared to neat PP, due to increase of rugosity and formation of microvoids. PP samples with different pro-degradant concentration under natural ageing presented a degree of crystallinity, obtained by Differential Scanning Calorimeter (DSC) increases in comparing the neat PP.« less

The chemical modification and characterization of polypropylene membrane with environment response by in-situ chlorinating graft copolymerization

NASA Astrophysics Data System (ADS)

Zhang, Yue; Liu, Jiankai; Hu, Wenjie; Feng, Ying; Zhao, Jiruo

2017-08-01

In this study, a novel chemical surface modification method of polyolefin membranes is applied following the in-situ chlorinating graft copolymerization (ISCGC). Polypropylene (PP)/methyl methacrylate (MMA) system was used as an example. A unique structure was formed by the modification process on the original membrane surface and the product exhibited an environmental response. Chlorine free radicals were generated using ultraviolet and heat and were used to capture the hydrogen in the polymer chains on the substrate surface. The formed macromolecular radicals could react with MMA over 2 h to achieve a high coverage ratio polymer on the PP membrane surface. The graft copolymers were characterized using FTIR, 1H-NMR, DSC, and XPS, which all proved the feasibility of chemically modifying the PP membrane surface by ISCGC. The surface morphology of the grafted PP membrane was characterized using SEM and AFM. The results showed that the grafted product presents a uniform, neat, and dense mastoid structure with an average thickness of 4.44 μm, which was expected to be similar to the brush-like surface structure. The contact angle and AFM tests indicated that the product surface is responsive to solvent and pH. The experimental results showed that the PP membrane surface structure can be reconstructed using ISCGC, a method that can be used for environment-responsive polymer materials. Moreover, the product has the characteristics of polymer interfacial brush.

Characterization of Potential Exposures to Nanoparticles and Fibers during Manufacturing and Recycling of Carbon Nanotube Reinforced Polypropylene Composites.

PubMed

Boonruksa, Pongsit; Bello, Dhimiter; Zhang, Jinde; Isaacs, Jacqueline A; Mead, Joey L; Woskie, Susan R

2016-01-01

Carbon nanotube (CNT) polymer composites are widely used as raw materials in multiple industries because of their excellent properties. This expansion, however, is accompanied by realistic concerns over potential release of CNTs and associated nanoparticles during the manufacturing, recycling, use, and disposal of CNT composite products. Such data continue to be limited, especially with regards to post-processing of CNT-enabled products, recycling and handling of nanowaste, and end-of-life disposal. This study investigated for the first time airborne nanoparticle and fibers exposures during injection molding and recycling of CNT polypropylene composites (CNT-PP) relative to that of PP. Exposure characterization focused on source emissions during loading, melting, molding, grinding, and recycling of scrap material over 20 cycles and included real-time characterization of total particle number concentration and size distribution, nanoparticle and fiber morphology, and fiber concentrations near the operator. Total airborne nanoparticle concentration emitted during loading, melting, molding, and grinding of CNT-PP had geometric mean ranging from 1.2 × 10(3) to 4.3 × 10(5) particles cm(-3), with the highest exposures being up to 2.9 and 300.7 times above the background for injection molding and grinding, respectively. Most of these emissions were similar to PP synthesis. Melting and molding of CNT-PP and PP produced exclusively nanoparticles. Grinding of CNT-PP but not PP generated larger particles with encapsulated CNTs, particles with CNT extrusions, and respirable fiber (up to 0.2 fibers cm(-3)). No free CNTs were found in any of the processes. The number of recycling runs had no significant impact on exposures. Further research into the chemical composition of the emitted nanoparticles is warranted. In the meanwhile, exposure controls should be instituted during processing and recycling of CNT-PP. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Effect of cellulose nanocrystals (CNC) on rheological and mechanical properties and crystallization behavior of PLA/CNC nanocomposites.

PubMed

Kamal, Musa R; Khoshkava, Vahid

2015-06-05

In earlier work, we reported that spray freeze drying of cellulose nanocrystals (CNC) yields porous agglomerate structures. On the other hand, the conventional spray dried CNC (CNCSD) and the freeze dried CNC (CNCFD) produce compact solid structures with very low porosity. As it is rather difficult to obtain direct microscopic evidence of the quality of dispersion of CNC in polymer nanocomposites, it was shown that supporting evidence of the quality and influence of dispersion in a polypropylene (PP)/CNC nanocomposite could be obtained by studying the rheological behavior, mechanical properties and crystallization characteristics of PP/CNC nanocomposites. In an effort to produce a sustainable, fully biosourced, biodegradable nanocomposite, this manuscript presents the results of a study of the rheological, mechanical and crystallization behavior of PLA/CNCSFD nanocomposites obtained by melt processing. The results are analyzed to determine CNC network formation, rheological percolation threshold concentrations, mechanical properties in the rubbery and glassy states, and the effect of CNCSFD on crystalline nucleation and crystallization rates of PLA. These results suggest that the porosity and network structure of CNCSFD agglomerates contribute significantly to good dispersion of CNC in the PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

Triple shape memory effects of cross-linked polyethylene/polypropylene blends with cocontinuous architecture.

PubMed

Zhao, Jun; Chen, Min; Wang, Xiaoyan; Zhao, Xiaodong; Wang, Zhenwen; Dang, Zhi-Min; Ma, Lan; Hu, Guo-Hua; Chen, Fenghua

2013-06-26

In this paper, the triple shape memory effects (SMEs) observed in chemically cross-linked polyethylene (PE)/polypropylene (PP) blends with cocontinuous architecture are systematically investigated. The cocontinuous window of typical immiscible PE/PP blends is the volume fraction of PE (v(PE)) of ca. 30-70 vol %. This architecture can be stabilized by chemical cross-linking. Different initiators, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane (DHBP), dicumylperoxide (DCP) coupled with divinylbenzene (DVB) (DCP-DVB), and their mixture (DHBP/DCP-DVB), are used for the cross-linking. According to the differential scanning calorimetry (DSC) measurements and gel fraction calculations, DHBP produces the best cross-linking and DCP-DVB the worst, and the mixture, DHBP/DCP-DVB, is in between. The chemical cross-linking causes lower melting temperature (Tm) and smaller melting enthalpy (ΔHm). The prepared triple shape memory polymers (SMPs) by cocontinuous immiscible PE/PP blends with v(PE) of 50 vol % show pronounced triple SMEs in the dynamic mechanical thermal analysis (DMTA) and visual observation. This new strategy of chemically cross-linked immiscible blends with cocontinuous architecture can be used to design and prepare new SMPs with triple SMEs.

Electromagnetic interference shielding effectiveness of polypropylene/conducting fiber composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Pyoung-Chan, E-mail: pclee@katech.re.kr; Kim, Bo-Ram; Jeoung, Sun Kyoung

Electromagnetic released from the automotive electronic parts is harmful to human body. Electromagnetic interference (EMT) shielding refers to the reflection and/or adsorption of electromagnetic radiation by a material, which thereby acts as a shield against the penetration of the radiation through the shield. Polypropylene (PP)/conductive micro fiber composites containing various fiber contents and fiber length were injection-molded. The effect of fiber content and length on electrical properties of the composites was studied by electrical resistivity and EMT shielding measurements. The through-plane electrical conductivity and dielectric permittivity were obtained by measuring dielectric properties. The EMT shielding effectiveness (SE) was investigated bymore » using S-parameter in the range of 100 ~ 1500 MHz. Reflection, absorption and multiple-reflection are the EMT attenuation mechanisms. From the measurement of S-Parameters, the absorption coefficient, reflection coefficient, and the shielding efficiency of the materials were calculated. The EMT SE of PP/conducing fiber composites is 40 dB over a wide frequency range up to 1.5 GHz, which is higher than that of PP/talc composite used automotive parts, viz. 0 dB.« less

Melamine-formaldehyde microcapsules filled sappan dye modified polypropylene composites: encapsulation and thermal properties

NASA Astrophysics Data System (ADS)

Phanyawong, Suphitcha; Siengchin, Suchart; Parameswaranpillai, Jyotishkumar; Asawapirom, Udom; Polpanich, Duangporn

2018-01-01

Sappan dye, a natural dye extracted from sappan wood is widely used in cosmetics, textile dyeing and as food additives. However, it was recognized that natural dyes cannot withstand high temperature. In this study, a protective coating of melamine-formaldehyde shell material was applied over the sappan dye to improve its thermal stability. The percentage of sappan dye used in the microencapsulation was 30, 40, 50, 60 and 70 wt%. The color, shape, size, and thermal stability of sappan dye microcapsules were investigated. It was found that increasing amount of sappan dye content in the microcapsules decreased the particle size. Thermal analysis reveals that the melamine-formaldehyde resin served as an efficient protective shell for sappan dye. Besides, 30 wt% sappan dye microcapsules with different weight percent (1, 3 and 5 wt%) of sappan dye was used as modifier for polypropylene (PP). All the prepared composites are red in color which supports the thermal stability of the microcapsules. The changes in crystallinity and melting behavior of PP by the addition of microcapsules were studied in detail by differential scanning calorimetry. Thermogravimetric studies showed that the thermal stability of PP composites increased by the addition of microcapsules.

Request for Symposia Support: Advances in Olefin Polymerization Catalysis

DTIC Science & Technology

2014-11-24

States Polyolefins, including polyethylene ( HDPE and LLDPE) ad polypropylene (PP), represent half of commercial polymers produced in the world...i.e. HDPE vs. UHMWPE) by simply changing the catalyst. Despite this success, the development of novel transition metal olefin polymerization

Reuse of EAF Slag as Reinforcing Filler for Polypropylene Matrix Composites

NASA Astrophysics Data System (ADS)

Cornacchia, G.; Agnelli, S.; Gelfi, M.; Ramorino, G.; Roberti, R.

2015-06-01

Electric-arc furnace (EAF) slag, the by-product of steel fabricated at the EAF, is in most cases still sent to dumps, with serious environmental consequences. This work shows an innovative, economically convenient application for EAF slag: its use as reinforcing filler for polypropylene. Composites based on polypropylene containing 10-40 wt.% of EAF slag particles were prepared by melt compounding followed by injection molding. A physical-chemical analysis of the EAF slag was performed to determine microstructural features and main component phases. Leaching tests demonstrated that, although EAF slag can release small amounts of toxic elements, such as heavy metals, incorporating such material into the polymeric matrix immobilizes the heavy metals inside that matrix. The mechanical characterization of the polymer-based composites was performed. Incorporating EAF slag particles raises the Young's modulus and the tensile strength at yield, whereas elongation at break and the impact strength of the polymer-based composite are significantly reduced only when large amounts of filler are added, i.e., 30% or more.

Novel PEPA-functionalized graphene oxide for fire safety enhancement of polypropylene

PubMed Central

Xu, Jia You; Liu, Jie; Li, Kai Dan; Tanemura, Sakae

2015-01-01

Polypropylene (PP) is a general-purpose plastic, but some applications are constrained by its high flammability. Thus, flame retardant PP is urgently demanded. In this article, intumescent flame retardant PP (IFRPP) composites with enhanced fire safety were prepared using 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo [2.2.2] octane (PEPA) functionalized graphene oxide (PGO) as synergist. The PGO was prepared through a mild chemical reaction by the covalent attachment of a caged-structure organic compound, PEPA, onto GO nanosheets using toluene diisocynate (TDI) as the intermediary agent. The novel PEPA-functionalized graphene oxide not only improves the heat resistance of GO but also converts GO and PEPA from hydrophobic to hydrophilic materials, which leads to even distribution in PP. In our case, 7 wt% addition of PGO as one of the fillers for IFRPP composites significantly reduces its inflammability and fire hazards when compared with PEPA, by the improvement of first release rate peak (PHRR), total heat release, first smoke release rate peak (PSRR) and total smoke release, suggesting its great potential as the IFR synergist in industry. The reason is mainly attributed to the barrier effect of the unburned graphene sheets, which protects by the decomposition products of PEPA and TDI, promotes the formation of graphitized carbon and inhibits the heat and gas release. PMID:27877775

Solid-state drawing of post-consumer isotactic poly(propylene): Effect of melt filtration and carbon black on structural and mechanical properties.

PubMed

Luijsterburg, B J; Jobse, P S; Spoelstra, A B; Goossens, J G P

2016-08-01

Post-consumer plastic waste obtained via mechanical recycling is usually applied in thick-walled products, because of the low mechanical strength due to the presence of contaminants. In fact, sorted post-consumer isotactic poly(propylene) (i-PP) can be considered as a blend of 95% i-PP and 5% poly(ethylene), with traces of poly(ethylene terephthalate) (PET). By applying a treatment such as solid-state drawing (SSD) after melt extrusion, the polymer chains can be oriented in one direction, thereby improving the stiffness and tensile strength. In this research, molecular processes such as crystal break-up and chain orientation of these complex blends were monitored as a function of draw ratio. The melt filter mesh size - used to exclude rigid PET particles - and the addition of carbon black (CB) - often added for coloration in the recycling industry - were varied to investigate their influence on the SSD process. This research shows that despite the blend complexity, the molecular processes during SSD compare to virgin i-PP and that similar draw ratios can be obtained (λmax=20), albeit at reduced stiffness and strength as a result of the foreign polymers present in post-consumer i-PP. It is observed that the process stability improves with decreasing mesh size and that higher draw ratios can be obtained. The addition of carbon black, which resides in the dispersed PE phase, also stabilizes the SSD process. Compared to isotropic post-consumer i-PP, the stiffness can be improved by a factor 10 to over 11GPa, while the tensile strength can be improved by a factor 15-385MPa, which is approx. 70% of the maximum tensile strength achieved for virgin i-PP. Copyright © 2016 Elsevier Ltd. All rights reserved.

Capillary-Channeled Polymer (C-CP) Fibers as a Stationary Phase for Sample Clean-Up of Protein Solutions for Matrix-Assisted Laser/Desorption Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Manard, Benjamin T.; Marcus, R. Kenneth

2012-08-01

Capillary-channeled polymer (C-CP) fibers are employed in a micropipette tip format to affect a stationary phase for the solid phase extraction (SPE) of proteins from buffer solutions prior to MALDI-MS analysis. Proteins readily adsorb to the polypropylene (PP) C-CP fibers while buffer species are easily washed off the tips using DI-H2O. Elution of the solutes is achieved with an aliquot of 50:50 ACN:H2O, which is compatible with the subsequent spotting on the MALDI target with the matrix solution. Lysozyme and cytochrome c are used as test species, with a primary buffer composition of 100 mM Tris-HCl. In this case, direct MALDI-MS produces no discernible protein signals. SPE on the C-CP fibers yields high fidelity mass spectra for 1 μL sample volumes. Limits of detection for cytochrome c in 100 mM Tris-HCl are on the order of 40 nM. Extraction of cytochrome c from buffer concentrations of up to 1 M Tris-HCl, provides signal recoveries that are suppressed by only ~50 % versus neat protein solutions. Finally, extraction of 3.1 μM cytochrome c from a synthetic urine matrix exhibits excellent recovery.

Effect of γ-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials

NASA Astrophysics Data System (ADS)

George, Johnsy; Kumar, R.; Sajeevkumar, V. A.; Sabapathy, S. N.; Vaijapurkar, S. G.; Kumar, D.; Kchawahha, A.; Bawa, A. S.

2007-07-01

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of γ-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity.

Recyclability assessment of nano-reinforced plastic packaging.

PubMed

Sánchez, C; Hortal, M; Aliaga, C; Devis, A; Cloquell-Ballester, V A

2014-12-01

Packaging is expected to become the leading application for nano-composites by 2020 due to the great advantages on mechanical and active properties achieved with these substances. As novel materials, and although there are some current applications in the market, there is still unknown areas under development. One key issue to be addressed is to know more about the implications of the nano-composite packaging materials once they become waste. The present study evaluates the extrusion process of four nanomaterials (Layered silicate modified nanoclay (Nanoclay1), Calcium Carbonate (CaCO3), Silver (Ag) and Zinc Oxide (ZnO) as part of different virgin polymer matrices of polyethylene (PE), Polypropylene (PP) and Polyethyleneterephtalate (PET). Thus, the following film plastic materials: (PE-Nanoclay1, PE-CaCO3, PP-Ag, PET-ZnO, PET-Ag, PET-Nanoclay1) have been processed considering different recycling scenarios. Results on recyclability show that for PE and PP, in general terms and except for some minor variations in yellowness index, tensile modulus, tensile strength and tear strength (PE with Nanoclay1, PP with Ag), the introduction of nanomaterial in the recycling streams for plastic films does not affect the final recycled plastic material in terms of mechanical properties and material quality compared to conventional recycled plastic. Regarding PET, results show that the increasing addition of nanomaterial into the recycled PET matrix (especially PET-Ag) could influence important properties of the recycled material, due to a slight degradation of the polymer, such as increasing pinholes, degradation fumes and elongation at break. Moreover, it should be noted that colour deviations were visible in most of the samples (PE, PP and PET) in levels higher than 0.3 units (limit perceivable by the human eye). The acceptance of these changes in the properties of recycled PE, PP and PET will depend on the specific applications considered (e.g. packaging applications are more strict in material quality that urban furniture or construction products). Copyright © 2014 Elsevier Ltd. All rights reserved.

Study of injection moulded long glass fibre-reinforced polypropylene and the effect on the fibre length and orientation distribution

NASA Astrophysics Data System (ADS)

Parveeen, B.; Caton-Rose, P.; Costa, F.; Jin, X.; Hine, P.

2014-05-01

Long glass fibre (LGF) composites are extensively used in manufacturing to produce components with enhanced mechanical properties. Long fibres with length 12 to 25mm are added to a thermoplastic matrix. However severe fibre breakage can occur in the injection moulding process resulting in shorter fibre length distribution (FLD). The majority of this breakage occurs due to the melt experiencing extreme shear stress during the preparation and injection stage. Care should be taken to ensure that the longer fibres make it through the injection moulding process without their length being significantly degraded. This study is based on commercial 12 mm long glass-fibre reinforced polypropylene (PP) and short glass fibre Nylon. Due to the semi-flexiable behaviour of long glass fibres, the fibre orientation distribution (FOD) will differ from the orientation distribution of short glass fibre in an injection molded part. In order to investigate the effect the change in fibre length has on the fibre orientation distribution or vice versa, FOD data was measured using the 2D section image analyser. The overall purpose of the research is to show how the orientation distribution chnages in an injection moulded centre gated disc and end gated plaque geometry and to compare this data against fibre orientation predictions obtained from Autodesk Moldflow Simulation Insight.

Tailoring the surface properties of polypropylene films through cold atmospheric pressure plasma (CAPP) assisted polymerization and immobilization of biomolecules for enhancement of anti-coagulation activity

NASA Astrophysics Data System (ADS)

Navaneetha Pandiyaraj, K.; Ram Kumar, M. C.; Arun Kumar, A.; Padmanabhan, P. V. A.; Deshmukh, R. R.; Bah, M.; Ismat Shah, S.; Su, Pi-Guey; Halleluyah, M.; Halim, A. S.

2016-05-01

Enhancement of anti-thrombogenic properties of polypropylene (PP) to avert the adsorption of plasma proteins (fibrinogen and albumin), adhesion and activation of the platelets are very important for vast biomedical applications. The cold atmospheric pressure plasma (CAPP) assisted polymerization has potential to create the specific functional groups such as Osbnd Cdbnd O, Cdbnd O, Csbnd N and Ssbnd S. on the surface of polymeric films using selective precursor in vapour phase to enhance anti-thrombogenic properties. Such functionalized polymeric surfaces would be suitable for various biomedical applications especially to improve the blood compatibility. The eventual aspiration of the present investigation is to develop the biofunctional coating onto the surface of PP films using acrylic acid (AAc) and polyethylene glycol (PEG) as a precursor in a vapour phase by incorporating specific functional groups for immobilization of biomolecules such as heparin (HEP), chitosan (CHI) and insulin (INS) on the surface of plasma modified PP films. The surface properties such as hydrophilicity, chemical composition, surface topography of the surface modified PP films were analyzed by contact angle (CA), Fourier transform infrared spectroscopy (FTIR), X-ray photo electron spectroscopy (XPS) and atomic force microscopy (AFM). Furthermore the anti-thrombogenic properties of the surface modified PP films were studied by in vitro tests which include platelet adhesion and protein adsorption analysis. It was found that the anti-thrombogenic properties of the PP films are effectively controlled by the CAPP grafting of AAc and PEG followed by immobilization of biomolecules of heparin, chitosan and insulin. The grafting and immobilization was confirmed by FTIR and XPS through the recognition of specific functional groups such as COOH, Csbnd O, Ssbnd S and Csbnd N. on the surface of PP film. Furthermore, the surface morphology and hydrophilic nature of the PP films also tailored significantly by the successful grafting and immobilization which is confirmed by AFM and CA analysis. Owing to the physico-chemical changes on the surface of PP films induced by CAPP assisted polymerization, the anti-thrombogenic properties of PP films were enhanced as confirmed by in vitro analysis.

Biodegradability of PP/HMSPP and natural and synthetic polymers blends in function of gamma irradiation degradation

NASA Astrophysics Data System (ADS)

Cardoso, Elisabeth C. L.; Scagliusi, Sandra R.; Lima, Luis F. C. P.; Bueno, Nelson R.; Brant, Antonio J. C.; Parra, Duclerc F.; Lugão, Ademar B.

2014-01-01

Polymers are used for numerous applications in different industrial segments, generating enormous quantities of discarding in the environment. Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. Polypropylene (PP) undergoes crosslinking and extensive main chain scissions when submitted to ionizing irradiation; as one of the most widely used linear hydrocarbon polymers, PP, made from cheap petrochemical feed stocks, shows easy processing leading it to a comprehensive list of finished products. Consequently, there is accumulation in the environment, at 25 million tons per year rate, since polymeric products are not easily consumed by microorganisms. PP polymers are very bio-resistant due to involvement of only carbon atoms in main chain with no hydrolysable functional group. Several possibilities have been considered to minimize the environmental impact caused by non-degradable plastics, subjecting them to: physical, chemical and biological degradation or combination of all these due to the presence of moisture, air, temperature, light, high energy radiation or microorganisms. There are three main classes of biodegradable polymers: synthetic polymers, natural polymers and blends of polymers in which one or more components are readily consumed by microorganisms. This work aims to biodegradability investigation of a PP/HMSPP (high melt strength polypropylene) blended with sugarcane bagasse, PHB (poly-hydroxy-butyrate) and PLA (poly-lactic acid), both synthetic polymers, at a 10% level, subjected to gamma radiation at 50, 100, 150 and 200 kGy doses. Characterization will comprise IR, DSC, TGA, OIT and Laboratory Soil Burial Test (LSBT).

Piezoelectricity and ferroelectricity of cellular polypropylene electrets films characterized by piezoresponse force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Hongchen; Sun, Yao; Zhou, Xilong

Cellular electrets polymer is a new ferroelectret material exhibiting large piezoelectricity and has attracted considerable attentions in researches and industries. Property characterization is very important for this material and current investigations are mostly on macroscopic properties. In this work, we conduct nanoscale piezoelectric and ferroelectric characterizations of cellular polypropylene (PP) films using piezoresponse force microscopy (PFM). First, both the single-frequency PFM and dual-frequency resonance-tracking PFM testings were conducted on the cellular PP film. The localized piezoelectric constant d{sub 33} is estimated to be 7–11pC/N by correcting the resonance magnification with quality factor and it is about one order lower thanmore » the macroscopic value. Next, using the switching spectroscopy PFM (SS-PFM), we studied polarization switching behavior of the cellular PP films. Results show that it exhibits the typical ferroelectric-like phase hysteresis loops and butterfly-shaped amplitude loops, which is similar to that of a poly(vinylidene fluoride) (PVDF) ferroelectric polymer film. However, both the phase and amplitude loops of the PP film are intensively asymmetric, which is thought to be caused by the nonzero remnant polarization after poling. Then, the D-E hysteresis loops of both the cellular PP film and PVDF film were measured by using the same wave form as that used in the SS-PFM, and the results show significant differences. Finally, we suggest that the ferroelectric-like behavior of cellular electrets films should be distinguished from that of typical ferroelectrics, both macroscopically and microscopically.« less

Effect of Nano-CuO on Engineering and Microstructure Properties of Fibre-Reinforced Mortars Incorporating Metakaolin: Experimental and Numerical Studies

PubMed Central

Ghanei, Amir; Jafari, Faezeh; Mehrinejad Khotbehsara, Mojdeh; Mohseni, Ehsan; Cui, Hongzhi

2017-01-01

In this study, the effects of nano-CuO (NC) on engineering properties of fibre-reinforced mortars incorporating metakaolin (MK) were investigated. The effects of polypropylene fibre (PP) were also examined. A total of twenty-six mixtures were prepared. The experimental results were compared with numerical results obtained by adaptive neuro-fuzzy inference system (ANFIS) and Primal Estimated sub-GrAdient Solver for SVM (Pegasos) algorithm. Scanning Electron Microscope (SEM) was also employed to investigate the microstructure of the cement matrix. The mechanical test results showed that both compressive and flexural strengths of cement mortars decreased with the increase of MK content, however the strength values increased significantly with increasing NC content in the mixture. The water absorption of samples decreased remarkably with increasing NC particles in the mixture. When PP fibres were added, the strengths of cement mortars were further enhanced accompanied with lower water absorption values. The addition of 2 wt % and 3 wt % nanoparticles in cement mortar led to a positive contribution to strength and resistance to water absorption. Mixture of PP-MK10NC3 indicated the best results for both compressive and flexural strengths at 28 and 90 days. SEM images illustrated that the morphology of cement matrix became more porous with increasing MK content, but the porosity reduced with the inclusion of NC. In addition, it is evident from the SEM images that more cement hydration products adhered onto the surface of fibres, which would improve the fibre–matrix interface. The numerical results obtained by ANFIS and Pegasos were close to the experimental results. The value of R2 obtained for each data set (validate, test and train) was higher than 0.90 and the values of mean absolute percentage error (MAPE) and the relative root mean squared error (PRMSE) were near zero. The ANFIS and Pegasos models can be used to predict the mechanical properties and water absorptions of fibre-reinforced mortars with MK and NC. PMID:29065559

Facile fabrication of multilayer separators for lithium-ion battery via multilayer coextrusion and thermal induced phase separation

NASA Astrophysics Data System (ADS)

Li, Yajie; Pu, Hongting

2018-04-01

Polypropylene (PP)/polyethylene (PE) multilayer separators with cellular-like submicron pore structure for lithium-ion battery are efficiently fabricated by the combination of multilayer coextrusion (MC) and thermal induced phase separation (TIPS). The as-prepared separators, referred to as MC-TIPS PP/PE, not only show efficacious thermal shutdown function and wider shutdown temperature window, but also exhibit higher thermal stability than the commercial separator with trilayer construction of PP and PE (Celgard® 2325). The dimensional shrinkage of MC-TIPS PP/PE can be negligible until 160 °C. In addition, compared to the commercial separator, MC-TIPS PP/PE exhibits higher porosity and electrolyte uptake, leading to higher ionic conductivity and better battery performances. The above-mentioned fascinating characteristics with the convenient preparation process make MC-TIPS PP/PE a promising candidate for the application as high performance lithium-ion battery separators.

Catalytic thermal cracking of post-consumer waste plastics to fuels: Part 1 - Kinetics and optimization

USDA-ARS?s Scientific Manuscript database

Thermogravimetric analysis (TGA) was used to investigate thermal and catalytic pyrolysis of waste plastics such as prescription bottles (polypropylene/PP), high density polyethylene, landfill liners (polyethylene/PE), packing materials (polystyrene/PS), and foams (polyurethane/PU) into crude plastic...

Orientation distribution of sheared isotactic polypropylene plates through thickness in the presence of sodium benzoate

NASA Astrophysics Data System (ADS)

Zhu, Peng-wei; Phillips, Andrew; Tung, Jason; Edward, Graham

2005-05-01

The orientation distribution of sheared isotactic polypropylene (iPP) containing different amount of sodium benzoate (SB) has been investigated through the gradient of shear flow field using microbeam of synchrotron wide-angle x-ray techniques. The degree of the overall orientation of α-phase crystal is found to increase with increasing concentration of SB. Compared with the sheared iPP in the absence of SB, the orientation of α-phase crystal is found to distribute over a broader range of shear flow field in the presence of SB. The overall orientation of α-phase crystal is explained in terms of a parent-daughter model or lamella-branched shish-kebab structure. As the concentration of SB increases, the contribution from the c-axis orientation of parent lamellae decreases in the flow direction. The contribution from the a*-axis orientation of daughter lamellae is developed to be dominant in the flow direction when the concentration of SB exceeds a critical value.

Plasma-induced graft-polymerization of polyethylene glycol acrylate on polypropylene substrates

NASA Astrophysics Data System (ADS)

Zanini, S.; Orlandi, M.; Colombo, C.; Grimoldi, E.; Riccardi, C.

2009-08-01

A detailed study of argon plasma-induced graft-polymerization of polyethylene glycol acrylate (PEGA) on polypropylene (PP) substrates (membranes and films) is presented. The process consists of four steps: (a) plasma pre-activation of the PP substrates; (b) immersion in a PEGA solution; (c) argon plasma-induced graft-polymerization; (d) washing and drying of the samples. Influence of the solution and plasma parameters on the process efficiency evaluated in terms of amount of grafted polymer, coverage uniformity and substrates wettability, are investigated. The plasma-induced graft-polymerization of PEGA is then followed by sample weighting, water droplet adsorption time and contact angle measurements, attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analyses. The stability of the obtained thin films was evaluated in water and in phosphate buffer saline (PBS) at 37 °C. Results clearly indicates that plasma-induced graft-polymerization of PEGA is a practical methodology for anti-fouling surface modification of materials.

Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP).

PubMed

Achilias, D S; Roupakias, C; Megalokonomos, P; Lappas, A A; Antonakou, Epsilon V

2007-11-19

The recycling of either model polymers or waste products based on low-density polyethylene (LDPE), high-density polyethylene (HDPE) or polypropylene (PP) is examined using the dissolution/reprecipitation method, as well as pyrolysis. In the first technique, different solvents/non-solvents were examined at different weight percent amounts and temperatures using as raw material both model polymers and commercial products (packaging film, bags, pipes, food-retail outlets). The recovery of polymer in every case was greater than 90%. FT-IR spectra and tensile mechanical properties of the samples before and after recycling were measured. Furthermore, catalytic pyrolysis was carried out in a laboratory fixed bed reactor with an FCC catalyst using again model polymers and waste products as raw materials. Analysis of the derived gases and oils showed that pyrolysis gave a mainly aliphatic composition consisting of a series of hydrocarbons (alkanes and alkenes), with a great potential to be recycled back into the petrochemical industry as a feedstock for the production of new plastics or refined fuels.

Triboelectrostatic separation of polypropylene, polyurethane, and polyvinylchloride used in passenger vehicles.

PubMed

Li, Tuyu; Yu, Dali; Zhang, Hongshen

2018-03-01

Recycling and reuse of automotive plastics have elicited global attention due to the increasing number of end-of-life vehicles. Through the single-factor experiment, a high-voltage triboelectrostatic sorting device was developed to separate polypropylene (PP), polyurethane (PU), and polyvinylchloride (PVC) in a plastic mixture commonly used in exterior and interior parts of passenger vehicles. Products of PP, PU, and PVC were obtained after two-stage separation; their purity exceeded 95%, and their productivities were 74%, 94%, and 41%, respectively. The appropriate experimental parameters for high voltage level and rotational speed of the friction drum and cylinder electrode for the first stage of separation were 35 kV, 30 rpm, and 35 rpm, respectively, and the parameters for the second stage of separation were 35 kV, 30 rpm, and 25 rpm, respectively. Results showed that hybrid materials should be selected based on the triboelectric series to separate three-component plastic mixtures feasibly. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silver nanoparticle deposition on inverse opal SiO2 films embedded in protective polypropylene micropits for SERS applications

NASA Astrophysics Data System (ADS)

Ammosova, Lena; Ankudze, Bright; Philip, Anish; Jiang, Yu; Pakkanen, Tuula T.; Pakkanen, Tapani A.

2018-01-01

Common methods to fabricate surface enhanced Raman scattering (SERS) substrates with controlled micro-nanohierarchy are often complex and expensive. In this study, we demonstrate a simple and cost effective method to fabricate SERS substrates with complex geometries. Microworking robot structuration is used to pattern a polypropylene (PP) substrate with micropits, facilitating protective microenvironment for brittle SiO2 inverse opal (IO) structure. Hierarchical SiO2 IO patterns were obtained using polystyrene (PS) spheres as a sacrificial template, and were selectively embedded into the hydrophilized PP micropits. The same microworking robot technique was subsequently used to deposit silver nanoparticle ink into the SiO2 IO cavities. The fabricated multi-level micro-nanohierarchy surface was studied to enhance Raman scattering of the 4-aminothiophenol (4-ATP) analyte molecule. The results show that the SERS performance of the micro-nanohierarchical substrate increases significantly the Raman scattering intensity compared to substrates with structured 2D surface geometries.

New understanding of microstructure formation of the rubber phase in thermoplastic vulcanizates (TPV).

PubMed

Wu, Hanguang; Tian, Ming; Zhang, Liqun; Tian, Hongchi; Wu, Youping; Ning, Nanying

2014-03-21

The breakup of the rubber phase in an ethylene-propylene-diene monomer (EPDM)/polypropylene (PP) blend at the early stage of dynamic vulcanization is similar to that in an unvulcanized EPDM/PP blend because of the low crosslink density of the EPDM phase. In this work, the minimum size of the rubber phase in the unvulcanized EPDM/PP blend was first calculated by using the critical breakup law of viscoelastic droplets in a matrix. The calculated results showed that the minimum size of the rubber phase in the unvulcanized blend was in the nanometer scale (25-46 nm), not the micrometer scale as reported in many works. Meanwhile, the actual size of the rubber phase in the thermoplastic vulcanizate (TPV) at both the early stage and the final stage of dynamic vulcanization was observed by using peak force tapping atomic force microscopy (PF-AFM). The results indicated that the EPDM phase indeed broke up into nanoparticles at the early stage of dynamic vulcanization, in good agreement with the calculated results. More interestingly, we first revealed that the micrometer-sized rubber particles commonly observed in TPV were actually the agglomerates of rubber nanoparticles with diameters between 40 and 60 nm. The mechanism for the formation of rubber nanoparticles and their agglomerates during dynamic vulcanization was then discussed. Our work provides guidance to control the microstructure of the rubber phase in TPV to prepare high performance TPV products for a wide range of applications in the automobile and electronic industries.

Simultaneous Effect of Mechanical Tension on Electrical Lifetime of Some Inorganic Composites

NASA Astrophysics Data System (ADS)

Özcanli, Y. Lenger; BoydaǦ, F. Ş.; Alekberov, V. A.; Hikmet, I.; Cantürk, M.

In this work, the simultaneous effect of mechanical tension (σ) and electrical strength (E) on electrical lifetime (τE) for pure low density polyethylene (LDPE)/polypropylene (PP) and composites with different commercial diamond-additive/glass fiber additive percentages is experimentally studied. The role of this effect on degradation mechanisms is investigated. logτE,σ-f(E) and Eσ-f(σ) graphs are drawn, new equations are proposed and determined parameters at constant temperature for pure LDPE and PP, and for optimum composites (LDPE/0.5% diamond, PP/0.5% glass fiber) are listed. The results indicate that the degradation speed decreases more for composites than for pure LDPE and PP. The electrical durability for composites after the simultaneous effect of σ decreases 18-20%, while for pure LDPE and PP, it decreases 50-55%.

An in-depth analysis of the physico-mechanical properties imparted by agricultural fibers and food processing residues in polypropylene biocomposites

NASA Astrophysics Data System (ADS)

Murdy, Rachel Campbell; Mak, Michelle; Misra, Manjusri; Mohanty, Amar K.

2015-05-01

The use of agricultural and food processing residues as potential reinforcements in plastics has been extensively studied. However, there is a large variation in the mechanical performance of agricultural fiber-based biocomposites due to different processing materials and parameters. An in-depth comparison of the resulting effect of the agricultural filler on the matrix is often not possible given the discrepancy in processing conditions. This study seeks to determine the intrinsic properties of agricultural fibers and food processing residues for their use in polypropylene biocomposites based on a standardization of experimental design. The effect of 25wt% loading of miscanthus, fall-and spring-harvest switchgrass, wheat straw, oat hull, soy hull, soy stalk, hemp and flax on the physico-mechanical properties of polypropylene biocomposites was investigated. The addition of fiber led to an improvement in flexural strength, flexural modulus, and tensile modulus, and a general decrease in tensile strength at yield, elongation at break and Izod impact strength. Scanning electron microscopy highlighted the interfacial adhesion, orientation and distribution of the fibers within the matrix, confirming that fiber length and dispersion within the matrix are positively correlated with mechanical properties. The crystallization of the polypropylene phase and a compositional analysis of the agricultural fibers and processing residues were also compared to offer insight into the effect of the filler's intrinsic properties on the resulting material performance.

Latest medical applications of polypropylene.

PubMed

Van Lierde, Stijn

2004-06-01

PP volumes for use in medical applications increase every year for some obvious reasons. The polymer can be processed by practically all techniques and sterilisation and transparency processes, and its properties are continuously improved. Furthermore, it can replace many other materials, and is attractive from a cost and versatility perspective.

Cross-linked xenogenic collagen implantation in the sheep model for vaginal surgery.

PubMed

Endo, Masayuki; Urbankova, Iva; Vlacil, Jaromir; Sengupta, Siddarth; Deprest, Thomas; Klosterhalfen, Bernd; Feola, Andrew; Deprest, Jan

The properties of meshes used in reconstructive surgery affect the host response and biomechanical characteristics of the grafted tissue. Whereas durable synthetics induce a chronic inflammation, biological grafts are usually considered as more biocompatible. The location of implantation is another determinant of the host response: the vagina is a different environment with specific function and anatomy. Herein, we evaluated a cross-linked acellular collagen matrix (ACM), pretreated by the anti-calcification procedure ADAPT® in a sheep model for vaginal surgery. Ten sheep were implanted with a cross-linked ACM, and six controls were implanted with a polypropylene (PP; 56 g/m 2 ) control. One implant was inserted in the lower rectovaginal septum, and one was used for abdominal wall defect reconstruction. Grafts were removed after 180 days; all graft-related complications were recorded, and explants underwent bi-axial tensiometry and contractility testing. Half of ACM-implanted animals had palpable induration in the vaginal implantation area, two of these also on the abdominal implant. One animal had a vaginal exposure. Vaginal ACMs were 63 % less stiff compared to abdominal ACM explants ( p  = 0.01) but comparable to vaginal PP explants. Seven anterior vaginal ACM explants showed areas of graft degradation on histology. There was no overall difference in vaginal contractility. Considering histologic degradation in the anterior vaginal implant as representative for the host, posterior ACM explants of animals with degradation had a 60 % reduced contractility as compared to PP ( p  = 0.048). Three abdominal implants showed histologic degradation; those were more compliant than non-degraded implants. Vaginal implantation with ACM was associated with graft-related complications (GRCs) and biomechanical properties comparable to PP. Partially degraded ACM had a decreased vaginal contractility.

PEG-template for surface modification of zeolite: A convenient material to the design of polypropylene based composite for packaging films

NASA Astrophysics Data System (ADS)

Toommee, S.; Pratumpong, P.

2018-06-01

Zeolite was successfully modified by conventional synthetic route. Polyethylene glycol was employed for surface modification of zeolite. The surface of zeolite exhibited therefore hydrophobic properties. Less than 5 wt% of modified zeolites with uniform size and shape were integrated into polypropylene matrix. Mechanical properties of composite exhibited the similar trend compare to neat polypropylene. Oxygen transmission rate and water vapor transmission rate were evaluated and it exhibited the strong potential to be a good candidate material in active packaging.

Basic poly(propylene glycols) as reference compounds for internal mass calibration in positive-ion matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Gross, Jürgen H

2017-12-01

Basic poly(propylene glycols), commercially available under the trade name Jeffamine, are evaluated for their potential use as internal mass calibrants in matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry. Due to their basic amino endgroups Jeffamines are expected to deliver [M+H] + ions in higher yields than neutral poly(propylene glycols) or poly(ethylene glycols). Aiming at accurate mass measurements and molecular formula determinations by matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry, four Jeffamines (M-600, M-2005, D-400, D-230) were thus compared. As a result, Jeffamine M-2005 is introduced as a new mass calibrant for positive-ion matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry in the range of m/z 200-1200 and the reference mass list is provided. While Jeffamine M-2005 is compatible with α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, and 2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile matrix, its use in combination with 2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile provides best results due to low laser fluence requirements. Applications to PEG 300, PEG 600, the ionic liquid trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl)-trifluorophosphate, and [60]fullerene demonstrate mass accuracies of 2-5 ppm.

Effects of Thickness and Amount of Carbon Nanofiber Coated Carbon Fiber on Improving the Mechanical Properties of Nanocomposites

PubMed Central

Ghaemi, Ferial; Ahmadian, Ali; Yunus, Robiah; Ismail, Fudziah; Rahmanian, Saeed

2016-01-01

In the current study, carbon nanofibers (CNFs) were grown on a carbon fiber (CF) surface by using the chemical vapor deposition method (CVD) and the influences of some parameters of the CVD method on improving the mechanical properties of a polypropylene (PP) composite were investigated. To obtain an optimum surface area, thickness, and yield of the CNFs, the parameters of the chemical vapor deposition (CVD) method, such as catalyst concentration, reaction temperature, reaction time, and hydrocarbon flow rate, were optimized. It was observed that the optimal surface area, thickness, and yield of the CNFs caused more adhesion of the fibers with the PP matrix, which enhanced the composite properties. Besides this, the effectiveness of reinforcement of fillers was fitted with a mathematical model obtaining good agreement between the experimental result and the theoretical prediction. By applying scanning electronic microscope (SEM), transmission electron microscope (TEM), and Raman spectroscopy, the surface morphology and structural information of the resultant CF-CNF were analyzed. Additionally, SEM images and a mechanical test of the composite with a proper layer of CNFs on the CF revealed not only a compactness effect but also the thickness and surface area roles of the CNF layers in improving the mechanical properties of the composites. PMID:28344263

Effects of environmental ageing on HMS-polypropylene/Cloisite nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komatsu, L. G. H., E-mail: dfparra@ipen.br; Oliani, W. L., E-mail: dfparra@ipen.br; Ferreto, H. F. R., E-mail: dfparra@ipen.br

High melt strength polypropylene Nanocomposites (NC-HMSPP) were obtained with concentrations of 0.1 and 5 wt% of Cloisite 20A. The melt intercalation, using twin screw extruder was done to homogenize the nanocomposite in presence of polypropylene graft maleic anhydride (PP-g-MA) compatibilizer agent. In this work, the manufactured dumbbell samples were settled in device for natural ageing assay. The period of exposition was January to December of 2012. The effects of environmental ageing was determined by carbonyl index (FT-IR) and the results showed that nanocomposites were more stable than HMSPP. The mechanical properties (elongation and rupture strength) were evaluated and the thermalmore » behavior was investigated by differential scanning calorimetry (DSC) and X ray diffraction (DRX). The morphology was observed by scanning electron microscopy (SEM) in which the nanocomposites showed intense cracks on the surface.« less

Effect of reprocessing cycles on the degradation of polypropylene copolymer filled with talc or montmorillonite during injection molding process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demori, R.; Mauler, R. S., E-mail: raquel.mauler@ufrgs.br; Ashton, E.

Mechanical recycling of polymeric materials is a favorable technique resulting in economic and environmental benefits, especially in the case of polymers with a high production volume as the polypropylene copolymer (PP). However, recycling by reprocessing techniques can lead to thermal, mechanical or thermo-oxidative degradation that can affect the structure of the polymer and subsequently the material properties. PP filled with montmorillonite (MMT) or talc are widely produced and studied, however, its degradation reactions by reprocessing cycles are poorly studied so far. In this study, the effects of reprocessing cycles in the structure and in the properties of the PP/MMT andmore » PP/Talc were evaluated. The samples were mixed with 5% talc or MMT Cloisite C15A in a twin-screw extrusion. After extrusion, this filled material was submitted to five reprocessing cycles through an injection molding process. In order to evaluate the changes induced by reprocessing techniques, the samples were characterized by DSC, FT-IR, Izod impact and tensile strength tests. The study showed that Young modulus, elongation at brake and Izod impact were not affected by reprocessing cycles, except when using talc. In this case, the elongation at brake reduced until the fourth cycle, showing rigidity increase. The DSC results showed that melting and crystallization temperature were not affected. A comparison of FT-IR spectra of the reprocessed indicated that in both samples, between the first and the fifth cycle, no noticeable change has occurred. Thus, there is no evidence of thermo oxidative degradation. In general, these results suggest that PP reprocessing cycles using MMT or talc does not change the material properties until the fifth cycle.« less

Influence of non-thermal TiCl4/Ar+O2 plasma-assisted TiOx based coatings on the surface of polypropylene (PP) films for the tailoring of surface properties and cytocompatibility.

PubMed

Pandiyaraj, K N; Kumar, A Arun; Ramkumar, M C; Sachdev, A; Gopinath, P; Cools, Pieter; De Geyter, N; Morent, R; Deshmukh, R R; Hegde, P; Han, C; Nadagouda, M N

2016-05-01

The superior bulk properties (corrosion resistance, high strength to weight ratio, relatively low cost and easy processing) of hydrocarbon based polymers such as polypropylene (PP) have contributed significantly to the development of new biomedical applications such as artificial organs and cell scaffolds. However, low cell affinity is one of the main draw backs for PP due to its poor surface properties. In tissue engineering, physico-chemical surface properties such as hydrophilicity, polar functional groups, surface charge and morphology play a crucial role to enrich the cell proliferation and adhesion. In this present investigation TiOx based biocompatible coatings were developed on the surface of PP films via DC excited glow discharge plasma, using TiCl4/Ar+O2 gas mixture as a precursor. Various TiOx-based coatings are deposited on the surface of PP films as a function of discharge power. The changes in hydrophilicity of the TiOx/PP film surfaces were studied using contact angle analysis and surface energy calculations by Fowke's approximation. X-ray photo-electron spectroscopy (XPS) was used to investigate the surface chemical composition of TiOx/PP films. The surface morphology of the obtained TiOx/PP films was investigated by scanning electron and transmission electron microscopy (SEM &TEM). Moreover, the surface topography of the material was analyzed by atomic force microscopy (AFM). The cytocompatibility of the TiOx/PP films was investigated via in vitro analysis (cell viability, adhesion and cytotoxicity) using NIH3T3 (mouse embryonic fibroblast) cells. Furthermore the antibacterial activities of TiOx/PP films were also evaluated against two distinct bacterial models namely Gram positive Staphylococcus aureus (S.aureus) and Gram negative Escherichia coli DH5α. (E.coli) bacteria. XPS results clearly indicate the successful incorporation of TiOx and oxygen containing polar functional groups on the surface of plasma treated PP films. Moreover the surface of modified PP films exhibited nano structured morphology, as confirmed by SEM, TEM and AFM. The physico-chemical changes have improved the hydrophilicity of the PP films. The in-vitro analysis clearly confirms that the TiOx coated PP films performs as good as the standard tissue culture plates and also are unlikely to impact the bacterial cell viability. Copyright © 2016 Elsevier B.V. All rights reserved.

Mechanical, thermal, rheological and morphological behaviour of irradiated PP/HA composites

NASA Astrophysics Data System (ADS)

Ramírez, C.; Albano, C.; Karam, A.; Domínguez, N.; Sánchez, Y.; González, G.

2005-07-01

Hydroxyapatite (HA) reinforced polypropylene (PP) composites are being developed as bone graft materials. In this research, the effect of γ irradiation on mechanical, rheological, thermal and morphological behaviour of PP-HA composites was studied. The melt flow index of polymer increased markedly when it was exposed to radiation. This is indicative of chain scission reaction as the predominant process. During the tensile testing, the composites exhibited brittle behaviour, showing no fluency point. Elongation at break showed a tendency to decrease with the increase in radiation dose while stress at break did not show significant variation with radiation dose. High HA content (>20%) and radiation dose (25 kGy) had significant influence on thermal stability.

Effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material

NASA Astrophysics Data System (ADS)

Zhu, J.; Zheng, W. Z.; Qin, C. Z.; Xu, Z. Z.; Wu, Y. Q.

2018-01-01

The effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material (AASCM) is studied. The research contents include: fiber type (plant fiber, polypropylene fiber), fiber content, mechanical property index, tensile stress-strain relationship curve, treating time. The test results showed that the compressive strength of two fibers reinforced AASCM was about 90 ~ 110MPa, and the tensile strength was about 3 ~ 5MPa. The reinforcement effect of polypropylene fiber is superior to that of plant fiber, and the mechanical properties of polypropylene fiber reinforced AASCM are superior to those of plant fiber, According to the comparison of SEM pictures, the plant fiber and polypropylene fiber are both closely bound with the matrix, and the transition zones are complete and close. Thus, it is proved that plant fiber and polypropylene fiber delay the crack extension and enhance the ductility of AASCM.

Study of Tensile Properties and Deflection Temperature of Polypropylene/Subang Pineapple Leaf Fiber Composites

NASA Astrophysics Data System (ADS)

Hafizhah, R.; Juwono, A. L.; Roseno, S.

2017-05-01

The development of eco-friendly composites has been increasing in the past four decades because the requirement of eco-friendly materials has been increasing. Indonesia has a lot of natural fiber resources and, pineapple leaf fiber is one of those fibers. This study aimed to determine the influence of weight fraction of pineapple leaf fibers, that were grown at Subang, to the tensile properties and the deflection temperature of polypropylene/Subang pineapple leaf fiber composites. Pineapple leaf fibers were pretreated by alkalization, while polypropylene pellets, as the matrix, were extruded into sheets. Hot press method was used to fabricate the composites. The results of the tensile test and Heat Deflection Temperature (HDT) test showed that the composites that contained of 30 wt.% pineapple leaf fiber was the best composite. The values of tensile strength, modulus of elasticity and deflection temperature were (64.04 ± 3.91) MPa; (3.98 ± 0.55) GPa and (156.05 ± 1.77) °C respectively, in which increased 187.36%, 198.60%, 264.72% respectively from the pristine polypropylene. The results of the observation on the fracture surfaces showed that the failure modes were fiber breakage and matrix failure.

An in-depth analysis of the physico-mechanical properties imparted by agricultural fibers and food processing residues in polypropylene biocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murdy, Rachel Campbell; Mak, Michelle; Misra, Manjusri

The use of agricultural and food processing residues as potential reinforcements in plastics has been extensively studied. However, there is a large variation in the mechanical performance of agricultural fiber-based biocomposites due to different processing materials and parameters. An in-depth comparison of the resulting effect of the agricultural filler on the matrix is often not possible given the discrepancy in processing conditions. This study seeks to determine the intrinsic properties of agricultural fibers and food processing residues for their use in polypropylene biocomposites based on a standardization of experimental design. The effect of 25wt% loading of miscanthus, fall-and spring-harvest switchgrass,more » wheat straw, oat hull, soy hull, soy stalk, hemp and flax on the physico-mechanical properties of polypropylene biocomposites was investigated. The addition of fiber led to an improvement in flexural strength, flexural modulus, and tensile modulus, and a general decrease in tensile strength at yield, elongation at break and Izod impact strength. Scanning electron microscopy highlighted the interfacial adhesion, orientation and distribution of the fibers within the matrix, confirming that fiber length and dispersion within the matrix are positively correlated with mechanical properties. The crystallization of the polypropylene phase and a compositional analysis of the agricultural fibers and processing residues were also compared to offer insight into the effect of the filler’s intrinsic properties on the resulting material performance.« less

ICI/BASF PP for acrylics swap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alperowicz, N.

ICI (London) and BASF (Ludwigshafen) have announced their long-awaited polypropylene (PP) for acrylics swap deal. ICI is buying BASF's European acrylic resin business, and the German firm will acquire ICI's European PP operations. The deal is due for completion by mid-1993, subject to regulatory approvals. BASF, hitherto a small-scale PP producer, doubles capacity to 600,000 m.t./year and moves up the European PP league to number three, behind Himont and Shell. BASF, whose process is used in the plants, secures a foothold in the UK PP market, where Shell - planning a merger with Himont - is the only other producer,more » with 170,000 m.t./year. ICI's purchase involves BASF's Resart GmbH and Critesa SA subsidiaries, located at Mainz, Germany and near Barcelona, Spain, respectively. The business - which will add about [Brit pounds]60 million ($93 million) to ICI Acrylics [Brit pounds]300-million revenues - employs 400 people, who will transfer to ICI.« less

Dielectric Properties of Generation 3 Pamam Dendrimer Nanocomposites

NASA Astrophysics Data System (ADS)

Ristić, Sanja; Mijović, Jovan

2008-08-01

Broadband dielectric relaxation spectroscopy (DRS) was employed to study molecular dynamics of blends composed of generation 3 poly(amidoamine) (PAMAM) dendrimers with ethylenediamine core and amino surface groups and four linear polymers: poly(propylene oxide)—PPO, two block copolymers, poly(propylene oxide)/poly(ethylene oxide)—PPO/PEO with different mol ratios (29/6 and 10/31) and poly(ethylene oxide)—PEO. The results were generated over a broad range of frequency. Dielectric spectra of dendrimers in PPO matrix reveal slight shift of normal and segmental processes to higher frequency with increasing concentration of dendrimers. In the 29PPO/6PEO matrix, no effect of concentration on the average relaxation time for normal and segmental processes was observed. In the 10PPO/31PEO matrix the relaxation time of the segmental process increases with increasing dendrimer concentration, while in the PEO matrix, local processes in dendrimers slow down. A detailed analysis of the effect of concentration of dendrimers and morphology of polymer matrix on the dielectric properties of dendrimer nanocomposites will be presented.

The Wetting Behavior of Imidazolium-Containing, Room-Temperature Molten Salt.

DTIC Science & Technology

1984-08-28

America, Inc.), Celgard 2500 and 3501 polypropylene film (Celanese Corp.) with 45% porosity and 0.04-pm pore size, and reticulated vitreous carbon or...E. Matijevic, ed., Wiley-Interscience, New York, pp. 85-153 (1969). (9) A. M. Schwartz , "Capillarity: Theory and Practice," Ind. Eng. Chem., 61, 10

Extensional Flow-Induced Dynamic Phase Transitions in Isotactic Polypropylene.

PubMed

Ju, Jianzhu; Wang, Zhen; Su, Fengmei; Ji, Youxin; Yang, Haoran; Chang, Jiarui; Ali, Sarmad; Li, Xiangyang; Li, Liangbin

2016-09-01

With a combination of fast extension rheometer and in situ synchrotron radiation ultra-fast small- and wide-angle X-ray scattering, flow-induced crystallization (FIC) of isotactic polypropylene (iPP) is studied at temperatures below and above the melting point of α crystals (Tmα). A flow phase diagram of iPP is constructed in strain rate-temperature space, composing of melt, non-crystalline shish, α and α&β coexistence regions, based on which the kinetic and dynamic competitions among these four phases are discussed. Above Tmα , imposing strong flow reverses thermodynamic stabilities of the disordered melt and the ordered phases, leading to the occurrence of FIC of β and α crystals as a dynamic phase transition. Either increasing temperature or stain rate favors the competiveness of the metastable β over the stable α crystals, which is attributed to kinetic rate rather than thermodynamic stability. The violent competitions among four phases near the boundary of crystal-melt may frustrate crystallization and result in the non-crystalline shish winning out. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of injection molding process parameters on fiber concentration distribution in long glass fiber reinforced polypropylene

NASA Astrophysics Data System (ADS)

Scantamburlo, Andrea; Gazzola, Luca; Sorgato, Marco; Lucchetta, Giovanni

2018-05-01

In parts manufactured by injection molding of long glass fiber reinforced polypropylene, the local fiber orientation, fiber concentration and fiber length distribution varies along both the thickness direction and the flow path. This heterogeneous microstructure significantly influences the mechanical properties variability in the molded parts. The aim of this work is to investigate the influence of the matrix viscosity, the injection speed and the mold geometry on the fiber concentration distribution. In particular, the factors involved in fiber-matrix separation and fiber pull-out during the injection phases were analyzed in order to understand the phenomenon.

Comparison of a lightweight polypropylene mesh (Optilene® LP) and a large-pore knitted PTFE mesh (GORE® INFINIT® mesh)--Biocompatibility in a standardized endoscopic extraperitoneal hernia model.

PubMed

Jacob, Dietmar A; Schug-Pass, Christine; Sommerer, Florian; Tannapfel, Andrea; Lippert, Hans; Köckerling, Ferdinand

2012-02-01

The use of a mesh with good biocompatibility properties is of decisive importance for the avoidance of recurrences and chronic pain in endoscopic hernia repair surgery. As we know from numerous experiments and clinical experience, large-pore, lightweight polypropylene meshes possess the best biocompatibility. However, large-pore meshes of different polymers may be used as well and might be an alternative solution. Utilizing a totally extraperitoneal technique in an established animal model, 20 domestic pigs were implanted with either a lightweight large-pore polypropylene (PP) mesh (Optilene® LP) or a medium-weight large-pore knitted polytetrafluorethylene (PTFE) mesh (GORE® INFINIT® mesh). After 94 days, the pigs were sacrificed and postmortem diagnostic laparoscopy was performed, followed by explantation of the specimens for macroscopic, histological and immunohistochemical evaluation. The mean mesh shrinkage rate was 14.2% for Optilene® LP vs. 24.7% for INFINIT® mesh (p = 0.017). The partial volume of the inflammatory cells was 11.2% for Optilene® LP vs. 13.9% for INFINIT (n.s.). CD68 was significantly higher for INFINIT (11.8% vs. 5.6%, p = 0.007). The markers of cell turnover, namely Ki67 and the apoptotic index, were comparable at 6.4% vs. 12.4% (n.s.) and 1.6% vs. 2.0% (n.s.). In the extracellular matrix, TGF-β was 35.4% for Optilene® LP and 31.0% for INFINIT® (n.s.). Collagen I (pos/300 μm) deposits were 117.8 and 114.9, respectively. In our experimental examinations, Optilene® LP and INFINIT® showed a comparable biocompatibility in terms of chronic inflammatory reaction; however, the shrinkage rate was significantly higher for INFINIT® after 3 months. The higher shrinkage rate of INFINIT® should be taken into account when choosing the mesh size for an adequate hernia overlap.

Study of rheological properties of polypropylene/organoclay hybrid materials.

PubMed

Yu, Suzhu; Liu, Songlin; Zhao, Jianhong; Yong, Ming Shyan

2006-12-01

Polypropylene nanocomposites reinforced with organic modified montmorillonite clay have been fabricated by melt compounding using extrusion. The morphology of the composites is studied with transmission electron microscopy and X-ray diffraction. The melt-state rheological properties of the nanocomposites have been investigated as a function of temperature and organoclay loading. It is found that the organoclays are intercalated and dispersed evenly in the matrix. The storage and loss moduli of the hybrid composites decrease with temperature and increase with organoclay concentration. Both polypropylene and its composites demonstrate a melt-like rheological behavior, indicating the low degree of exfoliation of the organoclay. A shear thinning behavior is found for both polypropylene and its composites, but the onset of shear thinning for organoclay composites occurs at lower shear rates.

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

DOE PAGES

Gao, Jun; Manard, Benjamin Thomas; Castro, Alonso; ...

2017-02-02

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of ninemore » materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. Finally, the microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.« less

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Jun; Manard, Benjamin Thomas; Castro, Alonso

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of ninemore » materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. Finally, the microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.« less

Metamaterial Behavior of Polymer Nanocomposites Based on Polypropylene/Multi-Walled Carbon Nanotubes Fabricated by Means of Ultrasound-Assisted Extrusion

PubMed Central

Pérez-Medina, Juan C.; Waldo-Mendoza, Miguel A.; Cruz-Delgado, Víctor J.; Quiñones-Jurado, Zoe V.; González-Morones, Pablo; Ziolo, Ronald F.; Martínez-Colunga, Juan G.; Soriano-Corral, Florentino; Avila-Orta, Carlos A.

2016-01-01

Metamaterial behavior of polymer nanocomposites (NCs) based on isotactic polypropylene (iPP) and multi-walled carbon nanotubes (MWCNTs) was investigated based on the observation of a negative dielectric constant (ε′). It is demonstrated that as the dielectric constant switches from negative to positive, the plasma frequency (ωp) depends strongly on the ultrasound-assisted fabrication method, as well as on the melt flow index of the iPP. NCs were fabricated using ultrasound-assisted extrusion methods with 10 wt % loadings of MWCNTs in iPPs with different melt flow indices (MFI). AC electrical conductivity (σ(AC)) as a function of frequency was determined to complement the electrical classification of the NCs, which were previously designated as insulating (I), static-dissipative (SD), and conductive (C) materials. It was found that the SD and C materials can also be classified as metamaterials (M). This type of behavior emerges from the negative dielectric constant observed at low frequencies although, at certain frequencies, the dielectric constant becomes positive. Our method of fabrication allows for the preparation of metamaterials with tunable ωp. iPP pure samples show only positive dielectric constants. Electrical conductivity increases in all cases with the addition of MWCNTs with the largest increases observed for samples with the highest MFI. A relationship between MFI and the fabrication method, with respect to electrical properties, is reported. PMID:28774042

Numerical and experimental investigation of bi-annulus heat exchanger for different alternative materials

NASA Astrophysics Data System (ADS)

Zeeshan, M.; Duggal, R.; Tated, M. K.; Singh, M.

2018-02-01

Heat exchangers are widely used in various energy-recovery applications. However, for specific applications where metallic tubes are subjected to various drawbacks i.e. cost, weight, corrosion etc. polymer materials are promising alternatives. In present study, various conventional as well as promising alternatives materials are chosen for investigation computationally. Experimentally, bi-annulus heat exchanger configuration is investigated for metallic materials. The simulations carried out conclude that the dimensionless temperature parameter for Cross-linked polypropylethylene (PEX) is greater than other polymers. It increases with increasing axial length of tube. The value for dimensionless temperature is higher for copper which is used as conventional tube material. Among different polymers highest temperature is observed for PEX followed by Low density polypropylene (LDPE), Polypropylene (PP) and Polyvinylidene fluoride (PVDF). For axial length up to 70mm approx. the temperature rises for PEX, LDPE is 28.3% and 26.4% respectively. However, temperature variation is same for PP and PVDF for same axial distance. This temperature variation is increased to 72.4%, 67.2%, 58.62% and 56.89% for PEX, LDPE, PP and PVDF respectively as axial distance variation reaches the end of pipe. The inner annulus temperature for PEX material at 10% length of tube is 28.3% of temperature achieved in copper tube which increases to 72.4% for full length of tube.

Crystalline modification of a rare earth nucleating agent for isotactic polypropylene based on its self-assembly.

PubMed

Zhang, Yuanming; Sun, Tingting; Jiang, Wei; Han, Guangting

2018-05-01

In this paper, the crystalline modification of a rare earth nucleating agent (WBG) for isotactic polypropylene (PP) based on its supramolecular self-assembly was investigated by differential scanning calorimetry, wide-angle X-ray diffraction and polarized optical microscopy. In addition, the relationship between the self-assembly structure of the nucleating agent and the crystalline structure, as well as the possible reason for the self-assembly behaviour, was further studied. The structure evolution of WBG showed that the self-assembly structure changed from a needle-like structure to a dendritic structure with increase in the content of WBG. When the content of WBG exceeded a critical value (0.4 wt%), it self-assembled into a strip structure. This revealed that the structure evolution of WBG contributed to the K β and the crystallization morphology of PP with different content of WBG. In addition, further studies implied that the behaviour of self-assembly was a liquid-solid transformation of WBG, followed by a liquid-liquid phase separation of molten isotactic PP and WBG. The formation of the self-assembly structure was based on the free molecules by hydrogen bond dissociation while being heated, followed by aggregation into another structure by hydrogen bond association while being cooled. Furthermore, self-assembly behaviour depends largely on the interaction between WBG themselves.

Shuttle Suppression by Polymer-Sealed Graphene-Coated Polypropylene Separator.

PubMed

Ou, Xuewu; Yu, Yanzi; Wu, Ruizhe; Tyagi, Abhishek; Zhuang, Minghao; Ding, Yao; Abidi, Irfan Haider; Wu, Hengan; Wang, Fengchao; Luo, Zhengtang

2018-02-14

"Shuttle effect" of lithium polysulfides (LiPS) leads to a poor performance and a short cycle life of the Li-S battery, thus limiting their practical application. We demonstrate here that after coating polypropylene (PP) separator with a continuous monolayer graphene, the shuttle effect can be significantly suppressed by limiting the passage of long-chain LiPS. The graphene/PP separator can be further modified by sealing the big holes or pores on graphene with in situ polymerized nylon-66 via an interfacial polymerization reaction between diamine and adipoyl chloride supplied by the aqueous and oil phase, respectively, from each side of the membrane. With this engineered membrane, an initial specific capacity of 1128.4 mAh g -1 at 0.05C is achieved after test in a coin cell, higher than that of 983.2 mAh g -1 with pristine PP, along with increased Coulombic efficiency from 96.0 to 99.9% and enhanced cycling durability. Molecular dynamics simulations attest that the nanopores with appropriate size and structure are effective in acting as a "sieve" to selectively allow only Li + ions to pass through but prevent LiPS from migrating to the anode, consequently alleviating the shuttle effect. Our method provides a facile solution toward the mitigated shuttle effect and eventually contributes to the high performance of Li-S battery.

Effect of electron beam irradiation on thermal and crystallization behavior of PP/EPDM blend

NASA Astrophysics Data System (ADS)

Balaji, Anand Bellam; Ratnam, Chantara Thevy; Khalid, Mohammad; Walvekar, Rashmi

2017-12-01

The irradiation stability of ethylene-propylene diene terpolymer (EPDM)/ polypropylene (PP) blends is studied in an attempt to develop radiation compatible PP/EPDM blends suitable for medical applications. The PP/EPDM blends with mixing ratios of 80/20, 50/50/ 20/80 were prepared in an internal mixer at 165 °C and a rotor speed of 50 rpm followed by compression molding. The blends and the individual components were irradiated using 3.0 MeV electron beam (EB) accelerator at doses ranging from 0 to 100 kGy in air and room temperature. Later, the PP/EPDM blends were subjected to gel content, thermal stability, crystallization and dynamic mechanical properties before and after irradiation. Results revealed that the irradiation-induced crosslinking in the PP/EPDM blend increases with the increasing irradiation dose and the EPDM content in the blend. However, the thermal stability of the blends did not show any significant changes upon irradiation. The dynamic mechanical analysis shows that the EPDM rich blend has higher compatibility than PP dominant blends. A further improvement in the blend compatibility found to be achieved upon irradiation.

Water Absorption and Thickness Swelling Behavior of Polypropylene Reinforced with Hybrid Recycled Newspaper and Glass Fiber

NASA Astrophysics Data System (ADS)

Shakeri, Alireza; Ghasemian, Ali

2010-04-01

This study aims to investigate the moisture absorption of recycled newspaper fiber and recycled newspaper-glass fiber hybrid reinforced polypropylene composites to study their suitability in outdoor applications. In this work composite materials were made from E-glass fiber (G), recycled newspaper (NP) and polypropylene (PP), by using internal mixing and hot-pressing molding. Long-term water absorption (WA) and thickness swelling (TS) kinetics of the composites was investigated with water immersion. It was found that the WA and TS increase with NP content in composite and water immersion time before an equilibrium condition was reached. Composites made from the NP show comparable results as those made of the hybrid fiber. The results suggest that the water absorption and thickness swelling composite decrease with increasing glass fiber contents in hybrid fiber composite. It is interesting to find that the WA and TS can be reduced significantly with incorporation of a coupling agent (maleated polypropylene) in the composite formulation. Further studies were conducted to model the water diffusion and thickness swelling of the composites. Diffusion coefficients and swelling rate parameters in the models were obtained by fitting the model predictions with the experimental data.

Study on Impact Acoustic—Visual Sensor-Based Sorting of ELV Plastic Materials

PubMed Central

Huang, Jiu; Tian, Chuyuan; Ren, Jingwei; Bian, Zhengfu

2017-01-01

This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles’ (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based sorting technologies have been utilized for material recycling for the last two decades. One of the problems still remaining results from black and dark dyed plastics which are very difficult to recognize using visual sensors. In this paper a new multi-sensor technology for black plastic recognition and sorting by using impact resonant acoustic emissions (AEs) and laser triangulation scanning was introduced. A pilot sorting system which consists of a 3-dimensional visual sensor and an acoustic sensor was also established; two kinds commonly used vehicle plastics, polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) and two kinds of modified vehicle plastics, polypropylene/ethylene-propylene-diene-monomer (PP-EPDM) and acrylonitrile-butadiene-styrene/polycarbonate (ABS-PC) were tested. In this study the geometrical features of tested plastic scraps were measured by the visual sensor, and their corresponding impact acoustic emission (AE) signals were acquired by the acoustic sensor. The signal processing and feature extraction of visual data as well as acoustic signals were realized by virtual instruments. Impact acoustic features were recognized by using FFT based power spectral density analysis. The results shows that the characteristics of the tested PP and ABS plastics were totally different, but similar to their respective modified materials. The probability of scrap material recognition rate, i.e., the theoretical sorting efficiency between PP and PP-EPDM, could reach about 50%, and between ABS and ABS-PC it could reach about 75% with diameters ranging from 14 mm to 23 mm, and with exclusion of abnormal impacts, the actual separation rates were 39.2% for PP, 41.4% for PP/EPDM scraps as well as 62.4% for ABS, and 70.8% for ABS/PC scraps. Within the diameter range of 8-13 mm, only 25% of PP and 27% of PP/EPDM scraps, as well as 43% of ABS, and 47% of ABS/PC scraps were finally separated. This research proposes a new approach for sensor-aided automatic recognition and sorting of black plastic materials, it is an effective method for ASR reduction and recycling. PMID:28594341

Study on Impact Acoustic-Visual Sensor-Based Sorting of ELV Plastic Materials.

PubMed

Huang, Jiu; Tian, Chuyuan; Ren, Jingwei; Bian, Zhengfu

2017-06-08

This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles' (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based sorting technologies have been utilized for material recycling for the last two decades. One of the problems still remaining results from black and dark dyed plastics which are very difficult to recognize using visual sensors. In this paper a new multi-sensor technology for black plastic recognition and sorting by using impact resonant acoustic emissions (AEs) and laser triangulation scanning was introduced. A pilot sorting system which consists of a 3-dimensional visual sensor and an acoustic sensor was also established; two kinds commonly used vehicle plastics, polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) and two kinds of modified vehicle plastics, polypropylene/ethylene-propylene-diene-monomer (PP-EPDM) and acrylonitrile-butadiene-styrene/polycarbonate (ABS-PC) were tested. In this study the geometrical features of tested plastic scraps were measured by the visual sensor, and their corresponding impact acoustic emission (AE) signals were acquired by the acoustic sensor. The signal processing and feature extraction of visual data as well as acoustic signals were realized by virtual instruments. Impact acoustic features were recognized by using FFT based power spectral density analysis. The results shows that the characteristics of the tested PP and ABS plastics were totally different, but similar to their respective modified materials. The probability of scrap material recognition rate, i.e., the theoretical sorting efficiency between PP and PP-EPDM, could reach about 50%, and between ABS and ABS-PC it could reach about 75% with diameters ranging from 14 mm to 23 mm, and with exclusion of abnormal impacts, the actual separation rates were 39.2% for PP, 41.4% for PP/EPDM scraps as well as 62.4% for ABS, and 70.8% for ABS/PC scraps. Within the diameter range of 8-13 mm, only 25% of PP and 27% of PP/EPDM scraps, as well as 43% of ABS, and 47% of ABS/PC scraps were finally separated. This research proposes a new approach for sensor-aided automatic recognition and sorting of black plastic materials, it is an effective method for ASR reduction and recycling.

On the mechanism of polypropylene fibres in preventing fire spalling in self-compacting and high-performance cement paste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, X.; Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Technologiepark-Zwijnaarde 904 B-9052, Ghent; Ye, G.

2008-04-15

With the increasing application of self-compacting concrete (SCC) in construction and infrastructure, the fire spalling behavior of SCC has been attracting due attention. In high performance concrete (HPC), addition of polypropylene fibers (PP fibers) is widely used as an effective method to prevent explosive spalling. Hence, it would be useful to investigate whether the PP fibers are also efficient in SCC to avoid explosive spalling. However, no universal agreement exists concerning the fundamental mechanism of reducing the spalling risk by adding PP fiber. For SCC, the reduction of flowability should be considered when adding a significant amount of fibres. Inmore » this investigation, both the micro-level and macro-level properties of pastes with different fiber contents were studied in order to investigate the role of PP fiber at elevated temperature in self-compacting cement paste samples. The micro properties were studied by backscattering electron microscopy (BSE) and mercury intrusion porosimetry (MIP) tests. The modification of the pore structure at elevated temperature was investigated as well as the morphology of the PP fibers. Some macro properties were measured, such as the gas permeability of self-compacting cement paste after heating at different temperatures. The factors influencing gas permeability were analyzed. It is shown that with the melting of PP fiber, no significant increase in total pore volume is obtained. However, the connectivity of isolated pores increases, leading to an increase of gas permeability. With the increase of temperature, the addition of PP fibers reduces the damage of cement pastes, as seen from the total pore volume and the threshold pore diameter changes. From this investigation, it is concluded that the connectivity of pores as well as the creation of micro cracks are the major factors which determine the gas permeability after exposure to high temperatures. Furthermore, the connectivity of the pores acts as a dominant factor for temperatures below 300 deg. C. For higher temperatures micro cracks are becoming the major factor which influences the gas permeability.« less

An experimental study on stabilization of Pekan clay using polyethylene and polypropylene

NASA Astrophysics Data System (ADS)

Zukri, Azhani; Nazir, Ramli; Mender, Fatin Nabilah

2017-10-01

Many countries are expressing concern over the growing issues of polyethylene terephthalate (PET) bottles and polypropylene (PP) products made by the household sector. The rapid increase in the generation of plastic waste all around the world is due to the economic development and population growth. PP is the world's second-most widely produced synthetic plastic, after polyethylene. Statistics show that nearly 50% of the municipal solid waste in Malaysia comes from the institutional, industrial, residential, and construction waste. This paper presents the results of an investigation on the utilisation of fibres as products of PET bottles and PP products in order to improve the engineering properties of clay soil in Pekan. The soil samples were taken from Kampung Tanjung Medang, Pekan, Pahang. The basic properties of the clay soil were determined as follows; optimum moisture content: 32.5%, maximum dry density: 13.43 kN/m3, specific gravity: 2.51, liquid limit: 74.67%, plastic limit: 45.98%, and plasticity index: 28.69%. This investigation concentrates on the shear strength of the reinforced clay soils with PET and PP in random orientation. The reinforced soil samples were subjected to unconfined compression test (UCT) to differentiate their shear strength with that of the unreinforced soil. The tests found that the waste fibres (PET and PP) improved the strength properties of the Pekan clayey soils. The unconfined compressive strength (UCS) value increased with the increasing percentage of PET fibre and reached the optimum content at 10% reinforcement, where it showed the highest improvement of 365 kN/m2 from 325 kN/m2 and depleted when the optimum content reached 20% reinforcement. For PP fibre, the reinforced soil showed the highest UCS at 20% reinforcement with the improvement of 367 kN/m2. The study concluded that the PET and PP fibres can be utilised successfully as reinforcement materials for the stabilisation of clayey soils. The use of these waste compounds as alternative materials for clay soil stabilisation is reasonable and cost effective since they are constantly available.

New CO2 adsorbent containing aminated poly(glycidyl methacrylate) grafted onto irradiated PE-PP nonwoven sheet

NASA Astrophysics Data System (ADS)

Mahmoud Nasef, Mohamed; Abbasi, Ali; Ting, T. M.

2014-10-01

A new CO2 adsorbent containing triethylamine (TEA) was prepared by radiation induced grafting of glycidyl methacrylate (GMA) onto polyethylene coated polypropylene (PE-PP) non-woven sheet followed by amination reaction. The degree of grafting (DOG%) was controlled by variation of monomer concentration and absorbed dose. The incorporation of aminated poly(GMA) was investigated by Fourier transform infrared (FTIR) and scanning electron microscope (SEM). The adsorbent with DOG of 350% and amination yield of 60% exhibited CO2 adsorption capacity of 4.52 mol/kg at ambient temperature and pressure.

Development of more friendly food packaging materials base on polypropylene through blending with polylacticacid

NASA Astrophysics Data System (ADS)

Setiawan, Achmad Hanafi; Aulia, Fauzan

2017-01-01

The commonly food packaging materials today is used a thin layer plastic or film, which is made of a synthetic polymer, such as polypropylene (PP). However, the use of these polymers has a negative impact on the environment, because the synthetic polymer is difficult to degrade naturally by the biotic components such as micro-organisms decomposers and abiotic components such as the sunshine. The use of the biodegradable polymeric material will reduce the use of synthetic polymer products, thereby reducing plastic waste pollution at relatively low cost, it is expected to produce positive effects both for the environment and in terms of economy. PLA is a biodegradable polymer that can be substituted totally or partially to synthetic polymers as far as could fulfill the main function of packaging in the protection and preservation of food. Increasing PLA content in polypropylene blend will affect to the increasing in its water absorption and also its biodegradable. 20% PLA may the optimum composition of poly-blend for food packaging.

Characterization of Thermal and Mechanical Properties of Polypropylene-Based Composites for Fuel Cell Bipolar Plates and Development of Educational Tools in Hydrogen and Fuel Cell Technologies

ERIC Educational Resources Information Center

Lopez Gaxiola, Daniel

2011-01-01

In this project we developed conductive thermoplastic resins by adding varying amounts of three different carbon fillers: carbon black (CB), synthetic graphite (SG) and multi-walled carbon nanotubes (CNT) to a polypropylene matrix for application as fuel cell bipolar plates. This component of fuel cells provides mechanical support to the stack,…

Cellulose nanocrystal/polyolefin biocomposites prepared by solid-state shear pulverization: Superior dispersion leading to synergistic property enhancements

Treesearch

Krishnan A. Iyer; Gregory T. Schueneman; John M. Torkelson

2015-01-01

Cellulose nanocrystals (CNCs), a class of renewable bionanomaterials with excellent mechanical properties, have gained major interest as filler for polymers. However, challenges associated with effective CNC dispersion have hindered the production of composites with desired property enhancements. Here, composites of polypropylene (PP) and low density polyethylene (LDPE...

Surface interactions and fouling properties of Micrococcus luteus with microfiltration membranes.

PubMed

Feng, Lei; Li, Xiufen; Song, Ping; Du, Guocheng; Chen, Jian

2011-11-01

This study was conducted to investigate microbial adhesion of Micrococcus luteus to polypropylene (PP) and polyvinylidene fluoride (PVDF) membranes in relation to the variation of the interfacial energies in the membrane-bacteria systems, for revealing effects of short-range surface interactions on filtration behavior. Both the membranes and M. luteus showed typical strong electron donors and hydrophilic properties. The AB component was dominant in the interfacial energies of the two membrane-bacteria systems. M. luteus presented larger negative U(mlb)(XDLVO) to the PP membrane than to the PVDF membrane. The adhesion experiments also proved that M. luteus had higher adhesion percentage to the PP membrane. This study demonstrated that the adhesion potentials of M. luteus to the PP and PVDF membranes might be explained in terms of bacterium, membrane, and intervening medium surface properties, which are mainly determined by the interfacial energies in the systems according to the XDLVO theory.

Effect of blend ratio of PP/kapok blend nonwoven fabrics on oil sorption capacity.

PubMed

Lee, Young-Hee; Kim, Ji-Soo; Kim, Do-Hyung; Shin, Min-Seung; Jung, Young-Jin; Lee, Dong-Jin; Kim, Han-Do

2013-01-01

More research and development on novel oil sorbent materials is needed to protect the environmental pollution. New nonwoven fabrics (pads) of polypropylene (PP)/kapok blends (blend ratio: 100/0, 75/25, 50/50, 25/75 and 10/90) were prepared by needle punching process at a fixed (optimized) condition (punch density: 50 punches/cm2 and depth: 4mm). This study focused on the effect of blend ratio of PP/kapok nonwoven fabrics on oil sorption capacities to find the best blend ratio having the highest synergy effect. The PP/kapok blend (50/50) sample has the lowest bulk density and showed the best oil absorption capacity. The oil sorption capacity of PP/kapok blend (50/50) nonwoven fabric for kerosene/soybean oil [21.09/27.01 (g oil/g sorbent)] was 1.5-2 times higher than those of commercial PP pad oil sorbents. The highest synergy effect of PP/kapok blend (50/50) was ascribed to the lowest bulk density of PP/kapok blend (50/50), which might be due to the highest morphologically incompatibility between PP fibre and kapok. These results suggest that the PP/kapok blend (50/50) having the highest synergy effect has a high potential as a new high-performance oil sorbent material.

Ultrasonic assisted consolidation of commingled thermoplastic/glass fibers rovings

NASA Astrophysics Data System (ADS)

Lionetto, Francesca; Dell'Anna, Riccardo; Montagna, Francesco; Maffezzoli, Alfonso

2015-04-01

Thermoplastic matrix composites are finding new applications in different industrial area thanks to their intrinsic advantages related to environmental compatibility and processability. The approach presented in this work consists in the development of a technology for the simultaneous deposition and consolidation of commingled thermoplastic rovings through to the application of high energy ultrasound. An experimental equipment, integrating both fiber impregnation and ply consolidation in a single process, has been designed and tested. It is made of an ultrasonic welder, whose titanium sonotrode is integrated on a filament winding machine. During winding, the commingled roving is at the same time in contact with the mandrel and the horn. The intermolecular friction generated by ultrasound is able to melt the thermoplastic matrix and impregnate the reinforcement fibers. The heat transfer phenomena occurring during the in situ consolidation were simulated solving by finite element (FE) analysis an energy balance accounting for the heat generated by ultrasonic waves and the melting characteristics of the matrix. To this aim, a calorimetric characterization of the thermoplastic matrix has been carried out to obtain the input parameters for the model. The FE analysis has enabled to predict the temperature distribution in the composite during heating and cooling The simulation results have been validated by the measurement of the temperature evolution during ultrasonic consolidation. The reliability of the developed consolidation equipment was proved by producing hoop wound cylinder prototypes using commingled continuous E-glass rovings and Polypropylene (PP) filaments. The consolidated composite cylinders are characterized by high mechanical properties, with values comparable with the theoretical ones predicted by the micromechanical analysis.

Review of hydrophilic PP membrane for organic waste removal

NASA Astrophysics Data System (ADS)

Ariono, Danu; Wardani, Anita Kusuma

2017-05-01

The acceleration of industrialization in developing countries has given an impact of environmental pollution rapidly, such as contamination of groundwater with organic waste. To solve this problem, some membrane techniques have been performed to remove organic waste from water, such as membrane contactors, membrane bioreactors, and supported liquid membranes. Polypropylene (PP) membrane is one of the promising candidates for these membrane processes due to its chemical stability, low cost, good mechanical resistance, and being easily available. However, different processes require membranes with different surface properties. Hydrophobic PP membranes with excellent chemical stability can be directly used in membrane contactors, in which the organic phase wets the porous membrane and slightly excessive pressure applied to the other phase. On the other hand, hydrophilization of PP membrane is necessary for some other processes, such as for fouling reduction on membrane bioreactors due to organic matters deposition. The aim of this paper is to give a brief overview of removal of organic waste by PP membrane. Moreover, the effects of PP surface hydrophilization on antifouling properties are also discussed.

Sonophotocatalytic degradation of dye C.I. Acid Orange 7 by TiO2 and Ag nanoparticles immobilized on corona pretreated polypropylene non-woven fabric.

PubMed

Marković, Darka; Šaponjić, Zoran; Radoičić, Marija; Radetić, Tamara; Vodnik, Vesna; Potkonjak, Branislav; Radetić, Maja

2015-05-01

This study discusses the possibility of using corona pre-treated polypropylene (PP) non-woven fabric as a support for immobilization of colloidal TiO2 and Ag nanoparticles in order to remove dye C.I. Acid Orange 7 from aqueous solution. Dye removal efficiency by sonocatalysis, photocatalysis and sonophotocatalysis was evaluated on corona pre-treated fabric loaded with TiO2 nanoparticles, corona pre-treated fabric double loaded with TiO2 nanoparticles and corona pre-treated fabrics loaded with TiO2 nanoparticles before and after deposition of Ag nanoparticles. In addition, the stability of PP non-woven fabric during these processes was investigated. The substrates were characterized by SEM, EDX and AAS analyses. The change of the dye concentration was evaluated by UV-VIS spectrophotometry. Unlike sonocatalysis and photocatalysis, complete dye removal from both solution and non-woven fabric was obtained already after 240-270 min of sonophotocatalysis. Corona pre-treated PP non-woven fabric loaded with Ag nanoparticles prior to deposition of TiO2 nanoparticles provided excellent degradation efficiency and superior reusability. Sonophotocatalytic degradation of dye in the presence of all investigated samples was the most prominent in acidic conditions. Although this nanocomposite system ensured fast discoloration of dye solution, TOC values of water measured after sonophotocatalysis were not satisfactory because of PP degradation. Therefore, it is suggested to include TOC evaluation in each case study where different supports for TiO2 nanoparticles are used since these nanoparticles may guarantee the dye removal from solution but the stability of support could be problematic causing even more serious environmental impact. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterisation and antimicrobial activity of active polypropylene films containing oregano essential oil and Allium extract to be used in packaging for meat products.

PubMed

Llana-Ruiz-Cabello, María; Pichardo, Silvia; Bermudez, José María; Baños, Alberto; Ariza, Juan José; Guillamón, Enrique; Aucejo, Susana; Cameán, Ana M

2018-04-01

Cooked ham is more prone to spoilage than other meat products, making preservation a key step in its commercialisation. One of the most promising preservation strategies is the use of active packaging. Oregano essential oil (OEO) and Proallium® (an Allium extract) have previously been shown to be useful in polylactic acid (PLA)-active films for ready-to-eat salads. The present work aims to study the suitability of polypropylene (PP) films containing OEO and Proallium® in the preservation of cooked ham. Concerning the technological features of the studied material, no significant changes in the mechanical or optical properties of PP films containing the active substances were recorded in comparison to the PP film without extracts. However, films containing both active substances were more flexible than the control film and less strong, highlighting the plasticisation effect of the natural extracts. Moreover, physical properties changed when active substances were added to the film. Incorporation of 4% Proallium® affected the transparency of the film to a higher extent compared to 8% OEO, undergoing decreases in transparency of 40% and 45%, respectively. Moreover, only the film containing the highest amount of OEO (8%) significantly decreased the thickness. Both active substances showed antibacterial properties; however, Proallium®-active films seemed to be more effective against Brochothrix thermosphacta than PP films containing OEO, with all percentages of Proallium® killing the bacterial population present in the ham after 60 days. In addition, materials containing the lowest Proallium® content exhibited higher acceptability by consumers in the sensory analyses with 63-100% willing to purchase, better even than the control package (56-89%). In fact, 2% of Proallium® obtained the best results in the odour study performed by the panellists.

Suture versus preperitoneal polypropylene mesh for elective umbilical hernia repairs.

PubMed

Berger, Rachel L; Li, Linda T; Hicks, Stephanie C; Liang, Mike K

2014-12-01

Repair of primary ventral hernias (PVH) such as umbilical hernias is a common surgical procedure. There is a paucity of risk-adjusted data comparing suture versus mesh repair of these hernias. We compared preperitoneal polypropylene (PP) repair versus suture repair for elective umbilical hernia repair. A retrospective review of all elective open PVH repairs at a single institution from 2000-2010 was performed. Only patients with suture or PP repair of umbilical hernias were included. Univariate analysis was conducted and propensity for treatment-adjusted multivariate logistic regression. There were 442 elective open PVH repairs performed; 392 met our inclusion criteria. Of these patients, 126 (32.1%) had a PP repair and 266 (67.9%) underwent suture repair. Median (range) follow-up was 60 mo (1-143). Patients who underwent PP repair had more surgical site infections (SSIs; 19.8% versus 7.9%, P < 0.01) and seromas (14.3% versus 4.1%, P < 0.01). There was no difference in recurrence (5.6% versus 7.5%, P = 0.53). On propensity score-adjusted multivariate analysis, we found that body mass index (odds ratio [OR], 1.10) and smoking status (OR, 2.3) were associated with recurrence. Mesh (OR, 2.34) and American Society of Anesthesiologists (OR, 1.95) were associated with SSI. Only mesh (OR, 3.41) was associated with seroma formation. Although there was a trend toward more recurrence with suture repair in our study, this was not statistically significant. Mesh repair was associated with more SSI and seromas. Further prospective randomized controlled trial is needed to clarify the role of suture and mesh repair in PVH. Copyright © 2014 Elsevier Inc. All rights reserved.

Mechanisms behind surface modification of polypropylene film using an atmospheric-pressure plasma jet

NASA Astrophysics Data System (ADS)

Shaw, David; West, Andrew; Bredin, Jerome; Wagenaars, Erik

2016-12-01

Plasma treatments are common for increasing the surface energy of plastics, such as polypropylene (PP), to create improved adhesive properties. Despite the significant differences in plasma sources and plasma properties used, similar effects on the plastic film can be achieved, suggesting a common dominant plasma constituent and underpinning mechanism. However, many details of this process are still unknown. Here we present a study into the mechanisms underpinning surface energy increase of PP using atmospheric-pressure plasmas. For this we use the effluent of an atmospheric-pressure plasma jet (APPJ) since, unlike most plasma sources used for these treatments, there is no direct contact between the plasma and the PP surface; the APPJ provides a neutral, radical-rich environment without charged particles and electric fields impinging on the PP surface. The APPJ is a RF-driven plasma operating in helium gas with small admixtures of O2 (0-1%), where the effluent propagates through open air towards the PP surface. Despite the lack of charged particles and electric fields on the PP surface, measurements of contact angle show a decrease from 93.9° to 70.1° in 1.4 s and to 35° in 120 s, corresponding to a rapid increase in surface energy from 36.4 mN m-1 to 66.5 mN m-1 in the short time of 1.4 s. These treatment effects are very similar to what is found in other devices, highlighting the importance of neutral radicals produced by the plasma. Furthermore, we find an optimum percentage of oxygen of 0.5% within the helium input gas, and a decrease of the treatment effect with distance between the APPJ and the PP surface. These observed effects are linked to two-photon absorption laser-induced fluorescence spectroscopy (TALIF) measurements of atomic oxygen density within the APPJ effluent which show similar trends, implying the importance of this radical in the surface treatment of PP. Analysis of the surface reveals a two stage mechanism for the production of polar bonds on the surface of the polymer: a fast reaction producing carboxylic acid, or a similar ketone, followed by a slower reaction that includes nitrogen from the atmosphere on the surface, producing amides from the ketones.

Estimation of crystallinity in isotropic isotactic polypropylene with Raman spectroscopy.

PubMed

Minogianni, Chrysa; Gatos, Konstantinos G; Galiotis, Costas

2005-09-01

The Raman spectrum of isotactic polypropylene (iPP) has been found to exhibit vibrational peaks in the region of 750 to 880 cm(-1) that are sensitive to the degree of crystallinity. These features are broadly assigned to various modes of methyl group rocking, rho(CH2), and there have been various attempts to assess crystallinity based on the integrated intensities of these bands. Various vibrational analyses performed in the past in combination with experimental studies have concluded that the presence of crystalline order with trans-gauche conformation gives rise to a peak at 809 cm(-1), which is assigned to a rho(CH2) mode coupled with the skeletal stretching mode. However, the presence of additional peaks at 830 cm(-1), 841 cm(-1), and 854 cm(-1), within the same envelope, have been the subject of controversy. In this work isotropic films of iPP derived from the same precursor of identical tacticity have been subjected to various degrees of annealing and the integrated intensities of the Raman bands were measured. The results showed that true 3d crystallinity in isotropic iPP can only be expressed by the 809 cm(-1) band whereas the band at 841 cm(-1) corresponds to an uncoupled rho(CH2) fundamental mode and thus is a measure of the amorphous content. The less intense satellite bands at 830 cm(-1) and 854 cm(-1) of solid iPP cannot be distinguished from the 841 cm(-1) band in the melt and are generally considered as intermediate phases possibly related to non-crystalline components with 3(1)-helical conformations. Independent differential scanning calorimetry (DSC) crystallinity measurements were in broad agreement with the Raman measurements based on the normalized intensity of the 809 cm(-1) Raman band. By comparing the Raman with the DSC data a new value for the theoretical heat of fusion for the 100% crystalline iPP has been proposed.

Recyclability assessment of nano-reinforced plastic packaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sánchez, C., E-mail: csanchez@itene.com; Hortal, M., E-mail: mhortal@itene.com; Aliaga, C., E-mail: caliaga@itene.com

2014-12-15

Highlights: • The study compares the recyclability of polymers with and without nanoparticles. • Visual appearance, material quality and mechanical properties are evaluated. • Minor variations in mechanical properties in R-PE and R-PP with nanoparticles. • Slight degradation of R-PET which affect mechanical properties. • Colour deviations in recycled PE, PP and PET in ranges higher that 0.3 units. - Abstract: Packaging is expected to become the leading application for nano-composites by 2020 due to the great advantages on mechanical and active properties achieved with these substances. As novel materials, and although there are some current applications in the market,more » there is still unknown areas under development. One key issue to be addressed is to know more about the implications of the nano-composite packaging materials once they become waste. The present study evaluates the extrusion process of four nanomaterials (Layered silicate modified nanoclay (Nanoclay1), Calcium Carbonate (CaCO{sub 3}), Silver (Ag) and Zinc Oxide (ZnO) as part of different virgin polymer matrices of polyethylene (PE), Polypropylene (PP) and Polyethyleneterephtalate (PET). Thus, the following film plastic materials: (PE–Nanoclay1, PE–CaCO{sub 3}, PP–Ag, PET–ZnO, PET–Ag, PET–Nanoclay1) have been processed considering different recycling scenarios. Results on recyclability show that for PE and PP, in general terms and except for some minor variations in yellowness index, tensile modulus, tensile strength and tear strength (PE with Nanoclay1, PP with Ag), the introduction of nanomaterial in the recycling streams for plastic films does not affect the final recycled plastic material in terms of mechanical properties and material quality compared to conventional recycled plastic. Regarding PET, results show that the increasing addition of nanomaterial into the recycled PET matrix (especially PET–Ag) could influence important properties of the recycled material, due to a slight degradation of the polymer, such as increasing pinholes, degradation fumes and elongation at break. Moreover, it should be noted that colour deviations were visible in most of the samples (PE, PP and PET) in levels higher than 0.3 units (limit perceivable by the human eye). The acceptance of these changes in the properties of recycled PE, PP and PET will depend on the specific applications considered (e.g. packaging applications are more strict in material quality that urban furniture or construction products)« less

Accurate Quasiparticle Spectra from the T-Matrix Self-Energy and the Particle-Particle Random Phase Approximation.

PubMed

Zhang, Du; Su, Neil Qiang; Yang, Weitao

2017-07-20

The GW self-energy, especially G 0 W 0 based on the particle-hole random phase approximation (phRPA), is widely used to study quasiparticle (QP) energies. Motivated by the desirable features of the particle-particle (pp) RPA compared to the conventional phRPA, we explore the pp counterpart of GW, that is, the T-matrix self-energy, formulated with the eigenvectors and eigenvalues of the ppRPA matrix. We demonstrate the accuracy of the T-matrix method for molecular QP energies, highlighting the importance of the pp channel for calculating QP spectra.

Compressive and flexural strength of concrete containing palm oil biomass clinker and polypropylene fibres

NASA Astrophysics Data System (ADS)

Ibrahim, M. H. Wan; Mangi, Sajjad Ali; Burhanudin, M. K.; Ridzuan, M. B.; Jamaluddin, N.; Shahidan, S.; Wong, YH; Faisal, SK; Fadzil, M. A.; Ramadhansyah, P. J.; Ayop, S. S.; Othman, N. H.

2017-11-01

This paper presents the effects of using palm oil biomass (POB) clinker with polypropylene (PP) fibres in concrete on its compressive and flexural strength performances. Due to infrastructural development works, the use of concrete in the construction industry has been increased. Simultaneously, it raises the demand natural sand, which causes depletion of natural resources. While considering the environmental and economic benefits, the utilization of industrial waste by-products in concrete will be the alternative solution of the problem. Among the waste products, one of such waste by-product is the palm oil biomass clinker, which is a waste product from burning processes of palm oil fibres. Therefore, it is important to utilize palm oil biomass clinker as partial replacement of fine aggregates in concrete. Considering the facts, an experimental study was conducted to find out the potential usage of palm oil fibres in concrete. In this study, total 48 number of specimens were cast to evaluate the compressive and flexural strength performances. Polypropylene fibre was added in concrete at the rate of 0.2%, 0.4% and 0.6%, and sand was replaced at a constant rate of 10% with palm oil biomass clinker. The flexural strength of concrete was noticed in the range of 2.25 MPa and 2.29 MPa, whereas, the higher value of flexural strength was recorded with 0.4% polypropylene fibre addition. Hence, these results show that the strength performances of concrete containing POB clinker could be improved with the addition of polypropylene fibre.

Effects of silane on the properties of wood-plastic composites with polyethylene-polypropylene blends as matrices

Treesearch

Craig M. Clemons; Ronald C. Sabo; Michael L. Kaland; Kolby C. Hirth

2011-01-01

The influence of 3-(trimethoxysilyl)propyl methacrylate and benzoyl peroxide on gel content, crystallinity, and mechanical performance of unfilled PP-PE blends, and their composites with wood was investigated. All materials were compounded in a twin screw extruder and then injection molded. Specimens were then exposed to high-humidity and elevated temperature in a...

Elastomer modified polypropylene–polyethylene blends as matrices for wood flour–plastic composites

Treesearch

Craig Clemons

2010-01-01

Blends of polyethylene (PE) and polypropylene (PP) could potentially be used as matrices for wood–plastic composites (WPCs). The mechanical performance and morphology of both the unfilled blends and wood-filled composites with various elastomers and coupling agents were investigated. Blending of the plastics resulted in either small domains of the minor phase in a...

Plaster mortars with polymer fibers and additives investigated by 1H NMR relaxometry

NASA Astrophysics Data System (ADS)

Mustea, Andrei; Manea, Daniela L.; Jumate, Elena; Orbán, Yvette A.; Fechete, Radu

2017-12-01

Plaster mortars with polypropylene (pp) fibers and/or additives were investigated by 1H NMR relaxometry. Two recipes are proposed and are based on a commercially available mortar or are self-prepared and have different content of polypropylene fibers, which play the role of reinforcement agent, and/or Sika additive which is a waterproofing agent. The distributions of transverse relaxation times, T2 were obtained at 1, 3, 7 and 28 days after preparation. For the majority of T2-distributions four peaks are observed and, are associated with the hydration water (to the mineralogical components) and water in small, medium and large pores. The evolution in time, from 1 to 28 days, of the T2-distributions indicates the effects of pp fibers and Sika additive in the formation of pore microstructure. The degree of homogeneity of prepared receipts was evaluated from the relative peak-width and compared with mechanical measurements. Finally, we shown that the inverse of the transverse relaxation time values, T2-1, characteristic to the hydration water depends linearly on the resistance at compression measured for the 1÷28 days period, proving the important role of hydrations to the mechanical properties of the final product.

Plasma Modified Polypropylene Membranes as the Lithium-Ion Battery Separators

NASA Astrophysics Data System (ADS)

Wang, Zhengduo; Zhu, Huiqin; Yang, Lizhen; Wang, Xinwei; Liu, Zhongwei; Chen, Qiang

2016-04-01

To reduce the thermal shrinkage of the polymeric separators and improve the safety of the Li-ion batteries, plasma treatment and plasma enhanced vapor chemical deposition (PECVD) of SiOx-like are carried out on polypropylene (PP) separators, respectively. Critical parameters for separator properties, such as the thermal shrinkage rate, porosity, wettability, and mechanical strength, are evaluated on the plasma treated PP membranes. O2 plasma treatment is found to remarkably improve the wettability, porosity and electrolyte uptake. PECVD SiOx-like coatings are found to be able to effectively reduce the thermal shrinkage rate of the membranes and increase the ionic conductivity. The electrolyte-philicity of the SiOx-like coating surface can be tuned by the varying O2 content in the gas mixture during the deposition. Though still acceptable, the mechanical strength is reduced after PECVD, which is due to the plasma etching. supported by National Natural Science Foundation of China (Nos. 11175024, 11375031), the Beijing Institute of Graphic and Communication Key Project of China (No. 23190113051), the Shenzhen Science and Technology Innovation Committee of China (No. JCYJ20130329181509637), BJNSFC (No. KZ201510015014), and the State Key Laboratory of Electrical Insulation and Power Equipment of China (No. EIPE15208)

Wear resistance of polypropylene-SiC composite

NASA Astrophysics Data System (ADS)

Abenojar, J.; Enciso, B.; Martínez, MA; Velasco, F.

2017-05-01

In this work, the wear resistance of thermoplastic composites with a high amount of ceramic is evaluated. Composites made of polypropylene (PP) and silicon carbide (SiC) powder at 50 wt% were used with the final objective of manufacturing ablative materials. This is the first part of a project studying the wear resistance and the mechanical properties of those composites, to be used in applications like habitat industry. In theory, the exposure to high temperature of ablative materials involves the elimination of thermal energy by the sacrifice of surface polymer. In our case, PP will act as a heat sink, up to the reaction temperature (melting or sublimation), where endothermic chemical decomposition into charred material and gaseous products occurs. As the surface is eroded, it is formed a SiC like-foam with improved insulation performance. Composites were produced by extrusion and hot compression. The wear characterization was performed by pin-on-disk test. Wear test was carried out under standard ASTM G99. The parameters were 120 rpm speed, 15 N load, a alumina ball with 6 mm as pin and 1000 m sliding distance. The tracks were also observed by opto-digital microscope.

Biodegradable FeMnSi Sputter-Coated Macroporous Polypropylene Membranes for the Sustained Release of Drugs

PubMed Central

Fornell, Jordina; Soriano, Jorge; Guerrero, Miguel; Sirvent, Juan de Dios; Ferran-Marqués, Marta; Ibáñez, Elena; Barrios, Leonardo; Baró, Maria Dolors; Suriñach, Santiago; Nogués, Carme; Sort, Jordi; Pellicer, Eva

2017-01-01

Pure Fe and FeMnSi thin films were sputtered on macroporous polypropylene (PP) membranes with the aim to obtain biocompatible, biodegradable and, eventually, magnetically-steerable platforms. Room-temperature ferromagnetic response was observed in both Fe- and FeMnSi-coated membranes. Good cell viability was observed in both cases by means of cytotoxicity studies, though the FeMnSi-coated membranes showed higher biodegradability than the Fe-coated ones. Various strategies to functionalize the porous platforms with transferrin-Alexa Fluor 488 (Tf-AF488) molecules were tested to determine an optimal balance between the functionalization yield and the cargo release. The distribution of Tf-AF488 within the FeMnSi-coated PP membranes, as well as its release and uptake by cells, was studied by confocal laser scanning microscopy. A homogeneous distribution of the drug within the membrane skeleton and its sustained release was achieved after three consecutive impregnations followed by the addition of a layer made of gelatin and maltodextrin, which prevented exceedingly fast release. The here-prepared organic-inorganic macroporous membranes could find applications as fixed or magnetically-steerable drug delivery platforms. PMID:28672792

Hemocompatible control of sulfobetaine-grafted polypropylene fibrous membranes in human whole blood via plasma-induced surface zwitterionization.

PubMed

Chen, Sheng-Han; Chang, Yung; Lee, Kueir-Rarn; Wei, Ta-Chin; Higuchi, Akon; Ho, Feng-Ming; Tsou, Chia-Chun; Ho, Hsin-Tsung; Lai, Juin-Yih

2012-12-21

In this work, the hemocompatibility of zwitterionic polypropylene (PP) fibrous membranes with varying grafting coverage of poly(sulfobetaine methacrylate) (PSBMA) via plasma-induced surface polymerization was studied. Charge neutrality of PSBMA-grafted layers on PP membrane surfaces was controlled by the low-pressure and atmospheric plasma treatment in this study. The effects of grafting composition, surface hydrophilicity, and hydration capability on blood compatibility of the membranes were determined. Protein adsorption onto the different PSBMA-grafted PP membranes from human fibrinogen solutions was measured by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies. Blood platelet adhesion and plasma clotting time measurements from a recalcified platelet-rich plasma solution were used to determine if platelet activation depends on the charge bias of the grafted PSBMA layer. The charge bias of PSBMA layer deviated from the electrical balance of positively and negatively charged moieties can be well-controlled via atmospheric plasma-induced interfacial zwitterionization and was further tested with human whole blood. The optimized PSBMA surface graft layer in overall charge neutrality has a high hydration capability and keeps its original blood-inert property of antifouling, anticoagulant, and antithrmbogenic activities when it comes into contact with human blood. This work suggests that the hemocompatible nature of grafted PSBMA polymers by controlling grafting quality via atmospheric plasma treatment gives a great potential in the surface zwitterionization of hydrophobic membranes for use in human whole blood.

Shear-induced conformational ordering, relaxation, and crystallization of isotactic polypropylene.

PubMed

An, Haining; Li, Xiangyang; Geng, Yong; Wang, Yunlong; Wang, Xiao; Li, Liangbin; Li, Zhongming; Yang, Chuanlu

2008-10-02

The shear-induced coil-helix transition of isotactic polypropylene (iPP) has been studied with time-resolved Fourier transform infrared spectroscopy at various temperatures. The effects of temperature, shear rate, and strain on the coil-helix transition were studied systematically. The induced conformational order increases with the shear rate and strain. A threshold of shear strain is required to induce conformational ordering. High temperature reduces the effect of shear on the conformational order, though a simple correlation was not found. Following the shear-induced conformational ordering, relaxation of helices occurs, which follows the first-order exponential decay at temperatures well above the normal melting point of iPP. The relaxation time versus temperature is fitted with an Arrhenius law, which generates an activation energy of 135 kJ/mol for the helix-coil transition of iPP. At temperatures around the normal melting point, two exponential decays are needed to fit well on the relaxation kinetic of helices. This suggests that two different states of helices are induced by shear: (i) isolated single helices far away from each other without interactions, which have a fast relaxation kinetic; (ii) aggregations of helices or helical bundles with strong interactions among each other, which have a much slower relaxation process. The helical bundles are assumed to be the precursors of nuclei for crystallization. The different helix concentrations and distributions are the origin of the three different processes of crystallization after shear. The correlation between the shear-induced conformational order and crystallization is discussed.

Vegetable fibres from agricultural residues as thermo-mechanical reinforcement in recycled polypropylene-based green foams.

PubMed

Ardanuy, Mònica; Antunes, Marcelo; Velasco, José Ignacio

2012-02-01

Novel lightweight composite foams based on recycled polypropylene reinforced with cellulosic fibres obtained from agricultural residues were prepared and characterized. These composites, initially prepared by melt-mixing recycled polypropylene with variable fibre concentrations (10-25 wt.%), were foamed by high-pressure CO(2) dissolution, a clean process which avoids the use of chemical blowing agents. With the aim of studying the influence of the fibre characteristics on the resultant foams, two chemical treatments were applied to the barley straw in order to increase the α-cellulose content of the fibres. The chemical composition, morphology and thermal stability of the fibres and composites were analyzed. Results indicate that fibre chemical treatment and later foaming of the composites resulted in foams with characteristic closed-cell microcellular structures, their specific storage modulus significantly increasing due to the higher stiffness of the fibres. The addition of the fibres also resulted in an increase in the glass transition temperature of PP in both the solid composites and more significantly in the foams. Copyright © 2011 Elsevier Ltd. All rights reserved.

Combating oil spill problem using plastic waste.

PubMed

Saleem, Junaid; Ning, Chao; Barford, John; McKay, Gordon

2015-10-01

Thermoplastic polymers (such as polypropylene, polyethylene, polyethylene terephthalate (PET) and high density polyethylene (HDPE)) constitute 5-15% of municipal solid waste produced across the world. A huge quantity of plastic waste is disposed of each year and is mostly either discarded in landfills or incinerated. On the other hand, the usage of synthetic polymers as oil sorbents, in particular, polyolefins, including polypropylene (PP), and polyethylene (PE) are the most commonly used oil sorbent materials mainly due to their low cost. However, they possess relatively low oil absorption capacities. In this work, we provide an innovative way to produce a value-added product such as oil-sorbent film with high practical oil uptake values in terms of g/g from waste HDPE bottles for rapid oil spill remedy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of low doses beta irradiation on micromechanical properties of surface layer of injection molded polypropylene composite

NASA Astrophysics Data System (ADS)

Manas, David; Manas, Miroslav; Gajzlerova, Lenka; Ovsik, Martin; Kratky, Petr; Senkerik, Vojtěch; Skrobak, Adam; Danek, Michal; Manas, Martin

2015-09-01

The influence of beta radiation on the changes in the structure and selected properties (mechanical and thermal) was proved. Using low doses of beta radiation for 25% glass fiber filled polypropylene and its influence on the changes of micromechanical properties of surface layer has not been studied in detail so far. The specimens of 25% glass fiber filled PP were made by injection molding technology and irradiated by low doses of beta radiation (0, 15 and 33 kGy). The changes in the microstructure and micromechanical properties of surface layer were evaluated using FTIR, SEM, WAXS and instrumented microhardness test. The results of the measurements showed considerable increase in micromechanical properties (indentation hardness, indentation elastic modulus) when low doses of beta radiation are used.

Composite panels made with biofiber or office wastepaper bonded with thermoplastic and/or thermosetting resin

Treesearch

James H. Muehl; Andrzej M. Krzysik; Poo Chow

2004-01-01

The purpose of this study was to evaluate two groups of composite panels made from two types of underutilized natural fiber sources, kenaf bast fiber and office wastepaper, for their suitability in composite panels. All panels were made with 5% thermosetting phenol-formaldehyde (PF) resin and 1.5% wax. Also, an additional 10% polypropylene (PP) thermoplastic resin was...

Development of Anti-Insect Microencapsulated Polypropylene Films Using a Large Scale Film Coating System.

PubMed

Song, Ah Young; Choi, Ha Young; Lee, Eun Song; Han, Jaejoon; Min, Sea C

2018-04-01

Films containing microencapsulated cinnamon oil (CO) were developed using a large-scale production system to protect against the Indian meal moth (Plodia interpunctella). CO at concentrations of 0%, 0.8%, or 1.7% (w/w ink mixture) was microencapsulated with polyvinyl alcohol. The microencapsulated CO emulsion was mixed with ink (47% or 59%, w/w) and thinner (20% or 25%, w/w) and coated on polypropylene (PP) films. The PP film was then laminated with a low-density polyethylene (LDPE) film on the coated side. The film with microencapsulated CO at 1.7% repelled P. interpunctella most effectively. Microencapsulation did not negatively affect insect repelling activity. The release rate of cinnamaldehyde, an active repellent, was lower when CO was microencapsulated than that in the absence of microencapsulation. Thermogravimetric analysis exhibited that microencapsulation prevented the volatilization of CO. The tensile strength, percentage elongation at break, elastic modulus, and water vapor permeability of the films indicated that microencapsulation did not affect the tensile and moisture barrier properties (P > 0.05). The results of this study suggest that effective films for the prevention of Indian meal moth invasion can be produced by the microencapsulation of CO using a large-scale film production system. Low-density polyethylene-laminated polypropylene films printed with ink incorporating microencapsulated cinnamon oil using a large-scale film production system effectively repelled Indian meal moth larvae. Without altering the tensile and moisture barrier properties of the film, microencapsulation resulted in the release of an active repellent for extended periods with a high thermal stability of cinnamon oil, enabling commercial film production at high temperatures. This anti-insect film system may have applications to other food-packaging films that use the same ink-printing platform. © 2018 Institute of Food Technologists®.

Efficacy of UV-C irradiation for inactivation of food-borne pathogens on sliced cheese packaged with different types and thicknesses of plastic films.

PubMed

Ha, Jae-Won; Back, Kyeong-Hwan; Kim, Yoon-Hee; Kang, Dong-Hyun

2016-08-01

In this study, the efficacy of using UV-C light to inactivate sliced cheese inoculated with Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and, packaged with 0.07 mm films of polyethylene terephthalate (PET), polyvinylchloride (PVC), polypropylene (PP), and polyethylene (PE) was investigated. The results show that compared with PET and PVC, PP and PE films showed significantly reduced levels of the three pathogens compared to inoculated but non-treated controls. Therefore, PP and PE films of different thicknesses (0.07 mm, 0.10 mm, and 0.13 mm) were then evaluated for pathogen reduction of inoculated sliced cheese samples. Compared with 0.10 and 0.13 mm, 0.07 mm thick PP and PE films did not show statistically significant reductions compared to non-packaged treated samples. Moreover, there were no statistically significant differences between the efficacy of PP and PE films. These results suggest that adjusted PP or PE film packaging in conjunction with UV-C radiation can be applied to control foodborne pathogens in the dairy industry. Copyright © 2016. Published by Elsevier Ltd.

Surface modification of carbon nanotubes using 3-aminopropyltriethoxysilane to improve mechanical properties of nanocomposite based polymer matrix: Experimental and Density functional theory study

NASA Astrophysics Data System (ADS)

Hamed Mashhadzadeh, A.; Fereidoon, Ab.; Ghorbanzadeh Ahangari, M.

2017-10-01

In current study we combined theoretical and experimental studies to evaluate the effect of functionalization and silanization on mechanical behavior of polymer-based/CNT nanocomposites. Epoxy was selected as thermoset polymer, polypropylene and poly vinyl chloride were selected as thermoplastic polymers. The whole procedure is divided to two sections . At first we applied density functional theory (DFT) to analyze the effect of functionalization on equilibrium distance and adsorption energy of unmodified, functionalized by sbnd OH group and silanized epoxy/CNT, PP/CNT and PVC/CNT nanocomposites and the results showed that functionalization increased adsorption energy and reduced the equilibrium distance in all studied nanocomposites and silanization had higher effect comparing to OH functionalizing. Then we prepared experimental samples of all mentioned nanocomposites and tested their tensile and flexural strength properties. The obtained results showed that functionalization increased the studied mechanical properties in all evaluated nanocomposites. Finally we compared the results of experimental and theoretical sections with each other and estimated a suitable agreement between these parts.

Temperature effects on quasi-isolated conjugated polymers as revealed by temperature-dependent optical spectra of 16-mer oligothiophene diluted in a sold matrix.

PubMed

Kanemoto, Katsuichi; Akai, Ichiro; Sugisaki, Mitsuru; Hashimoto, Hideki; Karasawa, Tsutomu; Negishi, Nobukazu; Aso, Yoshio

2009-06-21

Temperature dependences (4-300 K) of photoluminescence (PL) and absorption spectra of 16-mer oligothiophene (16 T) extremely diluted in polypropylene (PP) have been investigated in order to clarify temperature effects on quasi-isolated conjugated polymers. The PL and absorption spectra are found to blueshift with increasing temperature. The reason for the blueshift is discussed by comparing models based on the refractive index of the solvent (PP) and on the thermal conformational change of 16 T. The blueshift is concluded to result from the thermal conformational change. Time-resolved PL spectra show a redshift of PL band following photoexcitation (spectral migration). The amount of the migration is shown to increase with increasing temperature. The increased migration is concluded to be due to the thermal conformational change. The temperature dependence of the effective conjugation length (ECL) of 16 T is calculated for the absorption and PL transitions. The calculation suggests that ECL is reduced at room temperature to two-thirds of the intrinsic chain length. The activation energy of the conformational change is estimated to be 22.4 meV from the temperature dependence of ECL. We demonstrate that the steady-state PL spectra are well reproduced by simple Franck-Condon analyses using a single Huang-Ryes factor over a wide temperature range. The analyses reveal features of temperature dependence in important spectral parameters such as the Stokes shift, linewidth, and Huang-Ryes factor.

Resistance of pathogenic and spoilage microorganisms to disinfectants in the presence of organic matter and their residual effect on stainless steel and polypropylene.

PubMed

Iñiguez-Moreno, Maricarmen

2018-04-23

The effectiveness of disinfectants can vary according to the microorganism, type of residues and surface. Hence, the aim of this study was to determine the effectiveness of four disinfectants in the presence of organic matter and their residual effect on stainless steel grade 304 (SS) and polypropylene B (PP-B). The disinfectant effectiveness in the presence of meat extract, yolk egg and whole milk was determined according to AOAC and UNE-EN 1040:2015; the residual effect was realized according to UNE-EN 13697:2015, using approved strains. The disinfectant effectiveness was affect at different grades depending on the organic matter present; disinfectant A (400μgmL -1 , fifth generation quaternary ammonium compound, QAC) was most effective in the presence of 10% meat extract, while the disinfectant C (200μgmL -1 , peracetic acid) had better activity in the presence of 10% egg yolk and whole milk. In the evaluation of residual effect onto SS and PP-B, the QAC had the better effect, reducing 6 Log 10 CFU mL -1 of Listeria monocytogenes ATCC 19111 24h after their application. Conversely, the disinfectants had no residual effect against Pseudomonas aeruginosa ATCC 15442. The antimicrobial activity of disinfectants tested against pathogenic and spoilage microorganisms was affected according to the type of organic matter. Disinfectant A had a more residual effect than the other disinfectants evaluated. Moreover, the residual effect of a disinfectant is greater on SS than on PP-B and dependent on the microorganism tested. Copyright © 2018. Published by Elsevier Ltd.

Migration of selected hydrocarbon contaminants into dry semolina and egg pasta packed in direct contact with virgin paperboard and polypropylene film.

PubMed

Barp, Laura; Suman, Michele; Lambertini, Francesca; Moret, Sabrina

2015-01-01

Migration of mineral oil saturated hydrocarbons (MOSH), polyolefin oligomeric saturated hydrocarbons (POSH), and polyalphaolefins (PAO from hot melts) into dry semolina and egg pasta packed in direct contact with virgin paperboard or polypropylene (PP) flexible film was studied. Migration was monitored during shelf life (up to 24 months), through storage in a real supermarket (packs kept on shelves), conditions preventing exchange with the surrounding environment (packs wrapped in aluminium foil), and storage in a warehouse (packs inside of the transport box of corrugated board). Semolina pasta packed in virgin paperboard (without hot melts) had a MOSH content lower than 1.0 mg kg(-1). An increasing contamination with PAO belonging to the adhesives used to close the boxes was detected in egg pasta, wrapped in aluminium (1.5 and 5 mg kg(-1) after 3 and 24 months, respectively). An environmental contribution to total hydrocarbon contamination was observed in egg pasta kept on shelves that, after 3 and 24 months, showed levels of PAO/MOSH < C25 around 3 and 10 mg kg(-1), respectively. The migration of POSH from PP film into egg pasta wrapped in aluminium was around 0.6 mg kg(-1) after 3 months of contact and reached 1.7 mg kg(-1) after 24 months of contact. After 9 months of contact, semolina pasta packed in PP film and stored in the transport box showed that some MOSH migrated into the pasta from the board of the transport box (through the plastic film).

The effect of two sock fabrics on physiological parameters associated with blister incidence: a laboratory study.

PubMed

Bogerd, Cornelis Peter; Rechsteiner, Ivo; Wüst, Benno; Rossi, René M; Brühwiler, Paul A

2011-06-01

The goal of the present study was to investigate physiological effects, mainly at the level of the foot, of two sock fabrics with distinct moisture properties. Twelve participants wore two different socks, one on each foot. The following two sock types were used: PP: 99.6% polypropylene and 0.4% elastane and BLEND: 50% Merino wool, 33% polypropylene, and 17% polyamide. The participants walked three times on a treadmill at 5 km h(-1), with no gradient for the first and third phase and a 10% upward inclination for the second walking phase. The microclimate temperature between the boot and foot was measured during walking. Preceding and following the walking phases, additional measurements were carried out at the level of the foot, i.e. skin temperature and skin hydration on three locations and skin friction between the posterior surface of the calcaneus and a glass plate. In addition, the moisture absorption of boots and socks was determined. Differences between the sock fabrics were found for weight gain and microclimate temperature: (i) PP tended to hold less water compared to BLEND, (ii) the boot's microclimate temperature resulted in larger values for BLEND measured at the dorsal surface at the level of the third metatarsal, and (iii) warmer microclimates of the boot were measured for PP compared to BLEND at the distal anterior end of the tibia. The established differences in moisture behavior of both socks did not result in detectable differences in parameters measured on the skin of the foot.

Effect of Cold-Drawn Fibers on the Self-Reinforcement of PP/LDPE Composites

NASA Astrophysics Data System (ADS)

Zhou, Ying-Guo; Su, Bei; Wu, Hai-Hong

2017-08-01

In our previous study, a method to fabricate super-ductile polypropylene/low-density polyethylene (PP/LDPE) blends was proposed, and a fiber-shape structure was shown to be formed, presenting necking propagation during tensile testing. In this study, the mechanical properties and thermal behavior of the necking region of tested super-ductile PP/LDPE samples were carefully investigated and further compared with the melt-stretched, untested, and thermo-mechanical-history-removed samples by differential scanning calorimetry and tensile testing. The results suggest that the tested samples have high mechanical properties and are more thermo-mechanically stable than the common PP/LDPE blends and melt-stretched samples. Additionally, to investigate their structure-property relationship, the necking region of the tested samples was further characterized by scanning electron microscopy and hot-stage polarized light microscopy. It can be concluded that the variation of the microstructure can be attributed to the cold-drawn fibers (CDFs), which were more stable thermally, formed during the tensile test. Furthermore, the CDFs were used for the filler in PP/LDPE blends. The experimental results of the different PP/LDPE composites indicate that the CDFs are a good reinforcement candidate and have the ability to improve the mechanical properties of the PP/LDPE blends.

Multiscale characterization of chemical–mechanical interactions between polymer fibers and cementitious matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernández-Cruz, Daniel; Hargis, Craig W.; Bae, Sungchul

2014-04-01

Together with a series of mechanical tests, the interactions and potential bonding between polymeric fibers and cementitious materials were studied using scanning transmission X-ray microscopy (STXM) and microtomography (lCT). Experimental results showed that these techniques have great potential to characterize the polymer fiber-hydrated cement-paste matrix interface, as well as differentiating the chemistry of the two components of a bi-polymer (hybrid) fiber the polypropylene core and the ethylene acrylic acid copolymer sheath. Similarly, chemical interactions between the hybrid fiber and the cement hydration products were observed, indicating the chemical bonding between the sheath and the hardened cement paste matrix. Microtomography allowedmore » visualization of the performance of the samples, and the distribution and orientation of the two types of fiber in mortar. Beam flexure tests confirmed improved tensile strength of mixes containing hybrid fibers, and expansion bar tests showed similar reductions in expansion for the polypropylene and hybrid fiber mortar bars.« less

Effect of boron compounds on physical, mechanical, and fire properties of injection molded wood plastic composites

Treesearch

Nadir Ayrilmis; Turgay Akbulut; Turker Dundar; Robert H. White; Fatih Mengeloglu; Zeki Candan; Umit Buyuksari; Erkan Avci

2011-01-01

Physical, mechanical, and fire properties of the injection-molded wood flour/polypropylene composites (WPCs) incorporated with different levels of boron compounds, borax/boric acid (BX/BA) (0.5:0.5 wt %) and zinc borate (ZB) (4, 8, or 12 wt %) were investigated. The effect of the coupling agent loading (2, 4, or 6 wt %), maleic anhydride-grafted PP (MAPP), on the...

Effect of molecular-mass characteristics of ethylene-propylene-diene monomer rubber on impact resistance and mobility of the melt of its modified blends with polypropylene

NASA Astrophysics Data System (ADS)

Ryzhikova, I. G.; Bauman, N. A.; Volkov, A. M.; Kazakov, Yu. M.; Volfson, S. I.

2014-05-01

The study concerned the effect of molecular-mass characteristics and Mooney viscosity of the initial EPDM rubber on the changes in the structure, impact strength and rheological properties of PP/EPDM blends as a result of their modification in a melt under the action of organic peroxide and peroxide-trimethylolpropane triacrylate (TMPTA) system.

Deodorisation effect of diamond-like carbon/titanium dioxide multilayer thin films deposited onto polypropylene

NASA Astrophysics Data System (ADS)

Ozeki, K.; Hirakuri, K. K.; Masuzawa, T.

2011-04-01

Many types of plastic containers have been used for the storage of food. In the present study, diamond-like carbon (DLC)/titanium oxide (TiO2) multilayer thin films were deposited on polypropylene (PP) to prevent flavour retention and to remove flavour in plastic containers. For the flavour removal test, two types of multilayer films were prepared, DLC/TiO2 films and DLC/TiO2/DLC films. The residual gas concentration of acetaldehyde, ethylene, and turmeric compounds in bottle including the DLC/TiO2-coated and the DLC/TiO2/DLC-coated PP plates were measured after UV radiation, and the amount of adsorbed compounds to the plates was determined. The percentages of residual gas for acetaldehyde, ethylene, and turmeric with the DLC/TiO2 coated plates were 0.8%, 65.2% and 75.0% after 40 h of UV radiation, respectively. For the DLC/TiO2/DLC film, the percentages of residual gas for acetaldehyde, ethylene and turmeric decreased to 34.9%, 76.0% and 85.3% after 40 h of UV radiation, respectively. The DLC/TiO2/DLC film had a photocatalytic effect even though the TiO2 film was covered with the DLC film.

Temperature and strain rate dependent behavior of polymer separator for Li-ion batteries

DOE PAGES

Kalnaus, Sergiy; Wang, Yanli; Li, Jianlin; ...

2018-03-07

Safe performance of advanced Li-ion batteries relies on integrity of the separator membrane which prevents contact between electrodes of opposite polarity. Current work provides detailed study of mechanical behavior of such membrane. Temperature and strain rate sensitivity of the triple-layer polypropylene (PP)/polyethylene (PE)/polypropylene (PP) porous separator for Li-ion batteries was studied experimentally under controlled temperatures of up to 120° (393 K), and strain rates (from 1∙10-4s-1 to 0.1s-1). Digital image correlation was used to study strain localization in separator under load. The results show significant dependence of mechanical properties on temperature, with the yield stress decreasing by 30% and elasticmore » modulus decreasing by a factor of two when the temperature is increased from 20 °C to 50 °C. The strain rate strengthening also decreased with higher temperatures while the temperature softening remained independent of the applied strain rate. Application of temperature creates long lasting changes in mechanical behavior of separator as was revealed by performing experiments after the annealing. Such delayed effect of temperature application appears to have directional dependence. The results demonstrate complex behavior of polymer separator which needs to be considered in proper safety assessments of Li-ion batteries.« less

Photodegradation of ethylene by use of TiO2 sol-gel on polypropylene and on glass for application in the postharvest of papaya fruit.

PubMed

Lourenço, Ruth Evelyn R S; Linhares, Amanda A N; de Oliveira, André Vicente; da Silva, Marcelo Gomes; de Oliveira, Jurandi Gonçalves; Canela, Maria Cristina

2017-03-01

The papaya is a commercially important fruit commodity worldwide. Being a climacteric fruit, it is highly perishable. Thus, for the transportation of papaya fruit for long distances without loss of quality, it is necessary to avoid the autocatalytic effect of ethylene in accelerating the ripening of the fruit. This work addresses the application of heterogeneous photocatalysis to the degradation of ethylene. A TiO 2 sol-gel supported on polypropylene (PP) and on glass was used as the catalytic material, and a UV-A lamp was employed as the radiation source. Initially, a concentration of 500 ppbv ethylene was exposed to the catalyst material irradiated by UV-A radiation. A sensitive photoacoustic spectrometer was used to monitor the photocatalytic activity. The TiO 2 sol-gel supported on the glass substrate was more efficient than on the PP in degrading the ethylene. Under direct UV-A exposure, the skin appearance of 'Golden' papaya was damaged, depreciating the fruit quality and thus preventing its commercialization. However, the feasibility of the heterogeneous photocatalysis to preserve the fruit quality was achieved when ethylene was removed from the storage ambient using fans, and then, this plant hormone was degraded by a reactor set apart in a ventilation closed system.

Influence of polypropylene fibres on the tensile strength and thermal properties of various densities of foamed concrete

NASA Astrophysics Data System (ADS)

Jhatial, Ashfaque Ahmed; Inn, Goh Wan; Mohamad, Noridah; Johnson Alengaram, U.; Mo, Kim Hung; Abdullah, Redzuan

2017-11-01

As almost half of the world’s population now lives in the urban areas, the raise in temperature in these areas has necessitated the development of thermal insulating material. Conventional concrete absorbs solar radiation during the daytime while releasing it at night causing raise in temperature in urban areas. The thermal conductivity of 2200 kg/m3 density conventional concrete is 1.6 W/mK. Higher the thermal conductivity value, greater the heat flow through the material. To reduce this heat transfer, the construction industry has turned to lightweight foamed concrete. Foamed concrete, due to its air voids, gives excellent thermal properties and sound absorption apart from fire-resistance and self-leveling properties. But due to limited studies on different densities of foamed concrete, the thermal properties are not understood properly thus limiting its use as thermal insulating material. In this study, thermal conductivity is determined for 1400, 1600 and 1800 kg/m3 densities of foamed concrete. 0.8% of Polypropylene fibres (PP) is used to reinforce the foamed concrete and improve the mechanical properties. Based upon the results, it was found that addition of PP fibres enhances the tensile strength and slightly reduced the thermal conductivity for lower densities, while the reverse affect was noticed in 1800 kg/m3 density.

Synthesis of antibacterial surfaces by plasma grafting of zinc oxide based nanocomposites onto polypropylene.

PubMed

de Rancourt, Yoann; Couturaud, Benoit; Mas, André; Robin, Jean Jacques

2013-07-15

Antibacterial polymer surfaces were designed using ZnO nanoparticles as a bactericide. Mineral encapsulated nanoparticles were grafted onto activated polymer surfaces through their shells. Polypropylene (PP) surfaces were treated using an innovative process coupling core-shell technology and plasma grafting, well-known techniques commonly used to obtain active surfaces for biomedical applications. First, ZnO nanoparticles were encapsulated by (co)polymers: poly(acrylic acid) (PAA) or a poly(methyl methacrylate-co-methacrylic acid) copolymer [P(MMA-MA)]. Second, PP substrates were activated using plasma treatment. Finally, plasma-treated surfaces were immersed in solutions containing the encapsulated nanoparticles dispersed in an organic solvent and allowed to graft onto it. The presence of nanoparticles on the substrates was demonstrated using Fourier-Transform Infrared Spectroscopy (FTIR) analysis, Scanning Electron Microspcopy (SEM)/Energy-Dispersive X-ray (EDX), and Atomic Force Microscopy (AFM) studies. Indeed, the ZnO-functionalized substrates exhibited an antibacterial response in Escherichia coli adhesion tests. Moreover, this study revealed that, surprisingly, native ZnO nanoparticles without any previous functionalization could be directly grafted onto polymeric surfaces through plasma activation. The antibacterial activity of the resulting sample was shown to be comparable to that of the other samples. Copyright © 2013 Elsevier Inc. All rights reserved.

Temperature and strain rate dependent behavior of polymer separator for Li-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalnaus, Sergiy; Wang, Yanli; Li, Jianlin

Safe performance of advanced Li-ion batteries relies on integrity of the separator membrane which prevents contact between electrodes of opposite polarity. Current work provides detailed study of mechanical behavior of such membrane. Temperature and strain rate sensitivity of the triple-layer polypropylene (PP)/polyethylene (PE)/polypropylene (PP) porous separator for Li-ion batteries was studied experimentally under controlled temperatures of up to 120° (393 K), and strain rates (from 1∙10-4s-1 to 0.1s-1). Digital image correlation was used to study strain localization in separator under load. The results show significant dependence of mechanical properties on temperature, with the yield stress decreasing by 30% and elasticmore » modulus decreasing by a factor of two when the temperature is increased from 20 °C to 50 °C. The strain rate strengthening also decreased with higher temperatures while the temperature softening remained independent of the applied strain rate. Application of temperature creates long lasting changes in mechanical behavior of separator as was revealed by performing experiments after the annealing. Such delayed effect of temperature application appears to have directional dependence. The results demonstrate complex behavior of polymer separator which needs to be considered in proper safety assessments of Li-ion batteries.« less

Effect of microstructure on the thermo-oxidation of solid isotactic polypropylene-based polyolefins

PubMed Central

Hoyos, Mario; Tiemblo, Pilar; Gómez-Elvira, José Manuel

2008-01-01

In the present work we aim to clarify the role of the microstructure and the crystalline distribution from the thermo-oxidation of solid isotactic PP (iPP) and ethylene-propylene (EP) copolymers. The effects of the content and quality of the isotacticity interruptions, together with the associated average isotactic length, on the induction time (ti) as well as on the activation energy (Eact) of the thermo-oxidation are analysed. Both parameters have been found to change markedly at an average isotactic length (n1) of 30 propylene units. While ti reaches a minimum when n1 is approximately 30 units, Eact increases quasi-exponentially as the number of units decreases from 30. This variation can be explained in terms of changes induced in the crystalline interphase, i.e. local molecular dynamics, which are closely linked to the initiation of the thermo-oxidation of isotactic PP-based polyolefins. PMID:27877971

Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) Mapping Coupled with Multivariate Curve Resolution (MCR) for Studying the Miscibility of Chlorobutyl Rubber/Polyamide-12 Blends.

PubMed

Tang, Yongjiao; Jing, Nan; Zhang, Pudun

2015-11-01

A series of chlorobutyl rubber/polyamide-12 (CIIR/PA-12) blends compatibilized by different amounts of maleic anhydride (MAH) grafted polypropylene (PP-g-MAH) were investigated by attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) mapping. Multivariate curve resolution (MCR) was used to process the FT-IR images. Both the spectra of pure components in the blends and their concentration distributions in a micro-region were acquired. Our results demonstrated that the blend with 15 parts per hundred rubber PP-g-MAH showed the best miscibility. An amide interphase and an imide interphase were inferred by analyzing the spectra of MCR component 3 of the blends with and without PP-g-MAH, respectively. Correspondingly, two different compatibilizing mechanisms were proposed for these blends.

Effect of single flame retardant aluminum tri-hydroxide and boric acid against inflammability and biodegradability of recycled PP/KF composites

NASA Astrophysics Data System (ADS)

Suharty, Neng Sri; Dihardjo, Kuncoro; Handayani, Desi Suci; Firdaus, Maulidan

2016-03-01

Composites rPP/DVB/AA/KF had been reactively synthesized in melt using starting material: recycled polypropylene (rPP), kenaf fiber (KF), multifunctional compound acrylic acid (AA), compatibilizer divinyl benzene (DVB). To improve the inflammability of composites, single flame retardant aluminum tri-hydroxide (ATH) and boric acid (BA) as an additive was added. The inflammability of the composites was tested according to ASTM D635. By using 20% ATH and 5% BA additive in the composites it is effectively inhibiting its time to ignition (TTI). Its burning rate (BR) can be reduced and its heat realease (%HR) decreases. The biodegradability of composites was quantified by its losing weight (LW) of composites after buried for 4 months in the media with rich cellulolytic bacteria. The result shows that the LW of composites in the presence 20% ATH and 5% BA is 6.3%.

Catalytic pyrolysis of black-liquor lignin by co-feeding with different plastics in a fluidized bed reactor.

PubMed

Zhang, Huiyan; Xiao, Rui; Nie, Jianlong; Jin, Baosheng; Shao, Shanshan; Xiao, Guomin

2015-09-01

Catalytic co-pyrolysis of black-liquor lignin and waste plastics (polyethylene, PE; polypropylene PP; polystyrene, PS) was conducted in a fluidized bed. The effects of temperature, plastic to lignin ratio, catalyst and plastic types on product distributions were studied. Both aromatic and olefin yields increased with increasing PE proportion. Petrochemical yield of co-pyrolysis of PE and lignin was LOSA-1 > spent FCC > Gamma-Al2O3 > sand. The petrochemical yield with LOSA-1 is 43.9% which is more than two times of that without catalyst. The feedstock for co-pyrolysis with lignin is polystyrene > polyethylene > polypropylene. Catalytic co-pyrolysis of black-liquor lignin with PS produced the maximum aromatic yield (55.3%), while co-pyrolysis with PE produced the maximum olefin yield (13%). Copyright © 2015 Elsevier Ltd. All rights reserved.

Study on the fabricating process monitoring of thermoplastic based materials packaged OFBG and their sensing properties

NASA Astrophysics Data System (ADS)

Wang, Chuan; Zhou, Zhi; Zhang, Zhichun; Ou, Jinping

2007-04-01

As common materials or engineering materials, thermoplastic resin based materials can be used not only directly fabricating products but also FRTP(fiber reinforced thermoplastic polymer) materials for other uses. As one kind of FRTP material, GFRPP(glass fiber reinforced polypropylene) has lots of merits, such as: light weight, high strength, high tenacity, high elongation percentage, good durability, reshaping character and no environmental pollution characters. And they also can be conveniently formed hoop rebar in civil engineering. While a new kind of GFRPP-OFBG smart rod which combined GFRPP and OFBG together can be used as not only structure materials but also sensing materials. Meanwhile, PP packaged OFBG strain sensor can be expected for its low modulus, good sensitivity and good durability. Furthermore, it can be used for large strain measuring. In this paper, we have successfully fabricated a new kind of GFRPP-OFBG(Glass Fiber Reinforced Polypropylene-Optic Fiber Bragg Grating) rod by our own thermoplastic pultrusion production line and a new kind of PP packaged OFBG strain sensor by extruding techniques. And we monitored the inner strain and temperature changes with tow OFBG simultaneously of the fabricating process. The results show that: OFBG can truly reflect the strain and temperature changes in both the GFRPP rod and the PP packaged OFBG, these are very useful to modify our processing parameters. And we also find that because of the shrinkage of PP, this new kind of PP packaged OFBG have -13000μɛ storage, and the strain sensing performance is still very well, so which can be used for large strain measuring. Besides these, GFRPP-OFBG smart rod has good sensing performance in strain sensing just like that of FRSP-OFBG rod, the strain sensitivity coefficient is about1.19pm/μɛ. Besides these, the surface of GFRPP-OFBG rods can be handled just as steel bars and also can be bended and reshaped. These are all very useful and very important for the use of FRP materials in civil engineering structures.

Investigation on γ-irradiated PP/ethylene acrylic elastomer TPVs by rheological and thermal approaches

NASA Astrophysics Data System (ADS)

Dutta, Anindya; Ghosh, Anup K.

2018-03-01

Polypropylene (PP) was melt blended with varying concentration of ethylene acrylic elastomer (AEM) in a twin screw extruder and then γ-irradiated at several radiation doses to achieve a series of thermoplastic vulcanizates (TPV). The effect of AEM concentration and γ-irradiation on flow characteristics, crystallization and thermal degradation of blends were explained using melt dynamic rheology, differential scanning calorimetry and thermogravimetric analysis. Gel content values and dynamic rheological data of PP and AEM at different radiation doses confirmed the incessant scissioning of PP chains with radiation doses except for highest radiation dose, where crosslinking of PP chains took place and the incessant crosslinking of AEM chains irrespective of radiation doses. Oxidative degradation of PP was confirmed by FTIR spectroscopy, which also exhibited absence of any chemical interaction between two constituent polymers. Normalized crystallinity and melting point of compositions, obtained from DSC, decreased with the radiation doses. Furthermore, with the radiation doses clear shifts of maxima of the melting peak towards the lower temperature were observed for neat PP and blends. Thermal stability of PP and blends, as observed by TGA, reduced significantly with irradiation; whereas for AEM, no discernable change was observed. Enhanced chain scissioning of PP in presence of AEM reduced the thermal stability of blends, especially at lower irradiation. This reduction of thermal stability was established by "rule of mixture", applied to the activation energy of thermal degradation. Thus, optimization of radiation doses to prepare TPVs was established.

Physico-chemical characterization of functionalized polypropylenic fibers for prosthetic applications

NASA Astrophysics Data System (ADS)

Nisticò, Roberto; Faga, Maria Giulia; Gautier, Giovanna; Magnacca, Giuliana; D'Angelo, Domenico; Ciancio, Emanuele; Piacenza, Giacomo; Lamberti, Roberta; Martorana, Selanna

2012-08-01

Polypropylene (PP) fibers can be manufactured to form nets which can find application as prosthesis in hernioplasty. One of the most important problem to deal with when nets are applied in vivo consists in the reproduction of bacteria within the net fibers intersections. This occurs right after the application of the prosthesis, and causes infections, thus it is fundamental to remove bacteria in the very early stage of the nets application. This paper deals with the physico-chemical characterization of such nets, pre-treated by atmospheric pressure plasma dielectric barrier discharge apparatus (APP-DBD) and functionalized with an antibiotic drug such as chitosan. The physico-chemical characterization of sterilized nets, before and after the functionalization with chitosan, was carried out by means of scanning electron microscopy (SEM) coupled with EDS spectroscopy, FTIR spectroscopy, drop shape analysis (DSA), X-ray diffraction and thermal analyses (TGA and DSC). The aim of the work is to individuate a good strategy to characterize this kind of materials, to understand the effects of polypropylene pre-treatment on functionalization efficiency, to follow the materials ageing in order to study the effects of the surface treatment for in vivo applications.

Recycling disposable cups into paper plastic composites.

PubMed

Mitchell, Jonathan; Vandeperre, Luc; Dvorak, Rob; Kosior, Ed; Tarverdi, Karnik; Cheeseman, Christopher

2014-11-01

The majority of disposable cups are made from paper plastic laminates (PPL) which consist of high quality cellulose fibre with a thin internal polyethylene coating. There are limited recycling options for PPLs and this has contributed to disposable cups becoming a high profile, problematic waste. In this work disposable cups have been shredded to form PPL flakes and these have been used to reinforce polypropylene to form novel paper plastic composites (PPCs). The PPL flakes and polypropylene were mixed, extruded, pelletised and injection moulded at low temperatures to prevent degradation of the cellulose fibres. The level of PPL flake addition and the use of a maleated polyolefin coupling agent to enhance interfacial adhesion have been investigated. Samples have been characterised using tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis. Use of a coupling agent allows composites containing 40 wt.% of PPL flakes to increase tensile strength of PP by 50% to 30 MPa. The Young modulus also increases from 1 to 2.5 GPa and the work to fracture increases by a factor of 5. The work demonstrates that PPL disposable cups have potential to be beneficially reused as reinforcement in novel polypropylene composites. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of UV radiation from oxygen and argon plasma on the adhesion of organosilicon coatings on polypropylene

NASA Astrophysics Data System (ADS)

Jaritz, M.; Behm, H.; Hopmann, Ch; Kirchheim, D.; Mitschker, F.; Awakowicz, P.; Dahlmann, R.

2017-01-01

The influence of ultraviolet (UV) radiation from oxygen and argon pretreatment plasmas on a plastic substrate has not been fully understood yet. In particular, its influence on the adhesion properties has not been sufficiently researched so far. This paper addresses this issue by comparing the bond strength of a plasmapolymerized silicon organic coating (SiO x C y H z ) on polypropylene (PP) after oxygen and argon plasma pretreatment and pretreatment by UV radiation emitted by the same plasmas. The UV radiation is isolated from the other species from the plasma by means of a magnesium fluoride (MgF2) optical filter. It could be shown that UV radiation originating from an oxygen plasma has a significant impact on both substrate surface chemistry and coating adhesion. The same maximum bond strength enhancement can be reached by pretreating the polypropylene surface either with pulsed oxygen plasma, or with only the UV radiation from this oxygen plasma. Also, similar surface chemistry and topography modifications are induced. For argon plasma no significant influence of its UV radiation on the substrate could be observed in this study.

Determination of microplastic polyethylene (PE) and polypropylene (PP) in environmental samples using thermal analysis (TGA-DSC).

PubMed

Majewsky, Marius; Bitter, Hajo; Eiche, Elisabeth; Horn, Harald

2016-10-15

Microplastics are increasingly detected in the environment and the consequences on water resources and ecosystems are not clear to date. The present study provides a cost-effective and straightforward method to determine the mass concentrations of polymer types using thermal analysis. Characteristic endothermic phase transition temperatures were determined for seven plastic polymer types using TGA-DSC. Based on that, extracts from wastewater samples were analyzed. Results showed that among the studied polymers, only PE and PP could be clearly identified, while the phase transition signals of the other polymers largely overlap each other. Subsequently, calibration curves were run for PE and PP for qualitative measurements. 240 and 1540mg/m(3) of solid material (12µm to 1mm) was extracted from two wastewater effluent samples of a municipal WWTP of which 34% (81mg/m(3)) and 17% (257mg/m(3)) could be assigned to PE, while PP was not detected in any of the samples. The presented application of TGA-DSC provides a complementary or alternative method to FT-IR analyses for the determination of PE and PP in environmental samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Polypropylene Surgical Mesh Coated with Extracellular Matrix Mitigates the Host Foreign Body Response

PubMed Central

Wolf, Matthew T.; Carruthers, Christopher A.; Dearth, Christopher L.; Crapo, Peter M.; Huber, Alexander; Burnsed, Olivia A.; Londono, Ricardo; Johnson, Scott A.; Daly, Kerry A.; Stahl, Elizabeth C.; Freund, John M.; Medberry, Christopher J.; Carey, Lisa E.; Nieponice, Alejandro; Amoroso, Nicholas J.; Badylak, Stephen F.

2013-01-01

Surgical mesh devices composed of synthetic materials are commonly used for ventral hernia repair. These materials provide robust mechanical strength and are quickly incorporated into host tissue; factors which contribute to reduced hernia recurrence rates. However, such mesh devices cause a foreign body response with the associated complications of fibrosis and patient discomfort. In contrast, surgical mesh devices composed of naturally occurring extracellular matrix (ECM) are associated with constructive tissue remodeling, but lack the mechanical strength of synthetic materials. A method for applying a porcine dermal ECM hydrogel coating to a polypropylene mesh is described herein with the associated effects upon the host tissue response and biaxial mechanical behavior. Uncoated and ECM coated heavy-weight BARD™ Mesh were compared to the light-weight ULTRAPRO™ and BARD™ Soft Mesh devices in a rat partial thickness abdominal defect overlay model. The ECM coated mesh attenuated the pro-inflammatory response compared to all other devices, with a reduced cell accumulation and fewer foreign body giant cells. The ECM coating degraded by 35 days, and was replaced with loose connective tissue compared to the dense collagenous tissue associated with the uncoated polypropylene mesh device. Biaxial mechanical characterization showed that all of the mesh devices were of similar isotropic stiffness. Upon explantation, the light-weight mesh devices were more compliant than the coated or uncoated heavy-weight devices. The present study shows that an ECM coating alters the default host response to a polypropylene mesh, but not the mechanical properties in an acute in vivo abdominal repair model. PMID:23873846

Research on a Novel Low Modulus OFBG Strain Sensor for Pavement Monitoring

PubMed Central

Wang, Chuan; Hu, Qingli; Lu, Qiyu

2012-01-01

Because of the fatigue and deflection damage of asphalt pavement, it is very important for researchers to monitor the strain response of asphalt layers in service under vehicle loads, so in this paper a novel polypropylene based OFBG (Optical Fiber Bragg Gratings) strain sensor with low modulus and large strain sensing scale was designed and fabricated. PP with MA-G-PP is used to package OFBG. The fabrication techniques, the physical properties and the sensing properties were tested. The experimental results show that this kind of new OFBG strain sensor is a wonderful sensor with low modulus (about 1 GPa) and good sensitivity, which would meet the needs for monitoring some low modulus materials or structures. PMID:23112584

Influence of non-migratory metal-chelating active packaging film on food quality: impact on physical and chemical stability of emulsions.

PubMed

Tian, Fang; Decker, Eric A; McClements, D Julian; Goddard, Julie M

2014-05-15

Previously, we developed a novel metal-chelating packaging film (PP-g-PAA) by grafting acrylic acid (AA) monomer from polypropylene (PP) film surface, and demonstrated its potential in controlling iron-promoted lipid oxidation. Herein, we further established the industrial practicality of this active film. Specifically, the influence of film surface area-to-product volume ratio (SA/V) and product pH on the application of the film was investigated using an oil-in-water emulsion system. The films equally inhibited lipid oxidation throughout the range of SA/V ratios tested (2-8 cm(2)/ml). PP-g-PAA films were most effective at pH 7.0, and the activity decreased with decreasing pH. The particle size examination of emulsions indicated no adverse influence from the active film on the stability of this emulsion system. FTIR analysis suggested a non-migratory nature of PP-g-PAA films. These results provide fundamental knowledge that will facilitate the application of this effective and economical active packaging film in the food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

Recovery of polypropylene and polyethylene from packaging plastic wastes without contamination of chlorinated plastic films by the combination process of wet gravity separation and ozonation.

PubMed

Reddy, Mallampati Srinivasa; Okuda, Tetsuji; Nakai, Satoshi; Nishijima, Wataru; Okada, Mitsumasa

2011-08-01

Wet gravity separation technique has been regularly practiced to separate the polypropylene (PP) and polyethylene (PE) (light plastic films) from chlorinated plastic films (CP films) (heavy plastic films). The CP films including poly vinyl chloride (PVC) and poly vinylidene chloride (PVDC) would float in water even though its density is more than 1.0g/cm(3). This is because films are twisted in which air is sometimes entrapped inside the twisted CP films in real existing recycling plant. The present research improves the current process in separating the PP and PE from plastic packaging waste (PPW), by reducing entrapped air and by increasing the hydrophilicity of the CP films surface with ozonation. The present research also measures the hydrophilicity of the CP films. In ozonation process mixing of artificial films up to 10min reduces the contact angle from 78° to 62°, and also increases the hydrophilicity of CP films. The previous studies also performed show that the artificial PVDC films easily settle down by the same. The effect of ozonation after the wet gravity separation on light PPW films obtained from an actual PPW recycling plant was also evaluated. Although actual light PPW films contained 1.3% of CP films however in present case all the CP films were removed from the PPW films as a settled fraction in the combination process of ozonation and wet gravity separation. The combination process of ozonation and wet gravity separation is the more beneficial process in recovering of high purity PP and PE films from the PPW films. Copyright © 2011 Elsevier Ltd. All rights reserved.

Uterotrophic and Hershberger assays for endocrine disruption properties of plastic food contact materials polypropylene (PP) and polyethylene terephthalate (PET).

PubMed

Chung, Bu Young; Kyung, Minji; Lim, Seong Kwang; Choi, Seul Min; Lim, Duck Soo; Kwack, Seung Jun; Kim, Hyung Sik; Lee, Byung-Mu

2013-01-01

Plasticizers or plastic materials such as phthalates, bisphenol-A (BPA), and styrene are widely used in the plastic industry and are suspected endocrine-disrupting chemicals (EDC). Although plastic materials such as polypropylene (PP) and polyethylene terephthalate (PET) are not EDC and are considered to be safe, their potential properties as EDC have not been fully investigated. In this study, plastic samples eluted from plastic food containers (PP or PET) were investigated in Sprague-Dawley rats using Hershberger and uterotrophic assays. In the Hershberger assay, 6-wk-old castrated male rats were orally treated for 10 consecutive days with plastic effluent at 3 different doses (5 ml/kg) or vehicle control (corn oil, 1 ml/100 g) to determine the presence of both anti-androgenic and androgenic effects. Testosterone (0.4 mg/ml/kg) was subcutaneously administered for androgenic evaluation as a positive control, whereas testosterone (0.4 mg/ml/kg) and flutamide (3 mg/kg/day) were administered to a positive control group for anti-androgenic evaluation. The presence of any anti-androgenic or androgenic activities of plastic effluent was not detected. Sex accessory tissues such as ventral prostate or seminal vesicle showed no significant differences in weight between treated and control groups. For the uterotrophic assay, immature female rats were treated with plastic effluent at three different doses (5 ml/kg), with vehicle control (corn oil, 1 ml/100 g), or with ethinyl estradiol (3 μg/kg/d) for 3 d. There were no significant differences between test and control groups in vagina or uterine weight. Data suggest that effluents from plastic food containers do not appear to produce significant adverse effects according to Hershberger and uterotrophic assays.

Improvement of the adsorption of quaternary ammonium on polypropylene affinity membrane through the control of its surface properties.

PubMed

Hachache, Naima; Bal, Youcef; Debarnot, Dominique; Poncin-Epaillard, Fabienne

2014-02-01

Polypropylene fiber meshes were plasma-treated in order to attach new chemical functions corresponding to acidic or basic groups without altering the roughness of such thin material. An almost complete wettability of these plasma-treated materials is obtained. Because of the plasma-grafting of acid or amino moieties, such surface treatment allows increasing the adsorption rate of quaternary ammonium molecule like Aliquat 336. This increase was explained by specific interactions of ammonium head of the Aliquat 336 and hydrophilic group of plasma-treated PP, followed by the adsorption of a further layer of Aliquat 336 through hydrophobic interactions of its hydrocarbon chain. These interactions between the carrier and the polymeric surface were characterized leading to physisorption mechanism. Such new material could be applied to the extraction process since no evidence of aging was given. Copyright © 2013 Elsevier B.V. All rights reserved.

Sensitivity-Enhanced Wearable Active Voiceprint Sensor Based on Cellular Polypropylene Piezoelectret.

PubMed

Li, Wenbo; Zhao, Sheng; Wu, Nan; Zhong, Junwen; Wang, Bo; Lin, Shizhe; Chen, Shuwen; Yuan, Fang; Jiang, Hulin; Xiao, Yongjun; Hu, Bin; Zhou, Jun

2017-07-19

Wearable active sensors have extensive applications in mobile biosensing and human-machine interaction but require good flexibility, high sensitivity, excellent stability, and self-powered feature. In this work, cellular polypropylene (PP) piezoelectret was chosen as the core material of a sensitivity-enhanced wearable active voiceprint sensor (SWAVS) to realize voiceprint recognition. By virtue of the dipole orientation control method, the air layers in the piezoelectret were efficiently utilized, and the current sensitivity was enhanced (from 1.98 pA/Hz to 5.81 pA/Hz at 115 dB). The SWAVS exhibited the superiorities of high sensitivity, accurate frequency response, and excellent stability. The voiceprint recognition system could make correct reactions to human voices by judging both the password and speaker. This study presented a voiceprint sensor with potential applications in noncontact biometric recognition and safety guarantee systems, promoting the progress of wearable sensor networks.

Green Composites Based on Blends of Polypropylene with Liquid Wood Reinforced with Hemp Fibers: Thermomechanical Properties and the Effect of Recycling Cycles.

PubMed

Cicala, Gianluca; Tosto, Claudio; Latteri, Alberta; La Rosa, Angela Daniela; Blanco, Ignazio; Elsabbagh, Ahmed; Russo, Pietro; Ziegmann, Gerhard

2017-08-26

Green composites from polypropylene and lignin-based natural material were manufactured using a melt extrusion process. The lignin-based material used was the so called "liquid wood". The PP/"Liquid Wood" blends were extruded with "liquid wood" content varying from 20 wt % to 80 wt %. The blends were thoroughly characterized by flexural, impact, and dynamic mechanical testing. The addition of the Liquid Wood resulted in a great improvement in terms of both the flexural modulus and strength but, on the other hand, a reduction of the impact strength was observed. For one blend composition, the composites reinforced with hemp fibers were also studied. The addition of hemp allowed us to further improve the mechanical properties. The composite with 20 wt % of hemp, subjected to up to three recycling cycles, showed good mechanical property retention and thermal stability after recycling.

Green Composites Based on Blends of Polypropylene with Liquid Wood Reinforced with Hemp Fibers: Thermomechanical Properties and the Effect of Recycling Cycles

PubMed Central

Latteri, Alberta; La Rosa, Angela Daniela; Elsabbagh, Ahmed; Ziegmann, Gerhard

2017-01-01

Green composites from polypropylene and lignin-based natural material were manufactured using a melt extrusion process. The lignin-based material used was the so called “liquid wood”. The PP/“Liquid Wood” blends were extruded with “liquid wood” content varying from 20 wt % to 80 wt %. The blends were thoroughly characterized by flexural, impact, and dynamic mechanical testing. The addition of the Liquid Wood resulted in a great improvement in terms of both the flexural modulus and strength but, on the other hand, a reduction of the impact strength was observed. For one blend composition, the composites reinforced with hemp fibers were also studied. The addition of hemp allowed us to further improve the mechanical properties. The composite with 20 wt % of hemp, subjected to up to three recycling cycles, showed good mechanical property retention and thermal stability after recycling. PMID:28846607

HMSPP nanocomposite and Brazilian bentonite properties after gamma radiation exposure

NASA Astrophysics Data System (ADS)

Fermino, D. M.; Parra, D. F.; Oliani, W. L.; Lugao, A. B.; Díaz, F. R. V.

2013-03-01

This work concerns the study of the mechanical and thermal behavior of the nanocomposite high melt strength polypropylene (HMSPP) (obtained at a dose of 12.5 kGy) and a bentonite clay Brazilian Paraiba (PB), which is known as "chocolate" and is used in concentrations of 5% and 10% by weight, in comparison to the American Cloisite 20A clay nanocomposites. An agent compatibilizer polypropylene-graft (PP-g-AM) was added at a 3% concentration, and the clay was dispersed using the melt intercalation technique using a twin-screw extruder. The specimens were prepared by the injection process. The mechanical behavior was evaluated by strength, flexural strength and impact tests. The thermal behavior was evaluated by the techniques of differential scanning calorimetry (DSC) and thermogravimetry (TGA). The morphology of the nanocomposites was studied with scanning electron microscopy (SEM), while the organophilic bentonite and nanocomposites were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).

Stability of dendriplexes formed by anti-HIV genetic material and poly(propylene imine) dendrimers in the presence of glucosaminoglycans.

PubMed

Szewczyk, Michal; Drzewinska, Joanna; Dzmitruk, Volha; Shcharbin, Dzmitry; Klajnert, Barbara; Appelhans, Dietmar; Bryszewska, Maria

2012-12-20

There are several barriers to the application of dendriplexes formed by poly(propylene imine) dendrimers and genetic material for gene therapy. One limitation is their interaction with extracellular matrix components such as glucosaminoglycans. These can displace the genetic material from the dendriplexes, affecting their transfection activity. In this study, we analyzed the interaction between dendriplexes and the four main glucosaminoglycans (heparin, heparan sulfate, chondroitin sulfate, and hyaluronic acid) by fluorescence polarization and gel electrophoresis. Dendriplexes were formed by combining three anti-HIV antisense oligodeoxynucleotides with three poly(propylene imine) dendrimers of the fourth generation: unmodified and partially modified with maltose and maltotriose (open shell glycodendrimers). The data showed that the effect of glucosaminoglycans on dendriplexes depends on the glucosaminoglycan type and the oligosaccharide serving as the surface group of the dendrimer. Heparin at physiological concentrations destroys dendriplexes formed by open shell glycodendrimers, but dendriplexes based on unmodified poly(propylene imine) dendrimers are stable in its presence. The other glucosaminoglycans at physiological concentrations cannot destroy dendriplexes formed by any of the dendrimers studied.

Comparison of biodegradation of poly(ethylene glycol)s and poly(propylene glycol)s.

PubMed

Zgoła-Grześkowiak, Agnieszka; Grześkowiak, Tomasz; Zembrzuska, Joanna; Łukaszewski, Zenon

2006-07-01

The biodegradation of poly(ethylene glycol)s (PEGs) and poly(propylene glycol)s (PPGs), both being major by-products of non-ionic surfactants biodegradation, was studied under the conditions of the River Water Die-Away Test. PEGs were isolated from a water matrix using solid-phase extraction with graphitized carbon black sorbent, then derivatized with phenyl isocyanate and determined by HPLC with UV detection. PPGs were isolated from a water matrix by liquid-liquid extraction with chloroform, then derivatized with naphthyl isocyanate and determined by HPLC with fluorescence detection. The primary biodegradation of both PEGs and PPGs reached approximately 99% during the test. The tests show different biodegradation pathways of PEG and PPG. During PEG biodegradation, their chains are shortened leading to the formation of ethylene glycol and diethylene glycol. During PPG biodegradation, no short-chained biodegradation products were found.

Polymer composites and porous materials prepared by thermally induced phase separation and polymer-metal hybrid methods

NASA Astrophysics Data System (ADS)

Yoon, Joonsung

The primary objective of this research is to investigate the morphological and mechanical properties of composite materials and porous materials prepared by thermally induced phase separation. High melting crystallizable diluents were mixed with polymers so that the phase separation would be induced by the solidification of the diluents upon cooling. Theoretical phase diagrams were calculated using Flory-Huggins solution thermodynamics which show good agreement with the experimental results. Porous materials were prepared by the extraction of the crystallized diluents after cooling the mixtures (hexamethylbenzene/polyethylene and pyrene/polyethylene). Anisotropic structures show strong dependence on the identity of the diluents and the composition of the mixtures. Anisotropic crystal growth of the diluents was studied in terms of thermodynamics and kinetics using DSC, optical microscopy and SEM. Microstructures of the porous materials were explained in terms of supercooling and dendritic solidification. Dual functionality of the crystallizable diluents for composite materials was evaluated using isotactic polypropylene (iPP) and compatible diluents that crystallize upon cooling. The selected diluents form homogeneous mixtures with iPP at high temperature and lower the viscosity (improved processability), which undergo phase separation upon cooling to form solid particles that function as a toughening agent at room temperature. Tensile properties and morphology of the composites showed that organic crystalline particles have the similar effect as rigid particles to increase toughness; de-wetting between the particle and iPP matrix occurs at the early stage of deformation, followed by unhindered plastic flow that consumes significant amount of fracture energy. The effect of the diluents, however, strongly depends on the identity of the diluents that interact with the iPP during solidification step, which was demonstrated by comparing tetrabromobisphenol-A and phthalic anhydride. A simple method to prepare composite surfaces that can change the wettability in response to the temperature change was proposed and evaluated. Composite surfaces prepared by nanoporous alumina templates filled with polymers showed surface morphology and wettability that depend on temperature. This effect is attributed to the significant difference in thermal conductivity and the thermal expansion coefficient between the alumina and the polymers. The reversibility in thermal response depends on the properties of the polymers.

Macrophage polarization in response to ECM coated polypropylene mesh

PubMed Central

Wolf, MT; Dearth, CL; Ranallo, CA; LoPresti, S; Carey, LE; Daly, KA; Brown, BN; Badylak, SF

2015-01-01

The host response to implanted biomaterials is a highly regulated process that influences device functionality and clinical outcome. Non-degradable biomaterials, such as knitted polypropylene mesh, frequently elicit a chronic foreign body reaction with resultant fibrosis. Previous studies have shown that an extracellular matrix (ECM) hydrogel coating of polypropylene mesh reduces the intensity of the foreign body reaction, though the mode of action is unknown. Macrophage participation plays a key role in the development of the foreign body reaction to biomaterials, and therefore the present study investigated macrophage polarization following mesh implantation. Spatiotemporal analysis of macrophage polarization was conducted in response to uncoated polypropylene mesh and mesh coated with hydrated and dry forms of ECM hydrogels derived from either dermis or urinary bladder. Pro-inflammatory M1 macrophages (CD86+/CD68+), alternatively activated M2 macrophages (CD206+/CD68+), and foreign body giant cells were quantified between 3-35 days. Uncoated polypropylene mesh elicited a dominant M1 response at the mesh fiber surface, which was decreased by each ECM coating type beginning at 7 days. The diminished M1 response was accompanied by a reduction in the number of foreign body giant cells at 14 and 35 days, though there was a minimal effect upon the number of M2 macrophages at any time. These results show that ECM coatings attenuate the M1 macrophage response and increase the M2/M1 ratio to polypropylene mesh in vivo. PMID:24856104

Microplastics in Sediment Cores from Asia and Africa as Indicators of Temporal Trends in Plastic Pollution.

PubMed

Matsuguma, Yukari; Takada, Hideshige; Kumata, Hidetoshi; Kanke, Hirohide; Sakurai, Shigeaki; Suzuki, Tokuma; Itoh, Maki; Okazaki, Yohei; Boonyatumanond, Ruchaya; Zakaria, Mohamad Pauzi; Weerts, Steven; Newman, Brent

2017-08-01

Microplastics (<5 mm) were extracted from sediment cores collected in Japan, Thailand, Malaysia, and South Africa by density separation after hydrogen peroxide treatment to remove biofilms were and identified using FTIR. Carbonyl and vinyl indices were used to avoid counting biopolymers as plastics. Microplastics composed of variety of polymers, including polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethyleneterphthalates (PET), polyethylene-polypropylene copolymer (PEP), and polyacrylates (PAK), were identified in the sediment. We measured microplastics between 315 µm and 5 mm, most of which were in the range 315 µm-1 mm. The abundance of microplastics in surface sediment varied from 100 pieces/kg-dry sediment in a core collected in the Gulf of Thailand to 1900 pieces/kg-dry sediment in a core collected in a canal in Tokyo Bay. A far higher stock of PE and PP composed microplastics in sediment compared with surface water samples collected in a canal in Tokyo Bay suggests that sediment is an important sink for microplastics. In dated sediment cores from Japan, microplastic pollution started in 1950s, and their abundance increased markedly toward the surface layer (i.e., 2000s). In all sediment cores from Japan, Thailand, Malaysia, and South Africa, the abundance of microplastics increased toward the surface, suggesting the global occurrence of and an increase in microplastic pollution over time.

Removal of phosphate using copper-loaded polymeric ligand exchanger prepared by radiation grafting of polypropylene/polyethylene (PP/PE) nonwoven fabric

NASA Astrophysics Data System (ADS)

Barsbay, Murat; Kavaklı, Pınar Akkaş; Güven, Olgun

2010-03-01

A novel polymeric ligand exchanger (PLE) was prepared for the removal of phosphate ions from water. 2,2'-dipyridylamine (DPA), a bidentate ligand forming compound with high coordination capacity with a variety of metal ions was bound to glycidyl methacrylate (GMA) grafted polypropylene/polyethylene (PP/PE) nonwoven fabric synthesized by radiation-induced grafting technique. DPA attachment on epoxy ring of GMA units was tested in different solvents, i.e. methanol, ethanol, dioxane and dimethylsulfoxide (DMSO). The highest amount of modification was achieved in dioxane. In order to prepare the corresponding PLE for the removal of phosphate, DPA-immobilized fabric was loaded with Cu(II) ions. Phosphate adsorption experiments were performed in batch mode at different pH (5-9) and phosphate concentrations. The fabric was found to be effective for the removal of phosphate ions. At every stage of preparation and use, the nonwoven fabric was characterized by thermal (i.e. DSC and TGA) and spectroscopic (FTIR) methods. Competitive adsorption experiments were also carried out using two solutions with different concentration levels at pH 7 to see the effect of competing ions. Phosphate adsorption was found to be effective and selective from solutions having trace amounts of competitive anions. It is expected that the novel PLE synthesized can be used for the removal of phosphate ions in low concentrations over a large range of pH.

Environmental analysis of plastic production processes: comparing petroleum-based polypropylene and polyethylene with biologically-based poly-beta-hydroxybutyric acid using life cycle analysis.

PubMed

Harding, K G; Dennis, J S; von Blottnitz, H; Harrison, S T L

2007-05-31

Polymers based on olefins have wide commercial applicability. However, they are made from non-renewable resources and are characterised by difficulty in disposal where recycle and re-use is not feasible. Poly-beta-hydroxybutyric acid (PHB) provides one example of a polymer made from renewable resources. Before motivating its widespread use, the advantages of a renewable polymer must be weighed against the environmental aspects of its production. Previous studies relating the environmental impacts of petroleum-based and bio-plastics have centred on the impact categories of global warming and fossil fuel depletion. Cradle-to-grave studies report equivalent or reduced global warming impacts, in comparison to equivalent polyolefin processes. This stems from a perceived CO(2) neutral status of the renewable resource. Indeed, no previous work has reported the results of a life cycle assessment (LCA) giving the environmental impacts in all major categories. This study investigates a cradle-to-gate LCA of PHB production taking into account net CO(2) generation and all major impact categories. It compares the findings with similar studies of polypropylene (PP) and polyethylene (PE). It is found that, in all of the life cycle categories, PHB is superior to PP. Energy requirements are slightly lower than previously observed and significantly lower than those for polyolefin production. PE impacts are lower than PHB values in acidification and eutrophication.

PP/EPDM-blends by dynamic vulcanization: Influence of increasing peroxide concentration on mechanical, morphological and rheological characteristics

NASA Astrophysics Data System (ADS)

Patermann, S.; Altstädt, V.

2014-05-01

Thermoplastic vulcanizates (TPVs) combine the elastic properties of thermoset cross-linked rubbers with the melt processability of thermoplastics. The most representative examples of this class are the TPVs based on polypropylene (PP) and ethylene-propylenediene terpolymer rubber (EPDM). The PP/EPDM blends were produced by dynamic vulcanization in a continuous extrusion process. The influence of different peroxide concentrations was studied with regard to cross-link density, compression set, tensile strength/elongation at break and morphology. With increasing peroxide concentration, the cross-link density increases, leading to a reduction of the compression set by 50 %. The cross-linked blends show smaller dispersed EPDM particles than the uncured one. With a peroxide concentration between 0.2 and 0.6 % a maximum in tensile strength and elongation at break was found and with increasing peroxide concentration, the complex viscosity of the TPVs decreases. Compared to batch processes, the results show nearly the same trends.

Retaining Oxidative Stability of Emulsified Foods by Novel Nonmigratory Polyphenol Coated Active Packaging.

PubMed

Roman, Maxine J; Decker, Eric A; Goddard, Julie M

2016-07-13

Oxidation causes lipid rancidity, discoloration, and nutrient degradation that decrease shelf life of packaged foods. Synthetic additives are effective oxidation inhibitors, but are undesirable to consumers who prefer "clean" label products. The aim of this study was to improve oxidative stability of emulsified foods by a novel nonmigratory polyphenol coated active packaging. Polyphenol coatings were applied to chitosan functionalized polypropylene (PP) by laccase assisted polymerization of catechol and catechin. Polyphenol coated PP exhibited both metal chelating (39.3 ± 2.5 nmol Fe(3+) cm(-2), pH 4.0) and radical scavenging (up to 52.9 ± 1.8 nmol Trolox eq cm(-2)) capacity, resulting in dual antioxidant functionality to inhibit lipid oxidation and lycopene degradation in emulsions. Nonmigratory polyphenol coated PP inhibited ferric iron promoted degradation better than soluble chelators, potentially by partitioning iron from the emulsion droplet interface. This work demonstrates that polyphenol coatings can be designed for advanced material chemistry solutions in active food packaging.

The consequences of physical post-treatments (microwave and electron-beam) on food/packaging interactions: A physicochemical and toxicological approach.

PubMed

Riquet, A M; Breysse, C; Dahbi, L; Loriot, C; Severin, I; Chagnon, M C

2016-05-15

The safety of microwave and electron-beam treatments has been demonstrated, in regards to the formation of reaction products that could endanger human health. An integrated approach was used combining the potential toxicity of all the substances likely to migrate to their chemical characterizations. This approach was applied to polypropylene (PP) films prepared with a selection of additives. Components were identified by liquid and gas chromatography using a mass selective detector system. Their potential toxicity was assessed using three in vitro short-term bioassays and their migrations were carried out using a standards-based approach. After the electron-beam treatment some additives decomposed and there was a significant increase in the polyolefin oligomeric saturated hydrocarbons concentration. PP prepared with Irgafos 168 led to a significantly strong cytotoxic effect and PP prepared with Irganox 1076 induced a dose-dependant estrogenic effect in vitro. Migration values were low and below the detection limit of the analytical method applied. Copyright © 2015 Elsevier Ltd. All rights reserved.

Desorption modeling of hydrophobic organic chemicals from plastic sheets using experimentally determined diffusion coefficients in plastics.

PubMed

Lee, Hwang; Byun, Da-Eun; Kim, Ju Min; Kwon, Jung-Hwan

2018-01-01

To evaluate rate of migration from plastic debris, desorption of model hydrophobic organic chemicals (HOCs) from polyethylene (PE)/polypropylene (PP) films to water was measured using PE/PP films homogeneously loaded with the HOCs. The HOCs fractions remaining in the PE/PP films were compared with those predicted using a model characterized by the mass transfer Biot number. The experimental data agreed with the model simulation, indicating that HOCs desorption from plastic particles can generally be described by the model. For hexachlorocyclohexanes with lower plastic-water partition coefficients, desorption was dominated by diffusion in the plastic film, whereas desorption of chlorinated benzenes with higher partition coefficients was determined by diffusion in the aqueous boundary layer. Evaluation of the fraction of HOCs remaining in plastic films with respect to film thickness and desorption time showed that the partition coefficient between plastic and water is the most important parameter influencing the desorption half-life. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reinforcement of dynamically vulcanized EPDM/PP elastomers using organoclay fillers

PubMed Central

Tsai, Yuhsin; Wu, Jyh-Horng; Wu, Yao-Tsu; Li, Chia-Hao; Leu, Ming-Tsong

2008-01-01

Dynamically vulcanized EPDM/PP (ethylene-propylene-diene/polypropylene) elastomers reinforced with various amounts of organoclay were prepared using octylphenol-formaldehyde resin and stannous chloride dehydrate as vulcanizing agents. The effects of organoclay on vulcanization characteristics, rheological behavior, morphology, thermal stability and thermomechanical properties were studied. Experimental results showed that organoclay affected neither the vulcanization process nor the degree of vulcanization chemically. X-ray analysis revealed that these organoclay-filled thermoplastic vulcanizates (TPVs) were intercalated. With respect to the mechanical properties, organoclay increased both the strength and degree of elongation of TPVs. The morphological observation of fractured surfaces suggested that organoclay acted as a nucleating agent in TPVs, improving their mechanical properties. However, adding organoclay reduced the thermal stability of TPVs by decomposing the swelling agents in the organoclay. PMID:27878033

Reinforcement of dynamically vulcanized EPDM/PP elastomers using organoclay fillers.

PubMed

Tsai, Yuhsin; Wu, Jyh-Horng; Wu, Yao-Tsu; Li, Chia-Hao; Leu, Ming-Tsong

2008-12-01

Dynamically vulcanized EPDM/PP (ethylene-propylene-diene/polypropylene) elastomers reinforced with various amounts of organoclay were prepared using octylphenol-formaldehyde resin and stannous chloride dehydrate as vulcanizing agents. The effects of organoclay on vulcanization characteristics, rheological behavior, morphology, thermal stability and thermomechanical properties were studied. Experimental results showed that organoclay affected neither the vulcanization process nor the degree of vulcanization chemically. X-ray analysis revealed that these organoclay-filled thermoplastic vulcanizates (TPVs) were intercalated. With respect to the mechanical properties, organoclay increased both the strength and degree of elongation of TPVs. The morphological observation of fractured surfaces suggested that organoclay acted as a nucleating agent in TPVs, improving their mechanical properties. However, adding organoclay reduced the thermal stability of TPVs by decomposing the swelling agents in the organoclay.

The performance and long-term stability of low-cost separators in single-chamber bottle-type microbial fuel cells.

PubMed

Kondaveeti, Sanath; Kakarla, Ramesh; Kim, Hong Suck; Kim, Byung-Goon; Min, Booki

2018-02-01

This study evaluates long-term stability of low-cost separators in single-chamber bottle-type microbial fuel cells with domestic wastewater. Low-cost separators tested in this study were nonwoven fabrics (NWF) of polypropylene (PP80, PP100), textile fabrics of polyphenylene sulfide (PPS), sulfonated polyphenylene sulfide (SPPS), and cellulose esters. NWF PP80 separator generated the highest power density of 280 mW/m 2 , which was higher than with ion-exchange membranes (cation exchange membrane; CEM = 271 mW/m 2 , cation exchange membrane; CMI = 196 mW/m 2 , Nafion = 260 mW/m 2 ). MFC operations with other size-selective separators such as SPPS, PPS, and cellulose esters exhibited power densities of 261, 231, and 250 mW/m 2 , respectively. During a 280-day operation, initial power density of PP80 (278 mW/m 2 ) was decreased to 257 mW/m 2 , but this decrease was smaller than with others (Nafion: 265-230 mW/m 2 ; PP100: 220-126 mW/m 2 ). The anode potential of around -430 mV did not change much with all separators in the long-term operation, but the initial cathode potential gradually decreased. Fouling analysis suggested that the presence of carbonaceous substance on Nafion and PP80 after 280 days of operation and Nafion was subject to be more biofouling.

Titanium conversion coatings on the aluminum foil AA 8021 used for lithium-ion battery package

NASA Astrophysics Data System (ADS)

Xia, Xu-Feng; Gu, Ying-Ying; Xu, Shi-Ai

2017-10-01

In this study, an environment-friendly titanium (Ti) conversion coating was successfully deposited on the aluminum foil AA 8021 in the solution containing hexafluorotitanic acid (H2TiF6), and its morphology, composition, growth process, hydrophilicity and corrosion resistance were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), X-ray photoelectric spectroscopy (XPS), contact-angle measurements (CAM) and salt spray exposure. The peeling strength between the Ti treated Al foil and the modified polypropylene (PP) film (PP grafted with maleic anhydride, PP-g-MAH) (Al/PP-g-MAH) was measured by T-peeling test. The results show that the Ti conversion coating is a multi-component coating composed primarily of metal oxides (TiO2 and Al2O3) and metal fluoride (AlF3). Ti treated Al foil shows better corrosion resistance than untreated and alkali-cleaned Al foils. The peeling strength of PP-g-MAH film with Ti treated Al foils is approximately 30 times higher than that with untreated Al foils. Thus, Ti treatment is a promising approach to improve the corrosion resistance and peeling strength of aluminum/polymer composite film (Al/P) used in the lithium-ion battery package.

UPLC-Q-TOF-MS analysis of non-volatile migrants from new active packaging materials.

PubMed

Aznar, M; Rodriguez-Lafuente, A; Alfaro, P; Nerin, C

2012-10-01

Ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (MS) is a useful tool in the analysis of non-volatile compounds, and the use of a quadrupole-time-of-flight (Q-TOF) mass analyzer allows a high sensitivity and accuracy when acquiring full fragment mode, providing a high assurance of correct identification of unknown compounds. In this work, UPLC-Q-TOF-MS technology has been applied to the analysis of non-volatile migrants from new active packaging materials. The materials tested were based on polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH), and poly(ethylene terephthalate) (PET). The active packaging materials studied were one PP film containing a natural antioxidant, and two PP/EVOH films, two PET/EVOH films and one coextruded PP/EVOH/PP film containing natural antimicrobials. The chemical structure of several compounds was unequivocally identified. The analysis revealed the migration of some of the active substances used in the manufacture of active packaging, such as caffeine (0.07 ± 0.01 μg/g), carvacrol (0.31 ± 0.03 μg/g) and citral (0.20 ± 0.01 μg/g). Unintentionally added substances were also found, such as citral reaction compounds, or citral impurities present in the raw materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alperowicz, N.

Turkish acrylic fiber maker Aksa (Yalova), part of the Akkok textile conglomerate, is studying construction of a world-scale polypropylene (PP) plant as part of its diversification plans. The company says it is engaged in discussions with three multinations in the PP business' on the possibility of a joint venture. One of the firms is understood to be Amoco. Aksa is looking at three possible locations for the 100,000 m.t.-150,000 m.t./year plant: Yalova, near Istanbul, where its existing plants are located; Zonguldak, on the Black Sea coast; and within one of the existing complexes or a new site belonging to state-ownedmore » Petkim. Aksa has not yet discussed that option with Petkim, which recently received approval to build a $2.5-billion petrochemical complex. The Aksa PP plant would cost about $100 million and would use propylene from world markets. The onstream date depends on Aksa's ability to link up with a foreign partner, but it hopes to complete the unit within three years. Turkey has only one PP plant, a 65,000-m.t./year Petkim unit at Aliaga. The domestic market is currently two to three times that amount and is growing. Petkim also plans a 200,000-m.t./year PP plant as part of its new complex.« less

Effective Dual Polysulfide Rejection by a Tannic Acid/FeIII Complex-Coated Separator in Lithium-Sulfur Batteries.

PubMed

Zhang, Hong; Lin, Chuner; Hu, Xuanhe; Zhu, Baoku; Yu, Dingshan

2018-04-18

The solubility behaviour of polysulfides in electrolyte solutions is a major bottleneck prior to the practical application of the lithium-sulfur battery. To address this issue, we fabricate a tannic acid/Fe III complex-coated polypropylene (PP) separator (TA/Fe III -PP separator) via a simple, fast, and green method. Benefiting from dual-confinement effects based on Lewis acid-base interactions between Fe III and polysulfides as well as the dipole-dipole interactions between rich phenol groups and polysulfides, the migration of polysulfides is effectively suppressed. Meanwhile, the porous structure of the PP separator is not destroyed by an additional coating layer. Thus, the TA/Fe III -PP separator can retain rapid lithium ion transport, eventually leading to a significant improvement in both the discharge capacity and rate performance of the corresponding lithium-sulfur cells. The cell with the TA/Fe III -PP separator presents a low capacity fade of 0.06% per cycle over 1000 cycles at 2.0 C, along with a high Coulombic efficiency of >97% over 300 cycles at 0.5 C. With respect to the one with the bare PP separator, the cell with the TA/Fe III -PP separator exhibits a 1.7-fold increase in the discharge capacity at 3.0 C. The proposed simple and economical approach shows great potential in constructing advanced separators to retard the shuttle effect of polysulfides for lithium-sulfur batteries.

Controlling lipid oxidation via a biomimetic iron chelating active packaging material.

PubMed

Tian, Fang; Decker, Eric A; Goddard, Julie M

2013-12-18

Previously, a siderophore-mimetic metal chelating active packaging film was developed by grafting poly(hydroxamic acid) (PHA) from the surface of polypropylene (PP) films. The objective of the current work was to demonstrate the potential applicability of this PP-g-PHA film to control iron-promoted lipid oxidation in food emulsions. The iron chelating activity of this film was investigated, and the surface chemistry and color intensity of films were also analyzed after iron chelation. In comparison to the iron chelating activity in the free Fe(3+) solution, the PP-g-PHA film retained approximately 50 and 30% of its activity in nitrilotriacetic acid (NTA)/Fe(3+) and citric acid/Fe(3+) solutions, respectively (pH 5.0), indicating a strong chelating strength for iron. The ability of PP-g-PHA films to control lipid oxidation was demonstrated in a model emulsion system (pH 3.0). PP-g-PHA films performed even better than ethylenediaminetetraacetic acid (EDTA) in preventing the formation of volatile oxidation products. The particle size and ζ potential results of emulsions indicated that PP-g-PHA films had no adverse effects on the stability of the emulsion system. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis suggested a non-migratory nature of the PP-g-PHA film surface. These results suggest that such biomimetic, non-migratory metal chelating active packaging films have commercial potential in protecting foods against iron-promoted lipid oxidation.

Matrix Metalloproteinase Expression in the Rat Myometrium During Pregnancy, Term Labor, and Postpartum1

PubMed Central

Nguyen, Tina Tu-Thu Ngoc; Shynlova, Oksana; Lye, Stephen J.

2016-01-01

Pregnancy, spontaneous term labor (TL), and postpartum (PP) involution are associated with changes in the cellular and extracellular matrix composition of the uterus. Both the uterine smooth muscle (myometrium) and the infiltrating peripheral blood leukocytes involved in the activation of labor secrete extracellular matrix-degrading enzymes (matrix metalloproteinases, MMPs) that can modulate cellular behavior and barrier function. MMP expression is induced by mechanical stretch in several tissues. We hypothesized that the expression and activity of myometrial MMPs and their tissue inhibitors (TIMPs) are modulated in preparation for TL and PP involution and are regulated by mechanical stretch of uterine walls imposed by the growing fetus. Myometrial tissues were collected from bilaterally and unilaterally pregnant rats across gestation, TL, and PP. Total RNA and proteins were subjected to real-time PCR and immunoblotting, respectively, and tissue localization and activity was examined by immunohistochemistry and in situ zymography. We found that Mmp7, Mmp11, and Mmp12 mRNA levels were upregulated during TL and PP, while Mmp2, Mmp3, Mmp8, Mmp9, Mmp10, and Mmp13 mRNAs were only upregulated during PP. Timp1–Timp4 were stably expressed throughout gestation with some fluctuations PP. Active MMP2 was induced in the empty uterine horn during gestation and in the gravid PP uterus, suggesting negative regulation by biological mechanical stretch. We conclude that specific subsets of uterine MMPs are differentially regulated in the rat myometrium in preparation for two major events: TL and PP uterine involution. PMID:27251092

Dispersion of cellulose nanofibers in biopolymer based nanocomposites

NASA Astrophysics Data System (ADS)

Wang, Bei

The focus of this work was to understand the fundamental dispersion mechanism of cellulose based nanofibers in bionanocomposites. The cellulose nanofibers were extracted from soybean pod and hemp fibers by chemo-mechanical treatments. These are bundles of cellulose nanofibers with a diameter ranging between 50 to 100 nm and lengths of thousands of nanometers which results in very high aspect ratio. In combination with a suitable matrix polymer, cellulose nanofiber networks show considerable potential as an effective reinforcement for high quality specialty applications of bio-based nanocomposites. Cellulose fibrils have a high density of --OH groups on the surface, which have a tendency to form hydrogen bonds with adjacent fibrils, reducing interaction with the surrounding matrix. The use of nanofibers has been mostly restricted to water soluble polymers. This thesis is focused on synthesizing the nanocomposite using a solid phase matrix polypropylene (PP) or polyethylene (PE) by hot compression and poly (vinyl alcohol) (PVA) in an aqueous phase by film casting. The mechanical properties of nanofiber reinforced PVA film demonstrated a 4-5 fold increase in tensile strength, as compared to the untreated fiber-blend-PVA film. It is necessary to reduce the entanglement of the fibrils and improve their dispersion in the matrix by surface modification of fibers without deteriorating their reinforcing capability. Inverse gas chromatography (IGC) was used to explore how various surface treatments would change the dispersion component of surface energy and acid-base character of cellulose nanofibers and the effect of the incorporation of these modified nanofibers into a biopolymer matrix on the properties of their nano-composites. Poly (lactic acid) (PLA) and polyhydroxybutyrate (PHB) based nanocomposites using cellulose nanofibers were prepared by extrusion, injection molding and hot compression. The IGC results indicated that styrene maleic anhydride coated and ethylene-acrylic acid coated fibers improved their potential to interact with both acidic and basic resins. From transmission electron micrograph, it was shown that the nanofibers were partially dispersed in the polymer matrix. The mechanical properties of the nanocomposites were lower than those predicted by theoretical calculations for both nanofiber reinforced biopolymers.

Property Relationship in Organosilanes and Nanotubes Filled Polypropylene Hybrid Composites

PubMed Central

Monsiváis-Barrón, Alejandra J.; Bonilla-Rios, Jaime; Sánchez-Fernández, Antonio

2014-01-01

Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3 wt%. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, four different nanotubular fillers were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified halloysite, carbon nanotubes and functionalized halloysite and carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA and DSC measurements thermal behavior remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples with a major impact for materials containing silanol groups synthetized in formic acid. Rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanol groups and halloysite when compared to neat polypropylene. Finally, the oxygen transmission rate increased for all samples showing high barrier properties only for samples containing natural and functionalized halloysite nanotubes. PMID:28788233

Property Relationship in Organosilanes and Nanotubes Filled Polypropylene Hybrid Composites.

PubMed

Monsiváis-Barrón, Alejandra J; Bonilla-Rios, Jaime; Sánchez-Fernández, Antonio

2014-10-20

Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3 wt%. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, four different nanotubular fillers were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified halloysite, carbon nanotubes and functionalized halloysite and carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA and DSC measurements thermal behavior remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples with a major impact for materials containing silanol groups synthetized in formic acid. Rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanol groups and halloysite when compared to neat polypropylene. Finally, the oxygen transmission rate increased for all samples showing high barrier properties only for samples containing natural and functionalized halloysite nanotubes.

Antifriction basalt-plastics based on polypropylene

NASA Astrophysics Data System (ADS)

Bashtannik, P. I.; Ovcharenko, V. G.

1997-05-01

A study is made of the dependence of the mechanical and friction-engineering properties of polypropylene reinforced with basalt fibers on the viscosity of the polymer matrix. It is established that the main factors that determine the mechanical properties of the plastics are the quality of impregnation of the fibers by the binder and the residual length of the reinforcing filler in the composite after extrusion and injection molding. The material that was developed has a low friction coefficient and low rate of wear within a relatively brood range of friction conditions. The basalt-plastics can be used in the rubbing parts of machines and mechanisms subjected to dry friction.

Long-term field measurement of sorption of organic contaminants to five types of plastic pellets: implications for plastic marine debris.

PubMed

Rochman, Chelsea M; Hoh, Eunha; Hentschel, Brian T; Kaye, Shawn

2013-02-05

Concerns regarding marine plastic pollution and its affinity for chemical pollutants led us to quantify relationships between different types of mass-produced plastic and organic contaminants in an urban bay. At five locations in San Diego Bay, CA, we measured sorption of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) throughout a 12-month period to the five most common types of mass-produced plastic: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). During this long-term field experiment, sorption rates and concentrations of PCBs and PAHs varied significantly among plastic types and among locations. Our data suggest that for PAHs and PCBs, PET and PVC reach equilibrium in the marine environment much faster than HDPE, LDPE, and PP. Most importantly, concentrations of PAHs and PCBs sorbed to HDPE, LDPE, and PP were consistently much greater than concentrations sorbed to PET and PVC. These data imply that products made from HDPE, LDPE, and PP pose a greater risk than products made from PET and PVC of concentrating these hazardous chemicals onto fragmented plastic debris ingested by marine animals.

Material, process, and product design of thermoplastic composite materials

NASA Astrophysics Data System (ADS)

Dai, Heming

Thermoplastic composites made of polypropylene (PP) and E-glass fibers were investigated experimentally as well as theoretically for two new classes of product designs. The first application was for reinforcement of wood. Commingled PP/glass yarn was consolidated and bonded on wood panel using a tie layer. The processing parameters, including temperature, pressure, heating time, cooling time, bonding strength, and bending strength were tested experimentally and evaluated analytically. The thermoplastic adhesive interface was investigated with environmental scanning electron microscopy. The wood/composite structural design was optimized and evaluated using a Graphic Method. In the second application, we evaluated use of thermoplastic composites for explosion containment in an arrester. PP/glass yarn was fabricated in a sleeve form and wrapped around the arrester. After consolidation, the flexible composite sleeve forms a solid composite shell. The composite shell acts as a protection layer in a surge test to contain the fragments of the arrester. The manufacturing process for forming the composite shell was designed. Woven, knitted, and braided textile composite shells made of commingled PP/glass yarn were tested and evaluated. Mechanical performance of the woven, knitted, and braided composite shells was examined analytically. The theoretical predictions were used to verify the experimental results.

Preparation and characterization of thick-film Ni/MH battery.

PubMed

Do, Jing-Shan; Yu, Sen-Hao; Cheng, Suh-Fen

2004-07-30

Using the porous polypropylene (PP) films sputtered with gold and the Ni as current collectors, the electroactive materials (Ni(OH)2 and metal hydride (MH)) of positive and negative electrodes were prepared on the current collector using thick-film technology. Two types of cell configurations were prepared and the characteristics of these batteries were compared. The cycle number for the formation of batteries based on the porous PP film was found to be 2, which was significantly less than that of batteries based on the ceramic substrates. Using the porous PP film as substrate, the number of cycles for the formation of battery increased from 2 to 5 with the increase of the charge/discharge rate from 0.1C/0.025C to 2.0C/0.5C. The silver oxides dendrites formed by the oxidation of silver paste used to adhere the current collectors and the conducting wires in the charge/discharge process caused a short contact between the positive and negative electrodes, which then caused the battery failure. The cycle life of the battery based on the porous PP film was found to be greater than 400 when the charge/discharge rate was 2.0C/0.5C.

Air cathode structure manufacture

DOEpatents

Momyer, William R.; Littauer, Ernest L.

1985-01-01

An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

A Comprehensive Study of the Polypropylene Fiber Reinforced Fly Ash Based Geopolymer

PubMed Central

Ranjbar, Navid; Mehrali, Mehdi; Behnia, Arash; Javadi Pordsari, Alireza; Mehrali, Mohammad; Alengaram, U. Johnson; Jumaat, Mohd Zamin

2016-01-01

As a cementitious material, geopolymers show a high quasi-brittle behavior and a relatively low fracture energy. To overcome such a weakness, incorporation of fibers to a brittle matrix is a well-known technique to enhance the flexural properties. This study comprehensively evaluates the short and long term impacts of different volume percentages of polypropylene fiber (PPF) reinforcement on fly ash based geopolymer composites. Different characteristics of the composite were compared at fresh state by flow measurement and hardened state by variation of shrinkage over time to assess the response of composites under flexural and compressive load conditions. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that incorporation of PPF up to 3 wt % into the geopolymer paste reduces the shrinkage and enhances the energy absorption of the composites. While, it might reduce the ultimate flexural and compressive strength of the material depending on fiber content. PMID:26807825

A Comprehensive Study of the Polypropylene Fiber Reinforced Fly Ash Based Geopolymer.

PubMed

Ranjbar, Navid; Mehrali, Mehdi; Behnia, Arash; Javadi Pordsari, Alireza; Mehrali, Mohammad; Alengaram, U Johnson; Jumaat, Mohd Zamin

2016-01-01

As a cementitious material, geopolymers show a high quasi-brittle behavior and a relatively low fracture energy. To overcome such a weakness, incorporation of fibers to a brittle matrix is a well-known technique to enhance the flexural properties. This study comprehensively evaluates the short and long term impacts of different volume percentages of polypropylene fiber (PPF) reinforcement on fly ash based geopolymer composites. Different characteristics of the composite were compared at fresh state by flow measurement and hardened state by variation of shrinkage over time to assess the response of composites under flexural and compressive load conditions. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that incorporation of PPF up to 3 wt % into the geopolymer paste reduces the shrinkage and enhances the energy absorption of the composites. While, it might reduce the ultimate flexural and compressive strength of the material depending on fiber content.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Z Xu; C Chen; Y Wang

Combined effects of graphene nanosheets (GNSs) and shear flow on the crystallization behavior of isotactic polypropylene (iPP) were investigated by in-situ synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. For crystallization under quiescent condition (at 145 C), the half-crystallization time (t{sub 1/2}) of nanocomposites containing 0.05 and 0.1 wt % GNSs was reduced to at least 50% compared to that of neat iPP, indicating the high nucleation ability of GNSs. The crystallization rate of iPP was directly proportional to the GNS content. Under a relatively weak shear flow (at a rate of 20 s{sup -1} for 5more » s duration) and a low degree of supercooling, the neat iPP exhibited an isotropic structure due to the relaxation of row nuclei. However, visible antisotropic crystals appeared in sheared iPP/GNSs nanocomposites, indicating that GNSs induced a network structure hindering the mobility of iPP chains and allowing the survival of oriented row nuclei for a long period of time. The presence of GNSs clearly enhanced the effects of shear-induced nucleation as well as orientation of iPP crystals. Two kinds of nucleating origins coexisted in the sheared nanocomposite melt: heterogeneous nucleating sites initiated by GNSs and homogeneous nucleating sites (row nuclei) induced by shear. The difference of t{sub 1/2} of nanocomposites with and without shear was significantly larger than that of neat iPP. The presence of GNSs and shear flow exhibited a synergistic interaction on promoting crystallization kinetics of iPP, although the effect of GNS concentration was not apparent. From WAXD results of isothermal and nonisothermal crystallization of sheared iPP, it was found that the appearance of {beta}-crystals depended on the preservation of row nuclei, where the {alpha}-crystals were predominant in the iPP/GNSs nanocomposites, indicating that GNSs could directly induce {alpha}-crystals of iPP.« less

Dependence of Mechanical and Thermal Properties of Thermoplastic Composites on Electron Beam Irradiation

NASA Astrophysics Data System (ADS)

Kim, Sok Won; Park, K.; Lee, S. H.; Kang, J. S.; Kang, K. H.

2007-06-01

Since the restrictions for environmental protection being strengthened, thermoplastics reinforced with natural fibers (NF’s), such as jute, kenaf, flax, etc. have appeared as alternatives to chemical plastics for automobile interior materials. In this study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composed of 50% polypropylene (PP) and 50% natural fiber (NF) irradiated by an electron beam (energy: 0.5 MeV, dose: 0 20 kGy) were measured. The length and thickness of PP and NF are 80 ± 10 mm and 40 120 μm, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum, when the dose of the electron beam was 10 kGy. However, the effect of the dose on the deformation was not clear.

Sorption of 3,3',4,4'-tetrachlorobiphenyl by microplastics: A case study of polypropylene.

PubMed

Zhan, Zhiwei; Wang, Jundong; Peng, Jinping; Xie, Qilai; Huang, Ying; Gao, Yifan

2016-09-15

Though plastics show good chemical inertness, they could sorb polychlorinated biphenyls (PCBs) and other toxic pollutants from the surrounding environment. Thus, ingestion of microplastics by marine organisms potentially enhances the transport and bioavailability of toxic chemicals. However, there is lack of studies on the sorption capacity, mechanism and factors affecting the sorption behavior. Here, sorption of PCBs by microplastics in the simulated seawater was studied using the batch oscillation equilibration technique, in which polypropylene (PP) and 3,3',4,4'-tetrachlorobiphenyl (PCB77) acted as model plastic and PCB, respectively. Factors including particle size, temperature and solution environment were investigated. Results showed that, equilibrium sorption time is about 8h and sorption capacity increase with decreasing particle size and temperature. Different sorption capacity in three solution environments was observed. Equilibrium data in three solution environments fitted very well to the Langmuir sorption model, indicating chemical sorption is the predominant mechanism. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development and Mechanical Behavior of FML/Aluminium Foam Sandwiches

NASA Astrophysics Data System (ADS)

Baştürk, S. B.; Tanoğlu, M.

2013-10-01

In this study, the Fiber-Metal Laminates (FMLs) containing glass fiber reinforced polypropylene (GFPP) and aluminum (Al) sheet were consolidated with Al foam cores for preparing the sandwich panels. The aim of this article is the comparison of the flexural properties of FML/Al foam sandwich panels bonded with various surface modification approaches (silane treatment and combination of silane treatment with polypropylene (PP) based film addition). The FML/foam sandwich systems were fabricated by laminating the components in a mould at 200 °C under 1.5 MPa pressure. The energy absorbtion capacities and flexural mechanical properties of the prepared sandwich systems were evaluated by mechanical tests. Experiments were performed on samples of varying foam thicknesses (8, 20 and 30 mm). The bonding among the sandwich components were achieved by various surface modification techniques. The Al sheet/Al foam sandwiches were also consolidated by bonding the components with an epoxy adhesive to reveal the effect of GFPP on the flexural performance of the sandwich structures.

Surface structuring in polypropylene using Ar+ beam sputtering: Pattern transition from ripples to dot nanostructures

NASA Astrophysics Data System (ADS)

Goyal, Meetika; Aggarwal, Sanjeev; Sharma, Annu; Ojha, Sunil

2018-05-01

Temporal variations in nano-scale surface morphology generated on Polypropylene (PP) substrates utilizing 40 keV oblique argon ion beam have been presented. Due to controlled variation of crucial beam parameters i.e. ion incidence angle and erosion time, formation of ripple patterns and further its transition into dot nanostructures have been realized. Experimental investigations have been supported by evaluation of Bradley and Harper (B-H) coefficients estimated using SRIM (The Stopping and Range of Ions in Matter) simulations. Roughness of pristine target surfaces has been accredited to be a crucial factor behind the early time evolution of nano-scale patterns over the polymeric surface. Study of Power spectral density (PSD) spectra reveals that smoothing mechanism switch from ballistic drift to ion enhanced surface diffusion (ESD) which can be the most probable cause for such morphological transition under given experimental conditions. Compositional analysis and depth profiling of argon ion irradiated specimens using Rutherford Backscattering Spectroscopy (RBS) has also been correlated with the AFM findings.

Topological and thermal properties of polypropylene composites based on oil palm biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhat, A. H., E-mail: aamir.bhat@petronas.com.my, E-mail: anie-yal88@yahoo.com; Dasan, Y. K., E-mail: aamir.bhat@petronas.com.my, E-mail: anie-yal88@yahoo.com

Roughness on pristine and polymer composite surfaces is of enormous practical importance for polymer applications. This study deals with the use of varying quantity of oil palm ash as a nanofiller in a polypropylene based matrix. The oil palm ash sample was preprocessed to break the particles into small diameter by using ultra sonication before using microfluidizer for further deduction in size and homogenization. The oil palm ash was made to undergo many passes through the microfluidizer for fine distribution of particles. Polypropylene based composites containing different loading percentage oil palm ash was granulated by twin screw extruder and thenmore » injection molded. The surface morphology of the OPA passed through microfluidizer was analyzed by Tapping Mode - Atomic Force Microscopy (TMAFM). Thermal analysis results showed an increase in the activation energy values. The thermal stability of the composite samples showed improvement as compared to the virgin polymer as corroborated by the on-set degradation temperatures and the temperatures at which 50% degradation occurred.« less

Physico-chemical stability of eribulin mesylate containing concentrate and ready-to-administer solutions.

PubMed

Spindeldreier, Kirsten; Thiesen, Judith; Lipp, Hans-Peter; Krämer, Irene

2014-06-01

The aim of this study was to determine the stability of commercially available eribulin mesylate containing injection solution as well as diluted ready-to-administer solutions stored under refrigeration or at room temperature. Stability was studied by a novel developed stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) assay with ultraviolet detection (detection wavelength 200 nm). Triplicate test solutions of eribulin mesylate containing injection concentrate (0.5 mg/mL) and with 0.9% sodium chloride solution diluted ready-to-administer preparations (0.205 mg/mL eribulin mesylate in polypropylene (PP) syringes, 0.020 mg/mL eribulin mesylate in polypropylene/polyethylene (PE) bags) were stored protected from light either at room temperature (25) or under refrigeration (2-8). Samples were withdrawn on day 0 (initial), 1, 3, 5, 7, 14, 21 and 28 of storage and assayed. Physical stability was determined by measuring the pH value once a week and checking for visible precipitations or colour changes. The stability tests revealed that concentrations of eribulin mesylate remained unchanged over a period of 28 days irrespective of concentration, container material or storage temperature. Neither colour changes nor visible particles have been observed. The pH value varied slightly over time but remained in the stability favourable range of 5-9. Eribulin mesylate injection (0.5 mg/mL) is physico-chemically stable over a period of 28 days after first puncture of the vial. After dilution with 0.9% NaCl vehicle solution, ready-to-administer eribulin mesylate injection solutions (0.205 mg/mL in PP syringe) and infusion solutions (0.02 mg/mL in prefilled PP/PE bags) are physico-chemically stable for a period of at least four weeks either refrigerated or stored at room temperature. For microbiological reasons storage under refrigeration is recommended.

Cysteine-grafted nonwoven geotextile: a new and efficient material for heavy metals sorption--Part B.

PubMed

Vandenbossche, M; Vezin, H; Touati, N; Jimenez, M; Casetta, M; Traisnel, M

2014-10-01

The development of a new material designed to trap heavy metals from sediments or wastewater, based on a polypropylene non-woven covalently grafted with cysteine, has been reported in a previous paper (Part A). The non-woven was first functionalized with acrylic acid (AA) which is used as spacer, and then cysteine was immobilized on the substrate through covalent coupling in order to obtain the so-called PP-g-AA-cysteine. Some preliminary heavy metals adsorption tests gave interesting results: at 20 °C for 24 h and in a 1000 mg/L heavy metals solution, PP-g-AA-cysteine adsorbs 95 mg Cu/g PP (CuSO4 solution), 104 mg Cu/g PP (Cu(NO3)2 solution), 135 mg Pb/g PP (Pb(NO3)2 solution) and 21 mg Cr/g PP (Cr(NO3)3 solution). In this second part of the work, heavy metals sorption tests were carried out with Cu (II), Pb (II), and Cr (III) separately, in order to determine the sorption capacity of this new sorbent as a function of (i) the heavy metals concentration in the solution, (ii) the contact time with the solution, (iii) the pH and (iv) the ionic strength of the solution containing heavy metals. Moreover, the sorption capacity of PP-g-AA-Cysteine was studied using a polluted solution consisting of a mixture of these different heavy metals. An Electron Paramagnetic Resonance study was finally carried out in order to determine the coordination geometry in the environment of the copper trapped by the PP-g-AA-cysteine. Copyright © 2014 Elsevier Ltd. All rights reserved.

Figure of merit comparison of PP-based electret and PVDF-based piezoelectric polymer energy harvesters

NASA Astrophysics Data System (ADS)

Mrlík, M.; Leadenham, S.; AlMaadeed, M. A.; Erturk, A.

2016-04-01

The harvesting of mechanical strain and kinetic energy has received great attention over the past two decades in order to power wireless electronic components such as those used in passive and active monitoring applications. Piezoelectric ceramics, such as PZT (lead zirconate titanate), constitute the most commonly used electromechanical interface in vibration energy harvesters. However, there are applications in which piezoelectric ceramics cannot be used due to their low allowable curvature and brittle nature. Soft polymer PVDF (polyvinylidene fluoride) is arguably the most popular non-ceramic soft piezoelectric energy harvester material for such scenarios. Another type of polymer that has received less attention is PP (polypropylene) for electret-based energy harvesting using the thickness mode (33- mode). This work presents figure of merit comparison of PP versus PVDF for off-resonant energy harvesting in thickness mode operation, revealing substantial advantage of PP over PVDF. For thickness mode energy harvesting scenarios (e.g. dynamic compression) at reasonable ambient vibration frequencies, the figure of merit for the maximum power output is proportional to the square of the effective piezoelectric strain constant divided by the effective permittivity constant. Under optimal conditions and for the same volume, it is shown that PP can generate more than two orders of magnitude larger electrical power as compared to PVDF due to the larger effective piezoelectric strain constant and lower permittivity of the former.

Developing a tissue-engineered neural-electrical relay using encapsulated neuronal constructs on conducting polymer fibers.

PubMed

Cullen, D Kacy; R Patel, Ankur; Doorish, John F; Smith, Douglas H; Pfister, Bryan J

2008-12-01

Neural-electrical interface platforms are being developed to extracellularly monitor neuronal population activity. Polyaniline-based electrically conducting polymer fibers are attractive substrates for sustained functional interfaces with neurons due to their flexibility, tailored geometry and controlled electro-conductive properties. In this study, we addressed the neurobiological considerations of utilizing small diameter (<400 microm) fibers consisting of a blend of electrically conductive polyaniline and polypropylene (PA-PP) as the backbone of encapsulated tissue-engineered neural-electrical relays. We devised new approaches to promote survival, adhesion and neurite outgrowth of primary dorsal root ganglion neurons on PA-PP fibers. We attained a greater than ten-fold increase in the density of viable neurons on fiber surfaces to approximately 700 neurons mm(-2) by manipulating surrounding surface charges to bias settling neuronal suspensions toward fibers coated with cell-adhesive ligands. This stark increase in neuronal density resulted in robust neuritic extension and network formation directly along the fibers. Additionally, we encapsulated these neuronal networks on PA-PP fibers using agarose to form a protective barrier while potentially facilitating network stability. Following encapsulation, the neuronal networks maintained integrity, high viability (>85%) and intimate adhesion to PA-PP fibers. These efforts accomplished key prerequisites for the establishment of functional electrical interfaces with neuronal populations using small diameter PA-PP fibers-specifically, improved neurocompatibility, high-density neuronal adhesion and neuritic network development directly on fiber surfaces.

Real-space evidence of the equilibrium ordered bicontinuous double diamond structure of a diblock copolymer.

PubMed

Chu, C Y; Jiang, X; Jinnai, H; Pei, R Y; Lin, W F; Tsai, J C; Chen, H L

2015-03-14

The ordered bicontinuous double diamond (OBDD) structure has long been believed to be an unstable ordered network nanostructure, which is relative to the ordered bicontinuous double gyroid (OBDG) structure for diblock copolymers. Using electron tomography, we present the first real-space observation of the thermodynamically stable OBDD structure in a diblock copolymer composed of a stereoregular block, syndiotactic polypropylene-block-polystyrene (sPP-b-PS), in which the sPP tetrapods are interconnected via a bicontinuous network with Pn3̄m symmetry. The OBDD structure underwent a thermally reversible order-order transition (OOT) to OBDG upon heating, and the transition was accompanied with a slight reduction of domain spacing, as demonstrated both experimentally and theoretically. The thermodynamic stability of the OBDD structure was attributed to the ability of the configurationally regular sPP block to form helical segments, even above its melting point, as the reduction of internal energy associated with the helix formation may effectively compensate the greater packing frustration in OBDD relative to that in the tripods of OBDG.

DAMAGE MODELING OF INJECTION-MOLDED SHORT- AND LONG-FIBER THERMOPLASTICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

2009-10-30

This article applies the recent anisotropic rotary diffusion – reduced strain closure (ARD-RSC) model for predicting fiber orientation and a new damage model for injection-molded long-fiber thermoplastics (LFTs) to analyze progressive damage leading to total failure of injection-molded long-glass-fiber/polypropylene (PP) specimens. The ARD-RSC model was implemented in a research version of the Autodesk Moldflow Plastics Insight (MPI) processing code, and it has been used to simulate injection-molding of a long-glass-fiber/PP plaque. The damage model combines micromechanical modeling with a continuum damage mechanics description to predict the nonlinear behavior due to plasticity coupled with damage in LFTs. This model has beenmore » implemented in the ABAQUS finite element code via user-subroutines and has been used in the damage analyses of tensile specimens removed from the injection-molded long-glass-fiber/PP plaques. Experimental characterization and mechanical testing were performed to provide input data to support and validate both process modeling and damage analyses. The predictions are in agreement with the experimental results.« less

Preparation of thermo-responsive membranes. II.

PubMed

Nozawa, I; Suzuki, Y; Sato, S; Sugibayashi, K; Morimoto, Y

1991-05-01

Two types of liquid crystal (LC)-immobilized membranes were prepared by a soaking method and sandwich method to control the permeation of indomethacin, as a model drug, in response to local and systemic fever. Monooxyethylene trimethylolpropane tristearate (MTTS) was used as a model LC because it has a gel-liquid crystal phase transition temperature near the body temperature, 39-40 degrees C in phosphate buffered saline (pH 7.4). Two porous polypropylene (PP) membranes were soaked into 20% MTTS chloroform solution in the soaking method, and two PP membranes were poured with the melted MTTS and pressed in the sandwich method. Thermo-response efficacy of the soaked membrane was dependent upon the content of MTTS in MTTS membrane, and the MTTS content above the void volume of PP membrane (38%) was needed for high efficacy. On the other hand, the sandwich membrane exhibited higher thermo-response efficacy than the soaked membrane, because more LC was embedded in the pores of sandwich membrane than that of the soaked membrane. The sandwich membrane permeation of indomethacin was sharply controlled by temperature changes between 32 and 38 degrees C.

Estimation of polymer-surface interfacial interaction strength by a contact AFM technique.

PubMed

Dvir, H; Jopp, J; Gottlieb, M

2006-12-01

Atomic force microscopy (AFM) measurements were employed to assess polymer-surface interfacial interaction strength. The main feature of the measurement is the use of contact-mode AFM as a tool to scratch off the polymer monolayer adsorbed on the solid surface. Tapping-mode AFM was used to determine the depth of the scraped recess. Independent determination of the layer thickness obtained from optical phase interference microscopy (OPIM) confirmed the depth of the AFM scratch. The force required for the complete removal of the polymer layer with no apparent damage to the substrate surface was determined. Polypropylene (PP), low-density polyethylene (PE), and PP-grafted-maleic anhydride (PP-g-ma) were scraped off silane-treated glass slabs, and the strength of surface interaction of the polymer layer was determined. In all cases it was determined that the magnitude of surface interaction force is of the order of van der Waals (VDW) interactions. The interaction strength is influenced either by polymer ability to wet the surface (hydrophobic or hydrophilic interactions) or by hydrogen bonding between the polymer and the surface treatment.

An effective parameter optimization technique for vibration flow field characterization of PP melts via LS-SVM combined with SALS in an electromagnetism dynamic extruder

NASA Astrophysics Data System (ADS)

Xian, Guangming

2018-03-01

A method for predicting the optimal vibration field parameters by least square support vector machine (LS-SVM) is presented in this paper. One convenient and commonly used technique for characterizing the the vibration flow field of polymer melts films is small angle light scattering (SALS) in a visualized slit die of the electromagnetism dynamic extruder. The optimal value of vibration vibration frequency, vibration amplitude, and the maximum light intensity projection area can be obtained by using LS-SVM for prediction. For illustrating this method and show its validity, the flowing material is used with polypropylene (PP) and fifteen samples are tested at the rotation speed of screw at 36rpm. This paper first describes the apparatus of SALS to perform the experiments, then gives the theoretical basis of this new method, and detail the experimental results for parameter prediction of vibration flow field. It is demonstrated that it is possible to use the method of SALS and obtain detailed information on optimal parameter of vibration flow field of PP melts by LS-SVM.

The effect of polymer aging on the uptake of fuel aromatics and ethers by microplastics.

PubMed

Müller, Axel; Becker, Roland; Dorgerloh, Ute; Simon, Franz-Georg; Braun, Ulrike

2018-05-14

Microplastics are increasingly entering marine, limnic and terrestrial ecosystems worldwide, where they sorb hydrophobic organic contaminants. Here, the sorption behavior of the fuel-related water contaminants benzene, toluene, ethyl benzene and xylene (BTEX) and four tertiary butyl ethers to virgin and via UV radiation aged polypropylene (PP) and polystyrene (PS) pellets was investigated. Changes in material properties due to aging were recorded using appropriate polymer characterization methods, such as differential scanning calorimetry, Fourier transform infrared spectroscopy, gel permeation chromatography, X-ray photoelectron spectroscopy, and microscopy. Pellets were exposed to water containing BTEX and the ethers at 130-190 μg L -1 for up to two weeks. Aqueous sorbate concentrations were determined by headspace gas chromatography. Sorption to the polymers was correlated with the sorbate's K ow and was significant for BTEX and marginal for the ethers. Due to substantially lower glass transition temperatures, PP showed higher sorption than PS. Aging had no effect on the sorption behavior of PP. PS sorbed less BTEX after aging due to an oxidized surface layer. Copyright © 2018 Elsevier Ltd. All rights reserved.

Characterising the thermoforming behaviour of glass fibre textile reinforced thermoplastic composite materials

NASA Astrophysics Data System (ADS)

Kuhtz, M.; Maron, B.; Hornig, A.; Müller, M.; Langkamp, A.; Gude, M.

2018-05-01

Textile reinforced thermoplastic composites are predestined for highly automated medium- and high-volume production processes. The presented work focusses on experimental studies of different types of glass fibre reinforced polypropylene (GF-PP) semi-finished thermoplastic textiles to characterise the forming behaviour. The main deformation modes fabric shear, tension, thought-thickness compression and bending are investigated with special emphasis on the impact of the textile structure, the deformation temperature and rate dependency. The understanding of the fundamental forming behaviour is required to allow FEM based assessment and improvement of thermoforming process chains.

Mechanical, Thermal and Dynamic Mechanical Properties of PP/GF/xGnP Nanocomposites

NASA Astrophysics Data System (ADS)

Ashenai Ghasemi, F.; Ghorbani, A.; Ghasemi, I.

2017-03-01

The mechanical, thermal, and dynamic mechanical properties of ternary nanocomposites based on polypropylene, short glass fibers, and exfoliated graphene nanoplatelets were studied. To investigate the mechanical properties, uniaxial tensile and Charpy impact tests were carried out. To study the crystallinity of the compositions, a DSC test was performed. A dynamic mechanical analysis was used to characterize the storage modulus and loss factor (tan δ). The morphology of the composites was studied by a scanning electron microscope (SEM). The results obtained are presented in tables and graphics.

Graft polymerization of styryl bisphosphonate monomer onto polypropylene films for inhibition of biofilm formation.

PubMed

Steinmetz, Hanna P; Rudnick-Glick, Safra; Natan, Michal; Banin, Ehud; Margel, Shlomo

2016-11-01

There has been increased concern during the past few decades over the role bacterial biofilms play in causing a variety of health problems, especially since they exhibit a high degree of resistance to antibiotics and are able to survive in hostile environments. Biofilms consist of bacterial aggregates enveloped by a self-produced matrix attached to the surface. Ca(2+) ions promote the formation of biofilms, and enhance their stability, viscosity, and strength. Bisphosphonates exhibit a high affinity for Ca(2+) ions, and may inhibit the formation of biofilms by acting as sequestering agents for Ca(2+) ions. Although the antibacterial activity of bisphosphonates is well known, research into their anti-biofilm behavior is still in its early stages. In this study, we describe the synthesis of a new thin coating composed of poly(styryl bisphosphonate) grafted onto oxidized polypropylene films for anti-biofilm applications. This grafting process was performed by graft polymerization of styryl bisphosphonate vinylic monomer onto O2 plasma-treated polypropylene films. The surface modification of the polypropylene films was confirmed using surface measurements, including X-ray photoelectron spectroscopy, atomic force microscopy, and water contact angle goniometry. Significant inhibition of biofilm formation was achieved for both Gram-negative and Gram-positive bacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

Rheological Characterisation of the Flow Behaviour of Wood Plastic Composites in Consideration of Different Volume Fractions of Wood

NASA Astrophysics Data System (ADS)

Laufer, N.; Hansmann, H.; Koch, M.

2017-01-01

In this study, the rheological properties of wood plastic composites (WPC) with different polymeric matrices (LDPE, low-density polyethylene and PP, polypropylene) and with different types of wood filler (hardwood flour and softwood flour) have been investigated by means of high pressure capillary rheometry. The volume fraction of wood was varied between 0 and 60 %. The shear thinning behaviour of the WPC melts can be well described by the Ostwald - de Waele power law relationship. The flow consistency index K of the power law shows a good correlation with the volume fraction of wood. Interparticular interaction effects of wood particles can be mathematically taken into account by implementation of an interaction exponent (defined as the ratio between flow exponent of WPC and flow exponent of polymeric matrix). The interaction exponent shows a good correlation with the flow consistency index. On the basis of these relationships the concept of shear-stress-equivalent inner shear rate has been modified. Thus, the flow behaviour of the investigated wood filled polymer melts could be well described mathematically by the modified concept of shear-stress-equivalent inner shear rate. On this basis, the shear thinning behaviour of WPC can now be estimated with good accuracy, taking into account the volume fraction of wood.

Doxycycline alters collagen composition following ventral hernia repair.

PubMed

Tharappel, Job C; Harris, Jennifer W; Totten, Crystal; Zwischenberger, Brittany A; Roth, John S

2017-04-01

Doxycycline, a nonspecific metalloproteinase (MMP) inhibitor, has been demonstrated to impact the strength of the polypropylene (PP) mesh-repaired hernia with an increase in the deposition of collagen type 1. The impact of doxycycline with porcine acellular dermal matrices (PADM) is unknown; therefore, we evaluated the impact of doxycycline administration upon hernia repair with PP and PADM mesh. Sprague-Dawley rats weighing ~400 g underwent laparotomy with creation of a midline ventral hernia. After a 27-day recovery, animals were randomly assigned to four groups of eight and underwent intraperitoneal underlay hernia repair with either PP or PADM. Groups were assigned to daily normal saline (S) or daily doxycycline in normal saline 10 mg/kg (D) via oral gavage for 8 weeks beginning 24 h preoperatively. Animals were euthanized at 8 weeks and underwent tensiometric testing of the abdominal wall and western blot analyses for collagen subtypes and MMPs. Thirty-two animals underwent successful hernia creation and repair with either PADM or PP. At 8 weeks, 15 of 16 PP-implanted animals survived with only 12 of 16 PADM-implanted animals surviving. There were no differences in the mesh to fascial interface tensiometric strength between groups. Densitometric counts in the PADM-D group demonstrated increased collagen type 1 compared to PP-S (PADM-D [1286.5], PADM-S [906.9], PP-S [700.4], p = 0.037) and decreased collagen type 3 compared to PP-S (PADM-D [7446.9], PADM-S [8507.6], PP-S [11,297.1], p = 0.01). MMP-9 levels were increased in PADM-D (PP-S vs. PADM-D, p = 0.04), while MMP-2 levels were similar between PADM-D and PADM-S, respectively. Collagen type 1 deposition at the mesh to fascial interface is enhanced following administration of doxycycline in ventral hernia repairs with porcine acellular dermal matrices. Doxycycline administration may have implications for enhancing hernia repair outcomes using biologic mesh.

Retention of heavy metal ions on comb-type hydrogels based on acrylic acid and 4-vinylpyridine, synthesized by gamma radiation

NASA Astrophysics Data System (ADS)

González-Gómez, Roberto; Ortega, Alejandra; Lazo, Luz M.; Burillo, Guillermina

2014-09-01

Two novel comb-type hydrogels based on pH-sensitive monomers (acrylic acid (AAc) and 4-vinylpyridine (4VP) were synthesized by gamma radiation. The systems were as follows: a) comb-type hydrogels of an AAc network followed by grafting of 4VP ((net-PAAc)-g-4VP) and b) comb-type hydrogels of an AAc network grafted onto polypropylene (PP) followed by grafting of 4VP (net-(PP-g-AAc)-g-4VP). The equilibrium isotherms and kinetics were evaluated for copper and zinc ions in aqueous solutions. The Zn(II) retention obtained was 480 mg g-1 and 1086 mg g-1 for (net-PAAc)-g-4VP and net-(PP-g-AAc)-g-4VP, respectively. At concentrations as low as ppm, retention efficiencies of approximately 90% were achieved for Cu(II) on (net-PAAc)-g-4VP and for Zn(II) on net-(PP-g-AAc)-g-4VP. Desorption of the hydrogels was also studied, and the results indicated that they can be used repeatedly in aqueous solutions. For both systems, the adsorption of Cu(II) and Zn(II) obeyed the Freundlich model, indicating heterogeneous sorption, and the retention process occurred by chemisorption. The sorption process follows a pseudo-second-order model.

Polyolefin Nanocomposites with Enhanced Photostability Weathering Effect on Morphology and Mechanical Properties

NASA Astrophysics Data System (ADS)

Panda, Bishnu P.; Mohanty, Smita; Nayak, Sanjay K.

2014-09-01

This research aims to study the effect of accelerated weathering conditions on the photodegradation characteristics for fibrillar silicate clay-filled Polypropylene (PP) nanocomposites in the presence of metallocene linear low density polyethylene (m-LLDPE). Silane-treated attapulgite (ATP) clay along with ethylene octene elastomer-grafted maleic anhydride (POE-g-MAH) was used to compatibilize both blend and nanocomposite system. The result showed that developed PP/m-LLDPE nanocomposites displayed good UV resistance with little change in retained stress-at-break and elongation-at-break values. Balanced loss of toughness values noted maintaining higher fracture toughness values for nanocomposites containing 5 phr ATP clay. Infrared analysis was used to detect progress of degradation followed by change in carbonyl index revealed predominated chain scission in late irradiation, while crosslinking was dominant for initial irradiation period. An increase in crystallinity during UV exposure (chemi-crystallization) was detected with exposure time for all compositions and virtually independent of initial structure of the polymer. The highest value of crystallization observed for PP and the lowest one for nanocomposites containing 5 phr of ATP clay revealed good oxidation stability. Surface morphology revealed induced degradation throughout cross-section of PP, while severity of the surface degradation was significantly reduced for developed nanocomposites.

Experimental validation of analytical models for a rapid determination of cycle parameters in thermoplastic injection molding

NASA Astrophysics Data System (ADS)

Pignon, Baptiste; Sobotka, Vincent; Boyard, Nicolas; Delaunay, Didier

2017-10-01

Two different analytical models were presented to determine cycle parameters of thermoplastics injection process. The aim of these models was to provide quickly a first set of data for mold temperature and cooling time. The first model is specific to amorphous polymers and the second one is dedicated to semi-crystalline polymers taking the crystallization into account. In both cases, the nature of the contact between the polymer and the mold could be considered as perfect or not (thermal contact resistance was considered). Results from models are compared with experimental data obtained with an instrumented mold for an acrylonitrile butadiene styrene (ABS) and a polypropylene (PP). Good agreements were obtained for mold temperature variation and for heat flux. In the case of the PP, the analytical crystallization times were compared with those given by a coupled model between heat transfer and crystallization kinetics.

Further weight reduction of applications in long glass reinforced polymers

NASA Astrophysics Data System (ADS)

Yanev, A.; Schijve, W.; Martin, C.; Brands, D.

2014-05-01

Long glass reinforced materials are broadly used in the automotive industry due to their good mechanical performance, competitive price and options for functional integration in order to reduce weight. With rapidly changing environmental requirements, a demand for further weight reduction is growing constantly. Designs in LGF-PP can bring light weight solutions in combination with system cost improvement. There are quite some possibilities for applying weight reduction technologies nowadays. These technologies have to be evaluated based on weight reduction potential, but also on mechanical performance of the end application, where the latter is often the key to success. Different weight reduction technologies are applied to SABIC®STAMAX{trade mark, serif} material, a long glass fiber reinforced polypropylene (LGF-PP), in order to investigate and define best application performance. These techniques include: chemical foaming, physical foaming and thin wall applications. Results from this research will be presented, giving a guideline for your development.

Numerically design the injection process parameters of parts fabricated with ramie fiber reinforced green composites

NASA Astrophysics Data System (ADS)

Chen, L. P.; He, L. P.; Chen, D. C.; Lu, G.; Li, W. J.; Yuan, J. M.

2017-01-01

The warpage deformation plays an important role on the performance of automobile interior components fabricated with natural fiber reinforced composites. The present work investigated the influence of process parameters on the warpage behavior of A pillar trim made of ramie fiber (RF) reinforced polypropylene (PP) composites (RF/PP) via numerical simulation with orthogonal experiment method and range analysis. The results indicated that fiber addition and packing pressure were the most important factors affecting warpage. The A pillar trim can achieved the minimum warpage value as of 2.124 mm under the optimum parameters. The optimal process parameters are: 70% percent of the default value of injection pressure for the packing pressure, 20 wt% for the fiber addition, 185 °C for the melt °C for the mold temperature, 7 s for the filling time and 17 s for the packing time.

Formulation, caracterisation, modelisation et prevision du comportement thermomecanique des pieces plastiques et composites de fibres de bois : Application aux engrenages =

NASA Astrophysics Data System (ADS)

Mijiyawa, Faycal

Cette etude permet d'adapter des materiaux composites thermoplastiques a fibres de bois aux engrenages, de fabriquer de nouvelles generations d'engrenages et de predire le comportement thermique de ces engrenages. Apres une large revue de la litterature sur les materiaux thermoplastiques (polyethylene et polypropylene) renforces par les fibres de bois (bouleau et tremble), sur la formulation et l'etude du comportement thermomecanique des engrenages en plastique-composite; une relation a ete etablie avec notre presente these de doctorat. En effet, beaucoup d'etudes sur la formulation et la caracterisation des materiaux composites a fibres de bois ont ete deja realisees, mais aucune ne s'est interessee a la fabrication des engrenages. Les differentes techniques de formulation tirees de la litterature ont facilite l'obtention d'un materiau composite ayant presque les memes proprietes que les materiaux plastiques (nylon, acetal...) utilises dans la conception des engrenages. La formulation des materiaux thermoplastiques renforces par les fibres de bois a ete effectuee au Centre de recherche en materiaux lignocellulosiques (CRML) de l'Universite du Quebec a Trois-Rivieres (UQTR), en collaboration avec le departement de Genie Mecanique, en melangeant les composites avec deux rouleaux sur une machine de type Thermotron-C.W. Brabender (modele T-303, Allemand) ; puis des pieces ont ete fabriquees par thermocompression. Les thermoplastiques utilises dans le cadre de cette these sont le polypropylene (PP) et le polyethylene haute densite (HDPE), avec comme renfort des fibres de bouleau et de tremble. A cause de l'incompatibilite entre la fibre de bois et le thermoplastique, un traitement chimique a l'aide d'un agent de couplage a ete realise pour augmenter les proprietes mecaniques des materiaux composites. Pour les composites polypropylene/bois : (1) Les modules elastiques et les contraintes a la rupture en traction des composites PP/bouleau et PP/tremble evoluent lineairement en fonction du taux de fibres, avec ou sans agent de couplage (Maleate de polypropylene MAPP). De plus, l'adherence entre les fibres de bois et le plastique est amelioree en utilisant seulement 3 % MAPP, entrainant donc une augmentation de la contrainte maximale bien qu'aucun effet significatif ne soit observe sur le module d'elasticite. (2) Les resultats obtenus montrent que, en general, les proprietes en traction des composites polypropylene/bouleau, polypropylene/tremble et polypropylene/bouleau/ tremble sont tres semblables. Les composites plastique-bois (WPCs), en particulier ceux contenant 30 % et 40 % de fibres, ont des modules elastiques plus eleves que certains plastiques utilises dans l'application des engrenages (ex. Nylon). Pour les composites polyethylene/bois, avec 3%Maleate de polyethylene (MAPE): (1) Tests de traction : le module elastique passe de 1.34 GPa a 4.19 GPa pour le composite HDPE/bouleau, alors qu'il passe de 1.34 GPa a 3.86 GPa pour le composite HDPE/tremble. La contrainte maximale passe de 22 MPa a 42.65 MPa pour le composite HDPE/bouleau, alors qu'elle passe de 22 MPa a 43.48 MPa pour le composite HDPE/tremble. (2) Tests de flexion : le module elastique passe de 1.04 GPa a 3.47 GPa pour le composite HDPE/bouleau et a 3.64 GPa pour le composite HDPE/tremble. La contrainte maximale passe de 23.90 MPa a 66.70 MPa pour le composite HDPE/bouleau, alors qu'elle passe a 59.51 MPa pour le composite HDPE/tremble. (3) Le coefficient de Poisson determine par impulsion acoustique est autour de 0.35 pour tous les composites HDPE/bois. (4) Le test de degradation thermique TGA nous revele que les materiaux composites presentent une stabilite thermique intermediaire entre les fibres de bois et la matrice HDPE. (5) Le test de mouillabilite (angle de contact) revele que l'ajout de fibres de bois ne diminue pas de facon significative les angles de contact avec de l'eau parce que les fibres de bois (bouleau ou tremble) semblent etre enveloppees par la matrice sur la surface des composites, comme le montrent des images prises au microscope electronique a balayage MEB. (6) Le modele de Lavengoof-Goettler predit mieux le module elastique du composite thermoplastique/bois. (7) Le HDPE renforce par 40 % de bouleau est mieux adapte pour la fabrication des engrenages, car le retrait est moins important lors du refroidissement au moulage. La simulation numerique semble mieux predire la temperature d'equilibre a la vitesse de 500 tr/min; alors qu'a 1000 tr/min, on remarque une divergence du modele. (Abstract shortened by ProQuest.). None None None None None None None None

TiO₂ sol-gel for formaldehyde photodegradation using polymeric support: photocatalysis efficiency versus material stability.

PubMed

Curcio, Monique S; Oliveira, Michel P; Waldman, Walter R; Sánchez, Benigno; Canela, Maria Cristina

2015-01-01

Photocatalysts supported on polymers are not frequently used in heterogeneous photocatalysis because of problems such as wettability and stability that affect photocatalysis conditions. In this work, we used polypropylene as support for TiO2 sol-gel to evaluate its stability and efficiency under UV radiation. We also tested the effect of the thermo-pressing PP/TiO2 system on the photocatalytic efficiency and stability under UV radiation. The films were characterized by scanning electron microscopy (SEM), UV-Vis spectroscopy and X-ray diffraction (XRD). The SEM micrographs showed that the films of TiO2 sol-gel onto PP has approximately 1.0-μm thick and regular surface and the generation of polypropylene nanowires on hot-pressed samples. XRD showed the formation of TiO2 anatase on the surface of the films made by dip-coating. All photocatalysts were tested in decontaminating air-containing gaseous formaldehyde (70 ppmv) presenting degradation of the target compound to the limit of detection. The photocatalysts showed no deactivation during the entire period tested (30 h), and its reuse after washing showed better photocatalytic performance than on first use. The photocatalyst showed the best results were tested for 360 h with no observed deactivation. Aging studies showed that the film of TiO2 causes different effects on the photostability of composites, with stabilizing effect when exposed to most energetic UVC radiation (λmax = 254 nm) and degradative effects when exposed to UVA radiation (λmax = 365 nm).

High fiber-low matrix composites: kenaf fiber/polypropylene.

Treesearch

Anand R. Sanadi; J.F. Hunt; D.F. Caulfield; G. Kovacsvolgyi; B. Destree

2002-01-01

Considerable interest has been generated in the use of lignocellulosic fibers and wastes (both agricultural and wood based) as fillers and reinforcements in thermoplastics. In general, present technologies limit fiber loading in thermoplastics to about 60 percent by weight of fiber. To produce high fiber content composites for commercial use while maintaining adequate...

Low Cost Processing of Commingled Thermoplastic Composites

NASA Astrophysics Data System (ADS)

Chiasson, Matthew Lee

A low cost vacuum consolidation process has been investigated for use with commingled thermoplastic matrix composites. In particular, the vacuum consolidation behaviour of commingled polypropylene/glass fibre and commingled nylon/carbon fibre precursors were studied. Laminates were consolidated in a convection oven under vacuum pressure. During processing, the consolidation of the laminate packs was measured by use of non-contact eddy current sensors. The consolidation curves are then used to tune an empirical consolidation model. The overall quality of the resulting laminates is also discussed. Dynamic mechanical analysis, differential scanning calorimetry and mechanical tensile testing were also performed in order to determine the effects of varying processing parameters on the physical and mechanical properties of the laminates. Through this analysis, it was determined that the nylon/carbon fibre blend was not suitable for vacuum consolidation, while the polypropylene/glass fibre blend is a viable option for vacuum consolidation. The ultimate goal of this work is to provide a foundation from which low cost unmanned aerial vehicle (UAV) components can be designed and manufactured from thermoplastic matrix composites using a low cost processing technique as an alternative to traditional thermoset composite materials.

Accurate and efficient calculation of excitation energies with the active-space particle-particle random phase approximation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Du; Yang, Weitao

An efficient method for calculating excitation energies based on the particle-particle random phase approximation (ppRPA) is presented. Neglecting the contributions from the high-lying virtual states and the low-lying core states leads to the significantly smaller active-space ppRPA matrix while keeping the error to within 0.05 eV from the corresponding full ppRPA excitation energies. The resulting computational cost is significantly reduced and becomes less than the construction of the non-local Fock exchange potential matrix in the self-consistent-field (SCF) procedure. With only a modest number of active orbitals, the original ppRPA singlet-triplet (ST) gaps as well as the low-lying single and doublemore » excitation energies can be accurately reproduced at much reduced computational costs, up to 100 times faster than the iterative Davidson diagonalization of the original full ppRPA matrix. For high-lying Rydberg excitations where the Davidson algorithm fails, the computational savings of active-space ppRPA with respect to the direct diagonalization is even more dramatic. The virtues of the underlying full ppRPA combined with the significantly lower computational cost of the active-space approach will significantly expand the applicability of the ppRPA method to calculate excitation energies at a cost of O(K^{4}), with a prefactor much smaller than a single SCF Hartree-Fock (HF)/hybrid functional calculation, thus opening up new possibilities for the quantum mechanical study of excited state electronic structure of large systems.« less

Accurate and efficient calculation of excitation energies with the active-space particle-particle random phase approximation

DOE PAGES

Zhang, Du; Yang, Weitao

2016-10-13

An efficient method for calculating excitation energies based on the particle-particle random phase approximation (ppRPA) is presented. Neglecting the contributions from the high-lying virtual states and the low-lying core states leads to the significantly smaller active-space ppRPA matrix while keeping the error to within 0.05 eV from the corresponding full ppRPA excitation energies. The resulting computational cost is significantly reduced and becomes less than the construction of the non-local Fock exchange potential matrix in the self-consistent-field (SCF) procedure. With only a modest number of active orbitals, the original ppRPA singlet-triplet (ST) gaps as well as the low-lying single and doublemore » excitation energies can be accurately reproduced at much reduced computational costs, up to 100 times faster than the iterative Davidson diagonalization of the original full ppRPA matrix. For high-lying Rydberg excitations where the Davidson algorithm fails, the computational savings of active-space ppRPA with respect to the direct diagonalization is even more dramatic. The virtues of the underlying full ppRPA combined with the significantly lower computational cost of the active-space approach will significantly expand the applicability of the ppRPA method to calculate excitation energies at a cost of O(K^{4}), with a prefactor much smaller than a single SCF Hartree-Fock (HF)/hybrid functional calculation, thus opening up new possibilities for the quantum mechanical study of excited state electronic structure of large systems.« less

Strong enhancement effect of silver nanowires on fluorescent property of Eu3+-ligand complexes and desired fluorescent iPP composite materials

NASA Astrophysics Data System (ADS)

Zhang, Yu; Wang, Xinzhi; Tang, Jianguo; Wang, Wei; Wang, Jinping; Belfiore, Laurence A.

2017-04-01

In this contribution, we obtained the strong enhancement effect of silver nanowires(AgNWs) on fluorescent property of Eu3+-antenna complexes through the function of the surface plasmon resonance(SPR) effect. The key structural characteristics are: (1) AgNWs are covered by the Eu3+-ligand complex and spaced by SiO2 nano-layer between AgNWs and Eu3+-ligand complex (this structure is marked as AgNWs@SiO2@EuTP), and (2) AgNWs as nano-material with large ratio of length to diameter show their good dispersion and processability in isotactic polypropylene (iPP). We obtained the important data about the optimal spacer thickness of SiO2 is 15 nm that was not found in previous publications. The enhanced intensity of fluorescence of EuTP by AgNWs in AgNWs@SiO2@EuTP is 9 times compared with that of EuTP. All of these outstanding properties and fine structures were characterized by TEM, FT-IR, XRD, and fluorescence spectrophotometer. On the other hand, the desired fluorescent iPP composite material was obtained through blending AgNWs@SiO2@EuTP into iPP host. Very importantly, the enhancement effect of AgNWs on EuTP fluorescence in AgNWs@SiO2@EuTP is refrained from the quenching caused by host polymer of iPP.

Atomic layer deposition as pore diameter adjustment tool for nanoporous aluminum oxide injection molding masks.

PubMed

Miikkulainen, Ville; Rasilainen, Tiina; Puukilainen, Esa; Suvanto, Mika; Pakkanen, Tapani A

2008-05-06

The wetting properties of polypropylene (PP) surfaces were modified by adjusting the dimensions of the surface nanostructure. The nanostructures were generated by injection molding with nanoporous anodized aluminum oxide (AAO) as the mold insert. Atomic layer deposition (ALD) of molybdenum nitride film was used to control the pore diameters of the AAO inserts. The original 50-nm pore diameter of AAO was adjusted by depositing films of thickness 5, 10, and 15 nm on AAO. Bis(tert-butylimido)-bis(dimethylamido)molybdenum and ammonia were used as precursors in deposition. The resulting pore diameters in the nitride-coated AAO inserts were 40, 30, and 20 nm, respectively. Injection molding of PP was conducted with the coated inserts, as well as with the non-coated insert. Besides the pore diameter, the injection mold temperature was varied with temperatures of 50, 70, and 90 degrees C tested. Water contact angles of PP casts were measured and compared with theoretical contact angles calculated from Wenzel and Cassie-Baxter theories. The highest contact angle, 140 degrees , was observed for PP molded with the AAO mold insert with 30-nm pore diameter. The Cassie-Baxter theory showed better fit than the Wenzel theory to the experimental values. With the optimal AAO mask, the nanofeatures in the molded PP pieces were 100 nm high. In explanation of this finding, it is suggested that some sticking and stretching of the nanofeatures occurs during the molding. Increase in the mold temperature increased the contact angle.

Microplastic interactions with freshwater microalgae: Hetero-aggregation and changes in plastic density appear strongly dependent on polymer type.

PubMed

Lagarde, Fabienne; Olivier, Ophélie; Zanella, Marie; Daniel, Philippe; Hiard, Sophie; Caruso, Aurore

2016-08-01

In this study, the interactions between microplastics, chosen among the most widely used in industry such as polypropylene (PP) and high-density polyethylene (HDPE), and a model freshwater microalgae, Chlamydomas reinhardtii, were investigated. It was shown that the presence of high concentrations of microplastics with size >400 μm did not directly impact the growth of microalgae in the first days of contact and that the expression of three genes involved in the stress response was not modified after 78 days. In parallel, a similar colonization was observed for the two polymers. However, after 20 days of contact, in the case of PP only, hetero-aggregates constituted of microalgae, microplastics and exopolysaccharides were formed. An estimation of the hetero-aggregates composition was approximately 50% of PP fragments and 50% of microalgae, which led to a final density close to 1.2. Such hetero-aggregates appear as an important pathway for the vertical transport of PP microplastics from the water surface to sediment. Moreover, after more than 70 days of contact with microplastics, the microalgae genes involved in the sugar biosynthesis pathways were strongly over-expressed compared to control conditions. The levels of over-expression were higher in the case of HDPE than in PP condition. This work presents the first evidence that depending on their chemical nature, microplastics will follow different fates in the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis of polysiloxane with quaternized N-halamine moieties for antibacterial coating of polypropylene via supercritical impregnation technique

NASA Astrophysics Data System (ADS)

Chen, Yong; Yu, Panwei; Feng, Chunyan; Wang, Yuyu; Han, Qiuxia; Zhang, Qiang

2017-10-01

Development of polymers with enhanced biocidal ability to coated surfaces by a simple and versatile approach is very desirable in biomaterial area. A polysiloxane containing both quaternary ammonium and N-halamine was synthesized by silane alcoholysis between poly(methylhydrosiloxane) (PMHS) and 3-bromo-1-propanol, subsequent quaternization with 3-(3-(dimethylamino)propyl)-5,5-dimethylhydantoin (DMAPDMH), and chlorination with tert-butyl hypochlorite. The quaternized N-halamine polysiloxane was impregnated into polypropylene (PP) in supercritical carbon dioxide (scCO2) and formed an antibacterial coating layer of 61 nm. The synthetic procedures and coating results were characterized using FTIR, NMR, XPS, and SEM. The polysiloxane layer showed enhanced synergetic antibacterial ability, providing a total kill of a 7-log S. aureus and E. coli within 10 min of contact. The rechargability and stability of the coating layer toward washing cycles, storage, and UV irradiation were good. This coating procedure uses environmentally benign CO2 as solvent and affords a general method to functionalize inert polymers with biocidal capability.

Interfacial crystalline structures in injection over-molded polypropylene and bond strength.

PubMed

Yan, Bowen; Wu, Hong; Jiang, Genjie; Guo, Shaoyun; Huang, Jian

2010-11-01

This paper describes interfacial crystalline structures found in injection overmolded polypropylene components and the relationship of these structures to bond strength between the components. The combined effects of the development of hierarchical gradient structures and the particular thermomechanical environment near the interface on the interfacial crystalline structures were investigated in detail by PLM, SEM, DSC, WAXD, and infrared dichroism spectroscopy. The experimental results showed that during molding there was competitive formation of interfacial crystalline structures consisted of "shish-kebab" layer (SKL) and a transcrystalline layers (TCL). Variation in shear stress (controlled by injection pressure and injection speed) plays an important role in the formation of the SKL. The formation of TCL is influenced by the thermal environment, namely melt temperature and mold temperature. Increasing within certain limits, interfacial temperature and the thermal gradient near the interface promotes β-iPP growth. The relationship between interfacial crystalline structures and interfacial bond strength was established by lap shear measurement. The interfacial bond strength is improved by enhancing the formation of TCL, but reduced if SKL predominates.

Optical properties of polypropylene upon recycling.

PubMed

De Santis, Felice; Pantani, Roberto

2013-01-01

In the last few years there has been an increasing interest in the possibility of recycling polymeric materials, using physical recycling. However, is it well known that polymers experience a depletion of all the properties upon recycling. These effects have been widely characterized in the literature for what concerns the mechanical or rheological properties. The changes of optical properties after recycling have been much less studied, even if, especially in food packaging, optical characteristics (above all the opacity) are of extreme importance, and thus it is quite significant to assess the effect of recycling on these properties. In this work, the influence of recycling steps on the opacity of films of a commercial grade of isotactic polypropylene (i-PP) was studied. The material was extruded several times to mimic the effect of recycling procedures. After extrusion, films were obtained by cooling samples of material at different cooling rates. The opacity of the obtained films was then measured and related to their crystallinity and morphology. It was found that opacity generally increases on increasing the amount of α phase and for the same amount of α phase on increasing the size of the spherulites.

The potential of melt-mixed polypropylene-zeolite blends in the removal of heavy metals from aqueous media

NASA Astrophysics Data System (ADS)

Motsa, Machawe M.; Thwala, Justice M.; Msagati, Titus A. M.; Mamba, Bhekie B.

The continued deterioration of the water quality in natural water sources such as rivers and lakes has led to tensions amongst relevant stakeholders to such an extent that cooperative water resource management is being regarded as an ideal solution to culminate conflicts and maximise the benefits. The desire to develop technologies that combine the three most important aspects of integrated water resource management (namely social, economic and environmental) has been encouraged by relevant authorities. This paper therefore reports the application of clinoptilolite-polypropylene (CLI-PP) blends/composites for the removal of lead from aqueous media. Just like many other heavy metals, lead poses a threat to water and soil quality as well as to plant and animal health. The findings on the adsorption behaviour of clinoptilolite-polypropylene composites with respect to Pb 2+ are also reported here, with the aim of extending its application to wastewater and environmental water purification. The batch equilibrium adsorption method was employed and the influence of contact time, pH, initial metal-ion concentration, temperature and pretreatment was determined. The optimum pH was found to be between pH 6 and pH 8 while the maximum sorption of lead at optimal pH was 95%. No big difference was observed between the adsorption behaviour of composites functionalised with 20% and 30% clinoptilolite, respectively. The pretreatment with HCl and NaCl made a slight difference to the adsorption capacity of composites.

Production Principles and Technological Development of Novel Woven Spacer Preforms and Integrated Stiffener Structures

NASA Astrophysics Data System (ADS)

Torun, Ahmet R.; Mountasir, Adil; Hoffmann, Gerald; Cherif, Chokri

2013-06-01

3D textile preforms offer a high potential to increase mechanical properties of composites and/or decrease manufacturing costs. Within the scope of this study, production principles were developed for complex spacer preforms and integrated stiffeners. These principles were applied through technological further development of the well-known face-to-face and terry weaving techniques. Various woven preforms were produced with Glass fibre/Polypropylene (GF/PP) Commingled yarns, however, the technology is suitable for any type of reinforcement yarns. U-shaped woven spacer preform was consolidated into a sandwich composite component for lightweight applications.

Use of different surface analysis techniques for the study of the photo-degradation of a polymeric matrix composite

NASA Astrophysics Data System (ADS)

Larena, A.; Ochoa, S. Jimenez de

2004-11-01

Polypropylene matrix composites, with different reinforcement degrees of long glass fibres, are usually used in different fields of the industry, like aeronautics or automotive. Owed to their huge application field, and work under diverse and severe conditions, samples of the materials were exposed to artificial accelerated photo ageing in UV chamber (Heraeus Xenotest 15OS). Although the oxidative mechanism of the PP is known enough, the fact that the material presents a high content of glass fibre, cause a surface degradation higher than that the case of no reinforced materials, owed to the presence of the fibres near the surface. In order to study this topographic modifications, the optical confocal microscopy is used that allows us the analysis of the material surface with more accuracy than a surface profiler, and with nanometric precision. We also want a correlation between surface degradation studied by confocal microscopy and reflectometer measurements. By this way, we can know the surface state, and the degradation evolution, by means of a set of easy measurements, taken with a portable reflectometer, in samples at work, without preparation. Since these materials shall fulfil some aesthetic requirements, we study also, by means of UV-vis spectroscopy, Yellow Index and White Index variations, trying to explain the photochemical processes causing these modifications. Also, the fact that these materials are usually subjected to surface treatments like adhesion or painting makes necessary the study of surface energy. We study the variation of this factor with exposing time and percentage of fibre, by means of contact angle measurements, with different liquids of known surface tensions.

[Adhesion loss of syrups in a metering glass which consists of a low surface free energy material].

PubMed

Yamamoto, Yoshihisa; Suzuki, Toyofumi; Hashizaki, Kaname; Ogura, Masao; Umeda, Yukiko; Hidaka, Shinji; Fukami, Toshiro; Tomono, Kazuo

2010-08-01

We previously reported a strong positive correlation between syrup viscosity and the rate of syrup loss due to adhesion to a glass metering device. In this study, we examined differences in the surface free energies of metering devices made of different polymeric materials, since reducing adhesion loss to metering devices could improve the efficiency of drug preparation involving highly viscous syrups. Among metering devices made of glass only, glass with a silicone coating (SLC), polypropylene (PP), and polymethylpentene (PMP) the surface free energy of the glass-only metering device was the highest (49.2 mN/m). The adhesion loss obtained for highly viscous syrups in the PP and PMP metering devices was significantly lower than that of the glass metering device. Measurements of syrup contact angles suggested that in metering devices made of PP and PMP, which have low surface free energies, a decrease in the spreading wetting of syrups was a factor in reducing the rate of adhesion loss. Thus irrespective of the syrup viscosity being measured, metering devices produced from materials with low surface free energies can reduce the time required to prepare prescriptions without compromising the accuracy of drug preparation.

Antimicrobial, antioxidant and sensory features of eugenol, carvacrol and trans-anethole in active packaging for organic ready-to-eat iceberg lettuce.

PubMed

Wieczyńska, Justyna; Cavoski, Ivana

2018-09-01

In this study, bio-based emitting sachets containing eugenol (EUG), carvacrol (CAR) and trans-anethole (ANT) were inserted into cellulose (CE) and polypropylene (PP) pillow packages of organic ready-to-eat (RTE) iceberg lettuce to investigate their functional features. EUG, CAR and ANT sachets in CE; and CAR in PP packages showed antimicrobial activities against coliforms (Δlog CFU g -1 of -1.38, -0.91, -0.93 and -0.93, respectively). EUG and ANT sachets in both packages reduced discoloration (ΔE of 9.5, 1.8, 9.4 and 5.6, respectively). ANT in both, and EUG only in PP packages induced biosynthesis of caffeoyl derivatives (C a T A , D i C a T A , D i C a Q A ), total phenolics and antioxidant activity (FRAP). Also, ANT and EUG in both packages improved overall freshness and odor. Principal component analysis separated ANT and EUG from CAR in both packages. The Pearson correlation confirmed that overall quality improvements were more pronounced by ANT inside the packages in comparison to EUG and CAR. Copyright © 2018 Elsevier Ltd. All rights reserved.

Non-destructive investigation of thermoplastic reinforced composites

DOE PAGES

Hassen, Ahmed; Taheri, Hossein; Vaidya, Uday

2016-05-09

This paper studies various manufacturing defects in glass fiber/Polypropylene (PP) composite parts and their methods of detection. Foreign Object Inclusion (FOI) of different shapes, sizes, and materials were placed in a glass fiber/PP panel made by compression molding. The paper aims to characterize the fiber orientation and fiber related defects such as fiber waviness in the composite specimen. Comprehensive investigation for different Non Destructive Evaluation (NDE) techniques, namely X-ray radiography and Ultrasonic Testing (UT) techniques to trace and characterize the embedded defects and the composite texture are presented. Conventional X-ray radiography successfully identified the fiber orientation in two dimension (2-D)more » plane; however, information for the sample depth was not captured. The radiography techniques showed low relative errors for the defect size measurements (maximum error was below 9.5%) when compared to the ultrasonic techniques. Ultrasonic techniques were able to map all the embedded artificial defects. Phase Array (PA) ultrasonic technique was able to precisely locate the FOI in the glass fiber/PP specimen. Nerveless, the shape and size of the defects were not accurately determined due to the high signal attenuation and distortion characteristics of the E-glass fiber.« less

Effects of POE-g-MAH on properties of PP-based binder in metal injection molding

NASA Astrophysics Data System (ADS)

Li, Duxin; Zhang, Chenming; Ding, Chuxiong; Pan, Donghua; Lu, Renwei; Yang, Zhongchen

2018-06-01

The objective of this study is to explore the effects of maleic anhydride-grafted polyolefin elastomer (POE-g-MAH) on properties of polypropylene (PP)-based binder. The viscosity of feedstocks as well as properties of green parts, brown parts and sintered parts were investigated. Through the analysis of viscosity, the feedstock containing 8 vol% POE-g-MAH in binder was supposed to be more suitable for the injection molding. The impact absorbed energy at break increased with increasing POE-g-MAH content in binder while the bending strength decreased first and then increased. The introduction of POE-g-MAH improve the density distribution and increased the density of green parts. After debinding, most binder components were removed regardless of the POE-g-MAH content in binder. As for the parts after sintering, the carbon content decreased with an increase in POE-g-MAH content. The results suggest that POE-g-MAH act as a toughening agent as well as compatibilizer for PP-based binder/metal powder system. The mechanical properties of the green parts could be enhanced even after multiple injection and in addition the powder-binder separation trend could be decreased.

The Matrix Pencil and its Applications to Speech Processing

DTIC Science & Technology

2007-03-01

Elementary Linear Algebra ” 8th edition, pp. 278, 2000 John Wiley & Sons, Inc., New York [37] Wai C. Chu, “Speech Coding Algorithms”, New Jeresy: John...Ben; Daniel, James W.; “Applied Linear Algebra ”, pp. 342-345, 1988 Prentice Hall, Englewood Cliffs, NJ [35] Haykin, Simon “Applied Linear Adaptive...ABSTRACT Matrix Pencils facilitate the study of differential equations resulting from oscillating systems. Certain problems in linear ordinary

Assimilable organic carbon release, chemical migration, and drinking water impacts of multiple brands of plastic pipes available in the USA

NASA Astrophysics Data System (ADS)

Connell, Matthew

Increased installation of polymer potable water pipes in United States plumbing systems has created a need to thoroughly evaluate their water quality impacts. Eleven brands of new polymer drinking water pipe were evaluated for assimilable organic carbon (AOC) release at room temperature for 28 days. They included polyvinyl chloride (PVC), high-density polyethylene (HDPE), polypropylene (PP), and cross-linked polyethylene (PEX) pipes. Three of eight PEX pipe brands exceeded a 100 microg/L AOC threshold for microbial regrowth for the first exposure period and no brands exceeded this value on day 28. No detectable increase in AOC was found for PP and PEX-a1 pipes; the remaining pipe brands contributed marginal AOC levels. Water quality impacts were more fully evaluated for two brands of PEX-b and one brand of PP pipe. PEX pipes released more total organic carbon (TOC), volatile organic compounds (VOC), and semivolatile organic compounds (SVOC) and caused greater odor than the PP pipe. All three materials showed reductions in these water quality parameters over 30 days. Three PEX pipe field studies revealed that aged systems did not display more intense odors than distribution systems. However, the organic releases from polymer pipes may still alter water quality and contribute to rapid microbial growth, even though the aesthetic impacts are temporary.

The melt-recrystallization behavior of highly oriented α-iPP fibers embedded in a HIPS matrix.

PubMed

Ye, Liwei; Li, Huihui; Qiu, Zhaobin; Yan, Shouke

2015-03-21

The melt-recrystallization behavior of α-iPP fibers embedded in an amorphous HIPS matrix has been studied by means of optical microscopy. The amorphous HIPS serving as a supporter of iPP fibers does not become involved in the nucleation and crystallization process of the molten highly oriented iPP fibers. It also does not provide any birefringence under the optical microscope with crossed polarizers. This enables the study of orientation-induced β-iPP crystallization through a control of the melting status of the fibers. Through melting the fibers at different temperatures above 175 °C and subsequent recrystallization, some β-iPP crystals were always produced. The content of the β-iPP crystal depends strongly on the melting temperature and melting time of the iPP fibers. It was confirmed that melting the iPP fibers at relatively lower temperature, e.g. 176 °C, less amount of β-iPP crystals were observed. The content of β-iPP crystal enhances first with increasing melting temperature and then decreases with further increase of the fiber melting temperature. The β-iPP crystallization is found to be most favorable upon melting the fibers at 178 °C for 2 min. This demonstrates the requirement of a certain chain or chain segment orientation for generating β-iPP crystallization on the one hand, while higher orientation of the iPP chains or chain segments encourages the growth of iPP crystals in the α-form on the other hand. This has been further confirmed by varying the melting time of the fiber at different temperatures, since relaxation of the iPP molecular chains at a fixed temperature is time dependent. Moreover, the complete transformation of α-iPP fibers in some local places into β-iPP crystals implies that the αβ-transition may not be required for the orientation-induced β-iPP crystallization.

Effect of formation temperature on properties of graphite/stannum composite for bipolar plate

NASA Astrophysics Data System (ADS)

Selamat, Mohd Zulkefli; Yusuf, Muhammad Yusri Md; Wer, Tio Kok; Sahadan, Siti Norbaya; Malingam, Sivakumar Dhar; Mohamad, Noraiham

2016-03-01

Bipolar plates are key components in Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In this research, the raw materials used to fabricate the high performance bipolar plate are Graphite (Gr), Stannum (Sn) and Polypropylene (PP). All materials used was in powder form and Gr and Sn act as fillers and the PP acts as binder. The ratio of fillers (Gr/Sn) and binder (PP) was fixed at 80:20. For the multi-conductive filler, small amount of Sn, which is 10 up to 20wt% (from the total weight of fillers 80%) have been added into Gr/Sn/PP composite. The fillers were mixed by using the ball mill machine. The second stage of mixing process between the mixer of fillers and binder is also carried out by using ball mill machine before the compaction process by the hot press machine. The effect of formation temperatures (160°C-170°C) on the properties of Gr/Sn/PP composite had been studied in detail, especially the electrical conductivity, bulk density, hardness and microstructure analysis of Gr/Sn/PP composite. The result shows that there are significant improvement in the electrical conductivity and bulk density, which are exceeding the US-DoE target with the maximum value of 265.35 S/cm and 1.682g/cm3 respectively.

The essential work of fracture of thermoplastic orthodontic retainer materials.

PubMed

Pascual, Albert L; Beeman, Cynthia S; Hicks, E Preston; Bush, Heather M; Mitchell, Richard J

2010-05-01

To investigate whether oral cleansing agents affect the essential work of fracture (EWF) and plastic work of fracture (PWF) for two types of orthodontic thermoplastic retainer materials. Polyethylene-terephthalate-glycol (PETG; Tru-Tain Splint) and polypropylene/ethylene-propylene rubber (PP-EPR) blend (Essix-C+) sheets were compared. For each material, six sets of 25 sheets were thermoformed into double-edge-notched-tension specimens; subsets of five specimens were formed with internotch distances (L) equal to 6, 8, 10, 12, or 14 mm, respectively. Sets were stored (160 hours, 25 degrees C) in air (DRY), distilled water (DW), Original Listerine (LIS), mint Crest ProHealth (CPH), 3% hydrogen peroxide (HP), or Polident solution (POL). Specimens were fractured in tension at 2.54 mm/min. Areas under load-elongation curves were measured to determine total work of fracture (W(f)). Linear regressions (W(f) vs L [n = 25]) yielded intercepts (EWF) and slopes (PWF). Ninety-five percent confidence intervals were used to evaluate differences in EWF and PWF estimates. PP-EPR blends showed higher EWFs after storage in HP vs storage in DW. PP-EPR blend showed higher EWFs after storage in CPH vs PETG. After HP storage, PP-EPR exhibited lower PWFs than with any other storage conditions. PP-EPR exhibited higher PWFs than PETG after storage in DRY, DW, and LIS. Compared with DW, none of the cleansers decreased the energy to initiate fracture. With one exception, no cleanser decreased the energy to continue plastic fracture extension. In PP-EPR blend, increased resistance to fracture initiation was observed with CPH and HP, yet, surprisingly, HP decreased resistance to plastic fracture growth.

Investigation into the optimal prosthetic material for wound healing of abdominal wall defects

PubMed Central

Akcakaya, Adem; Aydogdu, Ibrahim; Citgez, Bulent

2018-01-01

The purpose of this experimental study is to investigate and compare the effects of prosthetic materials used for wound healing of abdominal wall hernias. A total of 60 rats were divided into five equal groups: Group I, control subjected to laparotomy; group II, abdominal wall defect 3×2 cm+polypropylene (PP) mesh; group III, abdominal wall defect 3×2 cm+PP mesh+hyaluronate and carboxymethylcellulose (H-CMC; Seprafilm®); group IV, abdominal wall defect 3×2 cm+polytetrafluoroethylene (PTFE; Composix™); and group V, abdominal wall defect 3×2 cm+polyethylene terephthalate (PET; Dacron®). A total of 14 days after the surgery, rats were sacrificed and the meshes with the surrounding tissue were extracted in block. The breaking strength of the mesh from the fascia was recorded. The healing tissue was examined with the index of histopathology and the hydroxyproline value was analyzed using the Switzer method. Both the breaking strength and histopathological index of the wound healing were significantly improved in groups II and III compared with that in groups IV and V (P<0.001). Hydroxyproline values were the highest in group I (P<0.001). There was also a statistically significant difference between groups II and IV, and group V and the other groups (P<0.001). The present findings demonstrated that PP mesh and PP mesh+H-CMC had a superior breaking strength and improved histopathologic indices compared with PTFE and PET. Furthermore, hydroxyproline values were the lowest in the PET group. In conclusion, wound healing was improved in the PP mesh group and the PP mesh+H-CMC group compared with the PTFE and PET groups according to the present study parameters. PMID:29399133

Photosensitized singlet oxygen luminescence from the protein matrix of Zn-substituted myoglobin.

PubMed

Lepeshkevich, Sergei V; Parkhats, Marina V; Stasheuski, Alexander S; Britikov, Vladimir V; Jarnikova, Ekaterina S; Usanov, Sergey A; Dzhagarov, Boris M

2014-03-13

A nanosecond laser near-infrared spectrometer was used to study singlet oxygen ((1)O2) emission in a protein matrix. Myoglobin in which the intact heme is substituted by Zn-protoporphyrin IX (ZnPP) was employed. Every collision of ground state molecular oxygen with ZnPP in the excited triplet state results in (1)O2 generation within the protein matrix. The quantum yield of (1)O2 generation was found to be equal to 0.9 ± 0.1. On the average, six from every 10 (1)O2 molecules succeed in escaping from the protein matrix into the solvent. A kinetic model for (1)O2 generation within the protein matrix and for a subsequent (1)O2 deactivation was introduced and discussed. Rate constants for radiative and nonradiative (1)O2 deactivation within the protein were determined. The first-order radiative rate constant for (1)O2 deactivation within the protein was found to be 8.1 ± 1.3 times larger than the one in aqueous solutions, indicating the strong influence of the protein matrix on the radiative (1)O2 deactivation. Collisions of singlet oxygen with each protein amino acid and ZnPP were assumed to contribute independently to the observed radiative as well as nonradiative rate constants.

Ultrasound-Assist Extrusion Methods for the Fabrication of Polymer Nanocomposites Based on Polypropylene/Multi-Wall Carbon Nanotubes

PubMed Central

Ávila-Orta, Carlos A.; Quiñones-Jurado, Zoe V.; Waldo-Mendoza, Miguel A.; Rivera-Paz, Erika A.; Cruz-Delgado, Víctor J.; Mata-Padilla, José M.; González-Morones, Pablo; Ziolo, Ronald F.

2015-01-01

Isotactic polypropylenes (iPP) with different melt flow indexes (MFI) were used to fabricate nanocomposites (NCs) with 10 wt % loadings of multi-wall carbon nanotubes (MWCNTs) using ultrasound-assisted extrusion methods to determine their effect on the morphology, melt flow, and electrical properties of the NCs. Three different types of iPPs were used with MFIs of 2.5, 34 and 1200 g/10 min. Four different NC fabrication methods based on melt extrusion were used. In the first method melt extrusion fabrication without ultrasound assistance was used. In the second and third methods, an ultrasound probe attached to a hot chamber located at the exit of the die was used to subject the sample to fixed frequency and variable frequency, respectively. The fourth method is similar to the first method, with the difference being that the carbon nanotubes were treated in a fluidized air-bed with an ultrasound probe before being used in the fabrication of the NCs with no ultrasound assistance during extrusion. The samples were characterized by MFI, Optical microscopy (OM), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), electrical surface resistivity, and electric charge. MFI decreases in all cases with addition of MWCNTs with the largest decrease observed for samples with the highest MFI. The surface resistivity, which ranged from 1013 to 105 Ω/sq, and electric charge, were observed to depend on the ultrasound-assisted fabrication method as well as on the melt flow index of the iPP. A relationship between agglomerate size and area ratio with electric charge was found. Several trends in the overall data were identified and are discussed in terms of MFI and the different fabrication methods. PMID:28793686

Adsorption and association of a symmetric PEO-PPO-PEO triblock copolymer on polypropylene, polyethylene, and cellulose surfaces.

PubMed

Li, Yan; Liu, Hongyi; Song, Junlong; Rojas, Orlando J; Hinestroza, Juan P

2011-07-01

The association of a symmetric polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO(19)-PPO(29)-PEO(19)) triblock copolymer adsorbed from aqueous solutions onto polypropylene (PP), polyethylene (PE), and cellulose surfaces was probed using Atomic Force Microscopy (AFM). Significant morphological differences between the polyolefin substrates (PP and PE) and the cellulose surfaces were observed after immersion of the films in the PEO(19)-PPO(29)-PEO(19) solutions. When the samples were scanned, while immersed in solutions of the triblock copolymer, it was revealed that the structures adsorbed on the polyolefin surfaces were smoothed by the adsorbed PEO(19)-PPO(29)-PEO(19). In contrast, those structures on the hydrophilic cellulose surfaces were sharpened. These observations were related to the roughness of the substrate and the energy of interaction between the surfaces and the PEO and PPO polymer segments. The interaction energy between each of the blocks and the surface was calculated using molecular dynamics simulations. It is speculated that the associative structures amply reported in aqueous solution at concentrations above the critical micelle concentration, CMC, are not necessarily preserved upon adsorption; instead, it appears that molecular arrangements of the anchor-buoy type and hemimicelles prevail. The reported data suggests that the roughness of the surface, as well as its degree of hydrophobicity, have a large influence on the nature of the resulting adsorbed layer. The reported observations are valuable in explaining the behavior of finishing additives and lubricants commonly used in textile and fiber processing, as well as the effect of the morphology of the boundary layers on friction and wear, especially in the case of symmetric triblock copolymers, which are commonly used as antifriction, antiwear additives.

Oil sorbents from plastic wastes and polymers: A review.

PubMed

Saleem, Junaid; Adil Riaz, Muhammad; Gordon, McKay

2018-01-05

A large volume of the waste produced across the world is composed of polymers from plastic wastes such as polyethylene (HDPE or LDPE), polypropylene (PP), and polyethylene terephthalate (PET) amongst others. For years, environmentalists have been looking for various ways to overcome the problems of such large quantities of plastic wastes being disposed of into landfill sites. On the other hand, the usage of synthetic polymers as oil sorbents in particular, polyolefins, including polypropylene (PP) and polyethylene (PE) have been reported. In recent years, the idea of using plastic wastes as the feed for the production of oil sorbents has gained momentum. However, the studies undertaking such feasibility are rather scattered. This review paper is the first of its kind reporting, compiling and reviewing these various processes. The production of an oil sorbent from plastic wastes is being seen to be satisfactorily achievable through a variety of methods Nevertheless, much work needs to be done regarding further investigation of the numerous parameters influencing production yields and sorbent qualities. For example, differences in results are seen due to varying operating conditions, experimental setups, and virgin or waste plastics being used as feeds. The field of producing oil sorbents from plastic wastes is still very open for further research, and seems to be a promising route for both waste reduction, and the synthesis of value-added products such as oil sorbents. In this review, the research related to the production of various oil sorbents based on plastics (plastic waste and virgin polymer) has been discussed. Further oil sorbent efficiency in terms of oil sorption capacity has been described. Copyright © 2017 Elsevier B.V. All rights reserved.

Mutual interaction between high and low stereo-regularity components for crystallization and melting behaviors of polypropylene blend fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawai, Kouya; Takarada, Wataru; Kikutani, Takeshi, E-mail: kikutani.t.aa@m.titech.ac.jp

Crystallization and melting behaviors of blend fibers of two types of polypropylene (PP), i.e. high stereo-regularity/high molecular weight PP (HPP) and low stereo-regularity/low molecular weight PP (LPP), was investigated. Blend fibers consisting of various HPP/LPP compositions were prepared through the melt spinning process. Differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC) and wide-angle X-ray diffraction (WAXD) analysis were applied for clarifying the crystallization and melting behaviors of individual components. In the DSC measurement of blend fibers with high LPP composition, continuous endothermic heat was detected between the melting peaks of LPP at around 40 °C and that of HPP atmore » around 160 °C. Such endothermic heat was more distinct for the blend fibers with higher LPP composition indicating that the melting of LPP in the heating process was hindered because of the presence of HPP crystals. On the other hand, heat of crystallization was detected at around 90 °C in the case of blend fibers with LPP content of 30 to 70 wt%, indicating that the crystallization of HPP component was taking place during the heating of as-spun blend fibers in the DSC measurement. Through the TMDSC analysis, re-organization of the crystalline structure through the simultaneous melting and re-crystallization was detected in the cases of HPP and blend fibers, whereas re-crystallization was not detected during the melting of LPP fibers. In the WAXD analysis during the heating of fibers, amount of a-form crystal was almost constant up to the melting in the case of single component HPP fibers, whereas there was a distinct increase of the intensity of crystalline reflections from around 100 °C, right after the melting of LPP in the case of blend fibers. These results suggested that the crystallization of HPP in the spinning process as well as during the conditioning process after spinning was hindered by the presence of LPP.« less

Effects of material parameters on the diffusion and sorption properties of wood-flour/polypropylene composites

Treesearch

Vera Steckel; Craig Merrill Clemons; Heiko Thoemen

2007-01-01

Composites of wood in a thermoplastic matrix (wood–plastic composites) are considered a low maintenance solution to using wood in outdoor applications. Knowledge of moisture uptake and transport properties would be useful in estimating moisture-related effects such as fungal attack and loss of mechanical strength. Our objectives were to determine how material...

The Effect of the Melt Viscosity and Impregnation of a Film on the Mechanical Properties of Thermoplastic Composites

PubMed Central

Kim, Jong Won; Lee, Joon Seok

2016-01-01

Generally, to produce film-type thermoplastic composites with good mechanical properties, high-performance reinforcement films are used. In this case, films used as a matrix are difficult to impregnate into tow due to their high melt viscosity and high molecular weight. To solve the problem, in this paper, three polypropylene (PP) films with different melt viscosities were used separately to produce film-type thermoplastic composites. A film with a low melt viscosity was stacked so that tow was impregnated first and a film with a higher melt viscosity was then stacked to produce the composite. Four different composites were produced by regulating the pressure rising time. The thickness, density, fiber volume fraction (Vf), and void content (Vc) were analyzed to identify the physical properties and compare them in terms of film stacking types. The thermal properties were identified by using differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The tensile property, flexural property, interlaminar shear strength (ILSS), and scanning electron microscopy (SEM) were performed to identify the mechanical properties. For the films with low molecular weight, impregnation could be completed fast but showed low strength. Additionally, the films with high molecular weight completed impregnation slowly but showed high strength. Therefore, appropriate films should be used considering the forming process time and their mechanical properties to produce film-type composites. PMID:28773572

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selamat, Mohd Zulkefli, E-mail: azulkeflis@utem.edu.my; Yusuf, Muhammad Yusri Md, E-mail: yusri.cheras@gmail.com; Wer, Tio Kok, E-mail: to91@hotmail.my

Bipolar plates are key components in Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In this research, the raw materials used to fabricate the high performance bipolar plate are Graphite (Gr), Stannum (Sn) and Polypropylene (PP). All materials used was in powder form and Gr and Sn act as fillers and the PPmore » acts as binder. The ratio of fillers (Gr/Sn) and binder (PP) was fixed at 80:20. For the multi-conductive filler, small amount of Sn, which is 10 up to 20wt% (from the total weight of fillers 80%) have been added into Gr/Sn/PP composite. The fillers were mixed by using the ball mill machine. The second stage of mixing process between the mixer of fillers and binder is also carried out by using ball mill machine before the compaction process by the hot press machine. The effect of formation temperatures (160°C-170°C) on the properties of Gr/Sn/PP composite had been studied in detail, especially the electrical conductivity, bulk density, hardness and microstructure analysis of Gr/Sn/PP composite. The result shows that there are significant improvement in the electrical conductivity and bulk density, which are exceeding the US-DoE target with the maximum value of 265.35 S/cm and 1.682g/cm{sup 3} respectively.« less

Friction between a surrogate skin (Lorica Soft) and nonwoven fabrics used in hygiene products

NASA Astrophysics Data System (ADS)

Falloon, Sabrina S.; Cottenden, Alan

2016-09-01

Incontinence pad wearers often suffer from sore skin, and a better understanding of friction between pads and skin is needed to inform the development of less damaging materials. This work investigated friction between a skin surrogate (Lorica Soft) and 13 nonwoven fabrics representing those currently used against the skin in commercial pads. All fabrics were found to behave consistently with Amontons’ law: coefficients of friction did not differ systematically when measured under two different loads. Although the 13 fabrics varied considerably in composition and structure, their coefficients of friction (static and dynamic) against Lorica Soft were remarkably similar, especially for the ten fabrics comprising just polypropylene (PP) fibres. The coefficients of friction for one PP fabric never differed by more than 15.7% from those of any other, suggesting that the ranges of fibre decitex (2.0-6.5), fabric area density (13-30 g m-2) and bonding area (11%-25%) they exhibited had only limited impact on their friction properties. It is likely that differences were largely attributable to variability in properties between multiple samples of a given fabric. Of the remaining fabrics, the one comprising polyester fibres had significantly higher coefficients of friction than the highest friction PP fabric (p < 0.005), while the one comprising PP fibres with a polyethylene sheath had significantly lower coefficients of friction than the lowest friction PP fabric (p < 10-8). However, fabrics differed in too many other ways to confidently attribute these differences in friction properties just to the choice of base polymer.

Surface ripple evolution by argon ion irradiation in polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goyal, Meetika; Aggarwal, Sanjeev, E-mail: write2sa@gmail.com; Sharma, Annu

In this report, an attempt has been made to investigate the morphological evolution of nanoscale surface ripples on aliphatic (polypropylene, PP) and aromatic (polyethylene terephthalate, PET) polymeric substrates irradiated with 50 keV Ar{sup +} ions. The specimens were sputtered at off normal incidence of 30° with 5 × 10{sup 16} Ar{sup +} cm{sup −2}. The topographical features and structural behavior of the specimens were studied using Atomic Force Microscopy (AFM) and UV-Visible spectroscopy techniques, respectively. The Stopping and Range of Ions in Matter simulations were performed to calculate sputtering yield of irradiated PP and PET polymers. Sputtering yield of carbon atoms has beenmore » found to be smaller for PP (0.40) as compared to PET (0.73), which is attributed to the different structures of two polymers. AFM analysis demonstrates the evolution of ripple like features with amplitude (2.50 nm) and wavelength (690 nm) on PET while that of lower amplitude (1.50 nm) and higher wavelength (980 nm) on PP specimen. The disorder parameter (Urbach energy) has been found to increase significantly from 0.30 eV to 1.67 eV in case of PP as compared to a lesser increase from 0.35 eV to 0.72 eV in case of PET as revealed by UV-Visible characterization. A mutual correlation between ion beam sputtering induced topographical variations with that of enhancement in the disorder parameter of the specimens has been discussed.« less

Effect of fungal decay on the hygroscopic thickness swelling rate of lignocellulosic filler-polyolefin biocomposites

NASA Astrophysics Data System (ADS)

Kord, B.; Hosseinihashemi, S. Kh.

2014-01-01

The influence of fungal decay on the hygroscopic thickness swelling rate of lignocellulosic filler-polyolefin biocomposites has been investigated. Composites based on polypropylene (PP), bagasse fiber (BF), and a coupling agent (PP-g-MA) were made by melt compounding and injection molding. The weigt ratio of BF to PP was controlled at 60/40 for all blends. The amount of coupling agent was fixed at 2% for all formulations. The samples obtained were exposed to the action of brown-rot (Coniophora puteana) and white-rot (Trametes versicolor) fungi for 8, 12, and 16 weeks according to the Kolle-flask method. The thickness swelling of the samples was evaluated by immersing them in water at room temperature for several weeks. The morphology of the composites was characterized using the scanning electron microscopy (SEM). The results indicated that the fungal decay had an adverse affect on the dimensional stability of BF/PP composites due to an increase in the thickness swelling rate. The thickness swelling of white-rotted samples was higher than that of brown-rotted ones and control samples. Also, the thickness swelling of BF/PP composites increased with increasing time of fungal decay. In addition, after 16 weeks of exposure to white-rot fungi, the composites exhibited a higher parameter of swelling rate K SR than control samples. The K SR of the composites was influenced both by the type of rooting and the exposure time. Furthermore, the SEM micrographs showed that the extent of degradation increased with growing exposure time to fungi.

The effect of thermal history on crystalline structure and mechanical properties of β-nucleated isotactic polypropylene

NASA Astrophysics Data System (ADS)

Tian, Yefei; Zhou, Jian; Feng, Jiachun

2018-04-01

The effect of thermal history on β-nucleated iPP was systematically investigated by comparing the variance of crystalline microstructures and mechanical property of stepwise crystallized sample and annealed sample, which experienced different thermal history. The mechanical property tests exhibit that that the toughness of stepwise crystallized sample and annealed sample were both decreased compared to control sample, while the tensile strength of the stepwise crystallized sample increased slightly. Structure investigation showed that the α-relaxation peak, which is related to the assignment of chains in rigid amorphous phase, moved to the high temperature region for stepwise crystallized sample, while it moved to the low temperature region for annealed sample. The results indicated the weakening in rigid amorphous fraction (RAF) and the increase in lamellar thickness of β-iPP after stepwise crystallization treatment. For annealed sample, the RAF strengthened and lamellar thickness decreased slightly after thermal treatment. A mechanism of crystalline microstructures evolution of restricted area between the main lamellar under different treatments was proposed.

Validation of ATR FT-IR to identify polymers of plastic marine debris, including those ingested by marine organisms.

PubMed

Jung, Melissa R; Horgen, F David; Orski, Sara V; Rodriguez C, Viviana; Beers, Kathryn L; Balazs, George H; Jones, T Todd; Work, Thierry M; Brignac, Kayla C; Royer, Sarah-Jeanne; Hyrenbach, K David; Jensen, Brenda A; Lynch, Jennifer M

2018-02-01

Polymer identification of plastic marine debris can help identify its sources, degradation, and fate. We optimized and validated a fast, simple, and accessible technique, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), to identify polymers contained in plastic ingested by sea turtles. Spectra of consumer good items with known resin identification codes #1-6 and several #7 plastics were compared to standard and raw manufactured polymers. High temperature size exclusion chromatography measurements confirmed ATR FT-IR could differentiate these polymers. High-density (HDPE) and low-density polyethylene (LDPE) discrimination is challenging but a clear step-by-step guide is provided that identified 78% of ingested PE samples. The optimal cleaning methods consisted of wiping ingested pieces with water or cutting. Of 828 ingested plastics pieces from 50 Pacific sea turtles, 96% were identified by ATR FT-IR as HDPE, LDPE, unknown PE, polypropylene (PP), PE and PP mixtures, polystyrene, polyvinyl chloride, and nylon. Published by Elsevier Ltd.

Cellulose microfibrils grafted with PBA via surface-initiated atom transfer radical polymerization for biocomposite reinforcement.

PubMed

Li, Shuzhao; Xiao, Miaomiao; Zheng, Anna; Xiao, Huining

2011-09-12

Immobilizing poly(butyl acrylate) (PBA) on cellulose microfibrils (CMFs) by atom transfer radical polymerization (ATRP) of butyl acrylate (BA) on the surface of 2-bromoisobutyryl-functionalized CMF generated highly hydrophobic microfibrils (CMF-PBA) with a hard core and a soft-shell structure. TGA and static water contact angle results suggested that the surfaces of the modified CMF samples were not completely covered by PBA chains until the molecular weight of grafts became sufficiently long. The GPC results indicated that the grafts with low molecular weight showed controlled/"living" characteristics of the surface-initiated ATRP; however, there existed more side reactions with the increase in molecular weights. Biocomposites consisting of polypropylene (PP) and CMF-PBA samples exhibited significantly improved compatibility, interface adhesion, and mechanical properties with the increase in PBA graft length. The findings confirmed that the longer grafts facilitated the better entanglement of PBA grafts with PP macromolecules and thus further improved the mechanical properties.

Factors influencing lead and iron release from some Egyptian drinking water pipes.

PubMed

Lasheen, M R; Sharaby, C M; El-Kholy, N G; Elsherif, I Y; El-Wakeel, S T

2008-12-30

The major objective of this study is to assess the effect of stagnation time, pipe age, pipes material and water quality parameters such as pH, alkalinity and chloride to sulfate mass ratio on lead and iron release from different types of water pipes used in Egypt namely polyvinyl chloride (PVC), polypropylene (PP) and galvanized iron (GI), by using fill and dump method. Low pH increased lead and iron release from pipes. Lead and iron release decreased as pH and alkalinity increased. Lead and iron release increased with increasing chloride to sulfate mass ratio in all pipes. EDTA was used as an example of natural organic matter which may be influence metals release. It is found that lead and iron release increased then this release decreased with time. In general, GI pipes showed to be the most effected by water quality parameters tested and the highest iron release. PVC pipes are the most lead releasing pipes while PP pipes are the least releasing.

Real-time measurements of temperature, pressure and moisture profiles in High-Performance Concrete exposed to high temperatures during neutron radiography imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toropovs, N., E-mail: nikolajs.toropovs@rtu.lv; Riga Technical University, Institute of Materials and Structures, Riga; Lo Monte, F.

2015-02-15

High-Performance Concrete (HPC) is particularly prone to explosive spalling when exposed to high temperature. Although the exact causes that lead to spalling are still being debated, moisture transport during heating plays an important role in all proposed mechanisms. In this study, slabs made of high-performance, low water-to-binder ratio mortars with addition of superabsorbent polymers (SAP) and polypropylene fibers (PP) were heated from one side on a temperature-controlled plate up to 550 °C. A combination of measurements was performed simultaneously on the same sample: moisture profiles via neutron radiography, temperature profiles with embedded thermocouples and pore pressure evolution with embedded pressuremore » sensors. Spalling occurred in the sample with SAP, where sharp profiles of moisture and temperature were observed. No spalling occurred when PP-fibers were introduced in addition to SAP. The experimental procedure described here is essential for developing and verifying numerical models and studying measures against fire spalling risk in HPC.« less

Sustainable, heat-resistant and flame-retardant cellulose-based composite separator for high-performance lithium ion battery

PubMed Central

Zhang, Jianjun; Yue, Liping; Kong, Qingshan; Liu, Zhihong; Zhou, Xinhong; Zhang, Chuanjian; Xu, Quan; Zhang, Bo; Ding, Guoliang; Qin, Bingsheng; Duan, Yulong; Wang, Qingfu; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-01-01

A sustainable, heat-resistant and flame-retardant cellulose-based composite nonwoven has been successfully fabricated and explored its potential application for promising separator of high-performance lithium ion battery. It was demonstrated that this flame-retardant cellulose-based composite separator possessed good flame retardancy, superior heat tolerance and proper mechanical strength. As compared to the commercialized polypropylene (PP) separator, such composite separator presented improved electrolyte uptake, better interface stability and enhanced ionic conductivity. In addition, the lithium cobalt oxide (LiCoO2)/graphite cell using this composite separator exhibited better rate capability and cycling retention than that for PP separator owing to its facile ion transport and excellent interfacial compatibility. Furthermore, the lithium iron phosphate (LiFePO4)/lithium cell with such composite separator delivered stable cycling performance and thermal dimensional stability even at an elevated temperature of 120°C. All these fascinating characteristics would boost the application of this composite separator for high-performance lithium ion battery. PMID:24488228

Degradation of propyl paraben by activated persulfate using iron-containing magnetic carbon xerogels: investigation of water matrix and process synergy effects.

PubMed

Metheniti, Maria Evangelia; Frontistis, Zacharias; Ribeiro, Rui S; Silva, Adrián M T; Faria, Joaquim L; Gomes, Helder T; Mantzavinos, Dionissios

2017-10-06

An advanced oxidation process comprising an iron-containing magnetic carbon xerogel (CX/Fe) and persulfate was tested for the degradation of propyl paraben (PP), a contaminant of emerging concern, in various water matrices. Moreover, the effect of 20 kHz ultrasound or light irradiation on process performance was evaluated. The pseudo-first order degradation rate of PP was found to increase with increasing SPS concentration (25-500 mg/L) and decreasing PP concentration (1690-420 μg/L) and solution pH (9-3). Furthermore, the effect of water matrix on kinetics was detrimental depending on the complexity (i.e., wastewater, river water, bottled water) and the concentration of matrix constituents (i.e., humic acid, chloride, bicarbonate). The simultaneous use of CX/Fe and ultrasound as persulfate activators resulted in a synergistic effect, with the level of synergy (between 35 and 50%) depending on the water matrix. Conversely, coupling CX/Fe with simulated solar or UVA irradiation resulted in a cumulative effect in experiments performed in ultrapure water.

Photochemical modification of polymeric materials and the polarization of light in ionomeric guest/host systems

NASA Astrophysics Data System (ADS)

Pan, Bo

Photochemical methods were introduced to develop important extrusion processes, through which polymers can either be functionalized or modified by altering molecular weight characteristics. Therefore, poly(methyl methacrylate) (PMMA) incorporated with a small amount of light-reactive functional groups was synthesized. These functional groups can be activated by UV irradiation in a post extrusion process to produce high molecular weight polymer and/or crosslinked polymer. Environmental stress cracking resistance of these polymers was examined and correlated to damping using dynamic mechanic analysis. To improve industrial reactive extrusion process of preparing maleic anhydride grafted polypropylene (MAR-g-PP), photografting was proposed and studied. Using benzophenone (BP) as the initiator, grafting efficiency was significantly improved compared to peroxide initiated grafting. Moreover, nearly constant conversion of maleic anhydride was observed in photografting. The high efficiency of benzophenone initiated photografting was attributed to the formation of the excited triplet state maleic anhydride. A rate constant of 6.0*109 M-1*sec-1 for the quenching of triplet state BP with MAH was obtained using laser photolysis spectroscopy. In a comparison, the hydrogen abstraction process from polypropylene by the triplet state BP molecules has a rate constant of 4.1*105 M-1*sec-1. In solution grafting with the use of benzene as the solvent, a facile triplet state energy transfer process may also occur leading to the formation of the excited triplet state MAH. Spectroscopic methods involving light were also used for the study of the guest-host interactions in polymer systems. The use of ionomers as the matrix for the oriented guest/host systems, cationic dye systems in particular, was shown to enhance polarization efficiency as well as dye uptake as comparing to conventional polymers, such as poly(vinyl alcohol). It was found that the dye molecules in carboxylated EVOH (EVOH-COONa) have higher degree of orientation than in EVOH, while polymer chain orientation is quite similar in these two polymers. The difference in the dye orientation was attributed to the ion-ion interactions between dye molecules and carboxylate groups of the modified polymer.

Influence of environmental and anthropogenic factors on the composition, concentration and spatial distribution of microplastics: A case study of the Bay of Brest (Brittany, France).

PubMed

Frère, L; Paul-Pont, I; Rinnert, E; Petton, S; Jaffré, J; Bihannic, I; Soudant, P; Lambert, C; Huvet, A

2017-06-01

The concentration and spatial distribution of microplastics in the Bay of Brest (Brittany, France) was investigated in two surveys. Surface water and sediment were sampled at nine locations in areas characterized by contrasting anthropic pressures, riverine influences or water mixing. Microplastics were categorized by their polymer type and size class. Microplastic contamination in surface water and sediment was dominated by polyethylene fragments (PE, 53-67%) followed by polypropylene (PP, 16-30%) and polystyrene (PS, 16-17%) microparticles. The presence of buoyant microplastics (PE, PP and PS) in sediment suggests the existence of physical and/or biological processes leading to vertical transfer of lightweight microplastics in the bay. In sediment (upper 5 cm), the percentage of particles identified by Raman micro-spectroscopy was lower (41%) than in surface water (79%) and may explain the apparent low concentration observed in this matrix (0.97 ± 2.08 MP kg -1 dry sediment). Mean microplastic concentration was 0.24 ± 0.35 MP m -3 in surface water. We suggest that the observed spatial MP distribution is related to proximity to urbanized areas and to hydrodynamics in the bay. A particle dispersal model was used to study the influence of hydrodynamics on surface microplastic distribution. The outputs of the model showed the presence of a transitional convergence zone in the centre of the bay during flood tide, where floating debris coming from the northern and southern parts of the bay tends to accumulate before being expelled from the bay. Further modelling work and observations integrating (i) the complex vertical motion of microplastics, and (ii) their point sources is required to better understand the fate of microplastics in such a complex coastal ecosystem. Copyright © 2017 Elsevier Ltd. All rights reserved.

A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

NASA Astrophysics Data System (ADS)

Hopmann, Ch.; Weber, M.; van Haag, J.; Schöngart, M.

2015-05-01

To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on the material's properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation- and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusion - reduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.

A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopmann, Ch.; Weber, M.; Haag, J. van

2015-05-22

To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on themore » material’s properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation- and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusion - reduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.« less

Evaluation of oxidation behavior of γ-irradiated EPDM/PP compounds

NASA Astrophysics Data System (ADS)

Zaharescu, T.; Jipa, S.; Setnescu, R.; Setnescu, T.

2007-12-01

The oxidation effect of irradiation on ethylene-propylene diene terpolymer/polypropylene blends is presented. The polymer samples consisting of both materials under various ratios (20:80, 40:60, 60:40 and 80:20) were exposed to γ-irradiation ( 137Cs). The irradiation effects were assessed by two methods: oxygen uptake and IR spectroscopy (1720 cm -1 and 3350 cm -1, the characteristic bands for carbonyl and hydroxyl groups, respectively). The carbonyl and hydroxyl indexes were calculated for all formulations. From oxygen uptake investigation the kinetic parameters for thermal oxidation of irradiated samples were calculated. The contribution of each component to the progress of degradation is discussed.

Turbidimetric method for the determination of particle sizes in polypropylene/clay-composites during extrusion.

PubMed

Becker, Wolfgang; Guschin, Viktor; Mikonsaari, Irma; Teipel, Ulrich; Kölle, Sabine; Weiss, Patrick

2017-01-01

Nanocomposites with polypropylene as matrix material and nanoclay as filler were produced in a double twin screw extruder. The extrusion was monitored with a spectrometer in the visible and near-infrared spectral region with a diode array spectrometer. Two probes were installed at the end at the extruder die and the transmission spectra were measured during the extrusion. After measuring the transmission spectra and converting into turbidity units, the particle distribution density was calculated via numerical linear equation system. The distribution density function shows either a bimodal or mono modal shape in dependence of the processing parameters like screw speed, dosage, and concentration of the nanoclays. The method was verified with SEM measurements which yield comparable results. The method is suitable for industrial in-line processing monitoring of particle radii and dispersion process, respectively.

A novel mitochondrial matrix serine/threonine protein phosphatase regulates the mitochondria permeability transition pore and is essential for cellular survival and development

PubMed Central

Lu, Gang; Ren, Shuxun; Korge, Paavo; Choi, Jayoung; Dong, Yuan; Weiss, James; Koehler, Carla; Chen, Jau-nian; Wang, Yibin

2007-01-01

Mitochondria play a central role in the regulation of programmed cell death signaling. Here, we report the finding of a mitochondrial matrix-targeted protein phosphatase 2C family member (PP2Cm) that regulates mitochondrial membrane permeability transition pore (MPTP) opening and is essential for cell survival, embryonic development, and cardiac function. PP2Cm is highly conserved among vertebrates, with the highest expression levels detected in the heart and brain. Small hairpin RNA (shRNA)-mediated knockdown of PP2Cm resulted in cell death associated with loss of mitochondrial membrane potential in cultured cardiac mycoytes and an induction of hepatocyte apoptosis in vivo. PP2Cm-deficient mitochondria showed elevated susceptibility to calcium-induced MPTP opening, whereas mitochondrial oxidative phosphorylation activities were not affected. Finally, inactivation of PP2Cm in developing zebrafish embryos caused abnormal cardiac and neural development as well as heart failure associated with induced apoptosis. These data suggest that PP2Cm is a novel mitochondrial protein phosphatase that has a critical function in cell death and survival, and may play a role in regulating the MPTP opening. PMID:17374715

Mechanism and significance of slip and new mixing elements during flow in modular intermeshing co-rotating twin screw extruders

NASA Astrophysics Data System (ADS)

Ban, Kyunha

We have investigated slippage effect on melt flow of various polyolefins and their compounds in modular intermeshing co-rotating twin screw extruder, which include high density polyethylene (HDPE), isotactic polypropylene (iPP), isotactic polybutene-1 (PB1), isotactic poly(4-methyl pentene-1) (P4MP1) and two different kinds of particle filled polypropylenes (PP/carbon black and PP/Silica). To induce slippage during the process, octadecanoic acid was introduced on the second port of the extruder. Length of fill, die pressure and screw characteristics in twin screw extruder were studied under varying processing parameters: volumetric flow rate, screw rotational speed, and die geometry. The effort to account for these variations on slippage effect was combined with considerations of the structures of polyolefins and polarities of fillers. One of five different polyolefins, CPO, has different backbone structure and the others have different pendant group. The order of pendant group size from small to big was found out to be HDPE > PP > PB1 > P4MP1. Two different kinds of inorganic particle fillers (carbon black and silica) were compounded to study the effect of polarity of inorganic particles on the slippage behavior. Carbon black represented non-polar filler and silica represented polar filler. In order to make objective and quantitative predictions in twin screw extrusion process, it was necessary to figure out slip velocity - shear stress relation since the boundary conditions on the barrel, screw and die surfaces are determined by slip velocities which are only can be predicted from applied shear stress fields. From the Mooney's method, we could find out slip velocity - shear stress relations using three different diameters of capillary dies having same L/D ratio. A numerical method (Flow Analysis Network method) was applied to simulate the effect of slippage on the flow in twin screw channel based on the slip velocity and shear stress relations obtained from capillary experiments. To confirm the simulation, length of fills for various process conditions were predicted by simulation and they were compared with experimental results. In addition, the screw characteristics and flow patterns for two different special mixing elements (SME, ZME) were obtained to investigate the mechanism and functions of these elements using the FAN method. The simulation of these special mixing elements were compared with conventional screw elements which having same helix angle, diameter and length.

Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coppola, B., E-mail: bcoppola@unisa.it; Di Maio, L.; Scarfato, P.

Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEMmore » investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers.« less

Optical Properties of Polypropylene upon Recycling

PubMed Central

2013-01-01

In the last few years there has been an increasing interest in the possibility of recycling polymeric materials, using physical recycling. However, is it well known that polymers experience a depletion of all the properties upon recycling. These effects have been widely characterized in the literature for what concerns the mechanical or rheological properties. The changes of optical properties after recycling have been much less studied, even if, especially in food packaging, optical characteristics (above all the opacity) are of extreme importance, and thus it is quite significant to assess the effect of recycling on these properties. In this work, the influence of recycling steps on the opacity of films of a commercial grade of isotactic polypropylene (i-PP) was studied. The material was extruded several times to mimic the effect of recycling procedures. After extrusion, films were obtained by cooling samples of material at different cooling rates. The opacity of the obtained films was then measured and related to their crystallinity and morphology. It was found that opacity generally increases on increasing the amount of α phase and for the same amount of α phase on increasing the size of the spherulites. PMID:24288478

Combating oil spill problem using plastic waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saleem, Junaid, E-mail: junaidupm@gmail.com; Ning, Chao; Barford, John

Highlights: • Up-cycling one type of pollution i.e. plastic waste and successfully using it to combat the other type of pollution i.e. oil spill. • Synthesized oil sorbent that has extremely high oil uptake of 90 g/g after prolonged dripping of 1 h. • Synthesized porous oil sorbent film which not only facilitates in oil sorption but also increases the affinity between sorbent and oil by means of adhesion. - Abstract: Thermoplastic polymers (such as polypropylene, polyethylene, polyethylene terephthalate (PET) and high density polyethylene (HDPE)) constitute 5–15% of municipal solid waste produced across the world. A huge quantity of plasticmore » waste is disposed of each year and is mostly either discarded in landfills or incinerated. On the other hand, the usage of synthetic polymers as oil sorbents, in particular, polyolefins, including polypropylene (PP), and polyethylene (PE) are the most commonly used oil sorbent materials mainly due to their low cost. However, they possess relatively low oil absorption capacities. In this work, we provide an innovative way to produce a value-added product such as oil-sorbent film with high practical oil uptake values in terms of g/g from waste HDPE bottles for rapid oil spill remedy.« less

Metal-chelating active packaging film enhances lysozyme inhibition of Listeria monocytogenes.

PubMed

Roman, Maxine J; Decker, Eric A; Goddard, Julie M

2014-07-01

Several studies have demonstrated that metal chelators enhance the antimicrobial activity of lysozyme. This study examined the effect of metal-chelating active packaging film on the antimicrobial activity of lysozyme against Listeria monocytogenes. Polypropylene films were surface modified by photoinitiated graft polymerization of acrylic acid (PP-g-PAA) from the food contact surface of the films to impart chelating activity based on electrostatic interactions. PP-g-PAA exhibited a carboxylic acid density of 113 ± 5.4 nmol cm(-2) and an iron chelating activity of 53.7 ± 9.8 nmol cm(-2). The antimicrobial interaction of lysozyme and PP-g-PAA depended on growth media composition. PP-g-PAA hindered lysozyme activity at low ionic strength (2.48-log increase at 64.4 mM total ionic strength) and enhanced lysozyme activity at moderate ionic strength (5.22-log reduction at 120 mM total ionic strength). These data support the hypothesis that at neutral pH, synergy between carboxylate metal-chelating films (pKa(bulk) 6.45) and lysozyme (pI 11.35) is optimal in solutions of moderate to high ionic strength to minimize undesirable charge interactions, such as lysozyme absorption onto film. These findings suggest that active packaging, which chelates metal ions based on ligand-specific interactions, in contrast to electrostatic interactions, may improve antimicrobial synergy. This work demonstrates the potential application of metal-chelating active packaging films to enhance the antimicrobial activity of membrane-disrupting antimicrobials, such as lysozyme.

Polystyrene plastic: a source and sink for polycyclic aromatic hydrocarbons in the marine environment

PubMed Central

Rochman, Chelsea M.; Manzano, Carlos; Hentschel, Brian T.; Massey Simonich, Staci L.; Hoh, Eunha

2014-01-01

Polycyclic aromatic hydrocarbons (PAHs) on virgin polystyrene (PS) and PS marine debris led us to examine PS as a source and sink for PAHs in the marine environment. At two locations in San Diego Bay, we measured sorption of PAHs to PS pellets, sampling at 0, 1, 3, 6, 9 and 12 months. We detected 25 PAHs using a new analytical method with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. Several congeners were detected on samples before deployment. After deployment, some concentrations decreased (1,3-dimethylnaphthalene and 2,6-methylnaphthalene) while most increased (2-methylanthracene and all parent PAHs (PPAHs) except fluorene and fluoranthene), suggesting PS debris is a source and sink for PAHs. When comparing sorbed concentrations of PPAHs on PS to the five most common polymers (polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP)), PS sorbed greater concentrations than PP, PET and PVC, similar to HDPE and LDPE. Most strikingly, at 0 months, PPAHs on PS ranged from 8-200 times greater than on PET, HDPE, PVC, LDPE, and PP. The combination of greater PAHs in virgin pellets and large sorption suggests that PS may pose a greater risk of exposure to PAHs upon ingestion. PMID:24341360

Polystyrene plastic: a source and sink for polycyclic aromatic hydrocarbons in the marine environment.

PubMed

Rochman, Chelsea M; Manzano, Carlos; Hentschel, Brian T; Simonich, Staci L Massey; Hoh, Eunha

2013-12-17

Polycyclic aromatic hydrocarbons (PAHs) on virgin polystyrene (PS) and PS marine debris led us to examine PS as a source and sink for PAHs in the marine environment. At two locations in San Diego Bay, we measured sorption of PAHs to PS pellets, sampling at 0, 1, 3, 6, 9, and 12 months. We detected 25 PAHs using a new analytical method with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. Several congeners were detected on samples before deployment. After deployment, some concentrations decreased (1,3-dimethylnaphthalene and 2,6-methylnaphthalene), while most increased [2-methylanthracene and all parent PAHs (PPAHs), except fluorene and fluoranthene], suggesting that PS debris is a source and sink for PAHs. When sorbed concentrations of PPAHs on PS are compared to the five most common polymers [polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP)], PS sorbed greater concentrations than PP, PET, and PVC, similar to HDPE and LDPE. Most strikingly, at 0 months, PPAHs on PS ranged from 8 to 200 times greater than on PET, HDPE, PVC, LDPE, and PP. The combination of greater PAHs in virgin pellets and large sorption suggests that PS may pose a greater risk of exposure to PAHs upon ingestion.

Interaction of antimicrobial preservatives with blow-fill-seal packs: correlating sorption with solubility parameters.

PubMed

Amin, Aeshna; Dare, Manish; Sangamwar, Abhay; Bansal, Arvind Kumar

2012-01-01

The aim of this work was to study the interaction of four commonly used ophthalmic antimicrobial preservatives [benzyl alcohol (BA), chlorbutol (CBL), benzalkonium chloride (BKC), and chlorhexidine gluconate (CG)] with Blow-Fill-Seal (BFS) packs. Effect of packaging material [low-density polyethylene (LDPE), polypropylene (PP)], humidity (25% RH, 75% RH) and concentration (0.5, 1.0, 2.0 mM BA/CBL in LDPE) was studied. BKC and CG gave negligible loss (<4%) in BFS packs over a period of 3 months. BA and CBL, however, gave marked losses in LDPE (ca. 70-90%) and PP (ca. 7-25%) packs. Humidity did not have any effect on the sorption loss of any preservative. Loss of BA switched from Case II to anomalous behavior with increasing initial concentration. A two-stage sorption behavior was inherent at all concentrations. Loss of CBL followed anomalous behavior with biphasic kinetics of loss. It was concluded that all the four preservatives were appropriate for use in PP BFS packs. However, only BKC and CG were amenable to be used in LDPE BFS packs. Lastly, an empirical expression consisting of the "solubility parameter distance" and "molar volume" of preservatives was developed to correlate the preservative loss in LDPE with the physicochemical properties of the preservatives.

Thermal stabilities of drops of burning thermoplastics under the UL 94 vertical test conditions.

PubMed

Wang, Yong; Zhang, Jun

2013-02-15

The properties of polymer melts will strongly affect the fire hazard of the pool induced by polymer melt flow. In this study the thermal stabilities of eight thermoplastic polymers as well as their melting drops generated under the UL 94 vertical burning test conditions were investigated by thermogravimetric experiments. It was found that the kinetic compensation effect existed for the decomposition reactions of the polymers and their drops. For polymethylmethacrylate (PMMA), high impact polystyrene (HIPS), poly(acrylonitrile-butadiene-styrene) (ABS), polyamide 6 (PA6), polypropylene (PP) and low density polyethylene (LDPE), the onset decomposition temperature and the two decomposition kinetic parameters (the pre-exponential factor and the activation energy) of the drop were less than those of the polymer. However, the onset decomposition temperature and the two kinetic parameters of PC's drop were greater than those of polycarbonate (PC). Interestingly, for polyethylenevinylacetate (EVA18) the drop hardly contained the vinyl acetate chain segments. Similarly, for the PMMA/LDPE blends and the PMMA/PP blends, when the volume fraction of PMMA was less than 50% the drop hardly contained PMMA, implying that the blend would not drip until PMMA burned away and its surface temperature approached the decomposition temperature of the continuous phase composed of LDPE or PP. Copyright © 2012 Elsevier B.V. All rights reserved.

Study of thermal, flammability and mechanical properties of intumescent flame retardant PP/kenaf nanocomposites

NASA Astrophysics Data System (ADS)

Subasinghe; Das; Bhattacharyya

2016-07-01

Detrimental physical and mechanical properties are common problems for composites when their flame retardancy is improved through filler additions. An increased interest of the synergistic nanoparticle addition to improve the flame retardancy of natural fiber composites is the aim of this work. The paper investigates the synergistic effect of two different nanoparticles (halloysite nanotubes (HNTs) and montmorillonite (MMT) nanoclay) on the flame and mechanical properties in an intumescent ammonium polyphosphate (APP)-based polypropylene (PP)/kenaf composite system. First, the nature of nanoparticle dispersion in PP through X-ray diffraction (XRD) and transmission electron microscopy (TEM) reveals that under twin screw compounding process, the partial exfoliation and intercalation have taken place within the nanocomposites. An increase in the decomposition temperature was observed under thermogravimetric analysis (TGA), with the presence of HNT. However, MMT tends to lower the maximum decomposition temperature under inert atmosphere. The flammability analysis in an intumescent flame retardant (IFR) system shows that the suitable amount of high aspect ratio nanoparticles with their exfoliation characteristics effectively helps to reduce the sustained combustion. Even though, improved stiffness properties can be observed with the presence of increased filler content, particle agglomeration tends to reduce the mechanical strengths of these composites due to low compatibilization and crack propagation.

Differential bioavailability of polychlorinated biphenyls associated with environmental particles: Microplastic in comparison to wood, coal and biochar.

PubMed

Beckingham, B; Ghosh, U

2017-01-01

Microplastic particles are increasingly being discovered in diverse habitats and a host of species are found to ingest them. Since plastics are known to sorb hydrophobic organic contaminants (HOCs) there is a question of what risk of chemical exposure is posed to aquatic biota from microplastic-associated contaminants. We investigate bioavailability of polychlorinated biphenyls (PCBs) from polypropylene microplastic by measuring solid-water distribution coefficients, gut fluid solubilization, and bioaccumulation using sediment invertebrate worms as a test system. Microplastic-associated PCBs are placed in a differential bioavailability framework by comparing the results to several other natural and anthrogenic particles, including wood, coal, and biochar. PCB distribution coefficients for polypropylene were higher than natural organic materials like wood, but in the range of lipids and sediment organic carbon, and smaller than black carbons like coal and biochars. Gut fluid solubilization potential increased in the order: coal < polypropylene < biochar < wood. Interestingly, lower gut fluid solubilization for polypropylene than biochar infers that gut fluid micelles may have solubilized part of the biochar matrix while bioaccessibility from plastic can be limited by the solubilizing potential of gut fluids dependent on the solid to liquid ratio or renewal of fluids in the gut. Biouptake in worms was lower by 76% when PCBs were associated with polypropylene compared to sediment. The presence of microplastics in sediments had an overall impact of reducing bioavailability and transfer of HOCs to sediment-ingesting organisms. Since the vast majority of sediment and suspended particles in the environment are natural organic and inorganic materials, pollutant transfer through particle ingestion will be dominated by these particles and not microplastics. Therefore, these results support the conclusion that in most cases the transfer of organic pollutants to aquatic organisms from microplastic in the diet is likely a small contribution compared to other natural pathways of exposure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Poly(carboxylic acid)-Cyclodextrin/Anionic Porphyrin Finished Fabrics as Photosensitizer Releasers for Antimicrobial Photodynamic Therapy.

PubMed

Castriciano, Maria Angela; Zagami, Roberto; Casaletto, Maria Pia; Martel, Bernard; Trapani, Mariachiara; Romeo, Andrea; Villari, Valentina; Sciortino, Maria Teresa; Grasso, Laura; Guglielmino, Salvatore; Scolaro, Luigi Monsù; Mazzaglia, Antonino

2017-04-10

In the development of new antibacterial therapeutic approaches to fight multidrug-resistant bacteria, antimicrobial photodynamic therapy (aPDT) represents a well-known alternative to treat local infections caused by different microorganisms. Here we present a polypropylene (PP) fabric finished with citrate-hydroxypropyl-βCD polymer (PP-CD) entrapping the tetra-anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (TPPS) as photosensitizer-eluting scaffold (PP-CD/TPPS) for aPDT. The concept is based on host-guest complexation of porphyrin in the cavities of CDs immobilized on the PP fibers, followed by its sustained and controlled delivery in release medium and simultaneous photoinactivation of microorganisms. Morphology of fabric was characterized by optical (OM) and scanning electron microscopies (SEM). Optical properties were investigated by UV-vis absorption, steady- and time-resolved fluorescence emission spectroscopy. X-ray photoelectron spectroscopy (XPS) and FT-IR revealed the surface chemical composition and the distribution map of the molecular components on the fabric, respectively. Direct 1 O 2 determination allowed to assess the potential photodynamic activity of the fabric. Release kinetics of TPPS in physiological conditions pointed out the role of the CD cavity to control the TPPS elution. Photoantimicrobial activity of the porphyrin-loaded textile was investigated against both Gram-positive Staphylococcus aureus ATCC 29213 (S. aureus) and Gram-negative Pseudomonas aeruginosa ATCC 27853 (P. aeruginosa). Optical microscopy coupled with UV-vis extinction and fluorescence spectra aim to ascertain the uptake of TPPS to S. aureus bacterial cells. Finally, PP-CD/TPPS fabric-treated S. aureus cells were photokilled of 99.98%. Moreover, low adhesion of S. aureus cells on textile was established. Conversely, no photodamage of fabric-treated P. aeruginosa cells was observed, together with their satisfying adhesion.

Triple-Layer Plastic Bags Protect Dry Common Beans (Phaseolus vulgaris) Against Damage by Acanthoscelides obtectus (Coleoptera: Chrysomelidae) During Storage.

PubMed

Mutungi, C; Affognon, H D; Njoroge, A W; Manono, J; Baributsa, D; Murdock, L L

2015-10-01

Fumigated dry common beans (Phaseolus vulgaris L.) that were artificially infested with Acanthoscelides obtectus Say, and others that were not artificially infested, were stored in hermetic triple-layer PICS (Lela Agro, Kano, Nigeria) or woven polypropylene (PP) bags for 6 mo at ambient laboratory temperature conditions of 22.6 ± 1.9°C and 60.1 ± 4.3% relative humidity. In an additional trial, beans contained in PP bags were treated with Actellic Super dust before introducing A. obtectus. Moisture content, number of live adult A. obtectus, seed damage, weight loss, and seed germination were determined at monthly intervals. At 6 mo, beans stored in PICS bags retained higher moisture than those stored in PP bags, but in all treatments the moisture level remained below that recommended for safe storage of beans. In the PICS bags, proliferation of A. obtectus did not proceed and at 6 mo, beans stored in these bags did not have insect-inflicted seed damage or weight loss. In contrast, seed damage and weight loss in PP bags exceeded economic threshold after 1 mo in the absence of Actellic Super dust (Syngenta Crop protection AG, Basle, Switzerland), and after 2 mo in the presence of it. Germination of beans stored in PP bags decreased greatly whereas the beans stored in PICS bags did not show reduced germination. Chemical free storage of common beans in PICS bags protects them against damage by A. obtectus. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Comparative study on the deposition of silicon oxide permeation barrier coatings for polymers using hexamethyldisilazane (HMDSN) and hexamethyldisiloxane (HMDSO)

NASA Astrophysics Data System (ADS)

Mitschker, F.; Schücke, L.; Hoppe, Ch; Jaritz, M.; Dahlmann, R.; de los Arcos, T.; Hopmann, Ch; Grundmeier, G.; Awakowicz, P.

2018-06-01

The effect of the selection of hexamethyldisiloxane (HMDSO) and hexamethyldisilazane (HMDSN) as a precursor in a microwave driven low pressure plasma on the deposition of silicon oxide barrier coatings and silicon based organic interlayers on polyethylene terephthalate (PET) and polypropylene (PP) substrates is investigated. Mass spectrometry is used to quantify the absolute gas density and the degree of depletion of neutral precursor molecules under variation of oxygen admixture. On average, HMDSN shows a smaller density, a higher depletion and the production of smaller fragments. Subsequently, this is correlated with barrier performance and chemical structure as a function of barrier layer thickness and oxygen admixture on PET. For this purpose, the oxygen transmission rate (OTR) is measured and Fourier transformed infrared (FTIR) spectroscopy as well as x-ray photoelectron spectroscopy (XPS) is performed. HMDSN based coatings exhibit significantly higher barrier performances for high admixtures of oxygen (200 sccm). In comparison to HMDSO based processes, however, a higher supply of oxygen is necessary to achieve a sufficient degree of oxidation, cross-linking and, therefore, barrier performance. FTIR and XPS reveal a distinct carbon content for low oxygen admixtures (10 and 20 sccm) in case of HMDSN based coatings. The variation of interlayer thickness also reveals significantly higher OTR for HMDSO based coatings on PET and PP. Barrier performance of HMDSO based coatings improves with increasing interlayer thickness up to 10 nm for PET and PP. HMDSN based coatings exhibit a minimum of OTR without interlayer on PP and for 2 nm interlayer thickness on PET. Furthermore, HMDSN based coatings show distinctly higher bond strengths to the PP substrate.

Drug product immobilization in recycled polyethylene/polypropylene reclaimed from municipal solid waste: experimental and numerical assessment.

PubMed

Saad, Walid; Slika, Wael; Mawla, Zara; Saad, George

2017-12-01

Recently, there has been a growing interest in identifying suitable routes for the disposal of pharmaceutical wastes. This study investigates the potential of matrix materials composed of recycled polyethylene/polypropylene reclaimed from municipal solid wastes at immobilizing pharmaceutical solid wastes. Diclofenac (DF) drug product was embedded in boards of recycled plastic material, and leaching in water was assessed at various temperatures. DF concentrations were determined by high-performance liquid chromatography and revealed a maximum leachable fraction of 4% under accelerated conditions of 70°C, and less than 0.3% following 39 days of exposure at 20°C. The Ensemble Kalman Filter was employed to characterize the leaching behavior of DF. The filter verified the occurrence of leaching through diffusion, and was successful in predicting the leaching behavior of DF at 50°C and 70°C.

Immobilized enzymes in blood plasma exchangers via radiation grafting

NASA Astrophysics Data System (ADS)

Gombotz, Wayne; Hoffman, Allan; Schmer, Gottfried; Uenoyama, Satoshi

The enzyme asparaginase was immobilized onto a porous hollow polypropylene (PP) fiber blood plasma exchange device for the treatment of acute lymphocytic leukemia. The devices were first radiation grafted with polymethacrylic acid (poly(MAAc)). This introduces carboxyl groups onto the surface of the fibers. Several variables were studied in the grafting reaction including the effects of solvent type and monomer concentration. The carboxyl groups were activated with N-hydroxy succinimide (NHS) using carbodiimide chemistry. Asparaginase was then covalently immobilized on the activated surfaces. Quantitative relationships were found relating the percent graft to the amount of immobilized enzyme which was active. The enzyme reactor was tested both in vitro and in vivo using a sheep as an animal model.

Nonlinear behavior of PP/PS blends with and without clay under large amplitude oscillatory shear (LAOS) flow

NASA Astrophysics Data System (ADS)

Salehiyan, Reza; Song, Hyeong Yong; Hyun, Kyu

2015-05-01

Dynamic oscillatory measurement, i.e., small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test was used to investigate linear and non-linear viscoelastic properties of Polypropylene (PP)/Polystyrene (PS) blends with and without 5 wt.% clay (C20A). Fourier transform (FT-Rheology), Lissajous curves and stress decomposition methods were used to analyze non-linear responses under LAOS flow. Composition effects of blends were investigated prior to compatibilization effects. Elevated concentrations of dispersed phase (PS) increased the moduli G'(ω) from SAOS test and G*( γ 0) from LAOS test of the blends as well as strain thinning behavior. Interestingly, addition of 5 wt.% clay (C20A) boosted moduli of the blends as well as led to similar strain thinning behaviors among the PP/PS/C20A blends, except for the (90/10) PP/PS blend. The latter did not show improved rheological properties despite morphological improvements, as shown by SEM. Results from SEM and improved rheological properties of PP/PS/C20A blends revealed the compatibilization effects of clay (C20A) particles regardless of size reduction mechanisms. Third relative intensities ( I 3/1) from FT-rheology were found to be sensitive to clay (C20A) additions for the (70/30) and (30/70) PP/PS blends. Similarly, Lissajous curves could detect changes upon clay (C20A) addition, specifically at lower strain amplitudes whereupon addition of 5 wt.% clay resulted in the closed loops of Lissajous curves showing a more ellipsoidal shape due to increased elasticity in the blends. However, detection of these changes at larger strain amplitudes was more challenging. Therefore, stress decomposition (SD) method was applied for more precise characterization as it decomposes the total stress (σ) into elastic stress (σ') and viscous stress (σ″). Using SD method, elastic stress was more distorted, especially, strain hardening, while the total stress response remained almost unchanged at larger strain amplitudes.

Morphological characteristics of waste polyethylene/polypropylene plastics during pyrolysis and representative morphological signal characterizing pyrolysis stages.

PubMed

Wang, H; Chen, D; Yuan, G; Ma, X; Dai, X

2013-02-01

In this work, the morphological characteristics of waste polyethylene (PE)/polypropylene (PP) plastics during their pyrolysis process were investigated, and based on their basic image changing patterns representative morphological signals describing the pyrolysis stages were obtained. PE and PP granules and films were used as typical plastics for testing, and influence of impurities was also investigated. During pyrolysis experiments, photographs of the testing samples were taken sequentially with a high-speed infrared camera, and the quantitative parameters that describe the morphological characteristics of these photographs were explored using the "Image Pro Plus (v6.3)" digital image processing software. The experimental results showed that plastics pyrolysis involved four stages: melting, two stages of decomposition which are characterized with bubble formation caused by volatile evaporating, and ash deposition; and each stage was characterized with its own phase changing behaviors and morphological features. Two stages of decomposition are the key step of pyrolysis since they took up half or more of the reaction time; melting step consumed another half of reaction time in experiments when raw materials were heated up from ambient temperatures; and coke-like deposition appeared as a result of decomposition completion. Two morphological signals defined from digital image processing, namely, pixel area of the interested reaction region and bubble ratio (BR) caused by volatile evaporating were found to change regularly with pyrolysis stages. In particular, for all experimental scenarios with plastics films and granules, the BR curves always exhibited a slowly drop as melting started and then a sharp increase followed by a deep decrease corresponding to the first stage of intense decomposition, afterwards a second increase - drop section corresponding to the second stage of decomposition appeared. As ash deposition happened, the BR dropped to zero or very low values. When impurities were involved, the shape of BR curves showed that intense decomposition started earlier but morphological characteristics remained the same. In addition, compared to parameters such as pressure, the BR reflects reaction stages better and its change with pyrolysis process of PE/PP plastics with or without impurities was more intrinsically process correlated; therefore it can be adopted as a signal for pyrolysis process characterization, as well as offering guide to process improvement and reactor design. Copyright © 2012 Elsevier Ltd. All rights reserved.

Wetting of polymer melts on coated and uncoated steel surfaces

NASA Astrophysics Data System (ADS)

Vera, Julie; Contraires, Elise; Brulez, Anne-Catherine; Larochette, Mathieu; Valette, Stéphane; Benayoun, Stéphane

2017-07-01

A comparative study of the wetting of three different commercial polymer melts on various coated and uncoated steel surfaces is described in this report. The wettability of steel and coatings (three different titanium nitride coatings, TiN, TiNOx, TiNOy, a chromium coating, CrN, and a diamond-like carbon coating, DLC) used for mold in polymer processing is determined at different temperatures between 25 °C and 120 °C. Contact angle measurements of melted polypropylene (PP), Acrylonitrile Butadiene Styrene (ABS) and Polycarbonate (PC) on steel and on the different coatings were performed to investigate the wetting behavior under closer-to-processing conditions. Recommendations for good measurement conditions were proposed. Moreover, the surface free energy of each melt polymer was determined. The works of adhesion between all polymers and all substrates were established. Among all tested polymers, the lowest value of the works of adhesion is calculated for ABS and for PC thereafter, and the highest value is calculated for PP. These results will be particularly important for such applications as determining the extent to which these polymers can contribute to the replication quality in injection molding.

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants.

PubMed

Simal-Gándara, J; Sarria-Vidal, M; Koorevaar, A; Rijk, R

2000-08-01

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick oriented PP) into the food stimulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.

Variation of mechanical and thermal properties of the thermoplastics reinforced with natural fibers by electron beam processing

NASA Astrophysics Data System (ADS)

Kim, Sok Won; Oh, Seungmin; Lee, Kyuse

2007-11-01

With restrictions for environmental protection being strengthened, the thermoplastics reinforced with natural fibers (NFs) such as jute, kenaf, flax, etc., appeared as an automobile interior material instead of the chemical plastics. Regardless of many advantages, one shortcoming is the deformation after being formed in high temperature of about 200 °C, caused by the poor adhesion between the natural fibers and thermoplastics. Also, the energy saving in connection with car air-conditioning becomes very important. In this study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composing of 50% polypropylene (PP) and 50% natural fiber irradiated by the electron beam (energy: 0.5 MeV, dose: 0-20 kGy) were measured. The length and thickness of PP and NF are 80±10 mm and 40-120 μm, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum when the dose of electron beam is 10 kGy, and the deformation after the thermal cycle were reduced by the electron beam.

Cross-Linked Poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-co-HFP) Gel Polymer Electrolyte for Flexible Li-Ion Battery Integrated with Organic Light Emitting Diode (OLED)

PubMed Central

Kim, Ilhwan; Kim, Bong Sung; Nam, Seunghoon; Lee, Hoo-Jeong; Chung, Ho Kyoon; Cho, Sung Min; Luu, Thi Hoai Thuong; Hyun, Seungmin; Kang, Chiwon

2018-01-01

Here, we fabricate poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-co-HFP) by electrospinning for a gel polymer electrolyte (GPE) for use in flexible Li-ion batteries (LIBs). As a solvent, we use N-methyl-2-pyrrolidone (NMP), which helps produce the cross-linked morphology of PVDF-co-HFP separator, owing to its low volatility. The cross-linked PVDF-co-HFP separator shows an uptake rate higher than that of a commercialized polypropylene (PP) separator. Moreover, the PVDF-co-HFP separator shows an ionic conductivity of 2.3 × 10−3 S/cm at room temperature, comparable with previously reported values. An LIB full-cell assembled with the PVDF-co-HFP-based GPE shows capacities higher than its counterpart with the commercialized PP separator, confirming that the cross-linked PVDF-co-HFP separator provides highly efficient ionic conducting pathways. In addition, we integrate a flexible LIB cell using the PVDF-co-HFP GPE with a flexible organic light emitting diode (OLED), demonstrating a fully flexible unit of LIB and OLED. PMID:29614800

Cross-Linked Poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-co-HFP) Gel Polymer Electrolyte for Flexible Li-Ion Battery Integrated with Organic Light Emitting Diode (OLED).

PubMed

Kim, Ilhwan; Kim, Bong Sung; Nam, Seunghoon; Lee, Hoo-Jeong; Chung, Ho Kyoon; Cho, Sung Min; Luu, Thi Hoai Thuong; Hyun, Seungmin; Kang, Chiwon

2018-04-02

Here, we fabricate poly(vinylidene fluoride- co -hexafluoropropene) (PVDF- co -HFP) by electrospinning for a gel polymer electrolyte (GPE) for use in flexible Li-ion batteries (LIBs). As a solvent, we use N -methyl-2-pyrrolidone (NMP), which helps produce the cross-linked morphology of PVDF- co -HFP separator, owing to its low volatility. The cross-linked PVDF- co -HFP separator shows an uptake rate higher than that of a commercialized polypropylene (PP) separator. Moreover, the PVDF- co -HFP separator shows an ionic conductivity of 2.3 × 10 -3 S/cm at room temperature, comparable with previously reported values. An LIB full-cell assembled with the PVDF- co -HFP-based GPE shows capacities higher than its counterpart with the commercialized PP separator, confirming that the cross-linked PVDF- co -HFP separator provides highly efficient ionic conducting pathways. In addition, we integrate a flexible LIB cell using the PVDF- co -HFP GPE with a flexible organic light emitting diode (OLED), demonstrating a fully flexible unit of LIB and OLED.

Validation of ATR FT-IR to identify polymers of plastic marine debris, including those ingested by marine organisms

USGS Publications Warehouse

Jung, Melissa R.; Horgen, F. David; Orski, Sara V.; Rodriguez, Viviana; Beers, Kathryn L.; Balazs, George H.; Jones, T. Todd; Work, Thierry M.; Brignac, Kayla C.; Royer, Sarah-Jeanne; Hyrenbach, David K.; Jensen, Brenda A.; Lynch, Jennifer M.

2018-01-01

Polymer identification of plastic marine debris can help identify its sources, degradation, and fate. We optimized and validated a fast, simple, and accessible technique, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), to identify polymers contained in plastic ingested by sea turtles. Spectra of consumer good items with known resin identification codes #1–6 and several #7 plastics were compared to standard and raw manufactured polymers. High temperature size exclusion chromatography measurements confirmed ATR FT-IR could differentiate these polymers. High-density (HDPE) and low-density polyethylene (LDPE) discrimination is challenging but a clear step-by-step guide is provided that identified 78% of ingested PE samples. The optimal cleaning methods consisted of wiping ingested pieces with water or cutting. Of 828 ingested plastics pieces from 50 Pacific sea turtles, 96% were identified by ATR FT-IR as HDPE, LDPE, unknown PE, polypropylene (PP), PE and PP mixtures, polystyrene, polyvinyl chloride, and nylon.

Effect of ionizing radiation on physicochemical and mechanical properties of commercial multilayer coextruded flexible plastics packaging materials

NASA Astrophysics Data System (ADS)

Goulas, Antonios E.; Riganakos, Kyriakos A.; Kontominas, Michael G.

2003-12-01

The effect of gamma radiation (doses: 5, 10 and 30 kGy) on mechanical properties, gas and water vapour permeability and overall migration values into distilled water, 3% aqueous acetic acid and iso-octane was studied for a series of commercial multilayer flexible packaging materials based on coextruded polypropylene (PP), ethylene vinyl alcohol (EVOH), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polyamide (PA) and Ionomer. The results showed that radiation doses of 5 and 10 kGy induced no statistically significant differences ( p>0.05) in all polymer properties examined. A dose of 30 kGy induced differences ( p<0.05) in the mechanical properties of PA/LDPE, LDPE/EVOH/LDPE and LDPE/PA/Ionomer films. In addition, the same dose induced differences ( p<0.05) in the overall migration from Ionomer/EVOH/LDPE and LDPE/PA/Ionomer films into 3% acetic acid and iso-octane and in the overall migration from PP/EVOH/LDPE-LLDPE into iso-octane. Differences recorded, are discussed in relation to food irradiation applications of respective packaging materials.

Laser welding process in PP moulding parts: Evaluation of seam performance

NASA Astrophysics Data System (ADS)

Oliveira, N.; Pontes, A. J.

2015-12-01

The Polypropylene is one of the most versatile polymer materials used in the industry. Due to this versatility, it is possible to use it in different products. This material can also be mixed with several additives namely glass fiber, carbon nanotubes, etc. This compatibility with different additives allows also obtaining products with characteristics that goes from an impact absorber to an electricity conductor. When is necessary to join components in PP they could be welded through hot plate, ultrasonic weld and also by laser. This study had the objective of study the influence of several variables, capable of influence the final quality of the seam. In this case were studied variables of the injection molding process as mold temperature and cooling time. Was also studied laser welding variables and different materials. The results showed that the variables that have the most influence were mould temperature, laser velocity and laser diameter. The seams were analyzed using Optical Microscopy technique. The seams showed perfect contact between the materials analyzed, despite the high standard variation presented in the mechanical testes.

Electric Charge Accumulation in Polar and Non-Polar Polymers under Electron Beam Irradiation

NASA Astrophysics Data System (ADS)

Nagasawa, Kenichiro; Honjoh, Masato; Takada, Tatsuo; Miyake, Hiroaki; Tanaka, Yasuhiro

The electric charge accumulation under an electron beam irradiation (40 keV and 60 keV) was measured by using the pressure wave propagation (PWP) method in the dielectric insulation materials, such as polar polymeric films (polycarbonate (PC), polyethylene-naphthalate (PEN), polyimide (PI), and polyethylene-terephthalate (PET)) and non-polar polymeric films (polystyrene (PS), polypropylene (PP), polyethylene (PE) and polytetrafluoroethylene (PTFE)). The PE and PTFE (non-polar polymers) showed the properties of large amount of electric charge accumulation over 50 C/m3 and long saturation time over 80 minutes. The PP and PS (non-polar polymer) showed the properties of middle amount of charge accumulation about 20 C/m3 and middle saturation time about 1 to 20 minutes. The PC, PEN, PI and PET (polar polymers) showed the properties of small amount of charge accumulation about 5 to 20 C/m3 and within short saturation time about 1.0 minutes. This paper summarizes the relationship between the properties of charge accumulation and chemical structural formula, and compares between the electro static potential distribution with negative charged polymer and its chemical structural formula.

Review of the partitioning of chemicals into different plastics: Consequences for the risk assessment of marine plastic debris.

PubMed

O'Connor, Isabel A; Golsteijn, Laura; Hendriks, A Jan

2016-12-15

Marine plastic debris are found worldwide in oceans and coastal areas. They degrade only slowly and contain chemicals added during manufacture or absorbed from the seawater. Therefore, they can pose a long-lasting contaminant source and potentially transfer chemicals to marine organisms when ingested. In order to assess their risk, the contaminant concentration in the plastics needs to be estimated and differences understood. We collected from literature plastic water partition coefficients of various organic chemicals for seven plastic types: polydimethylsiloxane (PDMS), high-density, low-density and ultra-high molecular weight polyethylene (LDPE, HDPE, UHMWPE), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC). Most data was available for PDMS (1060) and LDPE (220), but much less for the remaining plastics (73). Where possible, regression models were developed and the partitioning was compared between the different plastic types. The partitioning of chemicals follows the order of LDPE≈HDPE≥PP>PVC≈PS. Data describing the impact of weathering are urgently needed. Copyright © 2016 Elsevier Ltd. All rights reserved.