Investigation of Thermal Properties of High-Density Polyethylene/Aluminum Nanocomposites by Photothermal Infrared Radiometry

NASA Astrophysics Data System (ADS)

Koca, H. D.; Evgin, T.; Horny, N.; Chirtoc, M.; Turgut, A.; Tavman, I. H.

2017-12-01

In this study, thermal properties of high-density polyethylene (HDPE) filled with nanosized Al particles (80 nm) were investigated. Samples were prepared using melt mixing method up to filler volume fraction of 29 %, followed by compression molding. By using modulated photothermal radiometry (PTR) technique, thermal diffusivity and thermal effusivity were obtained. The effective thermal conductivity of nanocomposites was calculated directly from PTR measurements and from the measurements of density, specific heat capacity (by differential scanning calorimetry) and thermal diffusivity (obtained from PTR signal amplitude and phase). It is concluded that the thermal conductivity of HDPE composites increases with increasing Al fraction and the highest effective thermal conductivity enhancement of 205 % is achieved at a filler volume fraction of 29 %. The obtained results were compared with the theoretical models and experimental data given in the literature. The results demonstrate that Agari and Uno, and Cheng and Vachon models can predict well the thermal conductivity of HDPE/Al nanocomposites in the whole range of Al fractions.

High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

NASA Astrophysics Data System (ADS)

Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

2015-04-01

A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

A complete life cycle assessment of high density polyethylene plastic bottle

NASA Astrophysics Data System (ADS)

Treenate, P.; Limphitakphong, N.; Chavalparit, O.

2017-07-01

This study was aimed to determine environmental performances of a lubricant oil bottle made from high density polyethylene and to develop potential measures for reducing its impacts. A complete life cycle assessment was carried out to understand a whole effect on the environment from acquiring, processing, using, and disposing the product. Two scenarios of disposal phase; recycle and incineration: were examined to quantify a lesser degree on environmental impact. The results illustrated that major impacts of the two scenarios were at the same categories with the highest contributor of raw material acquisition and pre-processing. However, all impacts in case of recycling provided a lower point than that in case of incineration, except mineral extraction. Finally, feasible measures for reducing the environmental impact of high density polyethylene plastic bottle were proposed in accordance with 3Rs concept.

Mechanical properties of high density polyethylene--pennycress press cake composites

USDA-ARS?s Scientific Manuscript database

Pennycress press cake (PPC) is evaluated as a bio-based fiber reinforcement. PPC is a by-product of crop seed oil extraction. Composites with a high density polyethylene (HDPE) matrix are created by twin screw compounding of 25% by weight of PPC and either 0% or 5% by weight of maleated polyethyle...

High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance

PubMed Central

Huang, Runzhou; Xu, Xinwu; Lee, Sunyoung; Zhang, Yang; Kim, Birm-June; Wu, Qinglin

2013-01-01

The effect of individual and combined talc and glass fibers (GFs) on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE) composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE) values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites. PMID:28788322

The yield and post-yield behavior of high-density polyethylene

NASA Technical Reports Server (NTRS)

Semeliss, M. A.; Wong, R.; Tuttle, M. E.

1990-01-01

An experimental and analytical evaluation was made of the yield and post-yield behavior of high-density polyethylene, a semi-crystalline thermoplastic. Polyethylene was selected for study because it is very inexpensive and readily available in the form of thin-walled tubes. Thin-walled tubular specimens were subjected to axial loads and internal pressures, such that the specimens were subjected to a known biaxial loading. A constant octahederal shear stress rate was imposed during all tests. The measured yield and post-yield behavior was compared with predictions based on both isotropic and anisotropic models. Of particular interest was whether inelastic behavior was sensitive to the hydrostatic stress level. The major achievements and conclusions reached are discussed.

Mechanical and thermal properties of high density polyethylene – dried distillers grains with solubles composites

USDA-ARS?s Scientific Manuscript database

Dried Distillers Grain with Solubles (DDGS) is evaluated as a bio-based fiber reinforcement. Injection molded composites of high density polyethylene (HDPE), 25% by weight of DDGS, and either 5% of 0% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding and injection mo...

Thermal and catalytic degradation of high and low density polyethylene into fuel oil

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

Uddin, Azhar; Koizumi, Kazuo; Sakata, Yusaku

1996-12-31

The degradation of four different types of polyethylene (PE) namely high density PE (HDPE), low density PE (LDPE), linear low density PE (LLDPE), and cross-linked PE (XLPE) was carried out at 430 {degrees}C by batch operation using silica-alumina as a solid acid catalyst and thermally without any catalyst. For thermal degradation, both HDPE and XLPE produced significant amount of wax-like compounds and the yield of liquid products were lower than that of LDPE and LLDPE. LDPE and LLDPE also produced small amount of wax-like compounds. Thus the structure of the degrading polymers influenced the product yields. The liquid products frommore » thermal degradation were broadly distributed in the carbon fraction of n-C{sub 5} to n-C{sub 25} (boiling point range, 36-405 C). With silica-alumina, the polyethylenes were converted to liquid products with high yields (77-83 wt%) and without any wax production. The liquid products were distributed in the range of n-C{sub 5} to n-C{sub 20} (Mostly C{sub 5}-C{sub 12}). Solid acid catalyst indiscriminately degraded the various types of polyethylene into light fuel oil. 5 refs., 4 figs., 1 tab.« less

Biological degradation of gas-filled composite materials on the base of polyethylene

NASA Astrophysics Data System (ADS)

Grigoreva, E. A.; Kolesnikova, N. N.; Popov, A. A.; Olkhov, A. A.

2017-12-01

Gas-filled composite materials based on polyethylene were obtained. It was assumed that introduction of porosity in polyethylene will improve the biodegradability of synthetic materials. The morphological and structural changes were estimated, physical and mechanical properties, stability in water and soil of these materials were determined. It is stated that filling the polymer matrix with pores increases the ability to degrade in nature.

Radicals mediated magnetism in Ar plasma treated high-density polyethylene

NASA Astrophysics Data System (ADS)

Orendáč, M.; Čižmár, E.; Kažiková, V.; Orendáčová, A.; Řezníčková, A.; Kolská, Z.; Švorčík, V.

2018-05-01

Electron-spin resonance of high-density polyethylene treated by Ar plasma at 300 K was performed in X-band at temperatures from 2.1 K to 290 K. The observed spectra suggest presence of allyl radicals, whereas the central peak may be attributed to polyenyl radicals or dangled bonds. Pronounced narrowing of the resonance line observed above glassy temperature of polyethylene may be ascribed to thermally activated motional effect with the activation energy Ea /kB = 160 K. The absence of strong exchange interactions is suggested by negligible exchange narrowing found at 2.1 K. The suggestion is supported by the analysis of the temperature dependence of the intensity at low temperatures, which is explicable assuming the coexistence of non-interacting radicals and S = 1/2 dimers with a distribution of antiferromagnetic couplings varying from 2 K to nominally 25 K.

Catalytic and thermal depolymerization of low value post-consumer high density polyethylene plastic

USDA-ARS?s Scientific Manuscript database

The feasibility of catalytic and non-catalytic pyrolytic conversion of low value post-consumer high density polyethylene (HDPE) plastic into crude oil and subsequent distillation was explored. Translation of optimized conditions for catalytic and non-catalytic pyrolysis from TGA to a bench-scale sys...

On the mechanism of charge transport in low density polyethylene

NASA Astrophysics Data System (ADS)

Upadhyay, Avnish K.; Reddy, C. C.

2017-08-01

Polyethylene based polymeric insulators, are being increasingly used in the power industry for their inherent advantages over conventional insulation materials. Specifically, modern power cables are almost made with these materials, replacing the mass-impregnated oil-paper cable technology. However, for ultra-high dc voltage applications, the use of these polymeric cables is hindered by ununderstood charge transport and accumulation. The conventional conduction mechanisms (Pool-Frenkel, Schottky, etc.) fail to track high-field charge transport in low density polyethylene, which is semi-crystalline in nature. Until now, attention was devoted mainly to the amorphous region of the material. In this paper, authors propose a novel mechanism for conduction in low density polyethylene, which could successfully track experimental results. As an implication, a novel, substantial relationship is established for electrical conductivity that could be effectively used for understanding conduction and breakdown in polyethylene, which is vital for successful development of ultra-high voltage dc cables.

Influence of natural fibers on the phase transitions in high-density polyethylene composites using dynamic mechanical analysis

Treesearch

Mehdi Tajvidi; Robert H. Falk; John C. Hermanson; Colin Felton

2003-01-01

Dynamic mechanical analysis was employed to evaluate the performance of various natural fibers in high-density polyethylene composites. Kenaf, newsprint, rice hulls, and wood flour were sources of fiber. Composites were made at 25 percent and 50 percent by weight fiber contents. Maleic anhydride modified polyethylene was also added at 1:25 ratio to the fiber....

Establishing a design procedure for buried steel-reinforced high-density polyethylene pipes : a field study.

DOT National Transportation Integrated Search

2015-11-01

Two field tests were conducted to investigate the field performance of steel-reinforced high-density polyethylene : (SRHDPE) pipes during installation and under traffic loading. One test site was located on E 1000 road in Lawrence, KS, which is : clo...

Time–temperature superposition principle applied to a kenaf-fiber/high-density polyethylene composite

Treesearch

Mehdi Tajvidi; Robert H. Falk; John C. Hermanson

2005-01-01

The time–temperature superposition principle was applied to the viscoelastic properties of a kenaf- fiber/high-density polyethylene (HDPE) composite, and its validity was tested. With a composite of 50% kenaf fibers, 48% HDPE, and 2% compatibilizer, frequency scans from a dynamic mechanical analyzer were performed in the range of 0.1–10 Hz at five different...

Study on ternary low density polyethylene/linear low density polyethylene/thermoplastic starch blend films.

PubMed

Sabetzadeh, Maryam; Bagheri, Rouhollah; Masoomi, Mahmood

2015-03-30

In this work, low-density polyethylene/linear low-density polyethylene/thermoplastic starch (LDPE/LLDPE/TPS) films are prepared with the aim of obtaining environmentally friendly materials containing high TPS content with required packaging properties. Blending of LDPE/LLDPE (70/30 wt/wt) with 5-20 wt% of TPS and 3 wt% of PE-grafted maleic anhydride (PE-g-MA) is performed in a twin-screw extruder, followed by the blowing process. Differential scanning calorimetric results indicate starch has more pronounced effect on crystallization of LLDPE than LDPE. Scanning electron micrograph shows a fairly good dispersion of TPS in PE matrices. Fourier transfer infrared spectra confirm compatibility between polymers using PE-g-MA as the compatibilizer. Storage modulus, loss modulus and complex viscosity increase with incorporation of starch. Tensile strength and elongation-at-break decrease from 18 to 10.5 MPa and 340 to 200%, respectively when TPS increases from 5 to 20%. However, the required mechanical properties for packaging applications are attained when 15 wt% starch is added, as specified in ASTM D4635. Finally 12% increase in water uptake is achieved with inclusion of 15 wt% starch. Copyright © 2014 Elsevier Ltd. All rights reserved.

Solving a product safety problem using a recycled high density polyethylene container

NASA Technical Reports Server (NTRS)

Liu, Ping; Waskom, T. L.

1993-01-01

The objectives are to introduce basic problem-solving techniques for product safety including problem identification, definition, solution criteria, test process and design, and data analysis. The students are given a recycled milk jug made of high density polyethylene (HDPE) by blow molding. The objectives are to design and perform proper material test(s) so they can evaluate the product safety if the milk jug is used in a certain way which is specified in the description of the procedure for this investigation.

Strain-rate/temperature behavior of high density polyethylene in compression

NASA Technical Reports Server (NTRS)

Clements, L. L.; Sherby, O. D.

1978-01-01

The compressive strain rate/temperature behavior of highly linear, high density polyethylene was analyzed in terms of the predictive relations developed for metals and other crystalline materials. For strains of 5 percent and above, the relationship between applied strain rate, dotted epsilon, and resulting flow stress, sigma, was found to be: dotted epsilon exp times (Q sub f/RT) = k'(sigma/sigma sub c) to the nth power; the left-hand side is the activation-energy-compensated strain rate, where Q sub f is activation energy for flow, R is gas constant, and T is temperature; k is a constant, n is temperature-independent stress exponent, and sigma/sigma sub c is structure-compensated stress. A master curve resulted from a logarithmic plot of activation-energy-compensated strain rate versus structure-compensated stress.

Preparation and tensile properties of linear low density polyethylene/rambutan peels (Nephelium chryseum Blum.) flour blends

NASA Astrophysics Data System (ADS)

Nadhirah, A. Ainatun.; Sam, S. T.; Noriman, N. Z.; Voon, C. H.; Samera, S. S.

2015-05-01

The effect of rambutan peels flour (RPF) content on the tensile properties of linear low density polyethylene filled with rambutan peel flour was studied. RPF was melt blended with linear low-density polyethylene (LLDPE). LLDPE/RPF blends were prepared by using internal mixer (brabender) at 160 °C with the flour content ranged from 0 to 15 wt%. The tensile properties were tested by using a universal testing machine (UTM) according to ASTM D638. The highest tensile strength was observed for pure LLDPE while the tensile strength LLDPE/RPF decreased gradually with the addition of rambutan peels flour content from 0% to 15%. Young's modulus of 63 µm to 250 µm rambutan peels blends with LLDPE with the fiber loading of 0 - 15 wt% increased with increasing fiber loading.

Preparation of High Density Polyethylene/Waste Polyurethane Blends Compatibilized with Polyethylene-Graft-Maleic Anhydride by Radiation

PubMed Central

Park, Jong-Seok; Lim, Youn-Mook; Nho, Young-Chang

2015-01-01

Polyurethane (PU) is a very popular polymer that is used in a variety of applications due to its good mechanical, thermal, and chemical properties. However, PU recycling has received significant attention due to environmental issues. In this study, we developed a recycling method for waste PU that utilizes the radiation grafting technique. Grafting of waste PU was carried out using a radiation technique with polyethylene-graft-maleic anhydride (PE-g-MA). The PE-g-MA-grafted PU/high density polyethylene (HDPE) composite was prepared by melt-blending at various concentrations (0–10 phr) of PE-g-MA-grafted PU. The composites were characterized using fourier transform infrared spectroscopy (FT-IR), and their surface morphology and thermal/mechanical properties are reported. For 1 phr PU, the PU could be easily introduced to the HDPE during the melt processing in the blender after the radiation-induced grafting of PU with PE-g-MA. PE-g-MA was easily reacted with PU according to the increasing radiation dose and was located at the interface between the PU and the HDPE during the melt processing in the blender, which improved the interfacial interactions and the mechanical properties of the resultant composites. However, the elongation at break for a PU content >2 phr was drastically decreased. PMID:28788022

Conjunctivodacryocystorhinostomy using a high-density porous polyethylene-coated tear drain tube.

PubMed

Pushker, Neelam; Khurana, Saurbhi; Shrey, Dinesh; Bajaj, Mandeep S; Chawla, Bhavna; Chandra, Mahesh

2013-08-01

To evaluate the outcome of conjunctivodacryocystorhinostomy using a high-density porous polyethylene (HDPP)-coated tear drain tube. Patients with epiphora due to a proximal lacrimal system block were included in a prospective interventional case study. A total of 22 eyes were treated with lacrimal bypass surgery using the HDPP-coated tube. On follow-up (12-41 months), 21 eyes had a patent well-positioned tube with subjective relief of epiphora. In one eye, a loose sleeve was noted during surgery. The tube dislodged postoperatively and was removed. A high success rate with only a few minor complications is achievable using a HDPP-coated tear drain tube for lacrimal bypass surgery. Long-term follow-up is required to look for tube blockage due to conjunctival or nasal mucosal overgrowth.

Synthesis of carbon nanostructures from high density polyethylene (HDPE) and polyethylene terephthalate (PET) waste by chemical vapour deposition

NASA Astrophysics Data System (ADS)

Hatta, M. N. M.; Hashim, M. S.; Hussin, R.; Aida, S.; Kamdi, Z.; Ainuddin, AR; Yunos, MZ

2017-10-01

In this study, carbon nanostructures were synthesized from High Density Polyethylene (HDPE) and Polyethylene terephthalate (PET) waste by single-stage chemical vapour deposition (CVD) method. In CVD, iron was used as catalyst and pyrolitic of carbon source was conducted at temperature 700, 800 and 900°C for 30 minutes. Argon gas was used as carrier gas with flow at 90 sccm. The synthesized carbon nanostructures were characterized by FESEM, EDS and calculation of carbon yield (%). FESEM micrograph shows that the carbon nanostructures were only grown as nanofilament when synthesized from PET waste. The synthesization of carbon nanostructure at 700°C was produced smooth and the smallest diameter nanofilament compared to others. The carbon yield of synthesized carbon nanostructures from PET was lower from HDPE. Furthermore, the carbon yield is recorded to increase with increasing of reaction temperature for all samples. Elemental study by EDS analysis were carried out and the formation of carbon nanostructures was confirmed after CVD process. Utilization of polymer waste to produce carbon nanostructures is beneficial to ensure that the carbon nanotechnology will be sustained in future.

Ni-coated CaCu3Ti4O12/low density polyethylene composite material with ultra-high dielectric permittivity

NASA Astrophysics Data System (ADS)

Gao, L.; Wang, X.; Chen, Y.; Chi, Q. G.; Lei, Q. Q.

2015-08-01

We report a novel low-density polyethylene (LDPE) composite filled with nickel-coated CaCu3Ti4O12 ceramic (denoted as CCTO@Ni), prepared by a melt mixing technique, and its prominent dielectric characteristics. The effects of magnetic field treatment on the dielectric properties of CCTO@Ni/LDPE composite films with a low filler concentration of 10 vol.% were investigated. Our results show that the dielectric permittivity, loss tangent, and conductivity of the LDPE composite films initially improved and then decreased with increasing treatment time under the applied magnetic field. Magnetic field treatment for 60 min led to an ultra-high dielectric permittivity value of 1.57 × 104, four orders of magnitude higher than that of the pure LDPE material. Our results indicate that the magnetic treatment may have induced a percolation effect and enhanced the interfacial polarization of the CCTO@Ni/LDPE composite, resulting in the observed changes in its dielectric properties.

Thermal Diffusivity of High-Density Polyethylene Samples of Different Crystallinity Evaluated by Indirect Transmission Photoacoustics

NASA Astrophysics Data System (ADS)

Nesic, M.; Popovic, M.; Rabasovic, M.; Milicevic, D.; Suljovrujic, E.; Markushev, D.; Stojanovic, Z.

2018-02-01

In this work, thermal diffusivity of crystalline high-density polyethylene samples of various thickness, and prepared using different procedures, was evaluated by transmission gas-microphone frequency photoacoustics. The samples' composition analysis and their degree of crystallinity were determined from the wide-angle X-ray diffraction, which confirmed that high-density polyethylene samples, obtained by slow and fast cooling, were equivalent in composition but with different degrees of crystallinity. Structural analysis, performed by differential scanning calorimetry, demonstrated that all of the used samples had different levels of crystallinity, depending not only on the preparing procedure, but also on sample thickness. Therefore, in order to evaluate the samples' thermal diffusivity, it was necessary to modify standard photoacoustic fitting procedures (based on the normalization of photoacoustic amplitude and phase characteristics on two thickness levels) for the interpretation of photoacoustic measurements. The calculated values of thermal diffusivity were in the range of the expected literature values. Besides that, the obtained results indicate the unexpected correlation between the values of thermal diffusivity and thermal conductivity with the degree of crystallinity of the investigated geometrically thin samples. The results indicate the necessity of additional investigation of energy transport in macromolecular systems, as well as the possible employment of the photoacoustic techniques in order to clarify its mechanism.

The alterations in high density polyethylene properties with gamma irradiation

NASA Astrophysics Data System (ADS)

Zaki, M. F.; Elshaer, Y. H.; Taha, Doaa. H.

2017-10-01

In the present investigation, high density polyethylene (HDPE) polymer has been used to study the alterations in its properties under gamma-irradiation. Physico-chemical properties have been investigated with different spectroscopy techniques, Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), biocompatibility properties, as well as, mechanical properties change. The FT-IR analysis shows the formation of new band at 1716 cm-1 that is attributed to the oxidation of irradiated polymer chains, which is due to the formation of carbonyl groups (C˭O). XRD patterns show that a decrease in the crystallite size and increase in the Full Width at Half Maximum (FWHM). This means that the crystallinity of irradiated samples is decreased with increase in gamma dose. The contact angle measurements show an increase in the surface free energy as the gamma irradiation increases. The measurements of mechanical properties of irradiated HDPE samples were discussed.

High-density polyethylene pipe: A new material for pass-by passive integrated transponder antennas

USGS Publications Warehouse

Kazyak, David C.; Zydlewski, Joseph D.

2012-01-01

Pass-by passive integrated transponder (PIT) antennas are widely used to study the movements of fish in streams. At many sites, stream conditions make it difficult to maintain antennas and obtain a continuous record of movement. We constructed pass-by PIT antennas by using high-density polyethylene (HDPE) and found them to be robust to high flows and winter ice flows. Costs for HDPE antennas were similar to those of traditional polyvinyl chloride (PVC) antennas, although construction was somewhat more complicated. At sites where PVC antennas are frequently damaged, HDPE is a durable and economical alternative for PIT antenna construction.

Raman structural study of melt-mixed blends of isotactic polypropylene with polyethylene of various densities

NASA Astrophysics Data System (ADS)

Prokhorov, K. A.; Nikolaeva, G. Yu; Sagitova, E. A.; Pashinin, P. P.; Guseva, M. A.; Shklyaruk, B. F.; Gerasin, V. A.

2018-04-01

We report a Raman structural study of melt-mixed blends of isotactic polypropylene with two grades of polyethylene: linear high-density and branched low-density polyethylenes. Raman methods, which had been suggested for the analysis of neat polyethylene and isotactic polypropylene, were modified in this study for quantitative analysis of polyethylene/polypropylene blends. We revealed the dependence of the degree of crystallinity and conformational composition of macromolecules in the blends on relative content of the blend components and preparation conditions (quenching or annealing). We suggested a simple Raman method for evaluation of the relative content of the components in polyethylene/polypropylene blends. The degree of crystallinity of our samples, evaluated by Raman spectroscopy, is in good agreement with the results of analysis by differential scanning calorimetry.

Wet self-cleaning of superhydrophobic microfiber adhesives formed from high density polyethylene.

PubMed

Lee, Jongho; Fearing, Ronald S

2012-10-30

Biologically inspired adhesives developed for switchable and controllable adhesion often require repetitive uses in general, dirty, environments. Superhydrophobic microstructures on the lotus leaf lead to exceptional self-cleaning of dirt particles on nonadhesive surfaces with water droplets. This paper describes the self-cleaning properties of a hard-polymer-based adhesive formed with high-aspect-ratio microfibers from high-density polyethylene (HDPE). The microfiber adhesive shows almost complete wet self-cleaning of dirt particles with water droplets, recovering 98% of the adhesion of the pristine microfiber adhesives. The low contact angle hysteresis indicates that the surface of microfiber adhesives is superhydrophobic. Theoretical and experimental studies reveal a design parameter, length, which can control the adhesion without affecting the superhydrophobicity. The results suggest some properties of biologically inspired adhesives can be controlled independently by adjusting design parameters.

Substrate removal kinetics in high-rate upflow anaerobic filters packed with low-density polyethylene media treating high-strength agro-food wastewaters.

PubMed

Rajagopal, Rajinikanth; Torrijos, Michel; Kumar, Pradeep; Mehrotra, Indu

2013-02-15

The process kinetics for two upflow anaerobic filters (UAFs) treating high strength fruit canning and cheese-dairy wastewaters as feed were investigated. The experimental unit consisted of a 10-L (effective volume) reactor filled with low-density polyethylene media. COD removal efficiencies of about 80% were recorded at the maximum OLRs of 19 and 17 g COD L(-1) d(-1) for the fruit canning and cheese-dairy wastewaters, respectively. Modified Stover-Kincannon and second-order kinetic models were applied to data obtained from the experimental studies in order to determine the substrate removal kinetics. According to Stover-Kincannon model, U(max) and K(B) values were estimated as 109.9 and 109.7 g L(-1) d(-1) for fruit canning, and 53.5 and 49.7 g L(-1) d(-1) for cheese dairy wastewaters, respectively. The second order substrate removal rate k(2(s)) was found to be 5.0 and 1.93 d(-1) respectively for fruit canning and cheese dairy wastewaters. As both these models gave high correlation coefficients (R(2) = 98-99%), they could be used in predicting the behaviour or design of the UAF. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of gamma irradiation on high temperature hardness of low-density polyethylene

NASA Astrophysics Data System (ADS)

Chen, Pei-Yun; Yang, Fuqian; Lee, Sanboh

2015-11-01

Gamma irradiation can cause the change of microstructure and molecular structure of polymer, resulting in the change of mechanical properties of polymers. Using the hardness measurement, the effect of gamma irradiation on the high temperature hardness of low-density polyethylene (LDPE) was investigated. The gamma irradiation caused the increase in the melting point, the enthalpy of fusion, and the portion of crystallinity of LDPE. The Vickers hardness of the irradiated LDPE increases with increasing the irradiation dose, annealing temperature, and annealing time. The activation energy for the rate process controlling the reaction between defects linearly decreases with the irradiation dose. The process controlling the hardness evolution in LDPE is endothermic because LDPE is semi-crystalline.

RF plasma cleaning of silicon substrates with high-density polyethylene contamination

NASA Astrophysics Data System (ADS)

Cagomoc, Charisse Marie D.; De Leon, Mark Jeffry D.; Ebuen, Anna Sophia M.; Gilos, Marlo Nicole R.; Vasquez, Magdaleno R., Jr.

2018-01-01

Upon contact with a polymeric material, microparticles from the polymer may adhere to a silicon (Si) substrate during device processing. The adhesion contaminates the surface and, in turn, leads to defects in the fabricated Si-based microelectronic devices. In this study, Si substrates with artificially induced high-density polyethylene (HDPE) contamination was exposed to 13.56 MHz radio frequency (RF) plasma utilizing argon and oxygen gas admixtures at a power density of 5.6 W/cm2 and a working pressure of 110 Pa for up to 6 min of treatment. Optical microscopy studies revealed the removal of up to 74% of the polymer contamination upon plasma exposure. Surface free energy (SFE) increased owing to the removal of contaminants as well as the formation of polar groups on the Si surface after plasma treatment. Atomic force microscopy scans showed a decrease in surface roughness from 12.25 nm for contaminated samples to 0.77 nm after plasma cleaning. The smoothening effect can be attributed to the removal of HDPE particles from the surface. In addition, scanning electron microscope images showed that there was a decrease in the amount of HDPE contaminants adhering onto the surface after plasma exposure.

Calvarial reconstruction using high-density porous polyethylene cranial hemispheres

PubMed Central

Mokal, Nitin J.; Desai, Mahinoor F.

2011-01-01

Aims: Cranial vault reconstruction can be performed with a variety of autologous or alloplastic materials. We describe our experience using high-density porous polyethylene (HDPE) cranial hemisphere for cosmetic and functional restoration of skull defects. The porous nature of the implant allows soft tissue ingrowth, which decreases the incidence of infection. Hence, it can be used in proximity to paranasal sinuses and where previous alloplastic cranioplasties have failed due to implant infection. Materials and Methods: We used the HDPE implant in seven patients over a three-year period for reconstruction of moderate to large cranial defects. Two patients had composite defects, which required additional soft tissue in the form of free flap and tissue expansion. Results: In our series, decompressive craniectomy following trauma was the commonest aetiology and all defects were located in the fronto-parieto-temporal region. The defect size was 10 cm on average in the largest diameter. All patients had good post-operative cranial contour and we encountered no infections, implant exposure or implant migration. Conclusions: Our results indicate that the biocompatibility and flexibility of the HDPE cranial hemisphere implant make it an excellent alternative to existing methods of calvarial reconstruction. PMID:22279274

Fabrication, characterization and gamma rays shielding properties of nano and micro lead oxide-dispersed-high density polyethylene composites

NASA Astrophysics Data System (ADS)

Mahmoud, Mohamed E.; El-Khatib, Ahmed M.; Badawi, Mohamed S.; Rashad, Amal R.; El-Sharkawy, Rehab M.; Thabet, Abouzeid A.

2018-04-01

Polymer composites of high-density polyethylene (HD-PE) filled with powdered lead oxide nanoparticles (PbO NPs) and bulk lead oxide (PbO Blk) were prepared with filler weight fraction [10% and 50%]. These polymer composites were investigated for radiation-shielding of gamma-rays emitted from radioactive point sources [241Am, 133Ba, 137Cs, and 60Co]. The polymer was found to decrease the heaviness of the shielding material and increase the flexibility while the metal oxide fillers acted as principle radiation attenuators in the polymer composite. The prepared composites were characterized by Fourier transform infrared spectrophotometer (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area (BET) and field emission transmission electron microscope (FE-TEM). The morphological analysis of the assembled composites showed that, PbO NPs and PbO Blk materials exhibited homogenous dispersion in the polymer-matrix. Thermogravimetric analysis (TGA) demonstrated that the thermal-stability of HD-PE was enhanced in the presence of both PbO Blk and PbO NPs. The results declared that, the density of polymer composites was increase with the percentage of filler contents. The highest density value was identified as 1.652 g cm-3 for 50 wt% of PbO NPs. Linear attenuation coefficients (μ) have been estimated from the use of XCOM code and measured results. Reasonable agreement was attended between theoretical and experimental results. These composites were also found to display excellent percentage of heaviness with respect to other conventional materials.

Effect of ultraviolet radiation in the photo-oxidation of High Density Polyethylene and Biodegradable Polyethylene films

NASA Astrophysics Data System (ADS)

Martínez-Romo, A.; González Mota, R.; Bernal, J. J. Soto; Frausto Reyes, C.; Rosales Candelas, I.

2015-01-01

One of the most widely used plastics in the world is the High density polyethylene (HDPE), it is a stable material due to its carbon-carbon bonds, causing their slow degradation; which is why we are looking for alternative ways to accelerate the degradation process of this polymer. An alternative is the addition of oxidized groups in its molecular structure, which results in the development of polymers susceptible to biodegradation (PE-BIO). In this paper, HDPE and PE-BIO films were exposed to UV-B radiation (320-280 nm) at different exposure times, 0-60 days. The effects of UV radiation in samples of HDPE and PE-BIO were characterized using infrared spectroscopy with attenuated total reflectance (ATR). The results show that the exposed materials undergo changes in their molecular structure, due to the infrared bands formed which corresponds to the photo-oxidation of HDPE and PE films when submitted to UV-B radiation.

Preparation and properties of banana fiber-reinforced composites based on high density polyethylene (HDPE)/Nylon-6 blends.

PubMed

Liu, H; Wu, Q; Zhang, Q

2009-12-01

Banana fiber (BaF)-filled composites based on high density polyethylene (HDPE)/Nylon-6 blends were prepared via a two-step extrusion method. Maleic anhydride grafted styrene/ethylene-butylene/styrene triblock polymer (SEBS-g-MA) and maleic anhydride grafted polyethylene (PE-g-MA) were used to enhance impact performance and interfacial bonding between BaF and the resins. Mechanical, crystallization/melting, thermal stability, water absorption, and morphological properties of the composites were investigated. In the presence of SEBS-g-MA, better strengths and moduli were found for HDPE/Nylon-6 based composites compared with corresponding HDPE based composites. At a fixed weight ratio of PE-g-MA to BaF, an increase of BaF loading up to 48.2 wt.% led to a continuous improvement in moduli and flexural strength of final composites, while impact toughness was lowered gradually. Predicted tensile modulus by the Hones-Paul model for three-dimensional random fiber orientation agreed well with experimental data at the BaF loading of 29.3 wt.%. However, the randomly-oriented fiber models underestimated experimental data at higher fiber levels. It was found that the presence of SEBS-g-MA had a positive influence on reinforcing effect of the Nylon-6 component in the composites. Thermal analysis results showed that fractionated crystallization of the Nylon-6 component in the composites was induced by the addition of both SEBS-g-MA and PE-g-MA. Thermal stability of both composite systems differed slightly, except an additional decomposition peak related to the minor Nylon-6 for the composites from the HDPE/Nylon-6 blends. In the presence of SEBS-g-MA, the addition of Nylon-6 and increased BaF loading level led to an increase in the water absorption value of the composites.

High-density polyethylene (HDPE)-degrading potential bacteria from marine ecosystem of Gulf of Mannar, India.

PubMed

Balasubramanian, V; Natarajan, K; Hemambika, B; Ramesh, N; Sumathi, C S; Kottaimuthu, R; Rajesh Kannan, V

2010-08-01

Assessment of high-density polyethylene (HDPE)-degrading bacteria isolated from plastic waste dumpsites of Gulf of Mannar. Rationally, 15 bacteria (GMB1-GMB15) were isolated by enrichment technique. GMB5 and GMB7 were selected for further studies based on their efficiency to degrade the HDPE and identified as Arthrobacter sp. and Pseudomonas sp., respectively. Assessed weight loss of HDPE after 30 days of incubation was nearly 12% for Arthrobacter sp. and 15% for Pseudomonas sp. The bacterial adhesion to hydrocarbon (BATH) assay showed that the cell surface hydrophobicity of Pseudomonas sp. was higher than Arthrobacter sp. Both fluorescein diacetate hydrolysis and protein content of the biofilm were used to test the viability and protein density of the biomass. Acute peak elevation was observed between 2 and 5 days of inoculation for both bacteria. Fourier transform infrared (FT-IR) spectrum showed that keto carbonyl bond index (KCBI), Ester carbonyl bond index (ECBI) and Vinyl bond index (VBI) were increased indicating changes in functional group(s) and/or side chain modification confirming the biodegradation. The results pose us to suggest that both Pseudomonas sp. and Arthrobacter sp. were proven efficient to degrade HDPE, albeit the former was more efficacious, yet the ability of latter cannot be neglected. Recent alarm on ecological threats to marine system is dumping plastic waste in the marine ecosystem and coastal arena by anthropogenic activity. In maintenance phase of the plastic-derived polyethylene waste, the microbial degradation plays a major role; the information accomplished in this work will be the initiating point for the degradation of polyethylene by indigenous bacterial population in the marine ecosystem and provides a novel eco-friendly solution in eco-management.

[Study on biocompatibility of hydroxyapatite/high density polyethylene (HA/HDPE) nano-composites artificial ossicle].

PubMed

Wang, Guohui; Zhu, Shaihong; Tan, Guolin; Zhou, Kechao; Huang, Suping; Zhao, Yanzhong; Li, Zhiyou; Huang, Boyun

2008-06-01

This study was aimed to evaluate the biocompatibility of Hydroxyapatite/High density polyethylene (HA/ HDPE) nano-composites artificial ossicle. The percentage of S-period cells were detected by flow cytometry after L929 cells being incubated with extraction of the HA/HDPE nano-composites; the titanium materials for clinical application served as the contrast. In addition, both materials were implanted in animals and the histopathological evaluations were conducted. There were no statistically significant differences between the two groups (P >0.05). The results demonstrated that the HA/HDPE nano-composite artificial ossicle made by our laboratory is of a good biocompatibility and clinical application outlook.

Herbicide dissipation from low density polyethylene mulch

USDA-ARS?s Scientific Manuscript database

Field and laboratory studies were conducted to examine herbicide dissipation when applied to low density polyethylene (LDPE) mulch for dry scenarios vs. washing off with water. In field studies, halosulfuron, paraquat, carfentrazone, glyphosate, and flumioxazin were applied to black 1.25-mil LDPE at...

46 CFR 151.03-21 - Filling density.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Filling density. 151.03-21 Section 151.03-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-21 Filling density. The ratio, expressed as...

46 CFR 151.03-21 - Filling density.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Filling density. 151.03-21 Section 151.03-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-21 Filling density. The ratio, expressed as...

46 CFR 151.03-21 - Filling density.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Filling density. 151.03-21 Section 151.03-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-21 Filling density. The ratio, expressed as...

46 CFR 151.03-21 - Filling density.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Filling density. 151.03-21 Section 151.03-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-21 Filling density. The ratio, expressed as...

46 CFR 151.03-21 - Filling density.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Filling density. 151.03-21 Section 151.03-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-21 Filling density. The ratio, expressed as...

Sorption Isotherm of Southern Yellow Pine-High Density Polyethylene Composites.

PubMed

Liu, Feihong; Han, Guangping; Cheng, Wanli; Wu, Qinglin

2015-01-20

Temperature and relative humidity (RH) are two major external factors, which affect equilibrium moisture content (EMC) of wood-plastic composites (WPCs). In this study, the effect of different durability treatments on sorption and desorption isotherms of southern yellow pine (SYP)-high density polyethylene (HDPE) composites was investigated. All samples were equilibriumed at 20 °C and various RHs including 16%, 33%, 45%, 66%, 75%, 85%, 93%, and100%. EMCs obtained from desorption and absorption for different WPC samples were compared with Nelson's sorption isotherm model predictions using the same temperature and humidity conditions. The results indicated that the amount of moisture absorbed increased with the increases in RH at 20 °C. All samples showed sorption hysteresis at a fixed RH. Small difference between EMC data of WPC samples containing different amount of ultraviolet (UV) stabilizers were observed. Similar results were observed among the samples containing different amount of zinc borate (ZB). The experimental data of EMCs at various RHs fit to the Nelson's sorption isotherm model well. The Nelson's model can be used to predicate EMCs of WPCs under different RH environmental conditions.

Sorption Isotherm of Southern Yellow Pine—High Density Polyethylene Composites

PubMed Central

Liu, Feihong; Han, Guangping; Cheng, Wanli; Wu, Qinglin

2015-01-01

Temperature and relative humidity (RH) are two major external factors, which affect equilibrium moisture content (EMC) of wood-plastic composites (WPCs). In this study, the effect of different durability treatments on sorption and desorption isotherms of southern yellow pine (SYP)-high density polyethylene (HDPE) composites was investigated. All samples were equilibriumed at 20 °C and various RHs including 16%, 33%, 45%, 66%, 75%, 85%, 93%, and100%. EMCs obtained from desorption and absorption for different WPC samples were compared with Nelson’s sorption isotherm model predictions using the same temperature and humidity conditions. The results indicated that the amount of moisture absorbed increased with the increases in RH at 20 °C. All samples showed sorption hysteresis at a fixed RH. Small difference between EMC data of WPC samples containing different amount of ultraviolet (UV) stabilizers were observed. Similar results were observed among the samples containing different amount of zinc borate (ZB). The experimental data of EMCs at various RHs fit to the Nelson’s sorption isotherm model well. The Nelson’s model can be used to predicate EMCs of WPCs under different RH environmental conditions. PMID:28787943

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.

Radiation-assisted grafting of vinylidene chloride onto high-density polyethylene

NASA Astrophysics Data System (ADS)

Nagesh, N.; Dokhale, P. A.; Bhoraskar, V. N.

1999-06-01

6 MeV electrons and Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays were used for grafting vinylidene chloride (VDC) onto high-density polyethylene (HDPE) samples. The HDPE samples were immersed in vinylidene chloride and irradiated either with Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays or with 6 MeV electrons. In both cases, the radiation dose was varied in the range 1.25-7.5 kGy. The grafted samples were characterized by IR spectroscopy to obtain information about the chemical bonds and with the 14 MeV neutron activation analysis technique for estimating the number of chlorine atoms. The formation of stable bonds between the VDC molecules and the polymer chains could be achieved either with 6 MeV electrons or with Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays. Both the number of chlorine atoms and the sample-surface conductivity increased with the radiation dose but the increases achieved with 6 MeV electrons were greater than those achieved with Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays.

In-situ Production of High Density Polyethylene and Other Useful Materials on Mars

NASA Technical Reports Server (NTRS)

Flynn, Michael

2005-01-01

This paper describes a revolutionary materials structure and power storage concept based on the in-situ production of abiotic carbon 4 compounds. One of the largest single mass penalties required to support the human exploration of Mars is the surface habitat. This proposal will use physical chemical technologies to produce high density polyethylene (HDPE) inflatable structures and construction materials from Mars atmospheric CO2. The formation of polyethylene from Mars CO2 is based on the use of the Sabatier and modified Fischer Tropsch reactions. The proposed system will fully integrate with existing in-situ propellant production concepts. The technology will also be capable of supplementing human caloric requirements, providing solid and liquid fuels for energy storage, and providing significant reduction in mission risk. The NASA Mars Reference Mission Definition Team estimated that a conventional Mars surface habitat structure would weigh 10 tonnes. It is estimated that this technology could reduce this mass by 80%. This reduction in mass will significantly contribute to the reduction in total mission cost need to make a Mars mission a reality. In addition the potential reduction of risk provided by the ability to produce C4 and potentially higher carbon based materials in-situ on Mars is significant. Food, fuel, and shelter are only three of many requirements that would be impacted by this research.

Enhancement of the Mechanical Properties of Basalt Fiber-Wood-Plastic Composites via Maleic Anhydride Grafted High-Density Polyethylene (MAPE) Addition

PubMed Central

Chen, Jinxiang; Wang, Yong; Gu, Chenglong; Liu, Jianxun; Liu, Yufu; Li, Min; Lu, Yun

2013-01-01

This study investigated the mechanisms, using microscopy and strength testing approaches, by which the addition of maleic anhydride grafted high-density polyethylene (MAPE) enhances the mechanical properties of basalt fiber-wood-plastic composites (BF-WPCs). The maximum values of the specific tensile and flexural strengths areachieved at a MAPE content of 5%–8%. The elongation increases rapidly at first and then continues slowly. The nearly complete integration of the wood fiber with the high-density polyethylene upon MAPE addition to WPC is examined, and two models of interfacial behavior are proposed. We examined the physical significance of both interfacial models and their ability to accurately describe the effects of MAPE addition. The mechanism of formation of the Model I interface and the integrated matrix is outlined based on the chemical reactions that may occur between the various components as a result of hydrogen bond formation or based on the principle of compatibility, resulting from similar polarity. The Model I fracture occurred on the outer surface of the interfacial layer, visually demonstrating the compatibilization effect of MAPE addition. PMID:28809285

Enhancement of the Mechanical Properties of Basalt Fiber-Wood-Plastic Composites via Maleic Anhydride Grafted High-Density Polyethylene (MAPE) Addition.

PubMed

Chen, Jinxiang; Wang, Yong; Gu, Chenglong; Liu, Jianxun; Liu, Yufu; Li, Min; Lu, Yun

2013-06-18

This study investigated the mechanisms, using microscopy and strength testing approaches, by which the addition of maleic anhydride grafted high-density polyethylene (MAPE) enhances the mechanical properties of basalt fiber-wood-plastic composites (BF-WPCs). The maximum values of the specific tensile and flexural strengths are achieved at a MAPE content of 5%-8%. The elongation increases rapidly at first and then continues slowly. The nearly complete integration of the wood fiber with the high-density polyethylene upon MAPE addition to WPC is examined, and two models of interfacial behavior are proposed. We examined the physical significance of both interfacial models and their ability to accurately describe the effects of MAPE addition. The mechanism of formation of the Model I interface and the integrated matrix is outlined based on the chemical reactions that may occur between the various components as a result of hydrogen bond formation or based on the principle of compatibility, resulting from similar polarity. The Model I fracture occurred on the outer surface of the interfacial layer, visually demonstrating the compatibilization effect of MAPE addition.

Durability of a fin-tube latent heat storage using high density polyethylene as PCM

NASA Astrophysics Data System (ADS)

Zauner, Christoph; Hengstberger, Florian; Etzel, Mark; Lager, Daniel; Hofmann, Rene; Walter, Heimo

2017-10-01

Polymers have rarely been used as storage materials in latent heat storages up to now. Thus, we systematically screened all polymers available on a large-scale, selected promising ones based on their theoretical properties and experimentally tested more than 50 candidates. We found that polyethylene, polyoxymethylene and polyamides are promising even as recycled material. Especially high density polyethylene (HDPE) turned out to be suitable as was shown by detailed thermophysical characterization including more than 1000 heating and cooling cycles for INEOS Rigidex HD6070EA. We built a storage with 170 kg HDPE and a total mass of 600 kg based on a fin-tube heat exchanger and characterized its energy capacity, power characteristics and temperature profiles using a thermal oil test rig. In total we performed 30 melting and crystallization cycles where the whole storage was above 100 °C for more than 140 hours. After usage we examined the interior of the storage by cutting it into various pieces. A thin layer of degradation was observed on the surfaces of the PCM which is most likely related to thermo-oxidative degeneration of HDPE. However, the bulk of the PCM is still intact as well as the heat exchanger itself.

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

PORTSMOUTH ON-SITE DISPOSAL CELL HIGH DENSITY POLYETHYLENE GEOMEMBRANE LONGEVITY

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

Phifer, M.

It is anticipated that high density polyethylene (HDPE) geomembranes will be utilized within the liner and closure cap of the proposed On-Site Disposal Cell (OSDC) at the Portsmouth Gaseous Diffusion Plant. The likely longevity (i.e. service life) of HDPE geomembranes in OSDC service is evaluated within the following sections of this report: (1) Section 2.0 provides an overview of HDPE geomembranes, (2) Section 3.0 outlines potential HDPE geomembranes degradation mechanisms, (3) Section 4.0 evaluates the applicability of HDPE geomembrane degradation mechanisms to the Portsmouth OSDC, (4) Section 5.0 provides a discussion of the current state of knowledge relative to themore » longevity (service life) of HDPE geomembranes, including the relation of this knowledge to the Portsmouth OSDC, and (5) Section 6.0 provides summary and conclusions relative to the anticipated service life of HDPE geomembranes in OSDC service. Based upon this evaluation it is anticipated that the service life of HDPE geomembranes in OSDC service would be significantly greater than the 200 year service life assumed for the OSDC closure cap and liner HDPE geomembranes. That is, a 200 year OSDC HDPE geomembrane service life is considered a conservative assumption.« less

The effects of the concentration of high-density polyethylene particles on the bone-implant interface.

PubMed

Brooks, R A; Sharpe, J R; Wimhurst, J A; Myer, B J; Dawes, E N; Rushton, N

2000-05-01

We used a rat model in vivo to study the effects of the concentration of polyethylene particles on the bone-implant interface around stable implants in the proximal tibia. Intra-articular injections of 10(4), 10(6) or 10(8) high-density polyethylene (HDPE) particles per joint were given 8, 10 and 12 weeks after surgery. The animals were killed after 14 and 26 weeks and the response at the interface determined. Fibrous tissue was seen at the bone-implant interface when the head of the implant was flush with the top of the tibia but not when it was sunk below the tibial plateau. In the latter case the implant was completely surrounded by a shell of bone. The area of fibrous tissue and that of the gap between the implant and bone was related to the concentration of particles in the 14-week group (p < 0.05). Foreign-body granulomas containing HDPE particles were seen at the bone-implant interface in animals given 10(8) particles. The pathology resembles that seen around prostheses with aseptic loosening and we suggest that this is a useful model by which to study this process.

Shear-horizontal surface acoustic wave phononic device with high density filling material for ultra-low power sensing applications

NASA Astrophysics Data System (ADS)

Richardson, M.; Sankaranarayanan, S. K. R. S.; Bhethanabotla, V. R.

2014-06-01

Finite element simulations of a phononic shear-horizontal surface acoustic wave (SAW) sensor based on ST 90°-X Quartz reveal a dramatic reduction in power consumption. The phononic sensor is realized by artificially structuring the delay path to form an acoustic meta-material comprised of a periodic microcavity array incorporating high-density materials such as tantalum or tungsten. Constructive interference of the scattered and secondary reflected waves at every microcavity interface leads to acoustic energy confinement in the high-density regions translating into reduced power loss. Tantalum filled cavities show the best performance while tungsten inclusions create a phononic bandgap. Based on our simulation results, SAW devices with tantalum filled microcavities were fabricated and shown to significantly decrease insertion loss. Our findings offer encouraging prospects for designing low power, highly sensitive portable biosensors.

Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites.

PubMed

Liu, Tian; Wood, Weston; Zhong, Wei-Hong

2011-12-01

We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

Ultrasonic attenuation and phase velocity of high-density polyethylene pipe material.

PubMed

Egerton, J S; Lowe, M J S; Huthwaite, P; Halai, H V

2017-03-01

Knowledge of acoustic properties is crucial for ultrasonic or sonic imaging and signal detection in nondestructive evaluation (NDE), medical imaging, and seismology. Accurately and reliably obtaining these is particularly challenging for the NDE of high-density polyethylene (HDPE), such as is used in many water or gas pipes, because the properties vary greatly with frequency, temperature, direction and spatial location. Therefore the work reported here was undertaken in order to establish a basis for such a multiparameter description. The approach is general but the study specifically addresses HDPE and includes measured data values. Applicable to any such multiparameter acoustic properties dataset is a devised regression method that uses a neural network algorithm. This algorithm includes constraints to respect the Kramers-Kronig causality relationship between speed and attenuation of waves in a viscoelastic medium. These constrained acoustic properties are fully described in a multidimensional parameter space to vary with frequency, depth, temperature, and direction. The resulting uncertainties in acoustic properties dependence on the above variables are better than 4% and 2%, respectively, for attenuation and phase velocity and therefore can prevent major defect imaging errors.

[Determination of solubility parameters of high density polyethylene by inverse gas chromatography].

PubMed

Wang, Qiang; Chen, Yali; Liu, Ruiting; Shi, Yuge; Zhang, Zhengfang; Tang, Jun

2011-11-01

Inverse gas chromatographic (IGC) technology was used to determine the solubility parameters of high density polyethylene (HDPE) at the absolute temperatures from 303.15 to 343.15 K. Six solvents were applied as test probes including hexane (n-C6), heptane (n-C7), octane (n-C8), nonane (n-C9), chloroform (CHCl3) and ethyl acetate (EtAc). Some thermodynamic parameters were obtained by IGC data analysis such as the specific retention volumes of the solvents (V(0)(g)), the molar enthalpy of sorption (delta H(S)(1)), the partial molar enthalpy of mixing at infinite dilution (delta H(1)(infinity)), the molar enthalpy of vaporization (delta H(v)), the activity coefficients at infinite dilution (omega (1)(infinity)), and Flow-Huggins interaction parameters (X(1,2)(infinity)) between HDPE and probe solvents. The results showed that the above six probes are poor solvents for HDPE. The solubility parameter of HDPE at room temperature (298.15 K) was also derived as 19.00 (J/cm3)(0.5).

Degradation of lindane and hexachlorobenzene in supercritical carbon dioxide using palladium nanoparticles stabilized in microcellular high-density polyethylene.

PubMed

Wu, Bei-Zen; Chen, GuanYu; Yak, HwaKwang; Liao, Weisheng; Chiu, KongHwa; Peng, Shie-Ming

2016-06-01

Palladium nanoparticles stabilized in microcellular high-density polyethylene prepared through supercritical foaming, supercritical impregnation, and H2 reduction are used for the hydrodechlorination of lindane and hexachlorobenzene in supercritical carbon dioxide below 100 °C. Both lindane and hexachlorobenzene can be almost 100% transformed to cyclohexane in 1 h. Reaction intermediates, such as lower chlorinated products or benzene, are not observed or exist in trace amount indicating that most of them may undergo reactions without leaving the metal surface. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation and Characterisation of Linear Low-Density Polyethylene / Thermoplastic Starch Blends Filled with Banana Fibre

NASA Astrophysics Data System (ADS)

Kahar, A. W. M.; Ann, L. Ju

2017-06-01

In this study, the influence of banana fibre (BF) loading using sodium hydroxide (NaOH) pre-treated and succinic anhydride-treated (SA) BF on the mechanical properties of linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) matrix is investigated. LLDPE/TPS/BF composites were developed under different BF conditions, with and without chemical modifications with the BF content ranging from 5% to 30% based on the total composite. The tensile strength showed an increase with an increase of fibre content up to 10%, thereby decreasing gradually beyond this level. NaOH pre-treated and SA treated BF added with LLDPE/TPS composite displays a higher tensile strength as compared to untreated BF in LLDPE/TPS composites. Thermal behaviour of the BF incorporated in LLDPE/TPS composite was characterised using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). This showed that SA treated BF exhibits better thermal stability, compared to other composites. This is because of the improvement in interfacial adhesion existing between both the fibre and matrix. In addition, a morphology study confirmed that pre-treated and treated BF had excellent interfacial adhesion with LLDPE/TPS matrix, leading to better mechanical properties of resultant composites.

Small-bandgap polymer solar cells with unprecedented short-circuit current density and high fill factor.

PubMed

Choi, Hyosung; Ko, Seo-Jin; Kim, Taehyo; Morin, Pierre-Olivier; Walker, Bright; Lee, Byoung Hoon; Leclerc, Mario; Kim, Jin Young; Heeger, Alan J

2015-06-03

Small-bandgap polymer solar cells (PSCs) with a thick bulk heterojunction film of 340 nm exhibit high power conversion efficiencies of 9.40% resulting from high short-circuit current density (JSC ) of 20.07 mA cm(-2) and fill factor of 0.70. This remarkable efficiency is attributed to maximized light absorption by the thick active layer and minimized recombination by the optimized lateral and vertical morphology through the processing additive. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A new strategy to produce low-density polyethylene (LDPE)-based composites simultaneously with high flame retardancy and high mechanical properties

NASA Astrophysics Data System (ADS)

Shen, Liguo; Li, Jianxi; Li, Renjie; Lin, Hongjun; Chen, Jianrong; Liao, Bao-Qiang

2018-04-01

In this study, a new strategy which blends low-density polyethylene (LDPE), magnesium hydroxide (MH) and lauryl acrylate by electron-beam radiation for production of LDPE-based composites with high performance was proposed. It was found that, MH played main roles in flame retardancy but reduced processing flow and mechanical properties of the composites. Meanwhile, melt flow rate (MFR) increased while viscosity of the composites decreased with lauryl acrylate content increased, facilitating LDPE composites processing. Electron beam radiation could prompt crosslinking of lauryl acrylate, which significantly enhanced the mechanical properties of LDPE composites. Meanwhile, lauryl acrylate addition only slightly decreased the flame retardancy, suggesting that LDPE composites could remain high flame retardancy even when lauryl acrylate content was high. The study highly demonstrated the feasibility to produce LDPE-based composites simultaneously with high flame retardancy and high mechanical properties by the blending strategy provided in this study.

Shape stabilised phase change materials (SSPCMs): High density polyethylene and hydrocarbon waxes

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

Mu, Mulan, E-mail: mmu01@qub.ac.uk, E-mail: m.basheer@qub.ac.uk; Basheer, P. A. M., E-mail: mmu01@qub.ac.uk, E-mail: m.basheer@qub.ac.uk; Bai, Yun, E-mail: yun.bai@ucl.ac.uk

Shape stabilised phase change materials (SSPCMs) based on high density polyethylene (HDPE) with high (HPW, T{sub m}=56-58 °C) and low (L-PW, T{sub m}=18-23 °C) melting point waxes were prepared by melt-mixing in a twin-screw extruder and their potential in latent heat thermal energy storage (LHTES) applications for housing assessed. The structure and morphology of these blends were investigated by scanning electron microscopy (SEM). Both H-PW and L-PW were uniformly distributed throughout the HDPE matrix. The melting point and latent heat of the SSPCMs were determined by differential scanning calorimetry (DSC). The results demonstrated that both H-PW and L-PW have amore » plasticisation effect on the HDPE matrix. The tensile and flexural properties of the samples were measured at room temperature (RT, 20±2 °C) and 70 °C, respectively. All mechanical properties of HDPE/H-PW and HDPE/L-PW blends decreased from RT to 70 °C. In all instances at RT, modulus and stress, irrespective of the mode of deformation was greater for the HDPE/H-PW blends. However, at 70 °C, there was no significant difference in mechanical properties between the HDPE/H-PW and HDPE/L-PW blends.« less

Biocompatibility of modified ultra-high-molecular-weight polyethylene

NASA Astrophysics Data System (ADS)

Novotná, Z.; Lacmanová, V.; Rimpelová, S.; Juřik, P.; Polívková, M.; Å vorčik, V.

2016-09-01

Ultra-high-molecular-weight polyethylene (UHMWPE, PE) is a synthetic polymer used for biomedical applications because of its high impact resistance, ductility and stability in contact with physiological fluids. Therefore this material is being used in human orthopedic implants such as total joint replacements. Surface modification of this material relates to changes of its surface hydrophilicity, energy, microstructure, roughness, and morphology, all influencing its biological response. In our recent work, PE was treated by an Ar+ plasma discharge and then grafted with biologically active polyethylene glycol in order to enhance adhesion and proliferation of mouse fibroblast (L929). The surface properties of pristine PE and its grafted counterparts were studied by goniometry (surface wettability). Furthermore, Atomic Force Microscopy was used to determine the surface morphology and roughness. The biological response of the L929 cell lines seeded on untreated and plasma treated PE matrices was quantified in terms of the cell adhesion, density, and metabolic activity. Plasma treatment leads to the ablation of the polymer surface layers. Plasma treatment and subsequent poly(ethylene glycol) grafting lead to dramatic changes in the polymer surface morphology and roughness. Biological tests, performed in vitro, show increased adhesion and proliferation of cells on modified polymers. Grafting with poly(ethylene glycol) increases cell proliferation compared to plasma treatment.

Effect of nanoclay on the properties of low density polyethylene/linear low density polyethylene/thermoplastic starch blend films.

PubMed

Sabetzadeh, Maryam; Bagheri, Rouhollah; Masoomi, Mahmood

2016-05-05

The aim of this work is to study effect of nanoclay (Cloisite(®)15A) on morphology and properties of low-density polyethylene/linear low-density polyethylene/thermoplastic starch (LDPE/LLDPE/TPS) blend films. LDPE/LLDPE blend (70/30wt/wt) containing 15wt.% TPS in the presence of PE-grafted maleic anhydride (PE-g-MA, 3wt.%) with 1, 3 and 5phr of nanoclay are compounded in a twin-screw extruder and then film blown using a blowing machine. Nanocomposites with intercalated structures are obtained, based on the X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. However, some exfoliated single platelets in the samples are also observable. Scanning electron microscopic (SEM) images confirm the ability of both exfoliated nanoclay and PE-g-MA to reduce the size of TPS domains and deform their particles within the PE matrices. As the nanoclay content increases from 1 to 5phr, the tensile strength, tear resistance and impact strength of the films increase, whereas a slight decrease in the elongation at break is observed. The film samples with 5phr nanoclay possess the required packaging properties, as specified by ASTM D4635. These films provide desired optical transparency and surface roughness which are more attractive for packaging applications. Copyright © 2016. Published by Elsevier Ltd.

Radiation-Induced Grafting with One-Step Process of Waste Polyurethane onto High-Density Polyethylene

PubMed Central

Park, Jong-Seok; Lim, Youn-Mook; Nho, Young-Chang

2015-01-01

The recycling of waste polyurethane (PU) using radiation-induced grafting was investigated. The grafting of waste PU onto a high-density polyethylene (HDPE) matrix was carried out using a radiation technique with maleic anhydride (MAH). HDPE pellets and PU powders were immersed in a MAH-acetone solution. Finally, the prepared mixtures were irradiated with an electron beam accelerator. The grafted composites were characterized by Fourier transformed infrared spectroscopy (FT-IR), surface morphology, and mechanical properties. To make a good composite, the improvement in compatibility between HDPE and PU is an important factor. Radiation-induced grafting increased interfacial adhesion between the PU domain and the HDPE matrix. When the absorbed dose was 75 kGy, the surface morphology of the irradiated PU/HDPE composite was nearly a smooth and single phase, and the elongation at break increased by approximately three times compared with that of non-irradiated PU/HDPE composite. PMID:28787813

Evaluation of low density polyethylene and nylon for delivery of synthetic mosquito attractants

PubMed Central

2012-01-01

Background Synthetic odour baits present an unexploited potential for sampling, surveillance and control of malaria and other mosquito vectors. However, application of such baits is impeded by the unavailability of robust odour delivery devices that perform reliably under field conditions. In the present study the suitability of low density polyethylene (LDPE) and nylon strips for dispensing synthetic attractants of host-seeking Anopheles gambiae mosquitoes was evaluated. Methods Baseline experiments assessed the numbers of An. gambiae mosquitoes caught in response to low density polyethylene (LDPE) sachets filled with attractants, attractant-treated nylon strips, control LDPE sachets, and control nylon strips placed in separate MM-X traps. Residual attraction of An. gambiae to attractant-treated nylon strips was determined subsequently. The effects of sheet thickness and surface area on numbers of mosquitoes caught in MM-X traps containing the synthetic kairomone blend dispensed from LDPE sachets and nylon strips were also evaluated. Various treatments were tested through randomized 4 × 4 Latin Square experimental designs under semi-field conditions in western Kenya. Results Attractant-treated nylon strips collected 5.6 times more An. gambiae mosquitoes than LDPE sachets filled with the same attractants. The attractant-impregnated nylon strips were consistently more attractive (76.95%; n = 9,120) than sachets containing the same attractants (18.59%; n = 2,203), control nylon strips (2.17%; n = 257) and control LDPE sachets (2.29%; n = 271) up to 40 days post-treatment (P < 0.001). The higher catches of mosquitoes achieved with nylon strips were unrelated to differences in surface area between nylon strips and LDPE sachets. The proportion of mosquitoes trapped when individual components of the attractant were dispensed in LDPE sachets of optimized sheet thicknesses was significantly higher than when 0.03 mm-sachets were used (P < 0

Evaluation of low density polyethylene and nylon for delivery of synthetic mosquito attractants.

PubMed

Mukabana, Wolfgang R; Mweresa, Collins K; Omusula, Philemon; Orindi, Benedict O; Smallegange, Renate C; van Loon, Joop Ja; Takken, Willem

2012-09-19

Synthetic odour baits present an unexploited potential for sampling, surveillance and control of malaria and other mosquito vectors. However, application of such baits is impeded by the unavailability of robust odour delivery devices that perform reliably under field conditions. In the present study the suitability of low density polyethylene (LDPE) and nylon strips for dispensing synthetic attractants of host-seeking Anopheles gambiae mosquitoes was evaluated. Baseline experiments assessed the numbers of An. gambiae mosquitoes caught in response to low density polyethylene (LDPE) sachets filled with attractants, attractant-treated nylon strips, control LDPE sachets, and control nylon strips placed in separate MM-X traps. Residual attraction of An. gambiae to attractant-treated nylon strips was determined subsequently. The effects of sheet thickness and surface area on numbers of mosquitoes caught in MM-X traps containing the synthetic kairomone blend dispensed from LDPE sachets and nylon strips were also evaluated. Various treatments were tested through randomized 4 × 4 Latin Square experimental designs under semi-field conditions in western Kenya. Attractant-treated nylon strips collected 5.6 times more An. gambiae mosquitoes than LDPE sachets filled with the same attractants. The attractant-impregnated nylon strips were consistently more attractive (76.95%; n = 9,120) than sachets containing the same attractants (18.59%; n = 2,203), control nylon strips (2.17%; n = 257) and control LDPE sachets (2.29%; n = 271) up to 40 days post-treatment (P < 0.001). The higher catches of mosquitoes achieved with nylon strips were unrelated to differences in surface area between nylon strips and LDPE sachets. The proportion of mosquitoes trapped when individual components of the attractant were dispensed in LDPE sachets of optimized sheet thicknesses was significantly higher than when 0.03 mm-sachets were used (P < 0.001). Nylon strips

Characterization of laser beam transmission through a High Density Polyethylene (HDPE) plate

NASA Astrophysics Data System (ADS)

Genna, S.; Leone, C.; Tagliaferri, V.

2017-02-01

Infrared (IR) light propagation in semicrystalline polymers involves mechanisms such as reflection, transmission, absorption and internal scattering. These different rates determine either the interaction mechanism, either the temperatures reached in the IR heating processes. Consequently, the knowledge of these rates is fundamental in the development of IR heating processes in order to avoid the polymer's damage and to increase the process energy efficiency. Aim of this work is to assess a simple procedure to determine the rates of absorbed, reflected, transmitted and scattered energy in the case of an unfilled High Density Polyethylene (HDPE) plate. Experimental tests were performed by exposing a HDPE plate, 3 mm in thickness, to a diode laser source, working at the fundamental wavelength of 975 nm. The transmitted power was measured by power meter, the reflected one by applying the Beer-Lambert law to sample of different thickness. IR thermal images were adopted to measure the absorbed ratio. The scattered ratio was measured by energetic balance, as difference between the incoming power and the other ratios. Finally, IR thermal images were adopted to measure the scattered ratio and to validate the procedure.

Enhancement of in vitro high-density polyethylene (HDPE) degradation by physical, chemical, and biological treatments.

PubMed

Balasubramanian, V; Natarajan, K; Rajeshkannan, V; Perumal, P

2014-11-01

Partially degraded high-density polyethylene (HDPE) was collected from plastic waste dump yard for biodegradation using fungi. Of various fungi screened, strain MF12 was found efficient in degrading HDPE by weight loss and Fourier transform infrared (FT-IR) spectrophotometric analysis. Strain MF12 was selected as efficient HDPE degraders for further studies, and their growth medium composition was optimized. Among those different media used, basal minimal medium (BMM) was suitable for the HDPE degradation by strain MF12. Strain MF12 was subjected to 28S rRNA sequence analysis and identified as Aspergillus terreus MF12. HDPE degradation was carried out using combinatorial physical and chemical treatments in conjunction to biological treatment. The high level of HDPE degradation was observed in ultraviolet (UV) and KMnO4/HCl with A. terreus MF12 treatment, i.e., FT10. The abiotic physical and chemical factors enhance the biodegradation of HDPE using A. terreus MF12.

EVALUATION OF ULTRASONIC PHASED-ARRAY FOR DETECTION OF PLANAR FLAWS IN HIGH-DENSITY POLYETHYLENE (HDPE) BUTT-FUSION JOINTS

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

Prowant, Matthew S.; Denslow, Kayte M.; Moran, Traci L.

2016-09-21

The desire to use high-density polyethylene (HDPE) piping in buried Class 3 service and cooling water systems in nuclear power plants is primarily motivated by the material’s high resistance to corrosion relative to that of steel and metal alloys. The rules for construction of Class 3 HDPE pressure piping systems were originally published in Code Case N-755 and were recently incorporated into the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME BPVC) Section III as Mandatory Appendix XXVI (2015 Edition). The requirements for HDPE examination are guided by criteria developed for metal pipe and are based onmore » industry-led HDPE research or conservative calculations.« less

Nanocomposites of high-density polyethylene with amorphous calcium phosphate: in vitro biomineralization and cytocompatibility of human mesenchymal stem cells.

PubMed

Hild, Nora; Fuhrer, Roland; Mohn, Dirk; Bubenhofer, Stephanie B; Grass, Robert N; Luechinger, Norman A; Feldman, Kirill; Dora, Claudio; Stark, Wendelin J

2012-10-01

Polyethylene is widely used as a component of implants in medicine. Composites made of high-density polyethylene (HDPE) containing different amounts of amorphous calcium phosphate nanoparticles were investigated concerning their in vitro biomedical performance. The nanoparticles were produced by flame spray synthesis and extruded with HDPE, the latter complying with Food and Drug Administration regulations. Mechanical properties such as Young's modulus and contact angle as well as in vitro biomineralization of the nanocomposites hot-pressed into thin films were evaluated. The deposition of a hydroxyapatite layer occurred upon immersion in simulated body fluid. Additionally, a cell culture study with human mesenchymal stem cells for six weeks allowed a primary assessment of the cytocompatibility. Viability assays (alamarBlue and lactate dehydrogenase detection) proved the absence of cytotoxic effects of the scaffolds. Microscopic images after hematoxylin and eosin staining confirmed typical growth and morphology. A preliminary experiment analyzed the alkaline phosphatase activity after two weeks. These findings motivate further investigations on bioactive HDPE in bone tissue engineering.

A hierarchical classification approach for recognition of low-density (LDPE) and high-density polyethylene (HDPE) in mixed plastic waste based on short-wave infrared (SWIR) hyperspectral imaging

NASA Astrophysics Data System (ADS)

Bonifazi, Giuseppe; Capobianco, Giuseppe; Serranti, Silvia

2018-06-01

The aim of this work was to recognize different polymer flakes from mixed plastic waste through an innovative hierarchical classification strategy based on hyperspectral imaging, with particular reference to low density polyethylene (LDPE) and high-density polyethylene (HDPE). A plastic waste composition assessment, including also LDPE and HDPE identification, may help to define optimal recycling strategies for product quality control. Correct handling of plastic waste is essential for its further "sustainable" recovery, maximizing the sorting performance in particular for plastics with similar characteristics as LDPE and HDPE. Five different plastic waste samples were chosen for the investigation: polypropylene (PP), LDPE, HDPE, polystyrene (PS) and polyvinyl chloride (PVC). A calibration dataset was realized utilizing the corresponding virgin polymers. Hyperspectral imaging in the short-wave infrared range (1000-2500 nm) was thus applied to evaluate the different plastic spectral attributes finalized to perform their recognition/classification. After exploring polymer spectral differences by principal component analysis (PCA), a hierarchical partial least squares discriminant analysis (PLS-DA) model was built allowing the five different polymers to be recognized. The proposed methodology, based on hierarchical classification, is very powerful and fast, allowing to recognize the five different polymers in a single step.

Assessment of the impact that the capsule fill tube has on implosions conducted with high density carbon ablators

NASA Astrophysics Data System (ADS)

Pak, Arthur; Benedetti, L. R.; Berzak Hopkins, L. F.; Clark, D.; Divol, L.; Dewald, E. L.; Fittinghoff, D.; Izumi, N.; Khan, S. F.; Landen, O.; Lepape, S.; Ma, T.; Marley, E.; Nagel, S.; Volegov, P.; Weber, C.; Bradley, D. K.; Callahan, D.; Grim, G.; Hurricane, O. A.; Patel, P.; Schneider, M. B.; Edwards, M. J.

2017-10-01

In recent inertial confinement implosion experiments conducted at the National Ignition Facility, bright and spatially localized x-ray emission within the hot spot at stagnation has been observed. This emission is associated with higher Z ablator material that is injected into the hot spot by the hydrodynamic perturbation induced by the 5-10 um diameter capsule fill tube. The reactivity of the DT fuel and subsequent yield of the implosion are strongly dependent on the density, temperature, and confinement time achieved throughout the stagnation of the implosion. Radiative losses from higher Z ablator material that mixes into the hot spot as well as non-uniformities in the compression and confinement induced by the fill tube perturbation can degrade the yield of the implosion. This work will examine the impact to conditions at stagnation that results from the fill tube perturbation. This assessment will be based from a pair of experiments conducted with a high density carbon ablator where the only deliberate change was reduction in fill tube diameter from 10 to 5 um. An estimate of the radiative losses and impact on performance from ablator mix injected into the hot spot by the fill tube perturbation will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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.

Phase structure and properties of poly(ethylene terephthalate)/polyethylene based on recycled materials

Treesearch

Yong Lei; Qinglin Wu; Craig M. Clemons; Weihong Guo

2009-01-01

Blends based on recycled high density polyethylene (R-HDPE) and recycled poly(ethylene terephthalate) (R-PET) were made through reactive extrusion. The effects of maleated polyethylene (PE-g-MA), triblock copolymer of styrene and ethylene/butylene (SEBS), and 4,40-methylenedi(phenyl isocyanate) (MDI) on blend properties were studied. The 2% PE-g-MA improved the...

Mechanical, Rheological, and Bioactivity Properties of Ultra High-Molecular-Weight Polyethylene Bioactive Composites Containing Polyethylene Glycol and Hydroxyapatite

PubMed Central

Ahmad, Mazatusziha; Wahit, Mat Uzir; Abdul Kadir, Mohammed Rafiq; Mohd Dahlan, Khairul Zaman

2012-01-01

Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50 phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis. PMID:22666129

Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

PubMed

Mao, Feng; Ong, Say Kee; Gaunt, James A

2015-09-01

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

Catalytic co-pyrolysis of waste vegetable oil and high density polyethylene for hydrocarbon fuel production.

PubMed

Wang, Yunpu; Dai, Leilei; Fan, Liangliang; Cao, Leipeng; Zhou, Yue; Zhao, Yunfeng; Liu, Yuhuan; Ruan, Roger

2017-03-01

In this study, a ZrO 2 -based polycrystalline ceramic foam catalyst was prepared and used in catalytic co-pyrolysis of waste vegetable oil and high density polyethylene (HDPE) for hydrocarbon fuel production. The effects of pyrolysis temperature, catalyst dosage, and HDPE to waste vegetable oil ratio on the product distribution and hydrocarbon fuel composition were examined. Experimental results indicate that the maximum hydrocarbon fuel yield of 63.1wt. % was obtained at 430°C, and the oxygenates were rarely detected in the hydrocarbon fuel. The hydrocarbon fuel yield increased when the catalyst was used. At the catalyst dosage of 15wt.%, the proportion of alkanes in the hydrocarbon fuel reached 97.85wt.%, which greatly simplified the fuel composition and improved the fuel quality. With the augment of HDPE to waste vegetable oil ratio, the hydrocarbon fuel yield monotonously increased. At the HDPE to waste vegetable oil ratio of 1:1, the maximum proportion (97.85wt.%) of alkanes was obtained. Moreover, the properties of hydrocarbon fuel were superior to biodiesel and 0 # diesel due to higher calorific value, better low-temperature low fluidity, and lower density and viscosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Three-Dimensional Nanometer Features of Direct Current Electrical Trees in Low-Density Polyethylene.

PubMed

Pallon, Love K H; Nilsson, Fritjof; Yu, Shun; Liu, Dongming; Diaz, Ana; Holler, Mirko; Chen, Xiangrong R; Gubanski, Stanislaw; Hedenqvist, Mikael S; Olsson, Richard T; Gedde, Ulf W

2017-03-08

Electrical trees are one reason for the breakdown of insulating materials in electrical power systems. An understanding of the growth of electrical trees plays a crucial role in the development of reliable high voltage direct current (HVDC) power grid systems with transmission voltages up to 1 MV. A section that contained an electrical tree in low-density polyethylene (LDPE) has been visualized in three dimensions (3D) with a resolution of 92 nm by X-ray ptychographic tomography. The 3D imaging revealed prechannel-formations with a lower density with the width of a couple of hundred nanometers formed around the main branch of the electrical tree. The prechannel structures were partially connected with the main tree via paths through material with a lower density, proving that the tree had grown in a step-by-step manner via the prestep structures formed in front of the main channels. All the prechannel structures had a size well below the limit of the Paschen law and were thus not formed by partial discharges. Instead, it is suggested that the prechannel structures were formed by electro-mechanical stress and impact ionization, where the former was confirmed by simulations to be a potential explanation with electro-mechanical stress tensors being almost of the same order of magnitude as the short-term modulus of low-density polyethylene.

Low-Density, Aerogel-Filled Thermal-Insulation Tiles

NASA Technical Reports Server (NTRS)

Santos, Maryann; Heng, Vann; Barney, Andrea; Oka, Kris; Droege, Michael

2005-01-01

Aerogel fillings have been investigated in a continuing effort to develop low-density thermal-insulation tiles that, relative to prior such tiles, have greater dimensional stability (especially less shrinkage), equal or lower thermal conductivity, and greater strength and durability. In preparation for laboratory tests of dimensional and thermal stability, prototypes of aerogel-filled versions of recently developed low-density tiles have been fabricated by impregnating such tiles to various depths with aerogel formations ranging in density from 1.5 to 5.6 lb/ft3 (about 53 to 200 kg/cu m). Results available at the time of reporting the information for this article showed that the thermal-insulation properties of the partially or fully aerogel- impregnated tiles were equivalent or superior to those of the corresponding non-impregnated tiles and that the partially impregnated tiles exhibited minimal (<1.5 percent) shrinkage after multiple exposures at a temperature of 2,300 F (1,260 C). Latest developments have shown that tiles containing aerogels at the higher end of the density range are stable after multiple exposures at the said temperature.

A hierarchical classification approach for recognition of low-density (LDPE) and high-density polyethylene (HDPE) in mixed plastic waste based on short-wave infrared (SWIR) hyperspectral imaging.

PubMed

Bonifazi, Giuseppe; Capobianco, Giuseppe; Serranti, Silvia

2018-06-05

The aim of this work was to recognize different polymer flakes from mixed plastic waste through an innovative hierarchical classification strategy based on hyperspectral imaging, with particular reference to low density polyethylene (LDPE) and high-density polyethylene (HDPE). A plastic waste composition assessment, including also LDPE and HDPE identification, may help to define optimal recycling strategies for product quality control. Correct handling of plastic waste is essential for its further "sustainable" recovery, maximizing the sorting performance in particular for plastics with similar characteristics as LDPE and HDPE. Five different plastic waste samples were chosen for the investigation: polypropylene (PP), LDPE, HDPE, polystyrene (PS) and polyvinyl chloride (PVC). A calibration dataset was realized utilizing the corresponding virgin polymers. Hyperspectral imaging in the short-wave infrared range (1000-2500nm) was thus applied to evaluate the different plastic spectral attributes finalized to perform their recognition/classification. After exploring polymer spectral differences by principal component analysis (PCA), a hierarchical partial least squares discriminant analysis (PLS-DA) model was built allowing the five different polymers to be recognized. The proposed methodology, based on hierarchical classification, is very powerful and fast, allowing to recognize the five different polymers in a single step. Copyright © 2018 Elsevier B.V. All rights reserved.

Diffusion of multiwall carbon nanotubes (MWCNTs) through a high density polyethylene (HDPE) geomembrane

PubMed Central

Saheli, P. T.; Rowe, R. K.; Petersen, E. J.; O’Carroll, D. M.

2017-01-01

The new applications for carbon nanotubes (CNTs) in various fields and consequently their greater production volume have increased their potential release to the environment. Landfills are one of the major locations where carbon nanotubes are expected to be disposed and it is important to ensure that they can limit the release of CNTs. Diffusion of multiwall carbon nanotubes (MWCNTs) dispersed in an aqueous media through a high-density polyethylene (HDPE) geomembrane (as a part of the landfill barrier system) was examined. Based on the laboratory tests, the permeation coefficient was estimated to be less than 5.1×10−15 m2/s. The potential performance of a HDPE geomembrane and geosynthetic clay liner (GCL) as parts of a composite liner in containing MWCNTs was modelled for six different scenarios. The results suggest that the low value of permeation coefficient of an HDPE geomembrane makes it an effective diffusive barrier for MWCNTs and by keeping the geomembrane defects to minimum during the construction (e.g., number of holes and length of wrinkles) a composite liner commonly used in municipal solid waste landfills will effectively contain MWCNTs. PMID:28740357

Diffusion of multiwall carbon nanotubes (MWCNTs) through a high density polyethylene (HDPE) geomembrane.

PubMed

Saheli, P T; Rowe, R K; Petersen, E J; O'Carroll, D M

2017-05-01

The new applications for carbon nanotubes (CNTs) in various fields and consequently their greater production volume have increased their potential release to the environment. Landfills are one of the major locations where carbon nanotubes are expected to be disposed and it is important to ensure that they can limit the release of CNTs. Diffusion of multiwall carbon nanotubes (MWCNTs) dispersed in an aqueous media through a high-density polyethylene (HDPE) geomembrane (as a part of the landfill barrier system) was examined. Based on the laboratory tests, the permeation coefficient was estimated to be less than 5.1×10 -15 m 2 /s. The potential performance of a HDPE geomembrane and geosynthetic clay liner (GCL) as parts of a composite liner in containing MWCNTs was modelled for six different scenarios. The results suggest that the low value of permeation coefficient of an HDPE geomembrane makes it an effective diffusive barrier for MWCNTs and by keeping the geomembrane defects to minimum during the construction (e.g., number of holes and length of wrinkles) a composite liner commonly used in municipal solid waste landfills will effectively contain MWCNTs.

Biodegradation of thermally treated high-density polyethylene (HDPE) by Klebsiella pneumoniae CH001.

PubMed

Awasthi, Shraddha; Srivastava, Pratap; Singh, Pardeep; Tiwary, D; Mishra, Pradeep Kumar

2017-10-01

Biodegradation of plastics, which are the potential source of environmental pollution, has received a great deal of attention in the recent years. We aim to screen, identify, and characterize a bacterial strain capable of degrading high-density polyethylene (HDPE). In the present study, we studied HDPE biodegradation using a laboratory isolate, which was identified as Klebsiella pneumoniae CH001 (Accession No MF399051). The HDPE film was characterized by Universal Tensile Machine (UTM), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Atomic Force Microscope (AFM) before and after microbial incubation. We observed that this strain was capable of adhering strongly on HDPE surface and form a thick biofilm, when incubated in nutrient broth at 30 °C on 120 rpm for 60 days. UTM analysis showed a significant decrease in weight (18.4%) and reduction in tensile strength (60%) of HDPE film. Furthermore, SEM analysis showed the cracks on the HDPE surface, whereas AFM results showed an increase in surface roughness after bacterial incubation. Overall, these results indicate that K. pneumoniae CH001 can be used as potential candidate for HDPE degradation in eco-friendly and sustainable manner in the environment.

Molecular and Kinetic Models for High-rate Thermal Degradation of Polyethylene

DOE PAGES

Lane, J. Matthew; Moore, Nathan W.

2018-02-01

Thermal degradation of polyethylene is studied under the extremely high rate temperature ramps expected in laser-driven and X-ray ablation experiments—from 10 10 to 10 14 K/s in isochoric, condensed phases. The molecular evolution and macroscopic state variables are extracted as a function of density from reactive molecular dynamics simulations using the ReaxFF potential. The enthalpy, dissociation onset temperature, bond evolution, and observed cross-linking are shown to be rate dependent. These results are used to parametrize a kinetic rate model for the decomposition and coalescence of hydrocarbons as a function of temperature, temperature ramp rate, and density. In conclusion, the resultsmore » are contrasted to first-order random-scission macrokinetic models often assumed for pyrolysis of linear polyethylene under ambient conditions.« less

Molecular and Kinetic Models for High-rate Thermal Degradation of Polyethylene

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

Lane, J. Matthew; Moore, Nathan W.

Thermal degradation of polyethylene is studied under the extremely high rate temperature ramps expected in laser-driven and X-ray ablation experiments—from 10 10 to 10 14 K/s in isochoric, condensed phases. The molecular evolution and macroscopic state variables are extracted as a function of density from reactive molecular dynamics simulations using the ReaxFF potential. The enthalpy, dissociation onset temperature, bond evolution, and observed cross-linking are shown to be rate dependent. These results are used to parametrize a kinetic rate model for the decomposition and coalescence of hydrocarbons as a function of temperature, temperature ramp rate, and density. In conclusion, the resultsmore » are contrasted to first-order random-scission macrokinetic models often assumed for pyrolysis of linear polyethylene under ambient conditions.« less

Fast co-pyrolysis of waste newspaper with high-density polyethylene for high yields of alcohols and hydrocarbons.

PubMed

Chen, Weimin; Shi, Shukai; Chen, Minzhi; Zhou, Xiaoyan

2017-09-01

Waste newspaper (WP) was first co-pyrolyzed with high-density polyethylene (HDPE) using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to enhance the yields of alcohols and hydrocarbons. The effects of WP: HDPE feed ratio (100:0, 75:25, 50:50, 25:75, 0:100) and temperature (500-800°C) on products distribution were investigated and the interaction mechanism during co-pyrolysis was also proposed. Maximum yields of alcohols and hydrocarbons reached 85.88% (feed ratio 50:50wt.%, 600°C). Hydrogen supplements and deoxidation by HDPE and subsequently fragments recombination result in the conversion of aldehydes and ketones into branched hydrocarbons. Radicals from WP degradation favor the secondary crack for HDPE products resulting in the formation of linear hydrocarbons with low carbon number. Hydrocarbons with activated radical site from HDPE degradation were interacted with hydroxyl from WP degradation promoting the formation of linear long chain alcohols. Moreover, co-pyrolysis significantly enhanced condensable oil qualities, which were close to commercial diesel No. 0. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of solidified radioactive waste due to the incorporation of high- and low-density polyethylene granules and titanium dioxide in mortar matrices

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

Peric, A.

1997-12-31

The rutile form of titanium dioxide and granules of high density polyethylene (PEHD) and low density polyethylene (PELD) were used to prepare mortar matrices for immobilization of radioactive waste materials containing {sup 137}Cs. PELD, PEHD and TiO{sub 2} were added to mortar matrix preparations with the objective of improving physico-chemical characteristics of the radwaste-mortar matrix mixtures, in particular the leach-rate of the immobilized radionuclide. One type of PELD and two types of PEHD were used to replace 50 wt.% of stone granules normally used in the matrix, in order to decrease the porosity and density of the mortar matrix andmore » to avoid segregation of the stone particles at the bottom of the immobilized radioactive waste cylindrical form. TiO{sub 2} was also added to the mortar formulation, replacing 5 and 8 wt.% of the total cement weight. Cured samples were investigated under temperature stress conditions, where the temperature extremes were: T{sub min} = {minus}20 C, T{sub max} = +70 C. Samples were periodically immersed in distilled water at the ambient room temperature, after each freezing and heating treatment. Results of accelerated leaching experiments for these samples and samples prepared exclusively with polyethylenes replacing 100% of the stone granules and TiO{sub 2}, treated in nonaccelerated leaching experiments, were compared. Even using an accelerated ageing leach test that overestimates {sup 137}Cs leach rates, it can be deduced, that radionuclide leach rates from the radioactive waste mortar mixture forms were improved. Leach rates decreased from 5%, for the material prepared with stone aggregate, to 3.1 to 4.0%, for the materials prepared solely with PEHD, PELD or TiO{sub 2}, and to about 3% for all six types of the TiO{sub 2}-PEHD and TiO{sub 2}-PELD mixtures tested.« less

High density laser-driven target

DOEpatents

Lindl, John D.

1981-01-01

A high density target for implosion by laser energy composed of a central quantity of fuel surrounded by a high-Z pusher shell with a low-Z ablator-pusher shell spaced therefrom forming a region filled with low-density material.

Separating effective high density polyethylene segments from olefin block copolymers using high temperature liquid chromatography with a preloaded discrete adsorption promoting solvent barrier.

PubMed

Chatterjee, Tirtha; Rickard, Mark A; Pearce, Eric; Pangburn, Todd O; Li, Yongfu; Lyons, John W; Cong, Rongjuan; deGroot, A Willem; Meunier, David M

2016-09-23

Recent advances in catalyst technology have enabled the synthesis of olefin block copolymers (OBC). One type is a "hard-soft" OBC with a high density polyethylene (HDPE) block and a relatively low density polyethylene (VLDPE) block targeted as thermoplastic elastomers. Presently, one of the major challenges is to fractionate HDPE segments from the other components in an experimental OBC sample (block copolymers and VLDPE segments). Interactive high temperature liquid chromatography (HTLC) is ineffective for OBC separation as the HDPE segments and block copolymer chains experience nearly identical enthalpic interactions with the stationary phase and co-elute. In this work we have overcome this challenge by using liquid chromatography under the limiting conditions of desorption (LC LCD). A solvent plug (discrete barrier) is introduced in front of the sample which specifically promotes the adsorption of HDPE segments on the stationary phase (porous graphitic carbon). Under selected thermodynamic conditions, VLDPE segments and block copolymer chains crossed the barrier while HDPE segments followed the pore-included barrier solvent and thus enabled separation. The barrier solvent composition was optimized and the chemical composition of fractionated polymer chains was investigated as a function of barrier solvent strength using an online Fourier-transform infrared (FTIR) detector. Our study revealed that both the HDPE segments as well as asymmetric block copolymer chains (HDPE block length≫VLDPE block length) are retained in the separation and the barrier strength can be tailored to retain a particular composition. At the optimum barrier solvent composition, this method can be applied to separate effective HDPE segments from the other components, which has been demonstrated using an experimental OBC sample. Copyright © 2016 Elsevier B.V. All rights reserved.

Increase of Longevity of High Filled Composite Polymeric Materials Intended for Covering of Highways

NASA Astrophysics Data System (ADS)

Negmatov, S. S.; Sobirov, B. B.; Abdullaev, A. X.; Salimsakov, Yu. A.; Raxmonov, B. Sh.; Negmatova, K. S.; Ergashev, E.; Jonuzokov, A. A.

2008-08-01

In work the results of researches of influence of various components included in structure of high filled asphalt-concrete coverings and composite polymeric hermetic materials for sealing them deformed seams and cracks are given. The opportunity of increase of long lived operation of highways was shown using as filler the mechano-activated river and dune sands in a combination to secondary polyethylene.

Biodegradation of low-density polyethylene by marine bacteria from pelagic waters, Arabian Sea, India.

PubMed

Harshvardhan, Kumar; Jha, Bhavanath

2013-12-15

Sixty marine bacteria isolated from pelagic waters were screened for their ability to degrade low-density polyethylene; among them, three were positive and able to grow in a medium containing polythene as the sole carbon source. The positive isolates were identified as Kocuria palustris M16, Bacillus pumilus M27 and Bacillus subtilis H1584 based on the 16S rRNA gene sequence homology. The weight loss of polyethylene was 1%, 1.5% and 1.75% after 30 days of incubation with the M16, M27 and H1584 isolates, respectively. The maximum (32%) cell surface hydrophobicity was observed in M16, followed by the H1584 and M27 isolates. The viability of the isolates growing on the polyethylene surface was confirmed using a triphenyltetrazolium chloride reduction test. The viability was also correlated with a concomitant increase in the protein density of the biomass. Polyethylene biodegradation was further confirmed by an increase in the Keto Carbonyl Bond Index, the Ester Carbonyl Bond Index and the Vinyl Bond Index, which were calculated from FT-IR spectra. Copyright © 2013 Elsevier Ltd. All rights reserved.

Design options for improved performance with high-density carbon ablators and low-gas fill hohlraum targets

NASA Astrophysics Data System (ADS)

Berzak Hopkins, L.; Divol, L.; Lepape, S.; Meezan, N. B.; Dewald, E.; Ho, D.; Khan, S.; Pak, A.; Ralph, J.; Ross, J. S.

2016-10-01

Recent simulation-based and experimental work using high-density carbon ablators in unlined uranium hohlraums with 0.3 mg/cc helium fill have demonstrated round implosions with minimal evolution of Legendre moment P2 during burn. To extend this promising work, design studies have been performed to explore potential performance improvements with larger capsules, while maintaining similar case-to-capsule target ratios. We present here the results of these design studies, which will motivate a series of upcoming experiments at the National Ignition Facility. Prepared by LLNL under Contract DE-AC52-07NA27344.

Wine evolution and spatial distribution of oxygen during storage in high-density polyethylene tanks.

PubMed

del Alamo-Sanza, María; Laurie, V Felipe; Nevares, Ignacio

2015-04-01

Porous plastic tanks are permeable to oxygen due to the nature of the polymers with which they are manufactured. In the wine industry, these types of tanks are used mainly for storing wine surpluses. Lately, their use in combination with oak pieces has also been proposed as an alternative to mimic traditional barrel ageing. In this study, the spatial distribution of dissolved oxygen in a wine-like model solution, and the oxygen transfer rate (OTR) of high-density polyethylene tanks (HDPE), was analysed by means of a non-invasive opto-luminescence detector. Also, the chemical and sensory evolution of red wine, treated with oak pieces, and stored in HDPE tanks was examined and compared against traditional oak barrel ageing. The average OTR calculated for these tanks was within the commonly accepted amounts reported for new barrels. With regards to wine evolution, a number of compositional and sensory differences were observed between the wines aged in oak barrels and those stored in HDPE tanks with oak barrel alternatives. The use of HDPE tanks in combination with oak wood alternatives is a viable alternative too for ageing wine. © 2014 Society of Chemical Industry.

Interrelation of electret properties of polyethylene foam from the method of cross-linking

NASA Astrophysics Data System (ADS)

Gilmanov, I. R.; Galikhanov, M. F.; Gilmanova, A. R.

2017-09-01

The electret properties of chemically cross-linked polyethylene foam and physically cross-linked polyethylene foam have been studied. It has been shown that chemically cross-linked polyethylene foam has higher surface potential, effective surface charge density and electric field strength compared to physically bonded polyethylene foam. This is due to the presence of molecules and fragments of dicumyl peroxide, which can play the role of traps for injection charge carriers, a greater degree of cross-linking and with the oxidation of polyethylene, which occurs during irradiation during physical cross-linking. When the foam is deformed, its electret properties are reduced, and when the volume is relaxed, they are restored. This is due to the partial mutual compensation of homo- and heterocharge during compression and the return of the structure of the gas-filled polymer to its former position when the load is removed.

Morphology-Property relationship of high density Polyethylene/Hevea Brasiliensis Leaves/Imperata cylindrica hybrid composite: Impact strength

NASA Astrophysics Data System (ADS)

Rashidi, A. R.; Muhammad, A.; Roslan, A.

2017-09-01

This research studies about the Hevea Brasiliensis Leaves and Imperata Cylindrica that was used as filler in High Density Polyethylene (HDPE). The fillers content were varied in the composite by 5 wt%, 15 wt% and 25 wt% respectively. This polymer composite are being studied by using Impact Test and Scanning Electron Microscopy (SEM). The analysis show that the impact strength value increased when the percent of bio filler used is low. The result between pure HDPE and the composites shows an outcome of significant changes in impact energy values, while the values between different composite change slightly. A composite that contained 5 wt% of fillers is the better energy absorber than 15 wt% and 25 wt% according to impact testing. In addition, the morphology studies on the composite sample show that the bio-filler was successfully embedded. Overall, these finding suggest that HBL and IC can be an alternative filler to be incorporated in polymer matrix.

46 CFR 98.25-65 - Filling density.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Filling density. 98.25-65 Section 98.25-65 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk...

46 CFR 98.25-65 - Filling density.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Filling density. 98.25-65 Section 98.25-65 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk...

46 CFR 98.25-65 - Filling density.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Filling density. 98.25-65 Section 98.25-65 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk...

46 CFR 98.25-65 - Filling density.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Filling density. 98.25-65 Section 98.25-65 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk...

46 CFR 98.25-65 - Filling density.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Filling density. 98.25-65 Section 98.25-65 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk...

Method for making a low density polyethylene waste form for safe disposal of low level radioactive material

DOEpatents

Colombo, P.; Kalb, P.D.

1984-06-05

In the method of the invention low density polyethylene pellets are mixed in a predetermined ratio with radioactive particulate material, then the mixture is fed through a screw-type extruder that melts the low density polyethylene under a predetermined pressure and temperature to form a homogeneous matrix that is extruded and separated into solid monolithic waste forms. The solid waste forms are adapted to be safely handled, stored for a short time, and safely disposed of in approved depositories.

Methodology for Long-Term Permeation Test Periods for HD in High-Density Polyethylene: Universal Munitions Storage Container for the Non-Stockpile Chemical Materiel Program

DTIC Science & Technology

2016-05-01

measurements for distilled mustard (HD) and non- welded high-density polyethylene (HDPE) at 120 °F were completed for thicknesses of 20–80 mil for...extrapolation to the ~250 mil container thickness. A Fick’s law extrapolation inferred a breakthrough time of 10–11 days for the 250 mil non- welded HDPE at...8 3.2 Permeation Results for 20 mil HDPE at 100 °F: Welded ................................10 3.2.1 Confirmation Test: Welded

Biodegradation of thermally treated low density polyethylene by fungus Rhizopus oryzae NS 5.

PubMed

Awasthi, Shraddha; Srivastava, Neha; Singh, Tripti; Tiwary, D; Mishra, Pradeep Kumar

2017-05-01

Polythene is considered as one of the important object used in daily life. Being versatile in nature and resistant to microbial attack, they effectively cause environmental pollution. In the present study, biodegradation of low-density polyethylene (LDPE) have been performed using fungal lab isolate Rhizopus oryzae NS5. Lab isolate fungal strain capable of adhering to LDPE surface was used for the biodegradation of LDPE. This strain was identified as Rhizopus oryzae NS5 (Accession No. KT160362). Fungal growth was observed on the surface of the polyethylene when cultured in potato dextrose broth at 30 °C and 120 rpm, for 1 month. LDPE film was characterized before and after incubation by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and universal tensile machine. About 8.4 ± 3% decrease (gravimetrically) in weight and 60% reduction in tensile strength of polyethylene was observed. Scanning electron microscope analysis showed hyphal penetration and degradation on the surface of polyethylene. Atomic force microscope analysis showed increased surface roughness after treatment with fungal isolate. A thick network of fungal hyphae forming a biofilm was also observed on the surface of the polyethylene pieces. Present study shows the potential of Rhizopus oryzae NS5 in polyethylene degradation in eco friendly and sustainable manner.

Incorporation of Copper Enhances the Anti-Ageing Property of Flame-Sprayed High-Density Polyethylene Coatings

NASA Astrophysics Data System (ADS)

Jia, Zhengmei; Huang, Jing; Gong, Yongfeng; Jin, Peipeng; Suo, Xinkun; Li, Hua

2017-02-01

High-density polyethylene (HDPE)-copper (Cu) composite coatings were prepared through depositing HDPE-Cu core-shell particles by flame spraying. The HDPE-Cu composite coatings and the HDPE coatings were aged in xenon lamp ageing testing chamber. The variations of chemical compositions and surface morphology of the coatings before and after the ageing testing were analyzed using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and ultraviolet-visible spectrophotometer. Results show that there is no chemical composition variation in the HDPE-Cu coatings. Cracks were found on the surfaces of the HDPE coatings, while the HDPE-Cu coating shows almost intact surface morphology. These results suggest that the HDPE-Cu coatings present better anti-ageing performances than the HDPE coatings. Further assessment of the function of Cu shells on the anti-ageing property reveals that Cu shells not only enhanced the absorption of the coatings to ultraviolet, but also increased their reflectivity to visible light. Additionally, the Cu shells enhanced the decomposition temperature and thermal stability of HDPE in the composite coatings. These results give bright insight into potential anti-ageing applications of the polymer-based structures.

Separation of n-hexane/acetone mixtures by pervaporation using high density polyethylene/ethylene propylene diene terpolymer rubber blend membranes.

PubMed

Kumar, P V Anil; Anilkumar, S; Varughese, K T; Thomas, Sabu

2012-01-15

Polymer membranes were prepared by blending high density polyethylene (HDPE) with ethylene propylene diene terpolymer rubber (EPDM). These blend membranes were evaluated for the selective separation of n-hexane from acetone. The flux and selectivity of the membranes were determined both as a function of the blend composition and feed mixture composition. Results showed that polymer blending method could be very useful to develop new membranes with improved selectivity. Pervaporation properties could be optimized by adjusting the blend composition. The effects of blend ratio, feed composition, and penetrant size on the pervaporation process were analyzed. The permeation properties have been explained on the basis of interaction between the membrane and solvents and blend morphology. Flux increases with increasing alkane content in the feed composition. Copyright © 2011 Elsevier B.V. All rights reserved.

Regulating the surface poly(ethylene glycol) density of polymeric nanoparticles and evaluating its role in drug delivery in vivo.

PubMed

Du, Xiao-Jiao; Wang, Ji-Long; Liu, Wei-Wei; Yang, Jin-Xian; Sun, Chun-Yang; Sun, Rong; Li, Hong-Jun; Shen, Song; Luo, Ying-Li; Ye, Xiao-Dong; Zhu, Yan-Hua; Yang, Xian-Zhu; Wang, Jun

2015-11-01

Poly(ethylene glycol) (PEG) is usually used to protect nanoparticles from rapid clearance in blood. The effects are highly dependent on the surface PEG density of nanoparticles. However, there lacks a detailed and informative study in PEG density and in vivo drug delivery due to the critical techniques to precisely control the surface PEG density when maintaining other nano-properties. Here, we regulated the polymeric nanoparticles' size and surface PEG density by incorporating poly(ε-caprolactone) (PCL) homopolymer into poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-PCL) and adjusting the mass ratio of PCL to PEG-PCL during the nanoparticles preparation. We further developed a library of polymeric nanoparticles with different but controllable sizes and surface PEG densities by changing the molecular weight of the PCL block in PEG-PCL and tuning the molar ratio of repeating units of PCL (CL) to that of PEG (EG). We thus obtained a group of nanoparticles with variable surface PEG densities but with other nano-properties identical, and investigated the effects of surface PEG densities on the biological behaviors of nanoparticles in mice. We found that, high surface PEG density made the nanoparticles resistant to absorption of serum protein and uptake by macrophages, leading to a greater accumulation of nanoparticles in tumor tissue, which recuperated the defects of decreased internalization by tumor cells, resulting in superior antitumor efficacy when carrying docetaxel. Copyright © 2015 Elsevier Ltd. All rights reserved.

Application of support vector regression for optimization of vibration flow field of high-density polyethylene melts characterized by small angle light scattering

NASA Astrophysics Data System (ADS)

Xian, Guangming

2018-03-01

In this paper, the vibration flow field parameters of polymer melts in a visual slit die are optimized by using intelligent algorithm. Experimental small angle light scattering (SALS) patterns are shown to characterize the processing process. In order to capture the scattered light, a polarizer and an analyzer are placed before and after the polymer melts. The results reported in this study are obtained using high-density polyethylene (HDPE) with rotation speed at 28 rpm. In addition, support vector regression (SVR) analytical method is introduced for optimization the parameters of vibration flow field. This work establishes the general applicability of SVR for predicting the optimal parameters of vibration flow field.

Infrared-actuated recovery of polyurethane filled by reduced graphene oxide/carbon nanotube hybrids with high energy density.

PubMed

Feng, Yiyu; Qin, Mengmeng; Guo, Haiqiang; Yoshino, Katsumi; Feng, Wei

2013-11-13

Optically actuated shape recovery materials receive much interest because of their great ability to control the creation of mechanical motion remotely and precisely. An infrared (IR) triggered actuator based on shape recovery was fabricated using polyurethane (TPU) incorporated by sulfonated reduced graphene oxide (SRGO)/sulfonated carbon nanotube (SCNT) hybrid nanofillers. Interconnected SRGO/SCNT hybrid nanofillers at a low weight loading of 1% dispersed in TPU showed good IR absorption and improved the crystallization of soft segments for a large shape deformation. The output force, energy density and recovery time of IR-triggered actuators were dependent on weight ratios of SRGO to SCNT (SRGO:SCNT). TPU nanocomposites filled by a hybrid nanofiller with SRGO:SCNT of 3:1 showed the maximum IR-actuated stress recovery of lifting a 107.6 g weight up 4.7 cm in 18 s. The stress recovery delivered a high energy density of 0.63 J/g and shape recovery force up to 1.2 MPa due to high thermal conductivity (1.473 W/mK) and Young's modulus of 23.4 MPa. Results indicate that a trade-off between the stiffness and efficient heat transfer controlled by synergistic effect between SRGO and SCNT is critical for high mechanical power output of IR-triggered actuators. IR-actuated shape recovery of SRGO/SCNT/TPU nanocomposites combining high energy density and output forces can be further developed for advanced optomechanical systems.

Oil-Impregnated Polyethylene Films

NASA Astrophysics Data System (ADS)

Mukherjee, Ranit; Habibi, Mohammad; Rashed, Ziad; Berbert, Otacilio; Shi, Shawn; Boreyko, Jonathan

2017-11-01

Slippery liquid-infused porous surfaces (SLIPS) minimize the contact angle hysteresis of a wide range of liquids and aqueous food products. Although hydrophobic polymers are often used as the porous substrate for SLIPS, the choice of polymer has been limited to silicone-based or fluorine-based materials. Hydrocarbon-based polymers, such as polyethylene, are cost effective and widely used in food packaging applications where SLIPS would be highly desirable. However, to date there have been no reports on using polyethylene as a SLIPS substrate, as it is considered highly impermeable. Here, we show that thin films of low-density polyethylene can be stably impregnated with carbon-based oils without requiring any surface modification. Wicking tests reveal that oils with sufficient chemical compatibility follow Washburn's equation. The nanometric effective pore size of the polyethylene does result in a very low wicking speed, but by using micro-thin films and a drawdown coater, impregnation can still be completed in under one second. The oil-impregnated polyethylene films promoted ultra-slippery behavior for water, ketchup, and yogurt while remaining durable even after being submerged in ketchup for over one month. This work was supported by Bemis North America (AT-23981).

Study of microstructure and fracture properties of blunt notched and sharp cracked high density polyethylene specimens.

PubMed

Pan, Huanyu; Devasahayam, Sheila; Bandyopadhyay, Sri

2017-07-21

This paper examines the effect of a broad range of crosshead speed (0.05 to 100 mm/min) and a small range of temperature (25 °C and 45 °C) on the failure behaviour of high density polyethylene (HDPE) specimens containing a) standard size blunt notch and b) standard size blunt notch plus small sharp crack - all tested in air. It was observed that the yield stress properties showed linear increase with the natural logarithm of strain rate. The stress intensity factors under blunt notch and sharp crack conditions also increased linearly with natural logarithm of the crosshead speed. The results indicate that in the practical temperature range of 25 °C and 45 °C under normal atmosphere and increasing strain rates, HDPE specimens with both blunt notches and sharp cracks possess superior fracture properties. SEM microstructure studies of fracture surfaces showed craze initiation mechanisms at lower strain rate, whilst at higher strain rates there is evidence of dimple patterns absorbing the strain energy and creating plastic deformation. The stress intensity factor and the yield strength were higher at 25 °C compared to those at 45 °C.

Measurement of the loss tangent of low-density polyethylene with a nanoindentation technique

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

Loubet, J. L.; Oliver, W. C.; Lucas, B. N.

2000-05-01

This paper describes experimental measurements of the linear viscoelastic behavior of the surface of low-density (LD) polyethylene in contact with a pyramidal Berkovich diamond indenter. The experiments were carried out at two different temperatures, 15.9 and 27.2 degree sign C, between frequencies of 0.1 and 800 Hz. Using the shift of the loss tangent between the two temperatures at frequencies lower than 20 Hz and an Arrhenius equation, an activation energy of 105{+-}2 kJ/mol was obtained. This value is in good agreement with the bulk value of the {alpha} relaxation of LD polyethylene reported in the literature. (c) 2000 Materialsmore » Research Society.« less

Maleic anhydride-g-low density polyethylene: Modification of LDPE molecular structure by γ-irradiation

NASA Astrophysics Data System (ADS)

Sheeja, Manaf, O.; Sujith, A.

2017-06-01

Polymer modification by radiation grafting of monomers onto polymers has received much attention recently. In the current study, γ-irradiation technique was used to achieve graft copolymerization of maleic anhydride (MA) onto low-density polyethylene (LDPE). To optimize, the process was performed at different γ-irradiation doses and MA concentration. The microstructure of grafted polymer film has been characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, field emission-scanning electron microscopy, and atomic force microscopy. The studies performed made possible the selection of experimental protocols adequate for the production of new copolymeric materials with high grafting yield.

Evaluation of cotton byproducts as fillers for poly(lactic acid) and low density polyethylene

USDA-ARS?s Scientific Manuscript database

Polymeric composites based on cotton burr and cottonseed bull have been prepared by melt blending and extrusion. For poly(lactic acid) (PLA) and low-density polyethylene (LDPE), addition of the fillers only slightly changed the composite’s thermal properties and significantly decreased the composite...

Development of Functional Surfaces on High-Density Polyethylene (HDPE) via Gas-Assisted Etching (GAE) Using Focused Ion Beams.

PubMed

Sezen, Meltem; Bakan, Feray

2015-12-01

Irradiation damage, caused by the use of beams in electron and ion microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on electron/ion beam irradiation. Nevertheless, it is possible to turn degradation-dependent physical/chemical changes from negative to positive use when materials are intentionally exposed to beams. Especially, controllable surface modification allows tuning of surface properties for targeted purposes and thus provides the use of ultimate materials and their systems at the micro/nanoscale for creating functional surfaces. In this work, XeF2 and I2 gases were used in the focused ion beam scanning electron microscope instrument in combination with gallium ion etching of high-density polyethylene surfaces with different beam currents and accordingly different gas exposure times resulting at the same ion dose to optimize and develop new polymer surface properties and to create functional polymer surfaces. Alterations in the surface morphologies and surface chemistry due to gas-assisted etching-based nanostructuring with various processing parameters were tracked using high-resolution SEM imaging, complementary energy-dispersive spectroscopic analyses, and atomic force microscopic investigations.

The effect of polyethylene glycol on the characteristics of kenaf cellulose/low-density polyethylene biocomposites.

PubMed

Tajeddin, Behjat; Rahman, Russly Abdul; Abdulah, Luqman Chuah

2010-08-01

Toward the development of biocomposites for packaging applications, the possibility of using kenaf cellulose (KC) was investigated in the production of low-density polyethylene (LDPE)/KC/polyethylene glycol (PEG) biocomposites. First, cellulose was extracted from the cell walls of kenaf-bast fibers. Then, different weights of LDPE, KC, and PEG were blended, and the effects of varying the concentrations of KC and PEG on the synthesis process were evaluated, and the resulting composites were characterized with respect to their mechanical, thermal, biodegradability and water-absorption properties. A scanning electron microscope (SEM) was also used to observe the surface morphology of the samples before and after biodegradation tests. The results showed that the mechanical properties of the biocomposites decreased slightly as the KC content was increased from 0 to 50wt% in the biocomposite formulation; however, there was a good homogeneity between samples with added PEG. The addition of KC improved the thermal resistance of these biocomposites; PEG also had positive role in the thermal behavior of the composites. Based on a soil-burial test, the biodegradability of the composites showed a clear trend of increase degradation with increasing KC content in the formulation. While water-absorption values for the composites were higher than that of pure LDPE polymer, the addition of PEG to the formulation reduced the water absorption of the composites. Copyright 2010 Elsevier B.V. All rights reserved.

Ultraviolet weathering of photostabilized wood-flour-filled high-density polyethylene composites

Treesearch

Nicole M. Stark; Laurent M. Matuana

2003-01-01

Wood–plastic composites are being increasingly examined for nonstructural or semistructural building applications. As outdoor applications become more widespread, durability becomes an issue. Ultraviolet exposure can lead to photodegradation, which results in a change in appearance and/or mechanical properties. Photodegradation can be slowed through the addition of...

Clinical field follow-up of high density polyethylene (HDPE)-Jaipur prosthetic technology for trans-femoral amputees.

PubMed

Jensen, J S; Craig, J G; Mtalo, L B; Zelaya, C M

2004-08-01

The purpose of this study was to examine the outcome of the application of the high density polyethylene (HDPE)-Jaipur prosthetic construction in fitting trans-femoral amputees in a number of projects throughout the developing world. Projects in Honduras, Uganda and India were included. One hundred and fifty eight (158) patients had been provided with the HDPE-Jaipur prosthesis and of these 72 were seen for a clinical and technical follow-up after a median of 32 months. More than half the amputees seen had amputation due to trauma and the remainder due to disease. Fabrication and fitting in the three projects was carried out by individuals who had undertaken a three week training course provided by Bhagwan Mahaveer Viklang Sahayata Samiti limb centre in Jaipur. The individuals involved had limited background training in prosthetics. Craftsmanship and fit were assessed as being poor in 86% of cases. Failure requiring replacement of components was observed in 50% of cases. There was low patient satisfaction (58%) and patient compliance (65%). The outcome was considered unsatisfactory both technically and clinically. This was a reflection of the inadequacies of the prosthetic construction, particularly the knee joint, and the inadequate training of those involved in fitting and fabrication of the devices.

Clinical field follow-up of high density polyethylene (HDPE)-Jaipur prosthetic technology for trans-tibial amputees.

PubMed

Jensen, J S; Craig, J G; Mtalo, L B; Zelaya, C M

2004-12-01

The purpose of this study was to examine the outcome of the application of the High Density Polyethylene (HDPE)-Jaipur prosthetic construction in fitting trans-tibial amputees in a number of projects in the developing world. Projects in Honduras, Uganda and India were visited. Three hundred and twenty (320) patients had been provided with a HDPE-Jaipur prosthesis and of these 172 were seen for a technical and clinical follow-up after a median of 35 months. More than half the amputations were due to trauma, the remainder to disease. Fabrication and fitting in the three projects was carried out by individuals who had undertaken a twice week training course provided by Bhagwan Mahaveer Viklang Sahayata Samiti limb centre in Jaipur. The individuals involved had limited background training in prosthetics. Craftsmanship and fit were assessed as being poor in 56% of cases. The technical quality of the Jaipur foot was considered acceptable as its performance was better than previously observed results. Although there was patient satisfaction of 85% and compliance of 94% the HDPE-Jaipur trans-tibial system was not considered acceptable as 49% reported walking distances less than 1km and 36% discomfort. The major inadequacy in outcome relates to the use for fabrication and fitting of individuals with inadequate education and training.

Dielectric, thermal and mechanical properties of zirconium silicate reinforced high density polyethylene composites for antenna applications.

PubMed

Varghese, Jobin; Nair, Dinesh Raghavan; Mohanan, Pezholil; Sebastian, Mailadil Thomas

2015-06-14

A low cost and low dielectric loss zirconium silicate (ZrSiO4) reinforced HDPE (high-density polyethylene) composite has been developed for antenna applications. The 0-3 type composite is prepared by dispersing ZrSiO4 fillers for various volume fractions (0.1 to 0.5) in the HDPE matrix by the melt mixing process. The composite shows good microwave dielectric properties with a relative permittivity of 5.6 and a dielectric loss of 0.003 at 5 GHz at the maximum filler loading of 0.5 volume fraction. The composite exhibits low water absorption, excellent thermal and mechanical properties. It shows a water absorption of 0.03 wt%, a coefficient of thermal expansion of 70 ppm per °C and a room temperature thermal conductivity of 2.4 W mK(-1). The composite shows a tensile strength of 22 MPa and a microhardness of 13.9 kg mm(-2) for the filler loading of 0.5 volume fraction. The HDPE-ZrSiO4 composites show good dielectric, thermal and mechanical properties suitable for microwave soft substrate applications. A microstrip patch antenna is designed and fabricated using the HDPE-0.5 volume fraction ZrSiO4 substrate and the antenna parameters are investigated.

Study on the PTC/NTC effect of carbon black-filled polymer composites

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

Tang, Hao; Chen, Xinfang; Luo, Yunxia

1995-12-01

In this work, the effect of processing condition and radiation-crosslinking on the electrical and dynamic behaviors of carbon black filled low density polyethylene (LDPE) composites were investigated. Compared with the solution counterpart, the mechanical composites have a strong PTC effect and a great dynamic elastic mold, which results from the strong interaction between carbon black and LDPE. The experiment result shows that the NTC effect is caused by the decrease of elastic mold of LDPE at high temperature, and it can be declined significantly by radiation-crosslinking. We conclude that the strong interaction between polymer and carbon black is essentially importantmore » for composites to have a great PTC intensity good electrical reproducibility and high dynamic elastic sold.« less

Influence of triallyl cyanurate as co-agent on gamma irradiation cured high density polyethylene/reclaimed tire rubber blend

NASA Astrophysics Data System (ADS)

Mali, Manoj N.; Arakh, Amar A.; Dubey, K. A.; Mhaske, S. T.

2017-02-01

Utilization of waste from tire industry as reclaimed tire rubber (RTR) by formation of blends with high density polyethylene (HDPE) is great area to be focused. Enhancement of properties by the addition of triallyl cyanurate (TAC) as a co-agent with 1%, 3% and 5% to blend of HDPE 50 wt% and RTR 50 wt% in presence of gamma irradiation curing were investigated. Specifically, mechanical and thermal properties were studied as a function of amount of TAC and gamma irradiation dose in range of 50-200 kGy. The resultant blends were evaluated for the values of impact strength, gel content, thermal stability, tensile properties, rheological properties and morphological properties with increasing irradiation dosage and TAC loading. The mechanical properties tensile strength, hardness, impact strength of blend containing 3% of TAC were substantially increased with increasing irradiation dosage up to 150 KGy. Rheological analysis has shown increase in viscosity with increase in TAC loading up to 3% and 150 KGy irradiation dosages. 3% loading of TAC lead to better set of properties with150 KGy gamma irradiation dosage.

Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

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

Aras, Neny Rasnyanti M., E-mail: neny.rasnyanti@gmail.com; Arcana, I Made, E-mail: arcana@chem.itb.ac.id

An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearatemore » with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm{sup −1} which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0

Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

NASA Astrophysics Data System (ADS)

Aras, Neny Rasnyanti M.; Arcana, I. Made

2015-09-01

An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm-1 which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese stearate

Development of optimum process for electron beam cross-linking of high density polyethylene thermal energy storage pellets, process scale-up and production of application qualities of material

NASA Technical Reports Server (NTRS)

Salyer, I. O.

1980-01-01

The electron irradiation conditions required to prepare thermally from stable high density polyethylene (HDPE) were defined. The conditions were defined by evaluating the heat of fusion and the melting temperature of several HDPE specimens. The performance tests conducted on the specimens, including the thermal cycling tests in the thermal energy storage unit are described. The electron beam irradiation tests performed on the specimens, in which the total radiation dose received by the pellets, the electron beam current, the accelerating potential, and the atmospheres were varied, are discussed.

A novel model for through-silicon via (TSV) filling process simulation considering three additives and current density effect

NASA Astrophysics Data System (ADS)

Wang, Fuliang; Zhao, Zhipeng; Wang, Feng; Wang, Yan; Nie, Nantian

2017-12-01

Through-silicon via (TSV) filling by electrochemical deposition is still a challenge for 3D IC packaging, and three-component additive systems (accelerator, suppressor, and leveler) were commonly used in the industry to achieve void-free filling. However, models considering three additive systems and the current density effect have not been fully studied. In this paper, a novel three-component model was developed to study the TSV filling mechanism and process, where the interaction behavior of the three additives (accelerator, suppressor, and leveler) were considered, and the adsorption, desorption, and consumption coefficient of the three additives were changed with the current density. Based on this new model, the three filling types (seam void, ‘V’ shape, and key hole) were simulated under different current density conditions, and the filling results were verified by experiments. The effect of the current density on the copper ion concentration, additives surface coverage, and local current density distribution during the TSV filling process were obtained. Based on the simulation and experimental results, the diffusion-adsorption-desorption-consumption competition behavior between the suppressor, the accelerator, and the leveler were discussed. The filling mechanisms under different current densities were also analyzed.

The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Hall, G. N.; Jones, O. S.; Strozzi, D. J.; Moody, J. D.; Turnbull, D.; Ralph, J.; Michel, P. A.; Hohenberger, M.; Moore, A. S.; Landen, O. L.; Divol, L.; Bradley, D. K.; Hinkel, D. E.; Mackinnon, A. J.; Town, R. P. J.; Meezan, N. B.; Berzak Hopkins, L.; Izumi, N.

2017-05-01

Indirect drive inertial confinement fusion experiments were conducted at the National Ignition Facility to investigate the performance of the hohlraum drive as a function of hohlraum gas fill density by imploding high-density-carbon capsules using a 2-shock laser pulse. Measurements characterized the backscatter behavior, the production of hot electrons, the motion and brightness of the laser spots on the hohlraum wall, and the efficiency of the hohlraum x-ray drive as a function of gas fill density ρgf between 0.03 mg/cc ("near vacuum") and 1.6 mg/cc. For hohlraums with ρgf up to 0.85 mg/cc, very little stimulated Raman backscatter (SRS) was observed. For higher ρgf, significant SRS was produced and was observed to occur during the rise to peak laser power and throughout the main pulse. The efficiency with which laser energy absorbed by the hohlraum is converted into drive energy was measured to be the same for ρgf ≥ 0.6 mg/cc once the laser reached peak power. However, for the near vacuum case, the absorbed energy was converted to drive energy more efficiently throughout the pulse and maintained an efficiency ˜10% higher than the gas filled hohlraums throughout the main pulse.

The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility

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

Hall, G. N.; Jones, O. S.; Strozzi, D. J.

Indirect drive inertial confinement fusion experiments were conducted at the National Ignition Facility to investigate the performance of the hohlraum drive as a function of hohlraum gas fill density by imploding high-density-carbon capsules using a 2-shock laser pulse. Our ,easurements characterize the backscatter behavior, the production of hot electrons, the motion and brightness of the laser spots on the hohlraum wall, and the efficiency of the hohlraum x-ray drive as a function of gas fill density ρ gf between 0.03 mg/cc (“near vacuum”) and 1.6 mg/cc. For hohlraums with ρ gf up to 0.85 mg/cc, very little stimulated Raman backscattermore » (SRS) was observed. Furthermore, for higher ρ gf, significant SRS was produced and was observed to occur during the rise to peak laser power and throughout the main pulse. The efficiency with which laser energy absorbed by the hohlraum is converted into drive energy was measured to be the same for ρ gf ≥ 0.6 mg/cc once the laser reached peak power. But, for the near vacuum case, the absorbed energy was converted to drive energy more efficiently throughout the pulse and maintained an efficiency ~10% higher than the gas filled hohlraums throughout the main pulse.« less

The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility

DOE PAGES

Hall, G. N.; Jones, O. S.; Strozzi, D. J.; ...

2017-05-11

Indirect drive inertial confinement fusion experiments were conducted at the National Ignition Facility to investigate the performance of the hohlraum drive as a function of hohlraum gas fill density by imploding high-density-carbon capsules using a 2-shock laser pulse. Our ,easurements characterize the backscatter behavior, the production of hot electrons, the motion and brightness of the laser spots on the hohlraum wall, and the efficiency of the hohlraum x-ray drive as a function of gas fill density ρ gf between 0.03 mg/cc (“near vacuum”) and 1.6 mg/cc. For hohlraums with ρ gf up to 0.85 mg/cc, very little stimulated Raman backscattermore » (SRS) was observed. Furthermore, for higher ρ gf, significant SRS was produced and was observed to occur during the rise to peak laser power and throughout the main pulse. The efficiency with which laser energy absorbed by the hohlraum is converted into drive energy was measured to be the same for ρ gf ≥ 0.6 mg/cc once the laser reached peak power. But, for the near vacuum case, the absorbed energy was converted to drive energy more efficiently throughout the pulse and maintained an efficiency ~10% higher than the gas filled hohlraums throughout the main pulse.« less

Optimization of high filler loading on tensile properties of recycled HDPE/PET blends filled with rice husk

NASA Astrophysics Data System (ADS)

Chen, Ruey Shan; Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Salleh, Mohd Nazry

2014-09-01

Biocomposites of recycled high density polyethylene / recycled polyethylene terephthalate (rHDPE/rPET) blend incorporated with rice husk flour (RHF) were prepared using a corotating twin screw extruder. Maleic anhydride polyethylene (MAPE) was added as a coupling agent to improve the fibre-matrix interface adhesion. The effect of high filler loadings (50-90 wt%) on morphology and tensile properties of compatibilized rHDPE/rPET blend was investigated. The results of our study shown that composite with 70 wt% exhibited the highest tensile strength and Young's modulus, which are 22 MPa and 1752 MPa, respectively. The elongation at break decreased with increasing percentage of RHF. SEM micrograph confirmed fillers dispersion, morphological interaction and enhanced interfacial bonding between recycled polymer blends and rice husk. It can be concluded that the optimum RHF content is 70 wt% with maximum tensile strength.

Enhanced diesel fuel fraction from waste high-density polyethylene and heavy gas oil pyrolysis using factorial design methodology.

PubMed

Joppert, Ney; da Silva, Alexsandro Araujo; da Costa Marques, Mônica Regina

2015-02-01

Factorial Design Methodology (FDM) was developed to enhance diesel fuel fraction (C9-C23) from waste high-density polyethylene (HDPE) and Heavy Gas Oil (HGO) through co-pyrolysis. FDM was used for optimization of the following reaction parameters: temperature, catalyst and HDPE amounts. The HGO amount was constant (2.00 g) in all experiments. The model optimum conditions were determined to be temperature of 550 °C, HDPE = 0.20 g and no FCC catalyst. Under such conditions, 94% of pyrolytic oil was recovered, of which diesel fuel fraction was 93% (87% diesel fuel fraction yield), no residue was produced and 6% of noncondensable gaseous/volatile fraction was obtained. Seeking to reduce the cost due to high process temperatures, the impact of using higher catalyst content (25%) with a lower temperature (500 °C) was investigated. Under these conditions, 88% of pyrolytic oil was recovered (diesel fuel fraction yield was also 87%) as well as 12% of the noncondensable gaseous/volatile fraction. No waste was produced in these conditions, being an environmentally friendly approach for recycling the waste plastic. This paper demonstrated the usefulness of using FDM to predict and to optimize diesel fuel fraction yield with a great reduction in the number of experiments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Profiles in garbage: Polyethylene terephthalate

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

Miller, C.

1997-11-01

Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks -- along with salad dressing, fruit juices, peanut butter, and other household and consumer products -- use PET bottles. PET also is used for film, sheeting for cups and food trays, oven-safe trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early 1970s. Because it is an ``engineered`` resin, PET is more expensive than commodity resins such as high-density polyethylene (HDPE) and, for the same reason, it is usually the highest valued plastic recyclable.

A method for visualizing high-density porous polyethylene (medpor, porex) with computed tomographic scanning.

PubMed

Vendemia, Nicholas; Chao, Jerry; Ivanidze, Jana; Sanelli, Pina; Spinelli, Henry M

2011-01-01

Medpor (Porex Surgical, Inc, Newnan, GA) is composed of porous polyethylene and is commonly used in craniofacial reconstruction. When complications such as seroma or abscess formation arise, diagnostic modalities are limited because Medpor is radiolucent on conventional radiologic studies. This poses a problem in situations where imaging is necessary to distinguish the implant from surrounding tissues. To present a clinically useful method for imaging Medpor with conventional computed tomographic (CT) scanning. Eleven patients (12 total implants) who have undergone reconstructive surgery with Medpor were included in the study. A retrospective review of CT scans done between 1 and 16 months postoperatively was performed using 3 distinct CT window settings. Measurements of implant dimensions and Hounsfield units were recorded and qualitatively assessed. Of the 3 distinct window settings studied, namely, "bone" (W1100/L450), "soft tissue"; (W500/L50), and "implant" (W800/L200), the implant window proved the most ideal, allowing the investigators to visualize and evaluate Medpor in all cases. Qualitative analysis revealed that Medpor implants were able to be distinguished from surrounding tissue in both the implant and soft tissue windows, with a density falling between that of fat and fluid. In 1 case, Medpor could not be visualized in the soft tissue window, although it could be visualized in the implant window. Quantitative analysis demonstrated a mean (SD) density of -38.7 (7.4) Hounsfield units. Medpor may be optimally visualized on conventional CT scans using the implant window settings W800/L200, which can aid in imaging Medpor and diagnosing implant-related complications.

Effect of Aspergillus versicolor strain JASS1 on low density polyethylene degradation

NASA Astrophysics Data System (ADS)

Gajendiran, A.; Subramani, S.; Abraham, J.

2017-11-01

Low density polyethylene (LDPE) waste disposal remains one of the major environmental concerns faced by the world today. In past decades, major focus has been given to enhance the biodegradation of LDPE by microbial species. In this present study, Aspergillus versicolor with the ability to degrade LDPE was isolated from municipal landfill area using enrichment technique. Based on 18S rRNA gene sequencing confirmed its identity as Aspergillus versicolor. The biodegradation study was carried out for 90 d in M1 medium. The degradation behaviour of LDPE films by Aspergillus versicolor strain JASS1 were confirmed by weight loss, CO2 evolution, Scanning electron microscopy (SEM) analysis, Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) technique. From current investigation, it can be concluded that our isolated strain JASS1 had the potential to degrade LDPE films and it can be useful in solving the problem caused by polyethylene in the environment.

Aging Mechanisms and Nondestructive Aging Indicator of Filled Cross-linked Polyethylene (XLPE) Exposed to Simultaneous Thermal and Gamma Radiation

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

Liu, Shuaishuai; Fifield, Leonard S.; Bowler, Nicola

Aging mechanisms and a nondestructive aging indicator of filled cross-linked polyethylene (XLPE) cable insulation material used in nuclear power plants (NPPs) are studied. Using various material characterization techniques, likely candidates and functions for the main additives in a commercial filled-XLPE insulation material have been identified. These include decabromodiphenyl ether and Sb2O3 as flame retardants, ZnS as white pigment and polymerized 1,2-dihydro-2,2,4-trimethylquinoline as antioxidant. Gas chromatography-mass spectrometry, differential scanning calorimetry, oxidation induction time and measurements of dielectric loss tangent are utilized to monitor property changes as a function of thermal and radiation exposure of the cable material. Small-molecular-weight hydrocarbons are evolvemore » with gamma radiation aging at 90 °C. The level of antioxidant decreases with aging by volatilization and chemical reaction with free radicals. Thermal aging at 90 °C for 25 days or less causes no observable change to the cross-linked polymer structure. Gamma radiation causes damage to crystalline polymer regions and introduces defects. Dielectric loss tangent is shown to be an effective and reliable nondestructive indicator of the aging severity of the filled-XLPE insulation material.« less

Effect of Synthetic High Density Lipoproteins Modification with Polyethylene Glycol on Pharmacokinetics and Pharmacodynamics.

PubMed

Li, Dan; Fawaz, Maria V; Morin, Emily E; Ming, Ran; Sviridov, Denis; Tang, Jie; Ackermann, Rose; Olsen, Karl; Remaley, Alan T; Schwendeman, Anna

2018-01-02

Synthetic high density lipoprotein nanoparticles (sHDLs) capable of mobilizing excess cholesterol from atherosclerotic arteries and delivering it to the liver for elimination have been shown to reduce plaque burden in patients. Unfortunately, sHDLs have a narrow therapeutic index and relative to the endogenous HDL shorter circulation half-life. Surface modification with polyethylene glycol (PEG) was investigated for its potential to extend sHDL circulation in vivo. Various amounts (2.5, 5, and 10%) and different chain lengths (2 and 5 kDa) of PEG-modified lipids were incorporated in sHDL's lipid membrane. Incorporating PEG did not reduce the ability of sHDL to facilitate cholesterol efflux, nor did it inhibit cholesterol uptake by the liver cells. By either adding more PEG or using PEG of longer chain lengths, the circulation half-life was extended. Addition of PEG also increased the area under the curve for the phospholipid component of sHDL (p < 0.05), but not for the apolipoprotein A-I peptide component of sHDL, suggesting sHDL is remodeled by endogenous lipoproteins in vivo. The extended phospholipid circulation led to a higher mobilization of plasma free cholesterol, a biomarker for facilitation of reverse cholesterol transport. The area under the cholesterol mobilization increased about 2-4-fold (p < 0.05), with greater increases observed for longer PEG chains and higher molar percentages of incorporated PEGylated lipids. Mobilized cholesterol was associated primarily with the HDL fraction, led to a transient increase in VLDL cholesterol, and returned to baseline 24 h postdose. Overall, PEGylation of sHDL led to beneficial changes in sHDL particle pharmacokinetic and pharmacodynamic behaviors.

Effect of low-density polyethylene on smoke emissions from burning of simulated debris piles

Treesearch

Seyedehsan Hosseini; Qi Li; Manish Shrivastava; David R. Weise; David R. Cocker; J. Wayne Miller; Heejung S Jung

2014-01-01

Low-density polyethylene (LDPE) plastic is used to keep piled debris from silvicultural activities—activities associated with development and care of forests—dry to enable efficient disposal by burning. The effects of inclusion of LDPE in this manner on smoke emissions are not well known. In a combustion laboratory experiment, 2-kg mixtures of LDPE and manzanita (

Parameterization of an interfacial force field for accurate representation of peptide adsorption free energy on high-density polyethylene

PubMed Central

Abramyan, Tigran M.; Snyder, James A.; Yancey, Jeremy A.; Thyparambil, Aby A.; Wei, Yang; Stuart, Steven J.; Latour, Robert A.

2015-01-01

Interfacial force field (IFF) parameters for use with the CHARMM force field have been developed for interactions between peptides and high-density polyethylene (HDPE). Parameterization of the IFF was performed to achieve agreement between experimental and calculated adsorption free energies of small TGTG–X–GTGT host–guest peptides (T = threonine, G = glycine, and X = variable amino-acid residue) on HDPE, with ±0.5 kcal/mol agreement. This IFF parameter set consists of tuned nonbonded parameters (i.e., partial charges and Lennard–Jones parameters) for use with an in-house-modified CHARMM molecular dynamic program that enables the use of an independent set of force field parameters to control molecular behavior at a solid–liquid interface. The R correlation coefficient between the simulated and experimental peptide adsorption free energies increased from 0.00 for the standard CHARMM force field parameters to 0.88 for the tuned IFF parameters. Subsequent studies are planned to apply the tuned IFF parameter set for the simulation of protein adsorption behavior on an HDPE surface for comparison with experimental values of adsorbed protein orientation and conformation. PMID:25818122

The measurement of creep in ultrahigh molecular weight polyethylene: a comparison of conventional versus highly cross-linked polyethylene.

PubMed

Estok, Daniel M; Bragdon, Charles R; Plank, Gordon R; Huang, Anna; Muratoglu, Orhun K; Harris, William H

2005-02-01

Quantification of creep of highly cross-linked polyethylene would enable separation of creep from wear when evaluating femoral head penetration into polyethylene. We compared creep magnitude of a highly cross-linked versus conventional polyethylene in the laboratory. Twelve acetabular liners of each material were tested, 6 of which had a 32-mm inner diameter (ID) and 6 had 28-mm ID. Creep was measured using coordinate measuring machines during loading at 2 Hz without motion to 4 million cycles. Penetration into 32-mm ID conventional liners reached 97 microm versus 107 microm for highly cross-linked material, not significant. Penetration into 28-mm conventional liners was 132 microm versus 155 microm for highly cross-linked material (P = .017). Ninety percent of the creep had occurred by 2.5 million cycles.

Dielectric response of high permittivity polymer ceramic composite with low loss tangent

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

Subodh, G.; 1.Physikalisches Institut, Universitat Stuttgart, Pfaffenwaldring 57, Stuttgart 70550; Deepu, V.

2009-08-10

The present communication investigates the dielectric response of the Sr{sub 9}Ce{sub 2}Ti{sub 12}O{sub 36} ceramics loaded high density polyethylene and epoxy resin. Sr{sub 9}Ce{sub 2}Ti{sub 12}O{sub 36} ceramic filled polyethylene and epoxy composites were prepared using hot blending and mechanical mixing, respectively. 40 vol % ceramic loaded polyethylene has relative permittivity of 12.1 and loss tangent of 0.004 at 8 GHz, whereas the corresponding composite using epoxy as matrix has permittivity and loss tangent of 14.1 and 0.022, respectively. The effective medium theory fits relatively well for the observed permittivity of these composites.

Tailoring of physical properties in highly filled experimental nanohybrid resin composites.

PubMed

Pick, Bárbara; Pelka, Matthias; Belli, Renan; Braga, Roberto R; Lohbauer, Ulrich

2011-07-01

To assess the elastic modulus (EM), volumetric shrinkage (VS), and polymerization shrinkage stress (PSS) of experimental highly filled nanohybrid composites as a function of matrix composition, filler distribution, and density. One regular viscosity nanohybrid composite (Grandio, VOCO, Germany) and one flowable nanohybrid composite (Grandio Flow, VOCO) were tested as references along with six highly filled experimental nanohybrid composites (four Bis-GMA-based, one UDMA-based, and one Ormocer®-based). The experimental composites varied in filler size and density. EM values were obtained from the "three-point bending" load-displacement curve. VS was calculated with Archimedes' buoyancy principle. PSS was determined in 1-mm thick specimens placed between two (poly)methyl methacrylate rods (Ø=6mm) attached to an universal testing machine. Data were analyzed using oneway ANOVA, Tukey's test (α=0.05), and linear regression analyses. The flowable composite exhibited the highest VS and PSS but lowest EM. The PSS was significantly lower with Ormocer. The EM was significantly higher among experimental composites with highest filler levels. No significant differences were found between all other experimental composites regarding VS and PSS. Filler density and size did not influence EM, VS, or PSS. Neither the filler configuration nor matrix composition in the investigated materials significantly influenced composite shrinkage and mechanical properties. The highest filled experimental composite seemed to increase EM by keeping VS and PSS low; however, matrix composition seemed to be the determinant factor for shrinkage and stress development. The Ormocer, with reduced PSS, deserves further investigation. Filler size and density did not influence the tested parameters. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Enhanced biodegradation of low and high-density polyethylene by novel bacterial consortia formulated from plastic-contaminated cow dung under thermophilic conditions.

PubMed

Skariyachan, Sinosh; Setlur, Anagha Shamsundar; Naik, Sujay Yashwant; Naik, Ashwini Amaresh; Usharani, Makam; Vasist, Kiran S

2017-03-01

The current study aimed to devise eco-friendly, safe, and cost-effective strategies for enhanced degradation of low- and high-density polyethylene (LDPE and HDPE) using newly formulated thermophilic microbial consortia from cow dung and to assess the biodegradation end products. The plastic-degrading bacteria from cow dung samples gathered from highly plastic-acclimated environments were enriched by standard protocols. The degradation ability was comprehended by zone of clearance method, and the percentage of degradation was monitored by weight reduction process. The best isolates were characterized by standard microbiological and molecular biology protocols. The best isolates were employed to form several combinations of microbial consortia, and the degradation end products were analyzed. The stability of 16S ribosomal DNA (rDNA) was predicted by bioinformatics approach. This study identified 75 ± 2, 55 ± 2, 60 ± 3, and 43 ± 3% degradation for LDPE strips, pellets, HDPE strips, and pellets, respectively, for a period of 120 days (p < 0.05) at 55 °C by the formulated consortia of IS1-IS4, and the degradation efficiency was found to be better in comparison with other formulations. The end product analysis by Fourier transform infrared, scanning electron microscopy, energy-dispersive spectroscopy, and nuclear magnetic resonance showed major structural changes and formation of bacterial biofilm on plastic surfaces. These novel isolates were designated as Bacillus vallismortis bt-dsce01, Psuedomonas protegens bt-dsce02, Stenotrophomonas sp. bt-dsce03, and Paenibacillus sp.bt-dsce04 by 16S rDNA sequencing and suggested good gene stability with minimum Gibb's free energy. Therefore, this study imparts substantial information regarding the utilization of these thermophilic microbial consortia from cow dung for rapid polyethylene removal.

Optimization of High Temperature and Pressurized Steam Modified Wood Fibers for High-Density Polyethylene Matrix Composites Using the Orthogonal Design Method

PubMed Central

Gao, Xun; Li, Qingde; Cheng, Wanli; Han, Guangping; Xuan, Lihui

2016-01-01

The orthogonal design method was used to determine the optimum conditions for modifying poplar fibers through a high temperature and pressurized steam treatment for the subsequent preparation of wood fiber/high-density polyethylene (HDPE) composites. The extreme difference, variance, and significance analyses were performed to reveal the effect of the modification parameters on the mechanical properties of the prepared composites, and they yielded consistent results. The main findings indicated that the modification temperature most strongly affected the mechanical properties of the prepared composites, followed by the steam pressure. A temperature of 170 °C, a steam pressure of 0.8 MPa, and a processing time of 20 min were determined as the optimum parameters for fiber modification. Compared to the composites prepared from untreated fibers, the tensile, flexural, and impact strength of the composites prepared from modified fibers increased by 20.17%, 18.5%, and 19.3%, respectively. The effect on the properties of the composites was also investigated by scanning electron microscopy and dynamic mechanical analysis. When the temperature, steam pressure, and processing time reached the highest values, the composites exhibited the best mechanical properties, which were also well in agreement with the results of the extreme difference, variance, and significance analyses. Moreover, the crystallinity and thermal stability of the fibers and the storage modulus of the prepared composites improved; however, the hollocellulose content and the pH of the wood fibers decreased. PMID:28773963

Optimization of High Temperature and Pressurized Steam Modified Wood Fibers for High-Density Polyethylene Matrix Composites Using the Orthogonal Design Method.

PubMed

Gao, Xun; Li, Qingde; Cheng, Wanli; Han, Guangping; Xuan, Lihui

2016-10-18

The orthogonal design method was used to determine the optimum conditions for modifying poplar fibers through a high temperature and pressurized steam treatment for the subsequent preparation of wood fiber/high-density polyethylene (HDPE) composites. The extreme difference, variance, and significance analyses were performed to reveal the effect of the modification parameters on the mechanical properties of the prepared composites, and they yielded consistent results. The main findings indicated that the modification temperature most strongly affected the mechanical properties of the prepared composites, followed by the steam pressure. A temperature of 170 °C, a steam pressure of 0.8 MPa, and a processing time of 20 min were determined as the optimum parameters for fiber modification. Compared to the composites prepared from untreated fibers, the tensile, flexural, and impact strength of the composites prepared from modified fibers increased by 20.17%, 18.5%, and 19.3%, respectively. The effect on the properties of the composites was also investigated by scanning electron microscopy and dynamic mechanical analysis. When the temperature, steam pressure, and processing time reached the highest values, the composites exhibited the best mechanical properties, which were also well in agreement with the results of the extreme difference, variance, and significance analyses. Moreover, the crystallinity and thermal stability of the fibers and the storage modulus of the prepared composites improved; however, the hollocellulose content and the pH of the wood fibers decreased.

Dynamic mechanical analysis of compatibilizer effect on the mechanical properties of wood flour/high-density polyethylene composites

Treesearch

Mehdi Behzad; Medhi Tajvidi; Ghanbar Ehrahimi; Robert H. Falk

2004-01-01

In this study, effect of MAPE (maleic anhydride polyethylene) as the compatibilizer on the mechanical properties of wood-flour polyethylene composites has been investigated by using Dynamic Mechanical Analysis (DMA). Composites were made at 25% and 50% by weight fiber contents and 1% and 2% compatibilizer respectively. Controls were also made at the same fiber contents...

Optimization of gas-filled quartz capillary discharge waveguide for high-energy laser wakefield acceleration

NASA Astrophysics Data System (ADS)

Qin, Zhiyong; Li, Wentao; Liu, Jiansheng; Liu, Jiaqi; Yu, Changhai; Wang, Wentao; Qi, Rong; Zhang, Zhijun; Fang, Ming; Feng, Ke; Wu, Ying; Ke, Lintong; Chen, Yu; Wang, Cheng; Li, Ruxin; Xu, Zhizhan

2018-04-01

A hydrogen-filled capillary discharge waveguide made of quartz is presented for high-energy laser wakefield acceleration (LWFA). The experimental parameters (discharge current and gas pressure) were optimized to mitigate ablation by a quantitative analysis of the ablation plasma density inside the hydrogen-filled quartz capillary. The ablation plasma density was obtained by combining a spectroscopic measurement method with a calibrated gas transducer. In order to obtain a controllable plasma density and mitigate the ablation as much as possible, the range of suitable parameters was investigated. The experimental results demonstrated that the ablation in the quartz capillary could be mitigated by increasing the gas pressure to ˜7.5-14.7 Torr and decreasing the discharge current to ˜70-100 A. These optimized parameters are promising for future high-energy LWFA experiments based on the quartz capillary discharge waveguide.

A comparison of the wear of cross-linked polyethylene against itself with the wear of ultra-high molecular weight polyethylene against itself.

PubMed

Joyce, T J; Unsworth, A

1996-01-01

Wear tests were carried out on reciprocating pin-on-plate machines which had pins loaded at 10 N and 40 N. The materials tested were irradiated cross-linked polyethylene sliding against itself, irradiated ultra-high molecular weight polyethylene sliding against itself and non-irradiated ultra-high molecular weight polyethylene sliding against itself. After 153.5 km of sliding, the non-irradiated ultra-high molecular weight polyethylene plates and pins showed mean wear factors under 10 N loads, or a nominal contact stress of 0.51 MPa, of 84.0 x 10(-6) mm3/N m for the plates and 81.3 x 10(-6) mm3/N m for the pins. Under 40 N loads, or a nominal contact stress of 2.04 MPa, the non-irradiated ultra-high molecular weight polyethylene pins sheared at 22.3 km. At the last measurement point prior to this failure, 19.1 km, wear factors of 158 x 10(-6) mm3/N m for the plates and 85.0 x 10(-6) mm3/N m for the pins had been measured. After 152.8 km. the irradiated ultra-high molecular weight polyethylene plates and pins showed mean wear factors under 10 N loads of 59.8 x 10(-6) mm3/N m for the plates and 31.1 x 10(-6) mm3/N m for the pins. In contrast, after 150.2 km, a mean wear factor of 0.72 x 10(-6) mm3/N m was found for the irradiated cross-linked polyethylene plates compared with 0.053 x 10(-6) mm3/N m for the irradiated cross-linked polyethylene pins.

Retraction of cold-drawn polyethylene - Influence of lamellar thickness and density.

NASA Technical Reports Server (NTRS)

Falender, J. R.; Hansen, D.

1972-01-01

The role of crystal morphology in the retraction of oriented linear polyethylene was studied utilizing samples crystallized under conditions controlled to vary, separately, lamellar crystal thickness and density. Samples were oriented in a simple shear deformation to a strain of 4.0 prior to measuring retraction tendency in creep- and relaxation-type tests. Characterizations of specimens were made using wide- and small-angle x-ray techniques. The specific morphological variations were chosen to test the hypothesis that a long-range elastic restoring force can originate in conjunction with deformation of lamellar crystals and the consequent increase in lamellar crystal surface area and surface free energy. The results support this hypothesis.

The effects of oil-in-water nanoemulsion polyethylene glycol surface density on intracellular stability, pharmacokinetics, and biodistribution in tumor bearing mice.

PubMed

Hak, Sjoerd; Garaiova, Zuzana; Olsen, Linda Therese; Nilsen, Asbjørn Magne; de Lange Davies, Catharina

2015-04-01

Lipid-based nanoparticles are extensively studied for drug delivery. These nanoparticles are often surface-coated with polyethylene glycol (PEG) to improve their biodistribution. Until now, the effects of varying PEG surface density have been studied in a narrow and low range. Here, the effects of high and a broad range of PEG surface densities on the in vivo performance of lipid-based nanoparticles were studied. Oil-in-water nanoemulsions were prepared with PEG surface densities of 5-50 mol%. Confocal microscopy was used to assess intracellular disintegration in vitro. In vivo pharmacokinetics and biodistribution in tumor bearing mice were studied using a small animal optical imager. PEG surface density did not affect intracellular nanoemulsion stability. Surprisingly, circulation half-lives decreased with increasing PEG surface density. A plausible explanation was that nanoemulsion with high (50 mol%) PEG surface density activated the complement in a whole blood assay, whereas nanoemulsion with low (5 mol%) PEG density did not. In vivo, nanoemulsion with low PEG surface density was mostly confined to the tumor and organs of the mononuclear phagocyte system, whereas nanoemulsion with high PEG density accumulated throughout the mouse. Optimal PEG surface density of lipid-based nanoparticles for tumor targeting was found to be below 10 mol%.

Extremely High Thermal Conductivity of Aligned Carbon Nanotube-Polyethylene Composites.

PubMed

Liao, Quanwen; Liu, Zhichun; Liu, Wei; Deng, Chengcheng; Yang, Nuo

2015-11-10

The ultra-low thermal conductivity of bulk polymers may be enhanced by combining them with high thermal conductivity materials such as carbon nanotubes. Different from random doping, we find that the aligned carbon nanotube-polyethylene composites has a high thermal conductivity by non-equilibrium molecular dynamics simulations. The analyses indicate that the aligned composite not only take advantage of the high thermal conduction of carbon nanotubes, but enhance thermal conduction of polyethylene chains.

Enhancing Degradation of Low Density Polyethylene Films by Curvularia lunata SG1 Using Particle Swarm Optimization Strategy.

PubMed

Raut, Sangeeta; Raut, Smita; Sharma, Manisha; Srivastav, Chaitanya; Adhikari, Basudam; Sen, Sudip Kumar

2015-09-01

In the present study, artificial neural network (ANN) modelling coupled with particle swarm optimization (PSO) algorithm was used to optimize the process variables for enhanced low density polyethylene (LDPE) degradation by Curvularia lunata SG1. In the non-linear ANN model, temperature, pH, contact time and agitation were used as input variables and polyethylene bio-degradation as the output variable. Further, on application of PSO to the ANN model, the optimum values of the process parameters were as follows: pH = 7.6, temperature = 37.97 °C, agitation rate = 190.48 rpm and incubation time = 261.95 days. A comparison between the model results and experimental data gave a high correlation coefficient ([Formula: see text]). Significant enhancement of LDPE bio-degradation using C. lunata SG1by about 48 % was achieved under optimum conditions. Thus, the novelty of the work lies in the application of combination of ANN-PSO as optimization strategy to enhance the bio-degradation of LDPE.

The Influence of Sintering Method on Kaolin-Based Geopolymer Ceramics with Addition of Ultra High Molecular Weight Polyethylene as Binder

NASA Astrophysics Data System (ADS)

Romisuhani, A.; AlBakri, M. M.; Kamarudin, H.; Andrei, S. V.

2017-11-01

The influence of sintering method on kaolin-based geopolymer ceramics with addition of Ultra High Molecular Weight Polyethylene as binder were studied. Geopolymer were formed at room temperature from kaolin and sodium silicate in a highly alkaline medium, followed by curing and drying at 80 °C. 12 M of sodium hydroxide solution were mixed with sodium silicate at a ratio of 0.24 to form alkaline activator. Powder metallurgy technique were used in order to produce kaolin geopolymer ceramics with addition of Ultra High Molecular Weight Polyethylene. The samples were heated at temperature of 1200 °C with two different sintering method which are conventional method and two-step sintering method. The strength and density were tested.

Tensile properties and water absorption assessment of linear low-Density Polyethylene/Poly (Vinyl Alcohol)/Kenaf composites: effect of eco-friendly coupling agent

NASA Astrophysics Data System (ADS)

Pang, A. L.; Ismail, H.; Abu Bakar, A.

2018-02-01

Linear low-density polyethylene (LLDPE)/poly (vinyl alcohol) (PVOH) filled with untreated kenaf (UT-KNF) and eco-friendly coupling agent (ECA)-treated kenaf (ECAT-KNF) were prepared using ThermoHaake internal mixer, respectively. Filler loadings of UT-KNF and ECAT-KNF used in this study are 10 and 40 parts per hundred parts of resin (phr). The effect of ECA on tensile properties and water absorption of LLDPE/PVOH/KNF composites were investigated. Field emission scanning electron microscopy (FESEM) analysis was applied to visualize filler-matrix adhesion. The results indicate LLDPE/PVOH/ECAT-KNF composites possess higher tensile strength and tensile modulus, but lower elongation at break compared to LLDPE/PVOH/UT-KNF composites. The morphological studies of tensile fractured surfaces using FESEM support the increment in tensile properties of LLDPE/PVOH/ECAT-KNF composites. Nevertheless, LLDPE/PVOH/UT-KNF composites reveal higher water absorption compared to LLDPE/PVOH/ECAT-KNF composites.

Polyethylene Ear Reconstruction: A State-of-the-Art Surgical Journey.

PubMed

Reinisch, John; Tahiri, Youssef

2018-02-01

The use of a porous high-density polyethylene implant for ear reconstruction is gradually gaining acceptance because it allows for a pleasing ear reconstruction in young children before they enter school. In response to this growing interest, the authors decided to write an article clarifying in detail all the steps of this challenging procedure. In this article, the authors also answer all the common questions that surgeons have when they come to observe the operation, or when they go back to their respective practices and start performing this procedure. The authors describe in detail the operative steps that allow for a successful ear reconstruction using porous high-density polyethylene. The key parts of this operation are to meticulously harvest a well-vascularized superficial temporoparietal fascia flap and to use appropriate color-matched skin grafts. This method allows for a pleasing ear reconstruction with excellent definition, projection, symmetry, and long-term viability. The use of porous high-density polyethylene with a thin superficial temporoparietal fascia flap coverage is the authors' preferred method of ear reconstruction because it can be performed at an earlier age, in a single stage, as an outpatient procedure, and with minimal discomfort and psychological trauma for the patients and parents.

High density polyethylene/graphite nano-composites for total hip joint replacements: processing and in vitro characterization.

PubMed

Fouad, H; Elleithy, Rabeh

2011-10-01

The main objective of the present study is to investigate how the thermal, rheological, mechanical and cytotoxicity behavior of High Density Polyethylene (HDPE) can be changed by the addition of graphite nano particles (GNPs) at different contents. The HDPE/GNPs composites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. The in vitro tests results showed that the original material (HDPE) and all HDPE/GNPs composites do not exhibit any cytotoxicity to the WISH cell line. The microscopic examination of the nano-composite tensile-fractured surface found a good distribution of GNPs in the HDPE matrix. The Differential Scanning Calorimetry (DSC) results indicated that the crystallization percentage increased by adding GNPs to HDPE up to 4%. The XRD patterns of the HDPE/GNPs composites showed an increase in peak intensity compared to neat HDPE. This increase echoed the crystallinity results obtained from DSC. The rheological tests showed that the complex viscosity of the HDPE increased as the percentage of GNPs increased due to the restriction of the molecular mobility. The tensile test results showed that with increasing the GNPs content, Young's modulus and the yield strength of the HDPE/GNPs composite increased while the strain at fracture decreased. Finally, the preliminary results of the abrasion test indicated that the abrasion rate decreased by increasing the GNPs ratio up to 4% content. The prepared HDPE/GNPs composites appear to have fairly good comprehensive properties that make them a good candidate as a bearing material for the total joint replacement. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of Paulownia elongata wood polyethylene composites

USDA-ARS?s Scientific Manuscript database

Paulownia wood flour (PWF), a byproduct of milling lumber, was employed as a bio-filler and blended with high density polyethylene (HDPE) via extrusion. Paulownia wood (PW) shavings were milled through a 1-mm screen then separated via shaking into various particle fractions using sieves (#30 - < #2...

From macroplastic to microplastic: Degradation of high-density polyethylene, polypropylene, and polystyrene in a salt marsh habitat.

PubMed

Weinstein, John E; Crocker, Brittany K; Gray, Austin D

2016-07-01

As part of the degradation process, it is believed that most plastic debris becomes brittle over time, fragmenting into progressively smaller particles. The smallest of these particles, known as microplastics, have been receiving increased attention because of the hazards they present to wildlife. To understand the process of plastic degradation in an intertidal salt marsh habitat, strips (15.2 cm × 2.5 cm) of high-density polyethylene, polypropylene, and extruded polystyrene were field-deployed in June 2014 and monitored for biological succession, weight, surface area, ultraviolet (UV) transmittance, and fragmentation. Subsets of strips were collected after 4 wk, 8 wk, 16 wk, and 32 wk. After 4 wk, biofilm had developed on all 3 polymers with evidence of grazing periwinkles (Littoraria irrorata). The accreting biofilm resulted in an increased weight of the polypropylene and polystyrene strips at 32 wk by 33.5% and 167.0%, respectively, with a concomitant decrease in UV transmittance by approximately 99%. Beginning at 8 wk, microplastic fragments and fibers were produced from strips of all 3 polymers, and scanning electron microscopy revealed surface erosion of the strips characterized by extensive cracking and pitting. The results suggest that the degradation of plastic debris proceeds relatively quickly in salt marshes and that surface delamination is the primary mechanism by which microplastic particles are produced in the early stages of degradation. Environ Toxicol Chem 2016;35:1632-1640. © 2016 SETAC. © 2016 SETAC.

Retraction of cold drawn polyethylene: the influence of lamellar thickeness and density

NASA Technical Reports Server (NTRS)

Falender, J. R.; Hansen, D.

1971-01-01

The role of crystal morphology in the retraction of oriented, linear polyethylene was studied utilizing samples crystallized under conditions controlled to vary, separately, lamellar crystal thickness and density. Samples were oriented in a simple shear deformation to a strain of 4.0 prior to measuring retraction tendency in creep and relaxation type tests. Characterizations of specimens were made using wide and small angle X-ray techniques. The specific morphological variations were chosen to test the hypothesis that a long range elastic restoring force can originate in conjunction with deformation of lamellar crystals and the consequent increase in lamellar crystal surface area and surface free energy. The results support this hypothesis.

Tapanuli Organoclay Addition Into Linear Low Density Polyethylene-Pineapple Fiber Composites

NASA Astrophysics Data System (ADS)

Adawiyah, Robiatul; Juwono, Ariadne L.; Roseno, Seto

2010-12-01

Linear low density polyethylene-Tapanuli organoclay-pineapple fiber composites were succesfully synthesized by a melt intercalation method. The clay was modified as an organoclay by a cation exchange reaction using hexadecyl trimethyl ammonium bromide (HDTMABr) surfactant. The X-ray diffraction results of the organoclay exhibited a higher basal spacing of 1.87 nm compared to the unmodified clay of 1.46 nm. The composite tensile strength was enhanced up to 46.4% with the 1 wt% organoclay addition. Both tensile and flexural moduli increased up to 150.6% and 43% with the 3 wt% organoclay addition to the composites. However, the flexural strength of the composites was not improved with the organoclay addition. The addition of organoclay has also decreased the heat deflection temperature of the composites.

Radiation Transport Properties of Polyethylene-Fiber Composites

NASA Technical Reports Server (NTRS)

Kaul, Raj K.; Barghouty, A. F.; Dahche, H. M.

2003-01-01

Composite materials that can both serve as effective shielding materials against cosmic-ray and energetic solar particles in deep space as well as structural materials for habitat and spacecraft remain a critical and mission enabling piece in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density coupled with high hydrogen content. Polyethylene fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of Polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at NASA's Marshall Space Flight Center and tested against 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

High Density Methane Storage in Nanoporous Carbon

NASA Astrophysics Data System (ADS)

Rash, Tyler; Dohnke, Elmar; Soo, Yuchoong; Maland, Brett; Doynov, Plamen; Lin, Yuyi; Pfeifer, Peter; Mriglobal Collaboration; All-Craft Team

2014-03-01

Development of low-pressure, high-capacity adsorbent based storage technology for natural gas (NG) as fuel for advanced transportation (flat-panel tank for NG vehicles) is necessary in order to address the temperature, pressure, weight, and volume constraints present in conventional storage methods (CNG & LNG.) Subcritical nitrogen adsorption experiments show that our nanoporous carbon hosts extended narrow channels which generate a high surface area and strong Van der Waals forces capable of increasing the density of NG into a high-density fluid. This improvement in storage density over compressed natural gas without an adsorbent occurs at ambient temperature and pressures ranging from 0-260 bar (3600 psi.) The temperature, pressure, and storage capacity of a 40 L flat-panel adsorbed NG tank filled with 20 kg of nanoporous carbon will be featured.

Temperature increase and charging current in polyethylene film during application of high voltage

NASA Astrophysics Data System (ADS)

Zhang, Chao; Kaneko, Kazue; Mizutani, Teruyoshi

2001-12-01

Temperature increase in a low density polyethylene film during the application of high dc voltage was estimated by measuring the sound velocity with a pulsed electroacoustic method. The temperature shows no change under the electric field of 50 MVm-1 at ambient temperature of 30 °C. However, the temperature increases with time, and rises to 63.7 °C in 90 min of the voltage application at ambient temperature of 60 °C. The temperature increase was caused by Joule heating and it resulted in the increase of charging current during the application of high dc voltage. The increase in charging current calculated from the temperature increase agreed well with the experimental one.

Nonlinear viscoelastic response of highly filled elastomers under multiaxial finite deformation

NASA Technical Reports Server (NTRS)

Peng, Steven T. J.; Landel, Robert F.

1990-01-01

A biaxial tester was used to obtain precise biaxial stress responses of highly filled, high strain capability elastomers. Stress-relaxation experiments show that the time-dependent part of the relaxation response can be reasonably approximated by a function which is strain and biaxiality independent. Thus, isochronal data from the stress-relaxation curves can be used to determine the stored energy density function. The complex behavior of the elastomers under biaxial deformation may be caused by dewetting.

Study on Ballistic Absorbing Energy Character of High Performance Polyethylene Needle Felt

NASA Astrophysics Data System (ADS)

Kailiang, Zhu; Jianqiao, Fu

2017-11-01

The ballistic performance of polyethylene needle felt is tested and the failure morphology after test is also observed. The results showed that when the non-dimensionally non-stressed fibers in polyethylene needles are subjected to high-speed projectile, secondary movement such as stretching and twisting occurs first. This secondary movement is very full, it is the main way of ballistic absorbing energy of the polyethylene needle felt which can avoid the polyethylene fiber short-term rapid heating-up and destroyed. Analysis results show that under normal temperature and humidity conditions, the V50 of 6-layer forded polyethylene needle felt sample is 250m/s. At (450 ± 50) m/s speed range of the target missile, the mean value of the penetrative specific energy absorption for 3-layer forded polyethylene needle felt anti-1.1g simulated projectiles (tapered column) reaches 24.1J·m2/kg.

TECHNICAL GUIDANCE DOCUMENT: THE FABRICATION OF POLYETHYLENE FML FIELD SEAMS

EPA Science Inventory

This technical guidance document is meant to augment the numerous construction quality control and construction assurance (CQC and CQA) guidelines that are presently available for high density polyethylene (HDPE) liner installation and inspection.

Wearable supercapacitors on polyethylene terephthalate fabrics with good wash fastness and high flexibility

NASA Astrophysics Data System (ADS)

Wang, Guixia; Babaahmadi, Vahid; He, Nanfei; Liu, Yixin; Pan, Qin; Montazer, Majid; Gao, Wei

2017-11-01

All solid-state micro-supercapacitors (MSC) have emerged as attractive energy-storage units for portable and wearable electronics. Here, we describe a textile-based solid-state MSC via laser scribing of graphene oxide (GO) coatings on a flexible polyethylene terephthalate (PET) fabric. The laser-scribed graphene oxide layers (LGO) possess three-dimensionally porous structure suitable for electrochemical-double-layer formation. To improve the wash fastness and the flexibility of the as-prepared MSCs, glutaraldehyde (GA) was employed to crosslink the GO layers and PVA-gel electrolyte onto the PET fabric. The resultant all solid-state MSCs exhibited excellent flexibility, high areal specific capacitance (756 μF·cm-2 at 20 mV·s-1), and good rate capability when subject to bending and laundering. Furthermore, the MSC device showed a high power density of about 1.4 W·cm-3 and an energy density of 5.3 × 10-5 Wh·cm-3, and retained 98.3% of its initial capacitance after 1000 cycles at a current density of 0.5 mA·cm-2. This work is the first demonstration of in-plane MSCs on PET fabric surfaces with enhanced durability and flexibility.

Engineering cartilage substitute with a specific size and shape using porous high-density polyethylene (HDPE) as internal support.

PubMed

Wu, Yujia; Zhu, Lie; Jiang, Hua; Liu, Wei; Liu, Yu; Cao, Yilin; Zhou, Guangdong

2010-04-01

Despite the great advances in cartilage engineering, constructing cartilage of large sizes and appropriate shapes remains a great challenge, owing to limits in thickness of regenerated cartilage and to inferior mechanical properties of scaffolds. This study introduces a pre-shaped polyglycolic acid (PGA)-coated porous high-density polyethylene (HDPE) scaffold to overcome these challenges. HDPE was carved into cylindrical rods and wrapped around by PGA fibres to form PGA-HDPE scaffolds. Porcine chondrocytes were seeded into the scaffolds and the constructs were cultured in vitro for 2 weeks before subcutaneous implantation into nude mice. Scaffolds made purely of PGA with the same size and shape were used as a control. After 8 weeks of implantation, the construct formed cartilage-like tissue and retained its pre-designed shape and size. In addition, the regenerated cartilage grew and completely surrounded the HDPE core, which made the entire cartilage substitute biocompatible to its implanted environment as native cartilage similarly does. By contrast, the shape and size of the constructs in the control group seriously deformed and obvious hollow cavity and necrotic tissue were observed in the inner region. These results demonstrate that the use of HDPE as the internal support of a biodegradable scaffold has the potential to circumvent the problems of limitations in size and shape, with promising implications for the development of engineered cartilage appropriate for clinical applications. Copyright 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Achromobacter xylosoxidans as a new microorganism strain colonizing high-density polyethylene as a key step to its biodegradation.

PubMed

Kowalczyk, Anna; Chyc, Marek; Ryszka, Przemysław; Latowski, Dariusz

2016-06-01

This study presents results of research on isolation new bacteria strain Achromobacter xylosoxidans able to effect on the structure of high-density polyethylene (HDPE), polymer resistant to degradation in environment. New strain of A. xylosoxidans PE-1 was isolated from the soil and identified by analysis of the 16S ribosome subunit coding sequences. The substance to be degraded was HDPE in the form of thin foil films. The foil samples were analyzed with Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) as well as scanning electron microscope (SEM), and the results revealed degradation of chemical structure of HDPE. About 9 % loss of weight was also detected as a result of A. xylosoxidans PE-1 effect on HDPE foil. On the basis of comparative spectral analysis of the raw material before the bacteria treatment and the spectrum from a spectra database, it was assumed that the HDPE was the only source of carbon and energy for the microorganisms. No fillers or other additives used in the plastic processing were observed in HDPE before experiments. This is the first communication showing that A. xylosoxidans is able to modify chemical structure of HDPE, what was observed both on FTIR, in mass reduction of HDPE and SEM analysis. We also observed quite good growth of the bacteria also when the HDPE was the sole carbon source in the medium. These results prove that A. xylosoxidans is an organism worth applying in future HDPE biodegradation studies.

Microbial degradation of low-density polyethylene (LDPE) by Aspergillus clavatus strain JASK1 isolated from landfill soil.

PubMed

Gajendiran, Anudurga; Krishnamoorthy, Sharmila; Abraham, Jayanthi

2016-06-01

Polythene and plastic waste are found to accumulate in the environment, posing a major ecological threat. They are found to be considered non-degradable, once it enters the environment it has been found to remain there indefinitely. However, significant attention has been placed on biodegradable polymer, identification of microbes with degradative potential on plastic material. The aim of the present investigation was to biodegrade low-density polyethylene (LDPE) using potential fungi isolated from landfill soil. Based on 18S rRNA analyses the isolated strain was identified as Aspergillus clavatus. LDPE degradation by A. clavatus was monitored for 90 days of incubation in aqueous medium. The degradation was confirmed by changes in polyethylene weight, CO 2 evolution by Strum test, infrared spectra and morphological changes by SEM and AFM analysis.

Space radiation transport properties of polyethylene-based composites.

PubMed

Kaul, R K; Barghouty, A F; Dahche, H M

2004-11-01

Composite materials that can serve as both effective shielding materials against cosmic-ray and energetic solar particles in deep space, as well as structural materials for habitat and spacecraft, remain a critical and mission enabling component in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density, coupled with high hydrogen content. Polyethylene-fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at the NASA Marshall Space Flight Center and tested against a 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

Space radiation transport properties of polyethylene-based composites

NASA Technical Reports Server (NTRS)

Kaul, R. K.; Barghouty, A. F.; Dahche, H. M.

2004-01-01

Composite materials that can serve as both effective shielding materials against cosmic-ray and energetic solar particles in deep space, as well as structural materials for habitat and spacecraft, remain a critical and mission enabling component in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density, coupled with high hydrogen content. Polyethylene-fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at the NASA Marshall Space Flight Center and tested against a 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

Study on flavonoid migration from active low-density polyethylene film into aqueous food simulants.

PubMed

Zhang, Shuangling; Zhao, Haiyan

2014-08-15

The migration of flavonoids from low-density polyethylene (LDPE) film (0.4%, w/w) to aqueous food simulants over 16 weeks at 0, 15, and 30 °C was investigated. The migration amount of total flavonoids was calculated based on the rutin contents determined by high-performance liquid chromatography (HPLC). Diffusion and partition coefficients, along with the activation energy (Ea) were calculated based on Fick's second law. The results showed that the migration of flavonoids was influenced by temperature, time and the simulants. The Ea values for flavonoid diffusion were 49.2, 55.9, and 25.8 kJ mol(-1) in distilled water, 4% acetic acid and 30% ethanol, respectively. This study indicated that the flavonoids in LDPE film easily migrated into food simulants; and this behaviour was related to the low Ea values of flavonoid diffusion, especially in ethanol at 0-30 °C, when the antioxidants were released from the film. Copyright © 2014 Elsevier Ltd. All rights reserved.

ISTA 14-in-situ accumulation of PAHs in low-density polyethylene membranes in sediment.

PubMed

Devault, Damien A; Combe, Matthieu; Gourlay-Francé, Catherine

2010-10-01

The use of passive samplers for the assessment of organic contaminants has been extended to solid matrixes for the past decade. Passive sampling is usually applied to sediment in laboratory experiments involving significant upheaval, whereas in-situ experiments remain rare. In this study, low-density polyethylene (LDPE) strips were deployed within the sediments of a small river contaminated with polycyclic aromatic hydrocarbons (PAHs). LDPE strips were deployed in the 3-cm depth sediment layer. Over a period of 36 days, LDPE strips were regularly retrieved and accumulated PAHs in LDPE were extracted and analyzed. Accumulations of hydrophobic contaminants in LDPE directly exposed in the sediment were observed. Accumulations in LDPE were observed for moderately hydrophobic PAHs with the highest concentrations in the sediment. Low accumulations were observed for more hydrophobic compounds, despite their presence in high concentrations in the sediment. This was explained by very low exchange rates and competitive interactions with particles in the sediment. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010.

Waste product profile: Polyethylene terephthalate

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

Miller, C.

1996-02-01

Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks are the primary product packaged in PET. Salad dressing, peanut butter, and other household and consumer products also use PET bottles. PET is also used for film, sheeting for cups and food trays, ovenable trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early `70s. Because it is an ``engineered`` resin, it is more expensive than commodity resins such as high-density polyethylene (HDPE). The primary market for recycled PET is the fiber industry, which uses PET for carpet fiber, sweatersmore » and other clothing, and for other uses. Recycled PET can also be used for food and beverage containers. Export markets, particularly Asian countries, are becoming increasingly important.« less

Near-critical density filling of the SF6 fluid cell for the ALI-R-DECLIC experiment in weightlessness

NASA Astrophysics Data System (ADS)

Lecoutre, C.; Marre, S.; Garrabos, Y.; Beysens, D.; Hahn, I.

2018-05-01

Analyses of ground-based experiments on near-critical fluids to precisely determine their density can be hampered by several effects, especially the density stratification of the sample, the liquid wetting behavior at the cell walls, and a possible singular curvature of the "rectilinear" diameter of the density coexisting curve. For the latter effect, theoretical efforts have been made to understand the amplitude and shape of the critical hook of the density diameter, which depart from predictions from the so-called ideal lattice-gas model of the uniaxial 3D-Ising universality class. In order to optimize the observation of these subtle effects on the position and shape of the liquid-vapor meniscus in the particular case of SF6, we have designed and filled a cell that is highly symmetrized with respect to any median plane of the total fluid volume. In such a viewed quasi-perfect symmetrical fluid volume, the precise detection of the meniscus position and shape for different orientations of the cell with respect to the Earth's gravity acceleration field becomes a sensitive probe to estimate the cell mean density filling and to test the singular diameter effects. After integration of this cell in the ALI-R insert, we take benefit of the high optical and thermal performances of the DECLIC Engineering Model. Here we present the sensitive imaging method providing the precise ground-based SF6 benchmark data. From these data analysis it is found that the temperature dependence of the meniscus position does not reflect the expected critical hook in the rectilinear density diameter. Therefore the off-density criticality of the cell is accurately estimated, before near future experiments using the same ALI-R insert in the DECLIC facility already on-board the International Space Station.

Effect of admixed high-density polyethylene (HDPE) spheres on contraction stress and properties of experimental composites.

PubMed

Ferracane, J L; Ferracane, L L; Braga, R R

2003-07-15

Additives that provide stress relief may be incorporated into dental composites to reduce contraction stress (CS). This study attempted to test the hypothesis that conventional fillers could be replaced by high-density polyethylene (HDPE) spheres in hybrid and nanofill composites to reduce CS, but with minimal effect on mechanical properties. Nanofill and hybrid composites were made from a Bis-GMA/TEGDMA resin having either all silica nanofiller or 75 wt.% strontium glass + 5 wt.% silica and replacing some of the nanofiller or the glass with 0%, 5% (hybrid only), 10% or 20 wt.% HDPE. The surface of the HDPE was either left untreated or had a reactive gas surface treatment (RGST). Contraction stress (CS) was monitored for 10 min in a tensilometer (n = 5) after light curing for 60 s at 390 mW/cm(2). Other specimens (n = 5) were light cured 40 s from two sides in a light-curing unit and aged 1 d in water before testing fracture toughness (K(Ic)), flexure strength (FS), and modulus (E). Results were analyzed by ANOVA with Tukey's multiple comparison test at p < 0.05. There was no difference between composites with RGST and untreated HDPE except for FS-10% HDPE hybrid (RGST higher). An increased level of HDPE reduced contraction stress for both types of composites. Flexure strength, modulus (hybrid only), and fracture toughness were also reduced as the concentration of HDPE increased. SEM showed evidence for HDPE debonding and plastic deformation during fracture of the hybrid composites. In conclusion, the addition of HDPE spheres reduces contraction stress in composites, either through stress relief or a reduction in elastic modulus. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 318-323, 2003

Heat shrinkable behavior, physico-mechanical and structure properties of electron beam cross-linked blends of high-density polyethylene with acrylonitrile-butadiene rubber

NASA Astrophysics Data System (ADS)

Reinholds, Ingars; Kalkis, Valdis; Merijs-Meri, Remo; Zicans, Janis; Grigalovica, Agnese

2016-03-01

In this study, heat-shrinkable composites of electron beam irradiated high-density polyethylene (HDPE) composites with acrylonitrile-butadiene rubber (NBR) were investigated. HDPE/NBR blends at a ratio of components 100/0, 90/10, 80/20, 50/50 and 20/80 wt% were prepared using a two-roll mill. The compression molded films were irradiated high-energy (5 MeV) accelerated electrons up to irradiation absorbed doses of 100-300 kGy. The effect of electron beam induced cross-linking was evaluated by the changes of mechanical properties, gel content and by the differences of thermal properties, detected by differential scanning calorimetry. The thermo-shrinkage forces were determined as the kinetics of thermorelaxation and the residual shrinkage stresses of previously oriented (stretched up to 100% at above melting temperature of HDPE and followed by cooling to room temperature) specimens of irradiated HDPE/NBR blends under isometric heating-cooling mode. The compatibility between the both components was enhanced due to the formation of cross-linked sites at amorphous interphase. The results showed increase of mechanical stiffness of composites with increase of irradiation dose. The values of gel fraction compared to thermorelaxation stresses increased with the growth of irradiation dose level, as a result of formation cross-linked sites in amorphous PP/NBR interphase.

Extension and Density of Root Fillings and Post-operative Apical Radiolucencies in the Veterans Affairs Dental Longitudinal Study

PubMed Central

Zhong, Yan; Chasen, Joel; Yamanaka, Ryan; Garcia, Raul; Kaye, Elizabeth Krall; Kaufman, Jay S; Cai, Jianwen; Wilcosky, Tim; Trope, Martin; Caplan, Daniel J

2008-01-01

We evaluated the association between radiographically-assessed extension and density of root canal fillings and post-operative apical radiolucencies (AR) using data from 288 participants in the Veterans Affairs Dental Longitudinal Study. Study subjects were not VA patients; all received their medical and dental care in the private sector. Generalized Estimating Equations were used to account for multiple teeth within subjects and to control for covariates of interest. Defective root filling density was associated with increased odds of post-operative AR among teeth with no pre-operative AR (Odds Ratio=3.0, 95%CI=1.3–7.1), though pre-operative AR was the strongest risk factor for post-operative AR (Odds Ratio=29.2, 95%CI=13.6–63.0 among teeth with ideal density). Compared to well-extended root fillings, neither over- nor under-extended root fillings separately were related to post-operative AR, but when those two categories were collapsed into one “poorly-extended” category, poor extension was related to post-operative AR (Odds Ratio=1.8, 95%CI=1.1–3.2). PMID:18570982

Continuous Processing of High Thermal Conductivity Polyethylene Fibers and Sheets

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

None

2016-12-01

This factsheet describes a project that developed a new, continuous manufacturing process to make high molecular weight, high thermal conductivity polyethylene fibers and sheets to replace metals and ceramics in heat transfer applications.

Icephobicity and the effect of water condensation on the superhydrophobic low-density polyethylene surface

NASA Astrophysics Data System (ADS)

Yuan, Zhiqing; Wang, Menglei; Huang, Juan; Wang, Xian; Bin, Jiping; Peng, Chaoyi; Xing, Suli; Xiao, Jiayu; Zeng, Jingcheng; Xiao, Ximei; Fu, Xin; Gong, Huifang; Zhao, Dejian; Chen, Hong

2015-06-01

A superhydrophobic surface was obtained on a low-density polyethylene (LDPE) substrate using a facile method. The water contact angle and the sliding angle of the superhydrophobic LDPE surface were 155 ± 2° and 4°, respectively. The ice shear stress of the superhydrophobic LDPE surface was 2.08 times smaller than that of the flat LDPE surface. The superhydrophobic surface still showed excellent icephobicity and superhydrophobicity after undergoing a circulatory icing/deicing procedure five times. In addition, water condensation and its effect on the icephobicity of the as-prepared superhydrophobic surface were also studied.

Microstructure Filled Hohlraums

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

Moore, A. S.; Thomas, C. A.; Reese, T. M.

2017-02-24

We propose replacing the gas fill in a hohlraum with a low average density, variable uniformity 3D printed structure. This creates a bimodal hohlraum which acts like a vacuum hohlraum initially during the picket, but could protect the capsule from glint or direct illumination, and then once expanded, homogenizes to behave like a variable z gas-fill during peak portion of the drive. This is motivated by a two main aims: 1) reduction of the Au bubble velocity to improve inner beam propagation, and 2) the introduction of a low density, high-Z, x-ray converter to improve x-ray production in the hohlraummore » and uniformity of the radiation field seen by the capsule.« less

Radiolysis products and sensory properties of electron-beam-irradiated high-barrier food-packaging films containing a buried layer of recycled low-density polyethylene.

PubMed

Chytiri, S D; Badeka, A V; Riganakos, K A; Kontominas, M G

2010-04-01

The aim was to study the effect of electron-beam irradiation on the production of radiolysis products and sensory changes in experimental high-barrier packaging films composed of polyamide (PA), ethylene-vinyl alcohol (EVOH) and low-density polyethylene (LDPE). Films contained a middle buried layer of recycled LDPE, while films containing 100% virgin LDPE as the middle buried layer were taken as controls. Irradiation doses ranged between zero and 60 kGy. Generally, a large number of radiolysis products were produced during electron-beam irradiation, even at the lower absorbed doses of 5 and 10 kGy (approved doses for food 'cold pasteurization'). The quantity of radiolysis products increased with irradiation dose. There were no significant differences in radiolysis products identified between samples containing a recycled layer of LDPE and those containing virgin LDPE (all absorbed doses), indicating the 'functional barrier' properties of external virgin polymer layers. Sensory properties (mainly taste) of potable water were affected after contact with irradiated as low as 5 kGy packaging films. This effect increased with increasing irradiation dose.

Pervaporation and sorption behavior of zeolite-filled polyethylene glycol hybrid membranes for the removal of thiophene species.

PubMed

Lin, Ligang; Zhang, Yuzhong; Li, Hong

2010-10-01

Polyethylene glycol (PEG)-CuY zeolite hybrid membranes were prepared for sulfur removal from gasoline feed. The sorption and diffusion behavior of typical gasoline components through the hybrid membranes has been investigated by systematic studies of dynamic sorption curves. Influencing factors including feed temperature, permeate pressure, and zeolite content in the membranes on membrane performance have been evaluated. Immersion experiments results showed the preferential sorption of thiophene, which is key in fulfilling the separation of thiophene/hydrocarbon mixtures. The sorption, diffusion, and permeation coefficients of gasoline components in filled membranes are higher than those in unfilled membranes. Pervaporation (PV) and gas chromatography (GC) experiments results corresponded to the discussions on dynamic sorption curves. PV experiments showed that lower permeate pressure meant higher separation performance. The optimum temperature occurred at 383K, and an Arrhenius relationship existed between permeation flux and operating temperature. The CuY zeolite filling led to a significant increase of flux since the porous zeolite provides for more diffusion for small molecules in mixed matrix membranes. The sulfur enrichment factor increased first and then decreased with the increasing zeolite content, which was attributed to the combined influence of complexation force between CuY and thiophenes as well as the trade-off phenomenon between flux and selectivity. At 9 wt% CuY content, a higher permeation flux (3.19 kg/(m(2) h)) and sulfur enrichment factor (2.95) were obtained with 1190 microg/g sulfur content level in gasoline feed. Copyright 2010 Elsevier Inc. All rights reserved.

Effect of wood flour content on the optical color, surface chemistry, mechanical and morphological properties of wood flour/recycled high density polyethylene (rHDPE) composite

NASA Astrophysics Data System (ADS)

Sheng, Chan Kok; Amin, Khairul Anuar Mat; Kee, Kwa Bee; Hassan, Mohd Faiz; Ali, E. Ghapur E.

2018-05-01

In this study, effect of wood flour content on the color, surface chemistry, mechanical properties and surface morphology of wood-plastic composite (WPC) on different mixture ratios of recycled high density polyethylene (rHDPE) and wood flour were investigated in detail. The presence of wood flour in the composite indicates a significant total color change and a decrease of lightness. Functional groups of wood flour in WPC can be seen clearer from the Fourier transform infrared (FTIR) spectra as the wood flour content increases. The mechanical tensile testing shows that the tensile strength of Young's modulus is improved, whereas the strain and elongation at break were reduced by the addition of wood flour. The gap between the wood flour microvoid fibre and rHDPE matrix becomes closer when the wood flour content is increased as observed by scanning electron microscope (SEM) image. This finding implies a significant improvement on the interaction of interfacial adhesion between the rHDPE matrix and wood flour filler in the present WPC.

Mechanical properties of chemically modified Sansevieria trifasciata/natural rubber/high density polyethylene (STF/NR/HDPE) composites: Effect of silane coupling agent

NASA Astrophysics Data System (ADS)

Zakaria, Nurzam Ezdiani; Baharum, Azizah; Ahmad, Ishak

2018-04-01

The main objective of this research is to study the effects of chemical modification on the mechanical properties of treated Sansevieria trifasciata fiber/natural rubber/high density polyethylene (TSTF/NR/HDPE) composites. Processing of STF/NR/HDPE composites was done by using an internal mixer. The processing parameters used were 135°C for temperature and a mixing rotor speed of 55 rpm for 15 minutes. Filler loading was varied from 10% to 40% of STF and the fiber size used was 125 µm. The composite blends obtained then were pressed with a hot press machine to get test samples of 1 mm and 3 mm of thickness. Samples were evaluated via tensile tests, Izod impact test and scanning electron microscopy (SEM). Results showed that tensile strength and strain value decreased while tensile modulus increased when filler loading increased. Impact strength increased when filler loading increased and began to decrease after 10% of filler amount for treated composites. For untreated composites, impact strength began to decrease after 20% of filler loading. Chemical modification by using silane coupling agent has improved certain mechanical properties of the composites such as tensile strength, strain value and tensile modulus. Adding more amount of filler will also increase the viscosity and the stiffness of the materials.

Improvement of adhesion properties of low density polyethylene (LDPE) substrate using atmospheric plasma

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

Sanchez-Nacher, L.; Garcia-Sanoguera, D.; Fenollar, O.

2010-06-02

In this work we have used atmospheric plasma technology on polyethylene surface with different treatment conditions. These modify surface pre-treatments on polyethylene, thus having a positive effect on overall surface activity of polymer surface and, consequently, adhesion properties can be remarkably improved. We have evaluated the influence of the nozzle/substrate distance and atmospheric plasma speed on wettability changes and adhesion properties. Wettability changes have been studied by contact angle measurements and subsequent surface energy calculation. Mechanical characterization of adhesion joints has been carried out in two different ways: peel and shear tensile test. The overall results show a remarkable increasemore » in mechanical properties of adhesion joints for low nozzle/substrate distances and low speed. So plasma atmospheric technology is highly useful to increase adhesion properties of polypropylene.« less

Light stabilizers added to the shell of co-extruded wood/high-density polyethylene composites to improve mechanical and anti-UV ageing properties

PubMed Central

Mei, Changtong; Xu, Bing; Chen, Weimin; Yong, Cheng; Wang, Ke; Wu, Qinglin

2018-01-01

Weathering of wood--plastic composites (WPCs) leads to discoloration and cracks, which greatly limits their outdoor application. In this study, light stabilizers (including UV-327, HS-944 and nano-SiO2) were added to the shell of a co-extruded high-density polyethylene-based WPC to improve its anti-ultraviolet (UV) ageing properties and simultaneously to maintain its good mechanical properties. The results showed that UV-327 was the most effective light stabilizer for improving the mechanical and anti-UV ageing properties of the composites among the three stabilizers used. WPC samples combined with 2% UV-327 had the highest retention rates in flexural strength and also had the smoothest surface after 2500 h of UV ageing. The samples with 2% UV-327 added had the best protection for discoloration, showing the lowest values of ΔE* (colour difference) and ΔL* (luminescence) in all samples after 2500 h of UV ageing. WPC samples with 2% UV-327 were also oxidized the least after 2500 h of UV ageing. The results reported herein serve to enhance our understanding of the efficiency of light stabilizers in preventing UV degradation of WPCs, with a view to developing co-extruded WPCs with low cost, high anti-UV ageing properties and good mechanical properties for outdoor applications. PMID:29892445

Influence of third-body particles originating from bone void fillers on the wear of ultra-high-molecular-weight polyethylene

PubMed Central

Cowie, Raelene M; Carbone, Silvia; Aiken, Sean; Cooper, John J; Jennings, Louise M

2016-01-01

Calcium sulfate bone void fillers are increasingly being used for dead space management in infected arthroplasty revision surgery. The presence of these materials as loose beads close to the bearing surfaces of joint replacements gives the potential for them to enter the joint becoming trapped between the articulating surfaces; the resulting damage to cobalt chrome counterfaces and the subsequent wear of ultra-high-molecular-weight polyethylene is unknown. In this study, third-body damage to cobalt chrome counterfaces was simulated using particles of the calcium sulfate bone void fillers Stimulan® (Biocomposites Ltd., Keele, UK) and Osteoset® (Wright Medical Technology, TN, USA) using a bespoke rig. Scratches on the cobalt chrome plates were quantified in terms of their density and mean lip height, and the damage caused by the bone void fillers was compared to that caused by particles of SmartSet GMV PMMA bone cement (DePuy Synthes, IN, USA). The surface damage from Stimulan® was below the resolution of the analysis technique used; SmartSet GMV caused 0.19 scratches/mm with a mean lip height of 0.03 µm; Osteoset® led to a significantly higher number (1.62 scratches/mm) of scratches with a higher mean lip height (0.04 µm). Wear tests of ultra-high-molecular-weight polyethylene were carried out in a six-station multi-axial pin on plate reciprocating rig against the damaged plates and compared to negative (highly polished) and positive control plates damaged with a diamond stylus (2 µm lip height). The wear of ultra-high-molecular-weight polyethylene was shown to be similar against the negative control plates and those damaged with third-body particles; there was a significantly higher (p < 0.001) rate of ultra-high-molecular-weight polyethylene wear against the positive control plates. This study showed that bone void fillers of similar composition can cause varying damage to cobalt chrome counterfaces. However, the lip heights of the scratches

Effect of degrading yellow oxo-biodegradable low-density polyethylene films to water quality

NASA Astrophysics Data System (ADS)

Requejo, B. A.; Pajarito, B. B.

2017-05-01

Polyethylene (PE) contributes largely to plastic wastes that are disposed in aquatic environment as a consequence of its widespread use. In this study, yellow oxo-biodegradable low-density PE films were immersed in deionized water at 50°C for 49 days. Indicators of water quality: pH, oxidation-reduction potential, turbidity, and total dissolved solids (TDS), were monitored at regular intervals. It was observed that pH initially rises and then slowly decreases with time, oxidation-reduction potential decreases then slowly increases with time, turbidity rises above the control at varied rates, and TDS increases abruptly and rises at a hindered rate. Moreover, the films potentially leach out lead chromate. The results imply that degrading oxo-biodegradable LDPE films results to significant reduction of water quality.

Experimental study on axial pedicled composite flap prefabrication with high density porous polyethylene implants: medporocutaneous flap.

PubMed

Kocman, A Emre; Kose, Aydan A; Karabagli, Yakup; Baycu, Cengiz; Cetin, Cengiz

2008-01-01

Composite flaps including soft tissues with bone or cartilage are widely used in reconstruction of three-dimensional defects, but have some disadvantages. Flap prefabrication with alloplastic implants is an alternative procedure. Axial pattern vascularised high density porous polyethylene (HDPP) implants are capable of sustaining skin grafts. The purpose of this study was to examine the vascularisation pattern of the skin island in a composite flap prefabrication model prepared with vascularised HDPP implants. Forty male Wistar rats divided into four groups were used. A 9.5 x 6 x 2 mm HDPP block was centered on the dissected saphenous pedicle and anchored under the abdominal skin in the experimental group I (n=10). In experimental group II (n=10) saphenous artery and vein were put between the skin and the implant. Thus, the structures were laid as skin, HDPP block, pedicle in experimental group I and skin, pedicle, HDPP block in experimental group II. HDPP block-implanted and pedicle-implanted only groups served as control groups I and II, respectively. Eight weeks after prefabrication, skin islands 1.5 x 5 cm in size incorporated with implants were elevated based on saphenous vessels in the experimental groups and skin islands only based on the pedicle in control group II. Skin islands of the same dimensions were raised as grafts in control group I. Nylon sheets were put under the flaps and grafts to prevent vascularisation from the recipient bed. Flap viability was assessed by measuring the surface area on the 7th day. Total necrosis developed in composite grafts of control group I. Flap survival was higher in experimental group II and control group II (45% and 46.8%) than in group I (29.28%). Histologic studies demonstrated fibrovascular ingrowth into the HDPP implants, except in control group I, with significant inflammatory response and necrosis. Vascularisation of skin and implants from the pedicle was seen also microangiographically. In conclusion, a

Slip-additive migration, surface morphology, and performance on injection moulded high-density polyethylene closures.

PubMed

Dulal, Nabeen; Shanks, Robert; Gengenbach, Thomas; Gill, Harsharn; Chalmers, David; Adhikari, Benu; Pardo Martinez, Isaac

2017-11-01

The amount and distribution of slip agents, erucamide, and behenamide, on the surface of high-density polyethene, is determined by integral characteristics of slip agent structure and polymer morphology. A suite of surface analysis techniques was applied to correlate physicochemical properties with slip-additive migration behaviour and their surface morphology. The migration, surface morphology and physicochemical properties of the slip additives, crystallinity and orientation of polyethene spherulites and interaction between slip additives and high-density polyethene influence the surface characteristics. The high-density polyethene closures were produced with erucamide and behenamide separately and stored until they produced required torque. Surface composition was determined employing spectroscopy and gas chromatography. The distribution of additives was observed under optical, scanning electron and atomic force microscopes. The surface energy, crystallinity and application torque were measured using contact angle, differential scanning calorimeter and a torque force tester respectively. Each slip additive produced a characteristic amide peak at 1645cm -1 in infrared spectroscopy and peaks of oxygen and nitrogen in X-ray photoelectron spectroscopy, suggesting their presence on the surface. The erucamide produced placoid scale-like structures and behenamide formed denticulate structures. The surface erucamide and behenamide responsible for reducing the torque was found to be 15.7µg/cm 2 and 1.7µg/cm 2 . Copyright © 2017 Elsevier Inc. All rights reserved.

Enhanced adherence of mouse fibroblast and vascular cells to plasma modified polyethylene.

PubMed

Reznickova, Alena; Novotna, Zdenka; Kolska, Zdenka; Kasalkova, Nikola Slepickova; Rimpelova, Silvie; Svorcik, Vaclav

2015-01-01

Since the last decade, tissue engineering has shown a sensational promise in providing more viable alternatives to surgical procedures for harvested tissues, implants and prostheses. Biomedical polymers, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE), were activated by Ar plasma discharge. Degradation of polymer chains was examined by determination of the thickness of ablated layer. The amount of an ablated polymer layer was measured by gravimetry. Contact angle, measured by goniometry, was studied as a function of plasma exposure and post-exposure aging times. Chemical structure of modified polymers was characterized by angle resolved X-ray photoelectron spectroscopy. Surface chemistry and polarity of the samples were investigated by electrokinetic analysis. Changes in surface morphology were followed using atomic force microscopy. Cytocompatibility of plasma activated polyethylene foils was studied using two distinct model cell lines; VSMCs (vascular smooth muscle cells) as a model for vascular graft testing and connective tissue cells L929 (mouse fibroblasts) approved for standardized material cytotoxicity testing. Specifically, the cell number, morphology, and metabolic activity of the adhered and proliferated cells on the polyethylene matrices were studied in vitro. It was found that the plasma treatment caused ablation of the polymers, resulting in dramatic changes in their surface morphology and roughness. ARXPS and electrokinetic measurements revealed oxidation of the polymer surface. It was found that plasma activation has a positive effect on the adhesion and proliferation of VSMCs and L929 cells. Copyright © 2015 Elsevier B.V. All rights reserved.

Biodegradation of Low-Density Polyethylene (LDPE) by Mixed Culture of Lysinibacillus xylanilyticus and Aspergillus niger in Soil

PubMed Central

Esmaeili, Atefeh; Pourbabaee, Ahmad Ali; Alikhani, Hossein Ali; Shabani, Farzin; Esmaeili, Ensieh

2013-01-01

In this study, two strains of Aspergillus sp. and Lysinibacillus sp. with remarkable abilities to degrade low-density polyethylene (LDPE) were isolated from landfill soils in Tehran using enrichment culture and screening procedures. The biodegradation process was performed for 126 days in soil using UV- and non-UV-irradiated pure LDPE films without pro-oxidant additives in the presence and absence of mixed cultures of selected microorganisms. The process was monitored by measuring the microbial population, the biomass carbon, pH and respiration in the soil, and the mechanical properties of the films. The carbon dioxide measurements in the soil showed that the biodegradation in the un-inoculated treatments were slow and were about 7.6% and 8.6% of the mineralisation measured for the non-UV-irradiated and UV-irradiated LDPE, respectively, after 126 days. In contrast, in the presence of the selected microorganisms, biodegradation was much more efficient and the percentages of biodegradation were 29.5% and 15.8% for the UV-irradiated and non-UV-irradiated films, respectively. The percentage decrease in the carbonyl index was higher for the UV-irradiated LDPE when the biodegradation was performed in soil inoculated with the selected microorganisms. The percentage elongation of the films decreased during the biodegradation process. The Fourier transform infra-red (FT-IR), x-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine structural, morphological and surface changes on polyethylene. These analyses showed that the selected microorganisms could modify and colonise both types of polyethylene. This study also confirmed the ability of these isolates to utilise virgin polyethylene without pro-oxidant additives and oxidation pretreatment, as the carbon source. PMID:24086254

Biodegradation of low-density polyethylene (LDPE) by mixed culture of Lysinibacillus xylanilyticus and Aspergillus niger in soil.

PubMed

Esmaeili, Atefeh; Pourbabaee, Ahmad Ali; Alikhani, Hossein Ali; Shabani, Farzin; Esmaeili, Ensieh

2013-01-01

In this study, two strains of Aspergillus sp. and Lysinibacillus sp. with remarkable abilities to degrade low-density polyethylene (LDPE) were isolated from landfill soils in Tehran using enrichment culture and screening procedures. The biodegradation process was performed for 126 days in soil using UV- and non-UV-irradiated pure LDPE films without pro-oxidant additives in the presence and absence of mixed cultures of selected microorganisms. The process was monitored by measuring the microbial population, the biomass carbon, pH and respiration in the soil, and the mechanical properties of the films. The carbon dioxide measurements in the soil showed that the biodegradation in the un-inoculated treatments were slow and were about 7.6% and 8.6% of the mineralisation measured for the non-UV-irradiated and UV-irradiated LDPE, respectively, after 126 days. In contrast, in the presence of the selected microorganisms, biodegradation was much more efficient and the percentages of biodegradation were 29.5% and 15.8% for the UV-irradiated and non-UV-irradiated films, respectively. The percentage decrease in the carbonyl index was higher for the UV-irradiated LDPE when the biodegradation was performed in soil inoculated with the selected microorganisms. The percentage elongation of the films decreased during the biodegradation process. The Fourier transform infra-red (FT-IR), x-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine structural, morphological and surface changes on polyethylene. These analyses showed that the selected microorganisms could modify and colonise both types of polyethylene. This study also confirmed the ability of these isolates to utilise virgin polyethylene without pro-oxidant additives and oxidation pretreatment, as the carbon source.

Self-sensing performance of MWCNT-low density polyethylene nanocomposites

NASA Astrophysics Data System (ADS)

Gupta, Tejendra K.; Kumar, S.; Khan, Amal Z.; Varadarajan, Kartik M.; Cantwell, Wesley J.

2018-01-01

Carbon nanotubes (CNTs) based polymer nanocomposites offer a range of remarkable properties. Here, we demonstrate self-sensing performance of low density polyethylene (LDPE)-multiwalled carbon nanotubes (MWCNTs) nanocomposites for the first time. The dispersion of the CNTs and the morphology of the nanocomposites was investigated using scanning electron microscopy, x-ray diffraction and Raman spectroscopic techniques. The thermal properties were measured using thermal gravimetric analysis and differential scanning calorimetry and were found to increase with increasing wt% of MWCNTs in LDPE matrix. An overall improvement in ultimate tensile strength, yield strength and Young’s modulus was found to be 59.6%, 48.5% and 129.3%, respectively for 5.0 wt% loading of MWCNTs. The electrical percolation threshold was observed at 1.0 wt% of MWCNTs and the highest electrical conductivity of 2.8 × 10-2 Scm-1 was observed at 5.0 wt% loading of MWCNTs. These piezo-resistive nanocomposites offer tunable self-sensing capabilities with gauge factors in the ranges of 17-52 and 42-530 in linear elastic (strain ˜3%) and inelastic regimes (strain ˜15%) respectively. Our demonstration would provide guidelines for the fabrication of low cost, self-sensing MWCNT-LDPE nanocomposites for potential use as civil water pipelines and landfill membranes.

High density, uniformly distributed W/UO2 for use in Nuclear Thermal Propulsion

NASA Astrophysics Data System (ADS)

Tucker, Dennis S.; Barnes, Marvin W.; Hone, Lance; Cook, Steven

2017-04-01

An inexpensive, quick method has been developed to obtain uniform distributions of UO2 particles in a tungsten matrix utilizing 0.5 wt percent low density polyethylene. Powders were sintered in a Spark Plasma Sintering (SPS) furnace at 1600 °C, 1700 °C, 1750 °C, 1800 °C and 1850 °C using a modified sintering profile. This resulted in a uniform distribution of UO2 particles in a tungsten matrix with high densities, reaching 99.46% of theoretical for the sample sintered at 1850 °C. The powder process is described and the results of this study are given below.

Nanostructure and thermal properties of melt compounded PE/clay nanocomposites filled with an organosilylated montmorillonite

NASA Astrophysics Data System (ADS)

Scarfato, Paola; Incarnato, Loredana; Di Maio, Luciano; Dittrich, Bettina; Niebergall, Ute; Böhning, Martin; Schartel, Bernhard

2015-12-01

In this work we report on the functionalization of a natural sodium montmorillonite (MMT) with (3-glycidyloxypropyl)trimethoxysilane by a silylation procedure and on its use as nanofiller in melt compounding of polyethylene nanocomposites. The obtained organosilylated clay showed higher interlayer spacing than the original MMT and higher thermal stability with respect to most of commercial organoclays modified with alkylammonium salts. Its addition (at 5wt%) to two different polyethylene matrices (a low density polyethylene, LDPE, and a high density polyethylene, HDPE), processed in a pilot-scale twin-screw extruder, allowed to produce hybrids with nanoscale dispersion of the filler, as demonstrated by X-ray diffraction. Thermogravimetric and differential scanning thermal analyses point out that the obtained nanocomposites do not show noticeable changes in the thermal behavior of both LDPE and HDPE, even if a slight reduction in the overall bulk crystallinity was observed in presence of the nanofillers.

Characteristics of highly cross-linked polyethylene wear debris in vivo

PubMed Central

Baxter, Ryan M.; MacDonald, Daniel W.; Kurtz, Steven M.; Steinbeck, Marla J.

2014-01-01

Despite the widespread implementation of highly cross-linked polyethylene (HXLPE) liners to reduce the clinical incidence of osteolysis, it is not known if the improved wear resistance will outweigh the inflammatory potential of HXLPE wear debris generated in vivo. Thus, we asked: What are the differences in size, shape, number, and biological activity of polyethylene wear particles obtained from primary total hip arthroplasty revision surgery of conventional polyethylene (CPE) versus remelted or annealed HXLPE liners? Pseudocapsular tissue samples were collected from revision surgery of CPE and HXLPE (annealed and remelted) liners, and digested using nitric acid. The isolated polyethylene wear particles were evaluated using scanning electron microscopy. Tissues from both HXLPE cohorts contained an increased percentage of submicron particles compared to the CPE cohort. However, the total number of particles was lower for both HXLPE cohorts, as a result there was no significant difference in the volume fraction distribution and specific biological activity (SBA; the relative biological activity per unit volume) between cohorts. In contrast, based on the decreased size and number of HXLPE wear debris there was a significant decrease in total particle volume (mm3/g of tissue). Accordingly, when the SBA was normalized by total particle volume (mm3/gm tissue) or by component wear volume rate (mm3/year), functional biological activity of the HXLPE wear debris was significantly decreased compared to the CPE cohort. Indications for this study are that the osteolytic potential of wear debris generated by HXLPE liners in vivo is significantly reduced by improvements in polyethylene wear resistance. PMID:23436587

The impact of electron beam irradiation on Low density polyethylene and Ethylene vinyl acetate

NASA Astrophysics Data System (ADS)

Sabet, Maziyar; Soleimani, Hassan

2017-05-01

Improvement of measured gel content, hardness, tensile strength and elongation at break of Ethylene vinyl acetate (EVA) have confirmed positive effect of electron beam irradiation on EVA. Results obtained from both gel content tests show that degree of cross-linking in amorphous regions is dependent on dose. A significant improvement in tensile strength of neat EVA samples is obtained upon electron-beam radiation up to 210 kGy. Similarly, hardness properties of Low-density polyethylene (LDPE) improvewith increasing electron beam irradiation. This article deals with the impacts of electron beam (EB) irradiation on the properties of LDPE and Ethylene-Vinyl Acetate (EVA) as the two common based formulations for wire and cable applications.

Degradation assessment of natural weathering on low density polyethylene/thermoplastic soya spent powder blends

NASA Astrophysics Data System (ADS)

Nuradibah, M. A.; Sam, S. T.; Noriman, N. Z.; Ragunathan, S.; Ismail, H.

2015-07-01

Soya spent powder was blended with low density polyethylene (LDPE) ranging from 5-25 wt%. Glycerol was added to soya spent powder (SSP) for preparation of thermoplastic soya spent powder (TSSP). Then, the blends were exposed to natural weathering for 6 months. The susceptibility of the LDPE/soya spent powder blends based on its tensile, morphological properties and structural changes was measured every three months. The tensile strength of LDPE/TSSP blends after 6 months of weathering was the lowest compared to the other blends whereas LDPE/SSP blends after 6 months of weathering demonstrated the lowest elongation at break (Eb). Large pore can be seen on the surface of 25 wt% of LDPE/SSP blends.

Mechanical and morphological study of linear low density polyethylene (LLDPE)/cyperus odoratus (CY) biocomposites

NASA Astrophysics Data System (ADS)

Faris, N. A.; Noriman, N. Z.; Haron, Adli; Sam, S. T.; Hamzah, R.; Shayfull, Z.; Ghazali, M. F.

2017-09-01

The potential of Cyperus Odoratus (CY) as a filler was studied. The CY, in a powder form, was mixed with Linear Low Density Polyethylene (LLDPE), prior to being fed into a twin screw extruder and subsequently into an injection moulding machine to produce LLDPY/CY biocomposites. The Scanning Electron Microscope (SEM) was utilized and tensile tests were performed on the test specimens to characterize the structure and properties of the composites. The integration of CY powder and LLDPE resulted in an increment of the modulus of elasticity, but a reduction in tensile strength and elongation at break. The morphology characterization of these composites, determined through the SEM, showed poor interfacial adhesion between the filler and the thermoplastic LLDPE matrix.

Compressive strength and initial water absorption rate for cement brick containing high-density polyethylene (HDPE) as a substitutional material for sand

NASA Astrophysics Data System (ADS)

Ali, Noorwirdawati; Din, Norhasmiza; Sheikh Khalid, Faisal; Shahidan, Shahiron; Radziah Abdullah, Siti; Samad, Abdul Aziz Abdul; Mohamad, Noridah

2017-11-01

The rapid growth of today’s construction sector requires high amount of building materials. Bricks, known to have solid properties and easy to handle, which leads to the variety of materials added or replaced in its mixture. In this study, high density polyethylene (HDPE) was selected as the substitute materials in the making of bricks. The reason behind the use of HDPE is because of its recyclable properties and the recycling process that do not emit hazardous gases to the atmosphere. Other than that, the use of HDPE will help reducing the source of pollution by avoiding the millions of accumulated plastic waste in the disposal sites. Furthermore, the material has high endurance level and is weatherproof. This study was carried out on experimenting the substitute materials in the mixture of cement bricks, a component of building materials which is normally manufactured using the mixture of cement, sand and water, following a certain ratios, and left dried to produce blocks of bricks. A series of three different percentages of HDPE were used, which were 2.5%, 3.0% and 3.5%. Tests were done on the bricks, to study its compressive strength and the initial water absorption rate. Both tests were conducted on the seventh and 28th day. Based on the results acquired, for compressive strength tests on the 28th day, the use of 2.5% of HDPE shown values of 12.6 N/mm2 while the use of 3.0% of HDPE shown values of 12.5 N/mm2. Onto the next percentage, 3.5% of HDPE shown values of 12.5 N/mm2.

Field and in vitro insecticidal efficacy of alphacypermethrin-treated high density polyethylene mesh against Culicoides biting midges in South Africa.

PubMed

Page, P C; Labuschagne, K; Venter, G J; Schoeman, J P; Guthrie, A J

2014-06-16

The efficacy of untreated and alphacypermethrin-treated high density polyethylene (HDPE) mesh against Culicoides biting midges (Diptera: Ceratopogonidae) was determined using Onderstepoort downdraught black light traps and a contact bioassay. Three traps were operated overnight in four replicates of a 3×3 randomised Latin square design near horses under South African field conditions. Both the untreated and alphacypermethrin-treated HDPE mesh significantly (P<0.05) reduced the numbers of Culicoides midges, predominantly Culicoides (Avaritia) imicola Kieffer, collected in the light traps by 4.2 and 7.2 times, respectively. A repellent effect of the alphacypermethrin-treated mesh was not confirmed because the number of midges collected in the light traps with untreated and alphacypermethrin-treated HDPE mesh was not significantly different (P=0.656). Bioassay of the insecticidal contact efficacy indicated median C. imicola mortality of 100% from 30 and 10 min following exposure to the alphacypermethrin-treated HDPE mesh for 1 or 3 min, respectively. In the bioassay, mortality was significantly higher (P=0.016) at 5 min post exposure in the midges exposed to the alphacypermethrin-treated mesh for 3 min (74.8%) compared to the 1 min exposure group (59.5%). The HDPE mesh could be used to reduce exposure of housed animals to Culicoides midges, specifically C. imicola, and viruses transmitted by these midges. Mesh treated with alphacypermethrin had the additional benefit of a rapid insecticidal effect on C. imicola. Copyright © 2014 Elsevier B.V. All rights reserved.

A directional entrapment modification on the polyethylene surface by the amphiphilic modifier of stearyl-alcohol poly(ethylene oxide) ether

NASA Astrophysics Data System (ADS)

Lu, Qiang; Chen, Yi; Huang, Juexin; Huang, Jian; Wang, Xiaolin; Yao, Jiaying

2018-05-01

A novel entrapment modification method involving directional implantation of the amphiphilic modifier of stearyl-alcohol poly(ethylene oxide) ether (AEO) into the high-density polyethylene (HDPE) surface is proposed. This modification technique allows the AEO modifier to be able to spontaneously attain and subsequently penetrate into the swollen HDPE surface with its hydrophobic stearyl segment, while its hydrophilic poly(ethylene oxide) (PEO) segment spontaneously points to water. The AEO modifier with a HLB number below 8.7 was proved appropriate for the directional entrapment, Nevertheless, AEOs with larger HLB numbers were also effective modifiers in the presence of salt additives. In addition, a larger and hydrophobic micelle, induced respectively by the AEO concentration above 1.3 × 10-2 mol/L and the entrapping temperature above the cloud point of AEO, could lead to a sharp contact angle decline of the modified surface. Finally, a hydrophilic HDPE surface with the modifier coverage of 38.9% was reached by the directional entrapment method, which is far larger than that of 19.2% by the traditional entrapment method.

Nanostructure and thermal properties of melt compounded PE/clay nanocomposites filled with an organosilylated montmorillonite

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

Scarfato, Paola, E-mail: pscarfato@unisa.it; BAM - Federal Institute for Materials Research and Testing, 7.5 Technical Properties of Polymeric Materials, Unter den Eichen 87 - 12205 Berlin; Incarnato, Loredana

In this work we report on the functionalization of a natural sodium montmorillonite (MMT) with (3-glycidyloxypropyl)trimethoxysilane by a silylation procedure and on its use as nanofiller in melt compounding of polyethylene nanocomposites. The obtained organosilylated clay showed higher interlayer spacing than the original MMT and higher thermal stability with respect to most of commercial organoclays modified with alkylammonium salts. Its addition (at 5wt%) to two different polyethylene matrices (a low density polyethylene, LDPE, and a high density polyethylene, HDPE), processed in a pilot-scale twin-screw extruder, allowed to produce hybrids with nanoscale dispersion of the filler, as demonstrated by X-ray diffraction.more » Thermogravimetric and differential scanning thermal analyses point out that the obtained nanocomposites do not show noticeable changes in the thermal behavior of both LDPE and HDPE, even if a slight reduction in the overall bulk crystallinity was observed in presence of the nanofillers.« less

Leak detection in medium density polyethylene (MDPE) pipe using pressure transient method

NASA Astrophysics Data System (ADS)

Amin, M. M.; Ghazali, M. F.; PiRemli, M. A.; Hamat, A. M. A.; Adnan, N. F.

2015-12-01

Water is an essential part of commodity for a daily life usage for an average person, from personal uses such as residential or commercial consumers to industries utilization. This study emphasizes on detection of leaking in medium density polyethylene (MDPE) pipe using pressure transient method. This type of pipe is used to analyze the position of the leakage in the pipeline by using Ensemble Empirical Mode Decomposition Method (EEMD) with signal masking. Water hammer would induce an impulse throughout the pipeline that caused the system turns into a surge of water wave. Thus, solenoid valve is used to create a water hammer through the pipelines. The data from the pressure sensor is collected using DASYLab software. The data analysis of the pressure signal will be decomposed into a series of wave composition using EEMD signal masking method in matrix laboratory (MATLAB) software. The series of decomposition of signals is then carefully selected which reflected intrinsic mode function (IMF). These IMFs will be displayed by using a mathematical algorithm, known as Hilbert transform (HT) spectrum. The IMF signal was analysed to capture the differences. The analyzed data is compared with the actual measurement of the leakage in term of percentage error. The error recorded is below than 1% and it is proved that this method highly reliable and accurate for leak detection.

Biodegradation of polyethylene by the thermophilic bacterium Brevibacillus borstelensis.

PubMed

Hadad, D; Geresh, S; Sivan, A

2005-01-01

To select a polyethylene-degrading micro-organism and to study the factors affecting its biodegrading activity. A thermophilic bacterium Brevibaccillus borstelensis strain 707 (isolated from soil) utilized branched low-density polyethylene as the sole carbon source and degraded it. Incubation of polyethylene with B. borstelensis (30 days, 50 degrees C) reduced its gravimetric and molecular weights by 11 and 30% respectively. Brevibaccillus borstelensis also degraded polyethylene in the presence of mannitol. Biodegradation of u.v. photo-oxidized polyethylene increased with increasing irradiation time. Fourier Transform Infra-Red (FTIR) analysis of photo-oxidized polyethylene revealed a reduction in carbonyl groups after incubation with the bacteria. This study demonstrates that polyethylene--considered to be inert--can be biodegraded if the right microbial strain is isolated. Enrichment culture methods were effective for isolating a thermophilic bacterium capable of utilizing polyethylene as the sole carbon and energy source. Maximal biodegradation was obtained in combination with photo-oxidation, which showed that carbonyl residues formed by photo-oxidation play a role in biodegradation. Brevibaccillus borstelensis also degraded the CH2 backbone of nonirradiated polyethylene. Biodegradation of polyethylene by a single bacterial strain contributes to our understanding of the process and the factors affecting polyethylene biodegradation.

Validation of a dye stain assay for vaginally inserted HEC-filled microbicide applicators

PubMed Central

Katzen, Lauren L.; Fernández-Romero, José A.; Sarna, Avina; Murugavel, Kailapuri G.; Gawarecki, Daniel; Zydowsky, Thomas M.; Mensch, Barbara S.

2011-01-01

Background The reliability and validity of self-reports of vaginal microbicide use are questionable given the explicit understanding that participants are expected to comply with study protocols. Our objective was to optimize the Population Council's previously validated dye stain assay (DSA) and related procedures, and establish predictive values for the DSA's ability to identify vaginally inserted single-use, low-density polyethylene microbicide applicators filled with hydroxyethylcellulose gel. Methods Applicators, inserted by 252 female sex workers enrolled in a microbicide feasibility study in Southern India, served as positive controls for optimization and validation experiments. Prior to validation, optimal dye concentration and staining time were ascertained. Three validation experiments were conducted to determine sensitivity, specificity, negative predictive values and positive predictive values. Results The dye concentration of 0.05% (w/v) FD&C Blue No. 1 Granular Food Dye and staining time of five seconds were determined to be optimal and were used for the three validation experiments. There were a total of 1,848 possible applicator readings across validation experiments; 1,703 (92.2%) applicator readings were correct. On average, the DSA performed with 90.6% sensitivity, 93.9% specificity, and had a negative predictive value of 93.8% and a positive predictive value of 91.0%. No statistically significant differences between experiments were noted. Conclusions The DSA was optimized and successfully validated for use with single-use, low-density polyethylene applicators filled with hydroxyethylcellulose (HEC) gel. We recommend including the DSA in future microbicide trials involving vaginal gels in order to identify participants who have low adherence to dosing regimens. In doing so, we can develop strategies to improve adherence as well as investigate the association between product use and efficacy. PMID:21992983

Impact resistance and fractography in ultra high molecular weight polyethylenes.

PubMed

Puértolas, J A; Pascual, F J; Martínez-Morlanes, M J

2014-02-01

Highly crosslinked ultra high molecular weight polyethylenes (UHMWPE) stabilized by a remelting process or by the addition of an antioxidant are highly wear resistant and chemically stable. However, these polyethylenes currently used in total joint replacements suffer a loss of mechanical properties, especially in terms of fracture toughness. In this study we analyze the impact behavior of different polyethylenes using an instrumented double notch Izod test. The materials studied are three resins: GUR1050, GUR1020 with 0.1wt% of vitamin E, and MG003 with 0.1wt% of vitamin E. These resins were gamma irradiated at 90kGy, and pre and post-irradiation remelting processes were applied to GUR1050 for two different time periods. Microstructural data were determined by means of differential scanning calorimetry and transmission electron microscopy. Fractography carried out on the impact fracture surfaces and images obtained by scanning electron microscopy after etching indicated the existence of a fringe structure formed by consecutive ductile-brittle and brittle-ductile transitions, which is related to the appearance of discontinuities in the load-deflection curves. A correlation has been made of the macroscopic impact strength results and the molecular chain and microstructural characteristics of these aforementioned materials, with a view to designing future resins with improved impact resistance. The use of UHMWPE resins with low molecular weight or the application of a remelting treatment could contribute to obtain a better impact strength behavior. © 2013 Published by Elsevier Ltd.

Crystallization Kinetics of Indomethacin/Polyethylene Glycol Dispersions Containing High Drug Loadings.

PubMed

Duong, Tu Van; Van Humbeeck, Jan; Van den Mooter, Guy

2015-07-06

The reproducibility and consistency of physicochemical properties and pharmaceutical performance are major concerns during preparation of solid dispersions. The crystallization kinetics of drug/polyethylene glycol solid dispersions, an important factor that is governed by the properties of both drug and polymer has not been adequately explored, especially in systems containing high drug loadings. In this paper, by using standard and modulated differential scanning calorimetry and X-ray powder diffraction, we describe the influence of drug loading on crystallization behavior of dispersions made up of indomethacin and polyethylene glycol 6000. Higher drug loading increases the amorphicity of the polymer and inhibits the crystallization of PEG. At 52% drug loading, polyethylene glycol was completely transformed to the amorphous state. To the best of our knowledge, this is the first detailed investigation of the solubilization effect of a low molecular weight drug on a semicrystalline polymer in their dispersions. In mixtures containing up to 55% indomethacin, the dispersions exhibited distinct glass transition events resulting from amorphous-amorphous phase separation which generates polymer-rich and drug-rich domains upon the solidification of supercooled polyethylene glycol, whereas samples containing at least 60% drug showed a single amorphous phase during the period in which crystallization normally occurs. The current study demonstrates a wide range in physicochemical properties of drug/polyethylene glycol solid dispersions as a result of the complex nature in crystallization of this system, which should be taken into account during preparation and storage.

Effect of initiator concentration to low-density polyethylene production in a tubular reactor

NASA Astrophysics Data System (ADS)

Azmi, A.; Aziz, N.

2016-11-01

Low-density polyethylene (LDPE) is one of the most widely used polymers in the world, which is produced in high-capacity tubular and autoclave reactors. As the LDPE industry turn into more competitive and its market profit margins become tighter, manufacturers have to develop solutions to debottleneck the reactor output while abiding to the stringent product specification. A single polyolefin plant producing ten to forty grades of LDPE with various melt flow index (MFI), therefore understanding the reaction mechanism, the operating conditions as well as the dynamic behavior of tubular reactor is essential before any improvement can take place. In the present work, a steady state mathematical model representing a tubular reactor for the production of LDPE is simulated using MATLAB R2015a®. The model developed is a function of feed inlet, reactor jacket, single initiator injector and outlet stream. Analysis on the effect of initiator concentration (CI) shows sudden declining trend of initiator's concentration which indicates that all of the initiators are exhausted after polymerization reaction and no further reaction occur from this point onwards. Furthermore, the results demonstrate that the concentration of initiator gives significant impact on reactor temperature's profile and monomer conversion rate, since higher initiator concentration promotes greater polymerization rate, and therefore leads to higher monomer conversion throughput.

21 CFR 177.1610 - Polyethylene, chlorinated.

Code of Federal Regulations, 2014 CFR

2014-04-01

... chlorination of polyethylene conforming to the density, maximum n-hexane extractable fraction, and maximum..._federal_regulations/ibr_locations.html.), and has a 7.0 percent maximum extractable fraction in n-hexane...

Demonstration and Validation of a Regenerated Cellulose Dialysis Membrane Diffusion Sampler for Monitoring Ground-Water Quality and Remediation Progress at DoD Sites

DTIC Science & Technology

2010-04-01

LDPE low-density polyethylene LF low-flow purging LRL laboratory reporting level MDL minimum detection limit MNA monitored natural attenuation...shaped bag made of flexible low-density polyethylene ( LDPE ) (Vroblesky, 2001a, 2001b). The LDPE tube is heat-sealed on one end, filled with high...from small- diameter LDPE tubing that fits into small-diameter wells. These PDB samplers have been shown to be useful only for collection of VOCs

Post-consumer contamination in high-density polyethylene (HDPE) milk bottles and the design of a bottle-to-bottle recycling process.

PubMed

Welle, F

2005-10-01

Six hundred conventional recycled HDPE flake samples, which were recollected and sorted in the UK, were screened for post-consumer contamination levels. Each analysed sample consisted of 40-50 individual flakes so that the amount of analysed individual containers was in the range 24,000-30,000 post-consumer milk bottles. Predominant contaminants in hot-washed flake samples were unsaturated oligomers, which can be also be found in virgin high-density polyethylene (HDPE) pellet samples used for milk bottle production. In addition, the flavour compound limonene, the degradation product of antioxidant additives di-tert-butylphenol and low amounts of saturated oligomers were found in higher concentrations in the post-consumer samples in comparison with virgin HDPE. However, the overall concentrations in post-consumer recycled samples were similar to or lower than concentration ranges in comparison with virgin HDPE. Contamination with other HDPE untypical compounds was rare and was in most cases related to non-milk bottles, which are <2.1% of the input material of the recycling process. The maximum concentration found in one sample of 1 g was estimated as 130 mg kg(-1), which corresponds to a contamination of 5200-6500 mg kg(-1) in the individual bottle. The recycling process investigated was based on an efficient sorting process, a hot-washing of the ground bottles, and a further deep-cleaning of the flakes with high temperatures and vacuum. Based on the fact that the contamination levels of post-consumer flake samples are similar to virgin HDPE and on the high cleaning efficiency of the super-clean recycling process especially for highly volatile compounds, the recycling process investigated is suitable for recycled post-consumer HDPE bottles for direct food-contact applications. However, hand-picking after automatically sorting is recommended to decrease the amount of non-milk bottles. The conclusions for suitability are valid, provided that the migration testing of

Interferometer density measurements of a high-velocity plasmoid

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

Case, A.; Messer, S.; Bomgardner, R.

2010-05-15

The plasmoid produced by a half-scale contoured gap coaxial plasma accelerator using ablative polyethylene capillary plasma injectors is measured using a quadrature heterodyne HeNe interferometer. The plasmoid is found to have a sharp rise in density at the leading edge, with a gradual falloff after the peak density. For this early test series, an average bulk density of 5x10{sup 14} cm{sup -3} is observed, with densities up to 8x10{sup 14} cm{sup -3} seen on some shots. Although plasmoid mass is only about 58 mug due to the low current and injected mass used in these tests, good shot-to-shot repeatability ismore » attained making analysis relatively straightforward, thus providing a solid foundation for interpreting future experimental results.« less

Hull Fiber From DDGS and Corn Grain as Alternative Fillers in Polymer Composites with High Density Polyethylene

NASA Astrophysics Data System (ADS)

Pandey, Pankaj

The steady increase in corn based ethanol production has resulted in a dramatic rise in the supply of its co-product known as distillers' dried grain with solubles (DDGS). Currently, the main outlet for DDGS is the animal feed industry, but the presence of fibers makes them indigestible by non-ruminants such as swine and poultry. Separation of fiber from DDGS would increase the nutritional value of DDGS with higher protein and fat contents and reduced fiber content. The fiber from DDGS can be separated through a physical separation process known as elusieve. The DDGS fiber has the potential to be used as a fiber filler in thermoplastic composites. This research project evaluates DDGS fiber as a filler in thermoplastic composites. The fibers from corn hull and DDGS have been used as fillers at 30% and 50% fiber loading in high density polyethylene (HDPE) composites and compared against a standard oak fiber filler composites at a lab scale. DDGS and corn fiber composites showed comparable mechanical properties as the oak wood fiber HDPE composites. Further evaluation was completed on the performance of composite samples at commercial scale with six combinations of oak fiber, corn hull fiber and DDGS fiber with fiber loading maintained at 50%, and then samples were exposed to UV accelerated weathering for 2000 h. The UV weathering decreased the mechanical properties of all the exposed samples compared to the unexposed samples. Also, UV weathering resulted in a severe chain scission of the HDPE polymer, increasing their crystallinity. The performance of mercerized or sodium hydroxide (NaOH) treated DDGS fiber as filler was investigated by characterizing the effects of treated and untreated DDGS fibers on physical, mechanical, and thermal properties of HDPE composites. The NaOH treated DDGS fiber at 25% loading showed consistent improvement in flexural and tensile modulus of elasticities of the composites compared to the neat HDPE.

Improvement of nuclide leaching resistance of paraffin waste form with low density polyethylene.

PubMed

Kim, Chang Lak; Park, Joo Wan; Kim, Ju Youl; Chung, Chang Hyun

2002-01-01

Low-level liquid borate wastes have been immobilized with paraffin wax using a concentrate waste drying system (CWDS) in Korean nuclear power plants. The possibility for improving chemical durability of paraffin waste form was suggested in this study. A small amount of low density polyethylene (LDPE) was added to increase the leaching resistance of the existing paraffin waste form. The influence of LDPE on the leaching behavior of waste form was investigated by performing leaching test according to ANSI/ANS-16.1 procedure during 325 days. It was observed that the leaching of nuclides immobilized within paraffin waste form made a marked reduction although little content of LDPE was added to waste form. The acceptance criteria of paraffin waste form associated with leachability index (LI) and compressive strength after the leaching test were fully satisfied with the help of LDPE.

Safety and durability of low-density polyethylene bags in solar water disinfection applications.

PubMed

Danwittayakul, Supamas; Songngam, Supachai; Fhulua, Tipawan; Muangkasem, Panida; Sukkasi, Sittha

2017-08-01

Solar water disinfection (SODIS) is a simple point-of-use process that uses sunlight to disinfect water for drinking. Polyethylene terephthalate (PET) bottles are typically used as water containers for SODIS, but a new SODIS container design has recently been developed with low-density polyethylene (LDPE) bags and can overcome the drawbacks of PET bottles. Two nesting layers of LDPE bags are used in the new design: the inner layer containing the water to be disinfected and the outer one creating air insulation to minimize heat loss from the water to the surroundings. This work investigated the degradation of LDPE bags used in the new design in actual SODIS conditions over a period of 12 weeks. The degradation of the LDPE bags was investigated weekly using a scanning electron microscope, Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometer, and tensile strength tester. It was found that the LDPE bags gradually degraded under the sunlight due to photo-oxidation reactions, especially in the outer bags, which were directly exposed to the sun and surroundings, leading to the reduction of light transmittance (by 11% at 300 nm) and tensile strength (by 33%). In addition, possible leaching of organic compounds into the water contained in the inner bags was examined using gas chromatography-mass spectrometer. 2,4-Di-tert-butylphenol was found in some SODIS water samples as well as the as-received water samples, in the concentration range of 1-4 μg/L, which passes the Environmental Protection Agency Drinking Water Guidance on Disinfection By-Products.

Shockley-Read-Hall recombination in pre-filled and photo-filled intermediate band solar cells

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

Mayani, Maryam Gholami; Reenaas, Turid Worren, E-mail: turid.reenaas@ntnu.no

2014-08-18

In this work, we study how Shockley-Read-Hall (SRH) recombination via energy levels in the bandgap, caused by defects or impurities, affects the performance of both photo-filled and pre-filled intermediate band solar cells (IBSCs). For a pre-filled cell, the IB is half-filled in equilibrium, while it is empty for the photo-filled cell in equilibrium. The energy level, density, and capture cross-sections of the defects/impurities are varied systematically. We find that the photo-filled cells are, in general, less efficient than pre-filled cells, except when the defect level is between the conduction band and the IB. In that case, for a range ofmore » light intensities, the photo-filled cell performs better than the pre-filled. When the defect level is at the same energy as the IB, the efficiency is above 82% of the defect-free case, when less than 50% of the states at the IB lead to SRH recombination. This shows that even if SRH recombination via the IB takes place, high efficiencies can be achieved. We also show that band gap optimization can be used to reduce the SRH recombination.« less

Space-Filling Supercapacitor Carpets: Highly scalable fractal architecture for energy storage

NASA Astrophysics Data System (ADS)

Tiliakos, Athanasios; Trefilov, Alexandra M. I.; Tanasǎ, Eugenia; Balan, Adriana; Stamatin, Ioan

2018-04-01

Revamping ground-breaking ideas from fractal geometry, we propose an alternative micro-supercapacitor configuration realized by laser-induced graphene (LIG) foams produced via laser pyrolysis of inexpensive commercial polymers. The Space-Filling Supercapacitor Carpet (SFSC) architecture introduces the concept of nested electrodes based on the pre-fractal Peano space-filling curve, arranged in a symmetrical equilateral setup that incorporates multiple parallel capacitor cells sharing common electrodes for maximum efficiency and optimal length-to-area distribution. We elucidate on the theoretical foundations of the SFSC architecture, and we introduce innovations (high-resolution vector-mode printing) in the LIG method that allow for the realization of flexible and scalable devices based on low iterations of the Peano algorithm. SFSCs exhibit distributed capacitance properties, leading to capacitance, energy, and power ratings proportional to the number of nested electrodes (up to 4.3 mF, 0.4 μWh, and 0.2 mW for the largest tested model of low iteration using aqueous electrolytes), with competitively high energy and power densities. This can pave the road for full scalability in energy storage, reaching beyond the scale of micro-supercapacitors for incorporating into larger and more demanding applications.

Effect of gamma radiation on low density polyethylene (LDPE) films: optical, dielectric and FTIR studies.

PubMed

Moez, A Abdel; Aly, S S; Elshaer, Y H

2012-07-01

The low density polyethylene (LDPE) films were irradiated with gamma radiation in the dose range varied from 20 to 400 kGy. The induced changes in the chemical structure and dielectric properties for the irradiated films were investigated. The structure modifications: crystallinity as well as possible molecular changes of the polymer were recognized using Fourier Transform Infrared Spectroscopy (FTIR). The optical results were determined from transmission, reflection and absorption spectra for these films. The dielectric properties of these films were calculated using optical methods. Result indicates small variation in crystallinity which could be increased or decreased depending on the relative importance of the structural and chemical changes. Copyright © 2012 Elsevier B.V. All rights reserved.

In vitro and in vivo evaluation of a new nanocomposite, containing high density polyethylene, tricalcium phosphate, hydroxyapatite, and magnesium oxide nanoparticles.

PubMed

Pourdanesh, Fereydoun; Jebali, Ali; Hekmatimoghaddam, Seyedhossein; Allaveisie, Azra

2014-07-01

In this study, a new nanocomposite, which contained high density polyethylene (HDPE), tricalcium phosphate (Ca3(PO4)2) nanoparticles (TCP NPs), hydroxyapatite nanoparticles (HA NPs), and magnesium oxide nanoparticles (MgO NPs) was prepared. As in vitro experiment, human osteoblasts (HOB) cells were exposed to pristine HDPE and its nanocomposite for a period of 1, 4, and 7 days at 37 °C, and then different assays were carried out, including osteoblast cell proliferation, Trypan blue staining, cell viability, alkaline phosphatase (ALP), and cell adhesion. Antibacterial property of pristine HDPE and its nanocomposite was evaluated, and also their mechanical properties were measured after 2 and 4 months. As in vivo experiment, pristine HDPE and its nanocomposite were separately implanted on calvarium bone of rabbits, and tissue inflammation and osteogenesis were investigated after 2, 4, and 6 months. In case of HOB cells treated with HDPE or nanocomposite, as incubation time was increased, cell proliferation, live/dead ratio, and cell viability were decreased. But, the ALP activity and cell adhesion of HOB cells which treated with nanocomposite were raised after increase of incubation time. This study demonstrated that although the mechanical properties of nanocomposite were similar to HDPE sheet, but their antibacterial property was not similar. The in vivo experiment showed that both pristine HDPE and its nanocomposite had same inflammation responses. Interestingly, osteogenesis was observed after 2 months at bone/nanocomposite interface, and was highly increased after 4 and 6 months. It must be noted that such pattern was not seen at bone/HDPE interface. Copyright © 2014 Elsevier B.V. All rights reserved.

ac aging and space-charge characteristics in low-density polyethylene polymeric insulation

NASA Astrophysics Data System (ADS)

Chen, G.; Fu, M.; Liu, X. Z.; Zhong, L. S.

2005-04-01

In the present work efforts have been made to investigate the influence of ac aging on space-charge dynamics in low-density polyethylene (LDPE). LDPE films with 200 μm were aged under various electric stress levels at 50 Hz for various times at ambient temperature. Space-charge dynamics in the samples after aging were monitored using the pulsed electroacoustic technique. It has been revealed that the space charge under ac aging conditions is related to the level of the applied field, duration of the voltage application, as well as the electrode materials. By comparing with the results of unaged sample the results from aged sample provide a direct evidence of changing trapping characteristics after ac aging. Negative space charge is present in the bulk of the material and the total amount of charge increases with the aging time. The amount of charge increases with the applied field. Charge decay test indicates that the charges are captured in deep traps. These deep traps are believed to form during the aging and related to change caused by injected charge. By using different electrode materials such as gold, brass alloy, and polyethylene loaded with carbon black, it was found that the electrode has an important role in the formation of charge, hence subsequent changes caused by charge. The charge dynamics of the aged samples under dc bias differ from the sample without ac aging, indicating changes brought in by ac aging. Chemical analysis by Fourier transform infrared spectroscope and Raman microscope reveals no detectable chemical changes taken place in the bulk of the material after ac aging. Finally, the consequence of the accumulation of space charge under ac conditions on the lifetime of the material has been discussed. The presence of deeply trapped space charge leads to an electric stress enhancement which may shorten the lifetime of the insulation system.

The modification of renal transplantation with the usage of own polyethylene receptacle.

PubMed

Pupka, Artur; Chudoba, Paweł; Patrzałek, Dariusz; Janczak, Dariusz; Szyber, Piotr

2003-01-01

In this study a method of elimination of the second warm ischemia is shown. The method is based on the application of a specially constructed polyethylene bag, in which the transplanted kidney is placed in the time course from a removal from ice to the reconstruction of vessel flow. The bag is built of polyethylene foil HDPE of low density produced under high pressure. Own construction of the bag (three spaces and polyethylene) enables the storage of a transplanted organ at the stable temperature +4 Celsius degrees. Thanks to the separation of containers for melting ice and for the kidney, possible becomes unrestrained performance of both venous and arterial anastomosis independently of existing operative conditions. Due to the applied method of the elimination of the second warm ischemia with the usage of own construction of polyethylene bag HDPE, one can expect better early renal function after transplantation--decrease in the number of cases and shortening of the time of acute tubular necrosis (ATN--Acute Tubular Necrosis).

Enhanced energy density and thermal conductivity in poly(fluorovinylidene-co-hexafluoropropylene) nanocomposites incorporated with boron nitride nanosheets exfoliated under assistance of hyperbranched polyethylene.

PubMed

Ye, Huijian; Lu, Tiemei; Xu, Chunfeng; Zhong, Mingqiang; Xu, Lixin

2018-03-02

Polymer dielectric film with a large dielectric constant, high energy density and enhanced thermal conductivity are of significance for the development of impulse capacitors. However, the fabrication of polymer dielectrics combining high energy density and thermal conductivity is still a challenge at the moment. Here we demonstrate the facile exfoliation of hexagonal boron nitride nanosheets (BNNSs) in common organic solvents under sonication with the assistance of hyperbranched polyethylene (HBPE). The noncovalent CH-π interactions between the nanosheets and HBPE ensure the dispersion of BNNSs in organic solvents with high concentrations, because of the highly branched chain structure of HBPE. Subsequently, the resultant BNNSs with a few defects are distributed uniformly in the poly(fluorovinylidene-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposite films prepared via simple solution casting. The BNNS/P(VDF-HFP) nanocomposite exhibits outstanding dielectric properties, high energy density and high thermal conductivity. The dielectric constant of the 0.5 wt% nanocomposite film is 35.5 at 100 Hz with an energy density of 5.6 J cm -3 at 325 MV m -1 and a high charge-discharge efficiency of 79% due to the depression of the charge injection and chemical species ionization in a high field. Moreover, a thermal conductivity of 1.0 wt% nanocomposite film reaches 0.91 W·m -1  · K -1 , which is 3.13 times higher than that of the fluoropolymer matrix. With dipole accumulation and orientation in the interfacial zone, lightweight, flexible BNNS/P(VDF-HFP) nanocomposite films with high charge-discharge performance and thermal conductivity, exhibit promising applications in relatively high-temperature electronics and energy storage devices.

Enhanced energy density and thermal conductivity in poly(fluorovinylidene-co-hexafluoropropylene) nanocomposites incorporated with boron nitride nanosheets exfoliated under assistance of hyperbranched polyethylene

NASA Astrophysics Data System (ADS)

Ye, Huijian; Lu, Tiemei; Xu, Chunfeng; Zhong, Mingqiang; Xu, Lixin

2018-03-01

Polymer dielectric film with a large dielectric constant, high energy density and enhanced thermal conductivity are of significance for the development of impulse capacitors. However, the fabrication of polymer dielectrics combining high energy density and thermal conductivity is still a challenge at the moment. Here we demonstrate the facile exfoliation of hexagonal boron nitride nanosheets (BNNSs) in common organic solvents under sonication with the assistance of hyperbranched polyethylene (HBPE). The noncovalent CH-π interactions between the nanosheets and HBPE ensure the dispersion of BNNSs in organic solvents with high concentrations, because of the highly branched chain structure of HBPE. Subsequently, the resultant BNNSs with a few defects are distributed uniformly in the poly(fluorovinylidene-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposite films prepared via simple solution casting. The BNNS/P(VDF-HFP) nanocomposite exhibits outstanding dielectric properties, high energy density and high thermal conductivity. The dielectric constant of the 0.5 wt% nanocomposite film is 35.5 at 100 Hz with an energy density of 5.6 J cm-3 at 325 MV m-1 and a high charge-discharge efficiency of 79% due to the depression of the charge injection and chemical species ionization in a high field. Moreover, a thermal conductivity of 1.0 wt% nanocomposite film reaches 0.91 W·m-1 · K-1, which is 3.13 times higher than that of the fluoropolymer matrix. With dipole accumulation and orientation in the interfacial zone, lightweight, flexible BNNS/P(VDF-HFP) nanocomposite films with high charge-discharge performance and thermal conductivity, exhibit promising applications in relatively high-temperature electronics and energy storage devices.

Ultralow energy ion beam surface modification of low density polyethylene.

PubMed

Shenton, Martyn J; Bradley, James W; van den Berg, Jaap A; Armour, David G; Stevens, Gary C

2005-12-01

Ultralow energy Ar+ and O+ ion beam irradiation of low density polyethylene has been carried out under controlled dose and monoenergetic conditions. XPS of Ar+-treated surfaces exposed to ambient atmosphere show that the bombardment of 50 eV Ar+ ions at a total dose of 10(16) cm(-2) gives rise to very reactive surfaces with oxygen incorporation at about 50% of the species present in the upper surface layer. Using pure O+ beam irradiation, comparatively low O incorporation is achieved without exposure to atmosphere (approximately 13% O in the upper surface). However, if the surface is activated by Ar+ pretreatment, then large oxygen contents can be achieved under subsequent O+ irradiation (up to 48% O). The results show that for very low energy (20 eV) oxygen ions there is a dose threshold of about 5 x 10(15) cm(-2) before surface oxygen incorporation is observed. It appears that, for both Ar+ and O+ ions in this regime, the degree of surface modification is only very weakly dependent on the ion energy. The results suggest that in the nonequilibrium plasma treatment of polymers, where the ion flux is typically 10(18) m(-2) s(-1), low energy ions (<50 eV) may be responsible for surface chemical modification.

Demonstration and Validation of a Regenerated Cellulose Dialysis Membrane Diffusion Sampler for Monitoring Ground Water Quality and Remediation Progress at DoD Sites for Perchlorate and Explosives Compounds (ER-0313)

DTIC Science & Technology

2010-09-30

Inductively coupled plasma – mass spectrometry ITRC Interstate Technology Regulatory Council LRL Laboratory reporting level LDPE Low-density polyethylene...diameter of the well. Another diffusion membrane sampler design consists of a tubular-shaped bag made of flexible low-density polyethylene ( LDPE ...Vroblesky, 2001a, 2001b). The LDPE tube is heat-sealed on one end, filled with high-purity water, heat-sealed at the top, and then suspended in a well to

High efficiency solid state dye sensitized solar cells with graphene-polyethylene oxide composite electrolytes.

PubMed

Akhtar, M Shaheer; Kwon, Soonji; Stadler, Florian J; Yang, O Bong

2013-06-21

Novel and highly effective composite electrolytes were prepared by combining the two dimensional graphene (Gra) and polyethylene oxide (PEO) for the solid electrolyte of dye sensitized solar cells (DSSCs). Gra sheets were uniformly coated by the polymer layer through the ester carboxylate bonding between oxygenated species on Gra sheets and PEO. The Gra-PEO composite electrolyte showed the large scale generation of iodide ions in a redox couple. From rheological analysis, the decrease in viscosity after the addition of LiI and I2 in the Gra-PEO electrolyte might be explained by the dipolar interactions being severely disrupted by the ionic interactions of Li(+), I(-), and I3(-) ions. A composite electrolyte with 0.5 wt% Gra presented a higher ionic conductivity (3.32 mS cm(-1)) than those of PEO and other composite electrolytes at room temperature. A high overall conversion efficiency (∼5.23%) with a very high short circuit current (JSC) of 18.32 mA cm(-2), open circuit voltage (VOC) of 0.592 V and fill factor (FF) of 0.48 was achieved in DSSCs fabricated with the 0.5 wt% Gra-PEO composite electrolyte. This enhanced photovoltaic performance might be attributed to the large scale formation of iodide ions in the redox electrolyte and the relatively high ionic conductivity.

SEMICONDUCTOR TECHNOLOGY Dummy fill effect on CMP planarity

NASA Astrophysics Data System (ADS)

Junxiong, Zhou; Lan, Chen; Wenbiao, Ruan; Zhigang, Li; Weixiang, Shen; Tianchun, Ye

2010-10-01

With the use of a chemical-mechanical polishing (CMP) simulator verified by testing data from a foundry, the effect of dummy fill characteristics, such as fill size, fill density and fill shape, on CMP planarity is analyzed. The results indicate that dummy density has a significant impact on oxide erosion, and copper dishing is in proportion to dummy size. We also demonstrate that cross shape dummy fill can have the best dishing performance at the same density.

Influence of adipic acid on tensile and morphology properties of linear low density polyethylene/rambutan peels flour blends

NASA Astrophysics Data System (ADS)

Nadhirah, A. A.; Sam, S. T.; Noriman, N. Z.; Ragunathan, S.; Ismail, H.

2015-07-01

This study investigate about the tensile and morphological properties of degradable polymer produced from linear low density polyethylene/rambutan peel flour (LLDPE/RPF) blends and adipic acid (AA) was used as a compatibilizer by varying the rambutan peel flour (RPF) amount from 0-25wt%. The samples were subjected to tensile and morphological tests. AA compatibilized showed higher strength compared to uncompatibilized blends. The Young's modulus for LLDPE/RPF blends increased with increasing flour content. However, the addition of adipic acid had reduced the Young's Modulus.

Highly conductive solid polymer electrolyte membranes based on polyethylene glycol-bis-carbamate dimethacrylate networks

NASA Astrophysics Data System (ADS)

Fu, Guopeng; Dempsey, Janel; Izaki, Kosuke; Adachi, Kaoru; Tsukahara, Yasuhisa; Kyu, Thein

2017-08-01

In an effort to fabricate highly conductive, stable solid-state polymer electrolyte membranes (PEM), polyethylene glycol bis-carbamate (PEGBC) was synthesized via condensation reaction between polyethylene glycol diamine and ethylene carbonate. Subsequently, dimethacrylate groups were chemically attached to both ends of PEGBC to afford polyethylene glycol-bis-carbamate dimethacrylate (PEGBCDMA) precursor having crosslinking capability. The melt-mixed ternary mixtures consisting of PEGBCDMA, succinonitrile plasticizer, and lithium trifluorosulphonyl imide salt were completely miscible in a wide compositional range. Upon photo-crosslinking, the neat PEGBCDMA network was completely amorphous exhibiting higher tensile strength, modulus, and extensibility relative to polyethylene glycol diacrylate (PEGDA) counterpart. Likewise, the succinonitrile-plasticized PEM network containing PEGBCDMA remained completely amorphous and transparent upon photo-crosslinking, showing superionic conductivity, improved thermal stability, and superior tensile properties with improved capacity retention during charge/discharge cycling as compared to the PEGDA-based PEM.

Highly Branched Polyethylenes as Lubricant Viscosity and Friction Modifiers

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

Robinson, Joshua W.; Zhou, Yan; Qu, Jun

2016-10-08

A series of highly branched polyethylenes (BPE) were prepared and used in a Group I base oil as potential viscosity and friction modifiers. The lubricating performance of these BPEs supports the expected dual functionality. Changes in polarity, topology, and molecular weight of the BPEs showed significant effects on the lubricants’ performance, which provide scientific insights for polymer design in future lubricant development.

Synthesis and characterization of novel low density polyethylene-multiwall carbon nanotube porous composites

NASA Astrophysics Data System (ADS)

Rizvi, Reza; Kim, Jae-Kyung; Naguib, Hani

2009-10-01

This study details the synthesis and characterization of novel porous composites of low density polyethylene (PE) and multiwalled carbon nanotubes (MWNT). PE-MWNT composites were prepared by melt blending the components in a twin screw compounder and porous structures were produced by a batch technique using CO2 as the solvent. The composites were characterized for dispersion using scanning electron microscopy and transmission electron microscopy; the results indicate a finely dispersed MWNT phase in PE. Thermal, rheological, electrical and mechanical properties of the composites were characterized and results indicate an electrical and rheological percolation threshold concentration of between 1 and 2 wt% MWNT in PE. Substantial improvements in the mechanical and electrical properties of PE were observed with the addition of 5 wt% MWNT. The porous PE-MWNT composites fabricated in this study were found to be conductive and have potential applications as anti-static materials for electrostatic discharge prevention.

21 CFR 177.1610 - Polyethylene, chlorinated.

Code of Federal Regulations, 2010 CFR

2010-04-01

... produced by the direct chlorination of polyethylene conforming to the density, maximum n-hexane extractable... extractable fraction in n-hexane at 50 °C, as determined by the method described in § 177.1520(d)(3)(ii). (b...

21 CFR 177.1610 - Polyethylene, chlorinated.

Code of Federal Regulations, 2011 CFR

2011-04-01

... produced by the direct chlorination of polyethylene conforming to the density, maximum n-hexane extractable... extractable fraction in n-hexane at 50 °C, as determined by the method described in § 177.1520(d)(3)(ii). (b...

21 CFR 177.1610 - Polyethylene, chlorinated.

Code of Federal Regulations, 2012 CFR

2012-04-01

... produced by the direct chlorination of polyethylene conforming to the density, maximum n-hexane extractable... extractable fraction in n-hexane at 50 °C, as determined by the method described in § 177.1520(d)(3)(ii). (b...

21 CFR 177.1610 - Polyethylene, chlorinated.

Code of Federal Regulations, 2013 CFR

2013-04-01

... produced by the direct chlorination of polyethylene conforming to the density, maximum n-hexane extractable... extractable fraction in n-hexane at 50 °C, as determined by the method described in § 177.1520(d)(3)(ii). (b...

Thermal behavior of gamma-irradiated low-density polyethylene/paraffin wax blend

NASA Astrophysics Data System (ADS)

Abdou, Saleh M.; Elnahas, H. H.; El-Zahed, H.; Abdeldaym, A.

2016-05-01

The thermal properties of low-density polyethylene (LDPE)/paraffin wax blends were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and melt flow index (MFI). Blends of LDPE/wax in ratios of 100/0, 98/2, 96/4, 94/6, 92/8, 90/10 and 85/15 (w/w) were prepared by melt-mixing at the temperature of 150°C. It was found that increasing the wax content more than 15% leads to phase separation. DSC results showed that for all blends both the melting temperature (Tm) and the melting enthalpy (ΔHm) decrease linearly with an increase in wax content. TGA analysis showed that the thermal stability of all blends decreases linearly with increasing wax content. No clear correlation was observed between the melting point and thermal stability. Horowitz and Metzger method was used to determine the thermal activation energy (Ea). MFI increased exponentially by increasing the wax content. The effect of gamma irradiation on the thermal behavior of the blends was also investigated at different gamma irradiation doses. Significant correlations were found between the thermal parameters (Tm, ΔHm, T5%, Ea and MFI) and the amount of wax content and gamma irradiation.

Filling of High-Concentration Monoclonal Antibody Formulations into Pre-filled Syringes: Investigating Formulation-Nozzle Interactions To Minimize Nozzle Clogging.

PubMed

Shieu, Wendy; Stauch, Oliver B; Maa, Yuh-Fun

2015-01-01

Syringe filling of high-concentration/viscosity monoclonal antibody formulations is a complex process that is not fully understood. This study, which builds on a previous investigation that used a bench-top syringe filling unit to examine formulation drying at the filling nozzle tip and subsequent nozzle clogging, further explores the impact of formulation-nozzle material interactions on formulation drying and nozzle clogging. Syringe-filling nozzles made of glass, stainless steel, or plastic (polypropylene, silicone, and Teflon®), which represent a full range of materials with hydrophilic and hydrophobic properties as quantified by contact angle measurements, were used to fill liquids of different viscosity, including a high-concentration monoclonal antibody formulation. Compared with hydrophilic nozzles, hydrophobic nozzles offered two unique features that discouraged formulation drying and nozzle clogging: (1) the liquid formulation is more likely to be withdrawn into the hydrophobic nozzle under the same suck-back conditions, and (2) the residual liquid film left on the nozzle wall when using high suck-back settings settles to form a liquid plug away from the hydrophobic nozzle tip. Making the tip of the nozzle hydrophobic (silicone-coating on glass and Teflon-coating stainless steel) could achieve the same suck-back performance as plastic nozzles. This study demonstrated that using hydrophobic nozzles are most effective in reducing the risk of nozzle clogging by drying of high-concentration monoclonal antibody formulation during extended nozzle idle time in a large-scale filling facility and environment. Syringe filling is a well-established manufacturing process and has been implemented by numerous contract manufacturing organizations and biopharmaceutical companies. However, its technical details and associated critical process parameters are rarely published. Information on high-concentration/viscosity formulation filling is particularly lacking. This

Surface chemistry changes and microstructure evaluation of low density nanocluster polyethylene under natural weathering: A spectroscopic investigation

NASA Astrophysics Data System (ADS)

Hamzah, M.; Khenfouch, M.; Rjeb, A.; Sayouri, S.; Houssaini, D. S.; Darhouri, M.; Srinivasu, VV

2018-03-01

Polyethylene is the most commonly used plastic in daily life, covering wide areas of application e.g. this polymer is used as a greenhouses covering material. This article investigates the effect of photo-oxidation on commercial unstabilised Low Density Polyethylene (uLDPE), as result of outdoor weathering factors. In this study, the samples were exposed for four months to the natural weather. The physico-chemical effects of natural ageing were studied by attenuated total reflection Fourier transform infrared (ATR-FTIR) and X-ray photoelectron (XPS) spectroscopy to elucidate the chemical composition, the nature of chemical bonds established and further to interrogate the changes that occur on the surface of the uLDPE samples. The main chemical change of uLDPE results in the formation of different kinds of carbonyl and vinyl groups identifiable in the ATR-FTIR and XPS spectra. The degree of crystallinity for these samples was calculated in terms of time exposure. An increase in the degree of crystallinity due to chemicrystallization was observed, which we indicative of the occurrences of chain scission. During outdoor exposure it was found that the photo-oxidation results in the formation of chain scission occurrences via Norrish type II reactions.

[Biodegradation of polyethylene].

PubMed

Yang, Jun; Song, Yi-ling; Qin, Xiao-yan

2007-05-01

Plastic material is one of the most serious solid wastes pollution. More than 40 million tons of plastics produced each year are discarded into environment. Plastics accumulated in the environment is highly resistant to biodegradation and not be able to take part in substance recycle. To increase the biodegradation efficiency of plastics by different means is the main research direction. This article reviewed the recent research works of polyethylene biodegradation that included the modification and pretreatment of polyethylene, biodegradation pathway, the relevant microbes and enzymes and the changes of physical, chemical and biological properties after biodegradation. The study directions of exploiting the kinds of life-forms of biodegradation polyethylene except the microorganisms, isolating and cloning the key enzymes and gene that could produce active groups, and enhancing the study on polyethylene biodegradation without additive were proposed.

Streaked x-ray backlighting with twin-slit imager for study of density profile and trajectory of low-density foam target filled with deuterium liquid

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

Shiraga, H.; Mahigashi, N.; Yamada, T.

2008-10-15

Low-density plastic foam filled with liquid deuterium is one of the candidates for inertial fusion target. Density profile and trajectory of 527 nm laser-irradiated planer foam-deuterium target in the acceleration phase were observed with streaked side-on x-ray backlighting. An x-ray imager employing twin slits coupled to an x-ray streak camera was used to simultaneously observe three images of the target: self-emission from the target, x-ray backlighter profile, and the backlit target. The experimentally obtained density profile and trajectory were in good agreement with predictions by one-dimensional hydrodynamic simulation code ILESTA-1D.

Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies

PubMed Central

Ingham, Eileen; Fisher, John; Tipper, Joanne L

2014-01-01

It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies. PMID:24658586

Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies.

PubMed

Liu, Aiqin; Ingham, Eileen; Fisher, John; Tipper, Joanne L

2014-04-01

It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies.

Densities and filling factors of the diffuse ionized gas in the Solar neighbourhood

NASA Astrophysics Data System (ADS)

Berkhuijsen, E. M.; Müller, P.

2008-10-01

Aims: We analyse electron densities and filling factors of the diffuse ionized gas (DIG) in the Solar neighbourhood. Methods: We have combined dispersion measures and emission measures towards 38 pulsars at distances known to better than 50%, from which we derived the mean density in clouds, N_c, and their volume filling factor, F_v, averaged along the line of sight. The emission measures were corrected for absorption by dust and contributions from beyond the pulsar distance. Results: The scale height of the electron layer for our sample is 0.93± 0.13 kpc and the midplane electron density is 0.023± 0.004 cm-3, in agreement with earlier results. The average density along the line of sight is < n_e> = 0.018± 0.002 cm-3 and is nearly constant. Since < n_e> = F_vN_c, an inverse relationship between Fv and Nc is expected. We find F_v(N_c) = (0.011± 0.003) N_c-1.20± 0.13, which holds for the ranges N_c= 0.05-1 cm-3 and F_v= 0.4-0.01. Near the Galactic plane the dependence of Fv on Nc is significantly stronger than away from the plane. Fv does not systematically change along or perpendicular to the Galactic plane, but the spread about the mean value of 0.08± 0.02 is considerable. The total pathlength through the ionized regions increases linearly to about 80 pc towards |z| = 1 kpc. Conclusions: Our study of Fv and Nc of the DIG is the first one based on a sample of pulsars with known distances. We confirm the existence of a tight, nearly inverse correlation between Fv and Nc in the DIG. The exact form of this relation depends on the regions in the Galaxy probed by the pulsar sample. The inverse F_v-Nc relation is consistent with a hierarchical, fractal density distribution in the DIG caused by turbulence. The observed near constancy of < n_e> then is a signature of fractal structure in the ionized medium, which is most pronounced outside the thin disk.

Polyaniline nanofiber sponge filled graphene foam as high gravimetric and volumetric capacitance electrode

NASA Astrophysics Data System (ADS)

Pedrós, J.; Boscá, A.; Martínez, J.; Ruiz-Gómez, S.; Pérez, L.; Barranco, V.; Calle, F.

2016-06-01

A 3D hierarchical porous composite structure is developed via the controlled electrodeposition of a polyaniline nanofiber sponge (PANI-NFS) that fills the pores of a chemical vapor deposited graphene foam (GF). The PANI-NFS/GF composite combines the efficient electronic transport in the GF scaffold (with 100-500 μm pore size) with the rapid diffusion of the electrolyte ions into the high-specific-surface-area and densely-packed PANI-NFS (with 100-500 nm pore size). The factor of 1000 in the pore hierarchy and the synergy between the materials, that form a supercapacitor composite electrode with an integrated extended current collector, lead to both very high gravimetric and volumetric capacitances. In particular, values of 1474 F g-1 and 86 F cm-3 for a GF filling factor of 11% (leading to an estimated value of 782 F cm-3 for 100%), respectively, are obtained at a current density of 0.47 A g-1. Moreover, the composite electrode presents a capacitance retention of 83% after 15000 cycles. This excellent behavior makes the PANI-NFS/GF composite electrodes very attractive for high-performance supercapacitors.

Cure characteristics, crosslink density and degree of filler dispersion of kaolin-filled natural rubber compounds in the presence of alkanolamide

NASA Astrophysics Data System (ADS)

Surya, I.; Hayeemasae, N.; Ginting, M.

2018-03-01

The effects of alkanolamide (ALK) addition on cure characteristics, crosslink density and degree of filler dispersion of kaolin-filled natural rubber (NR) compounds were investigated. The kaolin filler was incorporated into NR compounds with a fixed loading, 30.0 phr. The ALK was prepared from Refined Bleached Deodorized Palm Stearin (RBDPS), a waste product of cooking oil production, and diethanolamine. The ALK is an oily material and added into the filled NR compounds as a rubber additive at different loadings, 0.0, 3.0, 5.0 and 7.0. The kaolin-filled NR compounds with and without ALK were vulcanized using a semi-efficient vulcanization system. It was found that ALK decreased the scorch and cure times and improved filler dispersion of the kaolin-filled NR compounds. The higher the ALK loading, the shorter were the scorch and cure times. It was also found that ALK increased the crosslink density of kaolin-filled NR compound up to 5.0 phr of loading. Due to its oily properties, The ALK acted as an internal plasticizer which decreased the minimum torque and improved the degree of kaolin dispersion in NR phases. The higher the ALK loading; the lower the minimum torque and better the filler dispersion.

New dual-curvature microlens array with a high fill-factor for organic light emitting diode modules

NASA Astrophysics Data System (ADS)

Lin, Tsung-Hung; Yang, Hsiharng; Chao, Ching-Kong; Shui, Hung-Chi

2013-09-01

A new method for fabricating a novel dual-curvature microlens array with a high fill-factor using proximity printing in a lithography process is reported. The lens shapes include dual-curvature, which is a novel shape composed of triangles and hexagons. We utilized UV proximity printing by controlling a printing gap between the mask and substrate. The designed high density microlens array pattern can fabricate a dual-curvature microlens array with a high fill-factor in a photoresist material. It is due to the UV light diffraction which deflects away from the aperture edges and produces a certain exposure in the photoresist material outside the aperture edges. A dual-curvature microlens array with a height ratio of 0.48 can boost axial luminance up to 22%. Therefore, the novel dual-curvature microlens array offers an economical solution for increasing the luminance of organic light emitting diodes.

Surface chemistry and mechanical property changes of wood-flour/high-density-polyethylene composites after accelerated weathering

Treesearch

Nicole M. Stark; Laurent M. Matuana

2004-01-01

Although wood–plastic composites have become more accepted and used in recent years and are promoted as low-maintenance, high-durability building products, they do experience a color change and a loss in mechanical properties with accelerated weathering. In this study, we attempted to characterize the modulus-of-elasticity (MOE) loss of photostabilized high- density...

Biological resistance of polyethylene composites made with chemically modified fiber or flour

Treesearch

Rebecca E. Ibach; Craig M. Clemons

2002-01-01

The role of moisture in the biological decay of wood-plastic composites was investigated. Southern pine wood fiber and ponderosa pine wood flour were chemically modified using either acetic anhydride (AA), butylene oxide (BO), or propylene oxide (PO). A 50:50 mixture of high density polyethylene and either chemically modified fiber or flour, or untreated fiber or flour...

Highly branched polyethylenes as lubricant viscosity and friction modifiers

DOE PAGES

Robinson, Joshua W.; Zhou, Yan; Qu, Jun; ...

2016-10-08

A series of highly branched polyethylene (BPE) were prepared and evaluated in a Group I base oil as potential viscosity and friction modifiers. The performance of these BPEs supports the expected dual functionality. Changes in polarity, topology, and molecular weight of the BPEs showed significant effects on the lubricants' performance with respect to viscosity index and friction reduction. In conclusion, this study provides scientific insights into polymer design for future lubricant development activities.

Development of high pressure-high vacuum-high conductance piston valve for gas-filled radiation detectors

NASA Astrophysics Data System (ADS)

Prasad, D. N.; Ayyappan, R.; Kamble, L. P.; Singh, J. P.; Muralikrishna, L. V.; Alex, M.; Balagi, V.; Mukhopadhyay, P. K.

2008-05-01

Gas-filled radiation detectors need gas filling at pressures that range from few cms of mercury to as high as 25kg/cm2 at room temperature. Before gas-filling these detectors require evacuation to a vacuum of the order of ~1 × 10-5 mbar. For these operations of evacuation and gas filling a system consisting of a vacuum pump with a high vacuum gauge, gas cylinder with a pressure gauge and a valve is used. The valve has to meet the three requirements of compatibility with high-pressure and high vacuum and high conductance. A piston valve suitable for the evacuation and gas filling of radiation detectors has been designed and fabricated to meet the above requirements. The stainless steel body (80mm×160mm overall dimensions) valve with a piston arrangement has a 1/2 inch inlet/outlet opening, neoprene/viton O-ring at piston face & diameter for sealing and a knob for opening and closing the valve. The piston movement mechanism is designed to have minimum wear of sealing O-rings. The valve has been hydrostatic pressure tested up to 75bars and has Helium leak rate of less than 9.6×10-9 m bar ltr/sec in vacuum mode and 2×10-7 mbar ltr/sec in pressure mode. As compared to a commercial diaphragm valve, which needed 3 hours to evacuate a 7 litre chamber to 2.5×10-5 mbar, the new valve achieved vacuum 7.4×10-6mbar in the same time under the same conditions.

Extraction of Volatile Flavor Compounds From Tobacco Leaf Through a Low-Density Polyethylene Membrane.

PubMed

Yokoi, Michinori; Shimoda, Mitsuya

2017-03-01

A low-density polyethylene (LDPE) membrane pouch method was developed to extract volatile flavor compounds from tobacco leaf. Tobacco leaf suspended in water was enclosed in a pouch prepared from a LDPE membrane of specific gravity 0.92 g/cm3 and 0.03 mm thickness and then extracted with diethyl ether. In comparison with direct solvent extraction, LDPE membrane excluded larger and higher boiling point compounds which could contaminate a gas chromatograph inlet and damage a column. Whilst being more convenient than a reduced-pressure steam distillation, it could extract volatile flavor compounds of wide range of molecular weight and polarity. Repeatabilities in the extracted amounts were ranged from 0.38% of 2.3-bipyridyl to 26% of β-ionone, and average value of 39 compounds was 5.9%. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Biodegradation of thermoplastic starch and its blends with poly(lactic acid) and polyethylene: influence of morphology

USDA-ARS?s Scientific Manuscript database

The room temperature mineralization of thermoplastic starch (TPS) with a high glycerol content and its blends with low-density polyethylene (LDPE) and polylactic acid (PLA) are examined under controlled degradation conditions. These results are correlated with the morphologies and continuity behavio...

Does cyclic stress and accelerated ageing influence the wear behavior of highly crosslinked polyethylene?

PubMed

Affatato, Saverio; De Mattia, Jonathan Salvatore; Bracco, Pierangiola; Pavoni, Eleonora; Taddei, Paola

2016-06-01

First-generation (irradiated and remelted or annealed) and second-generation (irradiated and vitamin E blended or doped) highly crosslinked polyethylenes were introduced in the last decade to solve the problems of wear and osteolysis. In this study, the influence of the Vitamin-E addition on crosslinked polyethylene (XLPE_VE) was evaluated by comparing the in vitro wear behavior of crosslinked polyethylene (XLPE) versus Vitamin-E blended polyethylene XLPE and conventional ultra-high molecular weight polyethylene (STD_PE) acetabular cups, after accelerated ageing according to ASTM F2003-02 (70.0±0.1°C, pure oxygen at 5bar for 14 days). The test was performed using a hip joint simulator run for two millions cycles, under bovine calf serum as lubricant. Mass loss was found to decrease along the series XLPE_VE>STD_PE>XLPE, although no statistically significant differences were found between the mass losses of the three sets of cups. Micro-Raman spectroscopy was used to investigate at a molecular level the morphology changes induced by wear. The spectroscopic analyses showed that the accelerated ageing determined different wear mechanisms and molecular rearrangements during testing with regards to the changes in both the chain orientation and the distribution of the all-trans sequences within the orthorhombic, amorphous and third phases. The results of the present study showed that the addition of vitamin E was not effective to improve the gravimetric wear of PE after accelerated ageing. However, from a molecular point of view, the XLPE_VE acetabular cups tested after accelerated ageing appeared definitely less damaged than the STD_PE ones and comparable to XLPE samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Facile preparation of high density polyethylene superhydrophobic/superoleophilic coatings on glass, copper and polyurethane sponge for self-cleaning, corrosion resistance and efficient oil/water separation.

PubMed

Cheng, Yuanyuan; Wu, Bei; Ma, Xiaofan; Lu, Shixiang; Xu, Wenguo; Szunerits, Sabine; Boukherroub, Rabah

2018-04-18

Inspired by the lotus effect and water-repellent properties of water striders' legs, superhydrophobic surfaces have been intensively investigated from both fundamental and applied perspectives for daily and industrial applications. Various techniques are available for the fabrication of artificial superoleophilic/superhydrophobic (SS). However, most of these techniques are tedious and often require hazardous or expensive equipment, which hampers their implementation for practical applications. In the present work, we used a versatile and straightforward technique based on polymer drop-casting for the preparation SS materials that can be implemented on any substrate. High density polyethylene (HDPE) SS coatings were prepared on different substrates (glass, copper mesh and polyurethane (PU) sponge) by drop casting the parent polymer xylene-ethanol solution at room temperature. All the substrates exhibited a superhydrophobic behavior with a water contact angle (WCA) greater than 150°. Furthermore, the corrosion resistance, stability, self-cleaning property, and water/oil separation of the developed materials were also assessed. While copper mesh and PU sponge exhibited good ability for oil and organic solvents separation from water, the HDPE-functionalized PU sponge displayed good adsorption capacity, 32-90 times the weight of adsorbed substance vs. the weight of adsorbent. Copyright © 2018 Elsevier Inc. All rights reserved.

Hip Resurfacing Using Highly Cross-linked Polyethylene: Prospective Study Results at 8.5 Years.

PubMed

Pritchett, James W

2016-10-01

Hip resurfacing is an option to consider when treating younger, more active patients. Advantages over total hip arthroplasty include a more normal gait and a lower incidence of thigh pain. In this prospective study, 190 hip resurfacing procedures (164 participants) were performed using a cobalt-chromium femoral component and a cementless acetabular cup with a 3.8-mm highly cross-linked polyethylene acetabular liner. The mean follow-up was 8.5 (range, 7-10) years. Two participants were lost to follow-up and 2 died. One participant underwent successful revision surgery for acetabular loosening. Four participants underwent successful revision to a total hip arthroplasty because of femoral neck fracture (2), femoral loosening, or infection. The Kaplan-Meier survivorship was 97%. Acetabular bone conservation was assessed using computed tomography by measuring the medial acetabular wall. The mean thickness was 9 mm. Femoral bone was well preserved with a mean head:neck ratio of 1.37. There were 4 (2%) osteolytic defects up to 0.9 cm(3) on computed tomography and no instances of impending polyethylene wear-through. Seven polyethylene retrievals had a measured wear rate of 0.05 mm/y. Hip resurfacing using a highly cross-linked polyethylene acetabular component is a reliable procedure. Both femoral and acetabular bones are reasonably preserved compared with prior resurfacing methods. The low incidence of osteolysis and the low rate of wear found on retrievals suggest that many years of use in highly active patients is possible. Copyright © 2016 Elsevier Inc. All rights reserved.

An improved model to estimate trapping parameters in polymeric materials and its application on normal and aged low-density polyethylenes

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

Liu, Ning, E-mail: nl4g12@soton.ac.uk; He, Miao; Alghamdi, Hisham

2015-08-14

Trapping parameters can be considered as one of the important attributes to describe polymeric materials. In the present paper, a more accurate charge dynamics model has been developed, which takes account of charge dynamics in both volts-on and off stage into simulation. By fitting with measured charge data with the highest R-square value, trapping parameters together with injection barrier of both normal and aged low-density polyethylene samples were estimated using the improved model. The results show that, after long-term ageing process, the injection barriers of both electrons and holes is lowered, overall trap depth is shallower, and trap density becomesmore » much greater. Additionally, the changes in parameters for electrons are more sensitive than those of holes after ageing.« less

Poly(ethylene imine)-based granular sorbents by a new process of templated gel-filling. High capacity and selectivity of copper sorption in acidic and alkaline media

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

Chanda, M.; Rempel, G.L.

A new process has been developed for making granular gel-type sorbents from chelating resins using metal ion as template. Named as templated gel-filling, the process uses the chosen metal as templating host ion on high-surface-area silica to build a templated gel layer from a solution of the chelating resin in a suitable solvent in which the resin is soluble but its metal complex is insoluble. After cross-linking the templated gel layer, the silica support is removed by alkali to produce a hollow shell of the templated gel. The shells are then soaked in a concentrated aqueous solution of the samemore » metal ion and suspended in the same resin solution to afford gel-filling. The shells thus filled with metal-templated gel are treated with cross-linking agent, followed by acid to remove the template ion and activate the resin for metal sorption. Poly(ethyleneimine) and its partially ethylated derivative have been used to produce granular gel-type sorbents by this process, with Cu(II) as the template ion. These sorbents are found to offer high capacity and selectivity for copper over nickel, cobalt, and zinc in both acidic and alkaline media. Containing a relatively high fraction of imbibed water, the sorbents exhibit markedly enhanced rate behavior, in both sorption and stripping.« less

Morphology and properties of wood-fiber reinforced blends of recycled polystyrene and polyethylene

Treesearch

John Simonsen; Timothy G. Rials

1996-01-01

Material properties of composites produced from recycled plastics and recycled wood fiber were compared. A blend of high-density polyethylene and polystyrene was used as a simulated mixed plastic. Stiffness was generally improved by the addition of fiber, as expected, but brittleness also increased. Pre-treatment of the wood filler with phenol-formaldehyde resins did...

Effect of thermal modification on rheological properties of polyethylene blends

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

Siriprumpoonthum, Monchai; Nobukawa, Shogo; Yamaguchi, Masayuki, E-mail: m-yama@jaist.ac.jp

2014-03-15

We examined the effects of thermal modification under flow field on the rheological properties of linear low-density polyethylene (LLDPE) with high molecular weight, low-density polyethylene (LDPE), and their blends, without thermal stabilizer. Although structural changes during processing are not detected by size extrusion chromatography or nuclear magnetic resonance spectroscopy, linear viscoelastic properties changed greatly, especially for the LLDPE. A cross-linking reaction took place, leading to, presumably, star-shaped long-chain branches. Consequently, the modified LLDPE, having high zero-shear viscosity, became a thermorheologically complex melt. Moreover, it should be noted that the drawdown force, defined as the uniaxial elongational force at a constantmore » draw ratio, was significantly enhanced for the blends. Enhancement of elongational viscosity was also detected. The drawdown force and elongational viscosity are marked for the thermally modified blend as compared with those for the blend of thermally modified pure components. Intermolecular cross-linking reactions between LDPE and LLDPE, yielding polymers with more than two branch points per chain, result in marked strain-hardening in the elongational viscosity behavior even at small strain. The recovery curve of the oscillatory modulus after the shear modification is further evidence of a branched structure.« less

Attenuation of heavy metals by geosynthetics in the coal gangue-filled columns.

PubMed

Wang, Ping; Hu, Zhenqi; Wang, Peijun

2013-01-01

In the subsided areas backfilled with coal gangue, an issue of continuing environmental concern is the migration of hazardous metals to the subsurface soil and groundwater. As an effective isolation material, geosynthetics have been scarcely applied into mining areas reclamation of China. This paper describes research aimed at characterizing the behaviours of different geosynthetics in the leaching columns filled with coal gangues. Four types of geosynthetics were selected: fibres needle-punched nonwoven geotextiles, high-density polyethylene, needle-punched Na-bentonite geosynthetic clay liner (GCL-NP) and Na-bentonite geosynthetic-overbited film. Heavy metals were significantly attenuated and by monitoring aqueous solutions in the whole percolation period, negative correlation was found between pH value and concentration of heavy metals. Generally, GCL-NP showed comparatively better effects on attenuating the migration of heavy metals. According to the meta-analysis of heavy metals present in the leachates and retained in the columns, geosynthetics have good capabilities of sorption and retardation, which can delay the breakthrough time of heavy metals and retard the accumulation in the subsurface. Future research will use X-ray diffraction and micro-imaging (electron microprobe and scanning electron microscopy) to further explain retention mechanisms.

Numerical simulation of transport processes in injection mold-filling during production of a cylindrical object under isothermal and non-isothermal conditions

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

Kumar, A.; Ghoshdastidar, P.S.

1999-07-01

In this paper, numerical simulation of injection mold-filling during the production of a cylindrical object under isothermal and non-isothermal conditions is presented. The material of the object is low density polyethylene (LDPE) following power-law viscosity model for non-zero shear rate zone. However, where shear rate becomes zero, zero-shear viscosity value has been used. Three cases have been considered, namely (1) Isothermal filling at constant injection pressure, (2) Isothermal filling at constant flow rate, and (3) Non-isothermal filling at constant flow rate. For the case-(3), the viscosity of LDPE is also a function of temperature. The material of the mold ismore » steel. For the non-isothermal filling, the concept of melt-mold thermal contact resistance coefficient has been incorporated in the model. The length and diameter of the body in all three cases have been taken as 0.254 m and 0.00508 m respectively. The finite-difference method has been used to solve the governing differential equations for the processes. The results show excellent agreement with the corresponding equations for the processes. The results show excellent agreement with the corresponding analytical solutions for the first two cases showing the correctness of the numerical method. The simulation results for non-isothermal filling show physically realistic trends and lend insight into various important aspects of mold-filling including frozen skin layer.« less

Influence of different factors on the destruction of films based on polylactic acid and oxidized polyethylene

NASA Astrophysics Data System (ADS)

Podzorova, M. V.; Tertyshnaya, Yu. V.; Pantyukhov, P. V.; Shibryaeva, L. S.; Popov, A. A.; Nikolaeva, S.

2016-11-01

Influence of different environmental factors on the degradation of film samples based on polylactic acid and low density polyethylene with the addition of oxidized polyethylene was studied in this work. Different methods were used to find the relationship between degradation and ultraviolet, moisture, oxygen. It was found that the addition of oxidized polyethylene, used as a model of recycled polyethylene, promotes the degradation of blends.

Effects of strain rate and temperature on the mechanical behavior of carbon black reinforced elastomers based on butyl rubber and high molecular weight polyethylene

NASA Astrophysics Data System (ADS)

Hussein, M.

2018-06-01

The influence of the mechanical property and morphology of different blend ratio of Butyl rubber (IIR)/high molecular weight polyethylene (PE) by temperature and strain rate are performed. Special attention has been considered to a ductile-brittle transition that is known to occur at around 60 °C. The idea is to explain the unexpected phenomenon of brittleness which directly related to all tensile mechanical properties such as the strength of blends, modulus of elasticity of filled and unfilled IIR-polyethylene blends. In particular, the initial Young's modulus, tensile strength and strain at failure exhibit similar dependency on strain rate and temperature. These quantities lowered and increased with an increment of temperature, whereas the increased with increasing of strain rate. Furthermore, the tensile strength and strain at failure decreases for all temperatures range with the increase of PE content in the blend, except Young's modulus in reverse. The strain rate sensitivity index parameter of the examined polymeric materials is consistent with the micro-mechanisms of deformation and the behavior was well described by an Eyring relationship leading to an activation volume of ∼1 nm3, except for the highest value of unfilled IIR ∼8.45 nm3.

Melt fracture of linear low-density polyethylenes: Die geometry and molecular weight characteristics

NASA Astrophysics Data System (ADS)

Ebrahimi, Marzieh; Tomkovic, Tanja; Liu, Guochang; Doufas, Antonios A.; Hatzikiriakos, Savvas G.

2018-05-01

The melt fracture phenomena of three linear low-density polyethylenes are investigated as a function of die geometry (capillary, slit, and annular) and molecular weight and its distribution. The onset of melt fracture instabilities is determined by using capillary rheometry, mainly studying the extrudate appearance using optical microscopy. It is found that the onset of flow instabilities (melt fracture phenomena) is significantly affected by die geometry and molecular weight characteristics of the polymers. Use of annular die eliminates the stick-slip transition (oscillating melt fracture) and delays the onset of sharkskin to higher values of shear rate and shear stress. Moreover, it is shown that the molecular weight characteristics of the polymers are well correlated with critical conditions for the onset of flow instabilities based on a criterion proposed in the literature [A. Allal et al., "Relationships between molecular structure and sharkskin defect for linear polymers," J. Non-Newtonian Fluid Mech. 134, 127-135 (2006) and A. Allal and B. Vergnes, "Molecular design to eliminate sharkskin defect for linear polymers," J. Non-Newtonian Fluid Mech. 146, 45-50 (2007)].

Properties of concrete modified with waste Low Density Polyethylene and saw dust ash

NASA Astrophysics Data System (ADS)

Srimanikandan, P.; Sreenath, S.

2017-07-01

The increase in industrialization creates need for disposal of large quantity of by-products. To overcome the difficulty of disposal, these by-products can be used as a replacement for raw material. In this concern, non-conventional industrial wastes such as plastic bags, PET bottles, pulverized waste Low Density Polyethylene (LDPE) and biological waste such as saw-dust ash, coconut coir were used as a replacement in concrete. In this project, saw-dust ash and pulverized waste LDPE were introduced as the partial replacement for cement and fine aggregates respectively. 0%, 5%, 10%, 15% and 20% of sand by volume was replaced with LDPE and 0%, 1%, 3%, 5% and 10% of cement by volume was replaced with saw dust ash. Standard cube, cylinder and prism specimens were cast to assess the compressive strength, split tensile strength and flexural strength of modified concrete after 28 days of curing. Optimum percentage of replacement was found by comparing the test results. The mix with 5% of LDPE and 3% of saw dust ash showed a better result among the other mixes.

Improving the circular economy via hydrothermal processing of high-density waste plastics.

PubMed

Helmer Pedersen, Thomas; Conti, Federica

2017-10-01

Rising environmental concerns on climate changes are causing an increasing attention on circular economies. The plastic economy, in particular, is in focus due to the accelerating consumption of plastics, mainly derived from virgin feedstock, combined with the lack of plastic recycling strategies. This work presents a novel outlook on the potential of using supercritical hydrothermal processing of waste plastic fractions for tertiary recycling. The study investigates hydrothermal processing of nine different, high-density types of plastics into original resin monomers and other value-added chemical compounds. The outlook presents conversion yields, carbon balances, and chemical details on the products obtained. It is found that all the investigated resins are prone to hydrothermal treatment, and that high yields of monomers and high value compounds (up to nearly 100%), suitable for chemicals and fuels applications, can be obtained. For instance, for polycarbonate, styrene-butadiene, poly(lactic acid), poly(ethylene terephthalate), and poly(butylene terephthalate), original monomeric compounds can be reclaimed for manufacturing new resins. The promising results presented demonstrate that hydrothermal processing of high-density plastics is a prospective technology for increasing the circularity of the plastic economy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Viscoelastic Response Of A Highly Filled Polymer

NASA Technical Reports Server (NTRS)

Peng, Steven T. J.; Landel, Robert F.

1992-01-01

Report describes experimental and theoretical studies of nonlinear viscoelastic response of elastomeric binder material filled with small particles of different material. Studies characterize response with sufficient accuracy for use in designing parts subjected to high strains.

Evaluation of the effect of reprocessing on the structure and properties of low density polyethylene/thermoplastic starch blends.

PubMed

Peres, Anderson M; Pires, Ruthe R; Oréfice, Rodrigo L

2016-01-20

The great quantity of synthetic plastic discarded inappropriately in the environment is forcing the search for materials that can be reprocessable and biodegradable. Blends between synthetic polymers and natural and biodegradable polymers can be good candidates of such novel materials because they can combine processability with biodegradation and the use of renewable raw materials. However, traditional polymers usually present high levels of recyclability and use the well-established recycling infrastructure that can eventually be affected by the introduction of systems containing natural polymers. Thus, this work aims to evaluate the effect of reprocessing (simulated here by multiple extrusions) on the structure and properties of a low density polyethylene/thermoplastic starch (LDPE/TPS) blend compared to LDPE. The results indicated that multiple extrusion steps led to a reduction in the average size of the starch-rich phases of LDPE/TPS blends and minor changes in the mechanical and rheological properties of the materials. Such results suggest that the LDPE/TPS blend presents similar reprocessability to the LDPE for the experimental conditions used. Copyright © 2015 Elsevier Ltd. All rights reserved.

Adhesion, Growth, and Maturation of Vascular Smooth Muscle Cells on Low-Density Polyethylene Grafted with Bioactive Substances

PubMed Central

Parizek, Martin; Slepickova Kasalkova, Nikola; Bacakova, Lucie; Bacakova, Marketa; Lisa, Vera; Svorcik, Vaclav

2013-01-01

The attractiveness of synthetic polymers for cell colonization can be affected by physical, chemical, and biological modification of the polymer surface. In this study, low-density polyethylene (LDPE) was treated by an Ar+ plasma discharge and then grafted with biologically active substances, namely, glycine (Gly), polyethylene glycol (PEG), bovine serum albumin (BSA), colloidal carbon particles (C), or BSA+C. All modifications increased the oxygen content, the wettability, and the surface free energy of the materials compared to the pristine LDPE, but these changes were most pronounced in LDPE with Gly or PEG, where all the three values were higher than in the only plasma-treated samples. When seeded with vascular smooth muscle cells (VSMCs), the Gly- or PEG-grafted samples increased mainly the spreading and concentration of focal adhesion proteins talin and vinculin in these cells. LDPE grafted with BSA or BSA+C showed a similar oxygen content and similar wettability, as the samples only treated with plasma, but the nano- and submicron-scale irregularities on their surface were more pronounced and of a different shape. These samples promoted predominantly the growth, the formation of a confluent layer, and phenotypic maturation of VSMC, demonstrated by higher concentrations of contractile proteins alpha-actin and SM1 and SM2 myosins. Thus, the behavior of VSMC on LDPE can be regulated by the type of bioactive substances that are grafted. PMID:23586032

Adhesion, growth, and maturation of vascular smooth muscle cells on low-density polyethylene grafted with bioactive substances.

PubMed

Parizek, Martin; Slepickova Kasalkova, Nikola; Bacakova, Lucie; Svindrych, Zdenek; Slepicka, Petr; Bacakova, Marketa; Lisa, Vera; Svorcik, Vaclav

2013-01-01

The attractiveness of synthetic polymers for cell colonization can be affected by physical, chemical, and biological modification of the polymer surface. In this study, low-density polyethylene (LDPE) was treated by an Ar(+) plasma discharge and then grafted with biologically active substances, namely, glycine (Gly), polyethylene glycol (PEG), bovine serum albumin (BSA), colloidal carbon particles (C), or BSA+C. All modifications increased the oxygen content, the wettability, and the surface free energy of the materials compared to the pristine LDPE, but these changes were most pronounced in LDPE with Gly or PEG, where all the three values were higher than in the only plasma-treated samples. When seeded with vascular smooth muscle cells (VSMCs), the Gly- or PEG-grafted samples increased mainly the spreading and concentration of focal adhesion proteins talin and vinculin in these cells. LDPE grafted with BSA or BSA+C showed a similar oxygen content and similar wettability, as the samples only treated with plasma, but the nano- and submicron-scale irregularities on their surface were more pronounced and of a different shape. These samples promoted predominantly the growth, the formation of a confluent layer, and phenotypic maturation of VSMC, demonstrated by higher concentrations of contractile proteins alpha-actin and SM1 and SM2 myosins. Thus, the behavior of VSMC on LDPE can be regulated by the type of bioactive substances that are grafted.

[Polyethylene disease].

PubMed

Sosna, A; Radonský, T; Pokorný, D; Veigl, D; Horák, Z; Jahoda, D

2003-01-01

The experience obtained during revision surgery and findings of polyethylene granulomas in surrounding tissues of replacement as well as marked differences in the viability of implants resulted in the study of polyethylene disease and its basic mechanisms producing the development of osteoaggressive granulomas. We investigated the morphology of particles and their number in tissues surrounding the implant. The aim of our study was to develop a method for the detection of polyethylene particles in tissues, to identify different types of wear and to assess factors that may influence the viability of joint arthroplasty in general. Every revizion of joint arthroplasty performed during the last five years was evaluated in terms of the presence of polyethylene granules and the viability state of articular polyethylene inserts. A total of 55 samples were taken from tissues around loosened endoprostheses. The location of each sample was exactly determined. A technique was developed to identify wear particles and to visualize them after all organic structures of a polyethylene granuloma were dissolved with nitrogenic acid. The viability of articular polyethylene implants showed extreme differences in relation to different periods of manufacture and probably also to different methods of sterilization. Articular inserts sterilized with formaldehyde (the method used at the beginning of arthroplasty in our country) showed the highest viability and the lowest wear. The polyethylene particles present in tissues surrounding the implant were characterized in terms of morphology and size. The comparison of literature data and our results has revealed that there are many unknown facts about the quality and structure of polyethylene. The method of sterilization also appears to play a role. Because the issue is complex, we were not able to identify all factors leading, in some cases, to an early and unexpected failure of the implant and we consider further investigation to be necessary

How Low Can You Go? Low Densities of Poly(ethylene glycol) Surfactants Attract Stealth Proteins.

PubMed

Seneca, Senne; Simon, Johanna; Weber, Claudia; Ghazaryan, Arthur; Ethirajan, Anitha; Mailaender, Volker; Morsbach, Svenja; Landfester, Katharina

2018-06-25

It is now well-established that the surface chemistry and "stealth" surface functionalities such as poly(ethylene glycol) (PEG) chains of nanocarriers play an important role to decrease unspecific protein adsorption of opsonizing proteins, to increase the enrichment of specific stealth proteins, and to prolong the circulation times of the nanocarriers. At the same time, PEG chains are used to provide colloidal stability for the nanoparticles. However, it is not clear how the chain length and density influence the unspecific and specific protein adsorption keeping at the same time the stability of the nanoparticles in a biological environment. Therefore, this study aims at characterizing the protein adsorption patterns depending on PEG chain length and density to define limits for the amount of PEG needed for a stealth effect by selective protein adsorption as well as colloidal stability during cell experiments. PEG chains are introduced using the PEGylated Lutensol AT surfactants, which allow easy modification of the nanoparticle surface. These findings indicate that a specific enrichment of stealth proteins already occurs at low PEG concentrations; for the decrease of unspecific protein adsorption and finally the colloidal stability a full surface coverage is advised. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Observation of Phase-Filling Singularities in the Optical Dielectric Function of Highly Doped n-Type Ge.

PubMed

Xu, Chi; Fernando, Nalin S; Zollner, Stefan; Kouvetakis, John; Menéndez, José

2017-06-30

Phase-filling singularities in the optical response function of highly doped (>10^{19}  cm^{-3}) germanium are theoretically predicted and experimentally confirmed using spectroscopic ellipsometry. Contrary to direct-gap semiconductors, which display the well-known Burstein-Moss phenomenology upon doping, the critical point in the joint density of electronic states associated with the partially filled conduction band in n-Ge corresponds to the so-called E_{1} and E_{1}+Δ_{1} transitions, which are two-dimensional in character. As a result of this reduced dimensionality, there is no edge shift induced by Pauli blocking. Instead, one observes the "original" critical point (shifted only by band gap renormalization) and an additional feature associated with the level occupation discontinuity at the Fermi level. The experimental observation of this feature is made possible by the recent development of low-temperature, in situ doping techniques that allow the fabrication of highly doped films with exceptionally flat doping profiles.

Near-vacuum hohlraums for driving fusion implosions with high density carbon ablatorsa)

NASA Astrophysics Data System (ADS)

Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N. B.; Mackinnon, A. J.; Ho, D. D.; Jones, O. S.; Khan, S.; Milovich, J. L.; Ross, J. S.; Amendt, P.; Casey, D.; Celliers, P. M.; Pak, A.; Peterson, J. L.; Ralph, J.; Rygg, J. R.

2015-05-01

Recent experiments at the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] have explored driving high-density carbon ablators with near-vacuum hohlraums, which use a minimal amount of helium gas fill. These hohlraums show improved efficiency relative to conventional gas-filled hohlraums in terms of minimal backscatter, minimal generation of suprathermal electrons, and increased hohlraum-capsule coupling. Given these advantages, near-vacuum hohlraums are a promising choice for pursuing high neutron yield implosions. Long pulse symmetry control, though, remains a challenge, as the hohlraum volume fills with material. Two mitigation methodologies have been explored, dynamic beam phasing and increased case-to-capsule ratio (larger hohlraum size relative to capsule). Unexpectedly, experiments have demonstrated that the inner laser beam propagation is better than predicted by nominal simulations, and an enhanced beam propagation model is required to match measured hot spot symmetry. Ongoing work is focused on developing a physical model which captures this enhanced propagation and on utilizing the enhanced propagation to drive longer laser pulses than originally predicted in order to reach alpha-heating dominated neutron yields.

In vitro osteogenic cell proliferation, mineralization, and in vivo osseointegration of injection molded high-density polyethylene-based hybrid composites in rabbit animal model.

PubMed

Tripathi, Garima; Basu, Bikramjit

2014-07-01

The present work reports the biocompatibility property of injection molded HDPE-HA-Al2O3 hybrid composites. In vitro cytocompatibility results reveal that osteogenic cell viability and bone mineralization are favorably supported in a statistically significant manner on HDPE-20% HA-20% Al2O3 composite, in comparison to HDPE-40 wt.% HA or HDPE-40 wt.% Al2O3 The difference in cytocompatibility property is explained in terms of difference in substrate wettability/surface energy and importantly, both the cell proliferation at 7 days or bone mineralization at 21 days on HDPE-20% HA-20% Al2O3 composite are either comparable or better than sintered HA. The progressive healing of cylindrical femoral bone defects in rabbit animal model was assessed by implantation experiments over 1, 4 and 12 weeks. Based on the histological analysis as well as histomorphometrical evaluation, a better efficacy of HDPE-20% HA-20% Al2O3 over high-density polyethylene (HDPE) for bone regeneration and neobone formation at host bone-implant interface was established. Taken together, the present study unequivocally establishes that despite the presence of 20% Al2O3, HDPE-based hybrid composites are as biocompatible as HA in vitro or better than HDPE in vivo. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

A Highly Flexible Supercapacitor Based on MnO2/RGO Nanosheets and Bacterial Cellulose-Filled Gel Electrolyte

PubMed Central

Fei, Haojie; Saha, Nabanita; Kazantseva, Natalia; Moucka, Robert; Cheng, Qilin; Saha, Petr

2017-01-01

The flexible supercapacitors (SCs) of the conventional sandwich-type structure have poor flexibility due to the large thickness of the final entire device. Herein, we have fabricated a highly flexible asymmetric SC using manganese dioxide (MnO2) and reduced graphene oxide (RGO) nanosheet-piled hydrogel films and a novel bacterial cellulose (BC)-filled polyacrylic acid sodium salt-Na2SO4 (BC/PAAS-Na2SO4) neutral gel electrolyte. Apart from being environmentally friendly, this BC/PAAS-Na2SO4 gel electrolyte has high viscosity and a sticky property, which enables it to combine two electrodes together. Meanwhile, the intertangling of the filled BC in the gel electrolyte hinders the decrease of the viscosity with temperature, and forms a separator to prevent the two electrodes from short-circuiting. Using these materials, the total thickness of the fabricated device does not exceed 120 μm. This SC device demonstrates high flexibility, where bending and even rolling have no obvious effect on the electrochemical performance. In addition, owing to the asymmetric configuration, the cell voltage of this flexible SC has been extended to 1.8 V, and the energy density can reach up to 11.7 Wh kg−1 at the power density of 441 W kg−1. This SC also exhibits a good cycling stability, with a capacitance retention of 85.5% over 5000 cycles. PMID:29084177

Yip - Development and Application of a High-Speed Three-Dimensional Density Measurement Technique for Aero-Optic Applications

DTIC Science & Technology

2011-03-25

mixing between two streams of different temperature/density. In addition, there are also regions of high density and high pressure in the braid region...acetone seeding in this work was as follows. A small pressure vessel was filled with liquid acetone and pressurized using a nitrogen tank. An EPDM hose ...through the EPDM hose , out of the pressure vessel, and ultimately through a wall fitting. This wall fitting was connected through the wall of the

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...

Thermally stimulated depolarization currents and dielectric properties of Mg0.95Ca0.05TiO3 filled HDPE composites

NASA Astrophysics Data System (ADS)

Shi, Yunzhou; Zhang, Li; Zhang, Jie; Yue, Zhenxing

2017-12-01

Mg0.95Ca0.05TiO3 (MCT) filled high density polyethylene (HDPE) composites were prepared by twin-screw extrusion followed by hot pressing technique. The thermally stimulated depolarization current (TSDC) measurement was performed to analyze the contribution of charge distribution and interfacial characteristics to the dielectric loss. TSDC spectra under different polarization conditions show that the introduction of ceramic fillers engenders shallow traps in the vicinity of ceramic-polymer interface, which hinders the injection of space charge from the electrode into the polymer matrix. In the composite materials applied to an external field, charges tend to be captured by these traps. The temperature dependence of relative permittivity and dielectric loss of the composites was measured, and a strong reliance of dielectric loss on temperature was observed. In the heating process, the release of charges accumulating at interfacial region is considered to contribute to the rise in dielectric loss with the increase of temperature.

Selective laser sintering of ultra high molecular weight polyethylene for clinical applications.

PubMed

Rimell, J T; Marquis, P M

2000-01-01

Rapid prototyping is a relatively new technology, which although prominent in the engineering industry is only just starting to make an impact in the medical field. Its current medical uses are mainly confined to surgical planning and teaching, but the technology also has the potential to allow for patient-tailored prostheses. The work reported here describes the application of a simplified selective laser sintering apparatus with ultra high molecular weight polyethylene (UHMWPE). The morphology and chemistry of the starting powders and lased material have been characterized using Fourier Transform Infra Red spectroscopy and a combination of light and scanning electron microscopy. It was found that solid linear continuous bodies could be formed, but material shrinkage caused problems when trying to form sheet-like structures. The porosity of the formed material was also a concern. The material exposed to the laser beam was shown to have undergone degradation in terms of chain scission, cross-linking, and oxidation. It has been concluded that to apply this technology to the fabrication of UHMWPE devices requires the development of improved starting powders, in particular with increased density. Copyright 2000 John Wiley & Sons, Inc.

Chemorheology of highly filled thermosets: Effects of fillers

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

Halley, P.J.

1996-12-31

Highly filled thermosets are utilised in the manufacture of many high value added products in the aerospace, communication, computer and automobile industries. A fundamental understanding of the processing of these materials has, however, been hindered by the inherent complexities of the flow and cure properties of these composite thermoset materials. A chemorheological (gel point and chemoviscosity) testing procedure is described here that uses dynamic multiwave tests on a modified Rheometrics RDSII system, using a filled epoxy moulding compound (EMC). Data from this testing procedure has been combined with physical property and kinetic data to produce realistic simulation results using flowmore » simulation software (TSET; MOLDFLOW Pty Ltd). This chemorheological testing procedure has now been successfully implemented commercially by MOLDFLOW Pty Ltd.« less

Polyethylene glycol grafted polyethylene: a versatile platform for nonmigratory active packaging applications.

PubMed

Barish, Jeffrey A; Goddard, Julie M

2011-01-01

Nonmigratory active packaging, in which bioactive components are tethered to the package, offers the potential to reduce the need for additives in food products while maintaining safety and quality. A challenge in developing nonmigratory active packaging materials is the loss of biomolecular activity that can occur when biomolecules are immobilized. In this work, we describe a method in which a biocompatible polymer (polyethylene glycol, PEG) is grafted from the surface of ozone-treated low-density polyethylene (LDPE) resulting in a surface functionalized polyethylene to which a range of amine-terminated bioactive molecules can be immobilized. Free radical graft polymerization is used to graft PEG onto the LDPE surface, followed by immobilization of ethylenediamine onto the PEG tether. Ethylenediamine was used to demonstrate that amine-terminated molecules could be covalently attached to the PEG-grafted film. Changes in surface chemistry and topography were measured by attenuated total reflectance Fourier transform infrared spectroscopy, contact angle, atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. We demonstrate the ability to graft PEG onto the surface of polymer packaging films by free radical graft polymerization, and to covalently link an amine-terminated molecule to the PEG tether, demonstrating that amine-terminated bioactive compounds (such as peptides, enzymes, and some antimicrobials) can be immobilized onto PEG-grafted LDPE in the development of nonmigratory active packaging.   Nonmigratory active packaging offers the potential for improving food safety and quality while minimizing the migration of the active agent into food. In this paper, we describe a technique to modify polyethylene packaging films such that active agents can be covalently immobilized by a biocompatible tether. Such a technique can be adapted to a number of applications such as antimicrobial, antioxidant, or immobilized enzyme active

Highly Crosslinked-remelted versus Less-crosslinked Polyethylene in Posterior Cruciate-retaining TKAs in the Same Patients.

PubMed

Kim, Young-Hoo; Park, Jang-Won; Kim, Jun-Shik; Lee, June-Hyung

2015-11-01

Concern regarding osteolysis attributable to polyethylene wear after TKA, particularly in younger patients, has prompted the introduction of highly crosslinked-remelted polyethylene (HXLPE) for TKAs. However, few in vivo comparative results of TKAs using HXLPE and less-crosslinked polyethylene inserts in the same patients are available, regarding fracture or failure of the locking mechanism of tibial polyethylene inserts or of osteolysis in patients younger than 60 years. We wanted to determine whether (1) survivorship free from aseptic loosening in knees with HXLPE inserts was different from survivorship in knees with less-crosslinked polyethylene inserts, (2) the prevalence of fracture or failure of the locking mechanism of the tibial polyethylene insert was greater in knees with HXLPE than in those with less-crosslinked polyethylene, and (3) the proportion of patients who had osteolysis develop was greater with HXLPE than with less-crosslinked polyethylene inserts. One hundred seventy-one patients with a mean age of 58 ± 8 years (range, 35-59 years) received posterior cruciate-retaining prostheses with a less-crosslinked polyethylene tibial insert in one knee and a HXLPE tibial insert in the contralateral knee. From January 2007 to January 2010, we performed 366 same-day bilateral simultaneous sequential posterior cruciate-retaining TKAs in 183 patients, of whom 171 (93%) participated in this study. All patients during this study period underwent posterior cruciate-retaining TKAs regardless of deformity of the knees and we did not perform posterior-stabilized TKAs during the same period. Patients who had bilateral end-stage osteoarthritis and were younger than 60 years were selected for inclusion. Six patients (4%) were lost to followup before 5 years. Twenty-six patients were males and 145 were females. The mean duration of followup was 6 years (range, 5-8 years). At each followup, patients were assessed for loosening of the components, fracture or failure of

The characterization of high-density polyethylene/organoclay nanocomposites

NASA Astrophysics Data System (ADS)

Rodrigues, Tathiane Cordeiro; Tavares, Maria Inês Bruno; Soares, Igor Lopes; Moreira, Ana M.

2009-01-01

Polymeric nanocomposites, which are hybrids of polymers and modified inorganic clay with organic surfactants, are extremely attractive in both science and industry. These materials present improvements in such polymer properties as modulus, heat capacity, thermal stability, flame resistance, and so on. Research has been conducted in recent decades to obtain high-quality materials that can be used in applications like food packing, car components, and combustible cells. Polymeric nanocomposites present many advantages in relation to composites due to the quantity of filler added to the polymer and also to the improved properties. In a composite, the quantity of filler must be as high as possible (i.e., over 30%). In the polymeric nanocomposite the quantity of filler varies from 1% to 5% because of the nanosize of the particles. These nanoparticles often have a large surface area that results in improved polymer-matrix properties.

Potential of bacteria isolated from landfill soil in degrading low density polyethylene plastic

NASA Astrophysics Data System (ADS)

Munir, E.; Sipayung, F. C.; Priyani, N.; Suryanto, D.

2018-03-01

Plastic is an important material and used for many purposes. It is returned to the environment as a waste which is recently considered as the second largest solid waste. The persistency of plastic in the environment has been attracted researchers from a different point of view. The study of the degradation of plastic using bacteria isolated from local landfill soil was conducted. Low density polyethylene (LDPE) plastic was used as tested material. Potential isolates were obtained by culturing the candidates in mineral salt medium broth containing LDPE powder. Two of ten exhibited better growth response in the selection media and were used in degradation study. Results showed that isolate SP2 and SP4 reduced the weight of LDPE film significantly to a weight loss of 10.16% and 12.06%, respectively after four weeks of incubation. Scanning electron micrograph analyses showed the surface of LDPE changed compared to the untreated film. It looked rough and cracked, and bacteria cells attached to the surface was also noticed. Fourier transform infrared spectroscopy analyses confirmed the degradation of LDPE film. These results indicated that bacteria isolated from landfill might play an important role in degrading plastic material in the landfill.

Thermal, creep-recovery and viscoelastic behavior of high density polyethylene/hydroxyapatite nano particles for bone substitutes: effects of gamma radiation.

PubMed

Alothman, Othman Y; Fouad, H; Al-Zahrani, S M; Eshra, Ayman; Al Rez, Mohammed Fayez; Ansari, S G

2014-08-28

High Density Polyethylene (HDPE) is one of the most often used polymers in biomedical applications. The limitations of HDPE are its visco-elastic behavior, low modulus and poor bioactivity. To improve HDPE properties, HA nanoparticles can be added to form polymer composite that can be used as alternatives to metals for bone substitutes and orthopaedic implant applications. In our previous work (BioMedical Engineering OnLine 2013), different ratios of HDPE/HA nanocomposites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. The accelerated aging effects on the tensile properties and torsional viscoelastic behavior (storage modulus (G') and Loss modulus (G")) at 80°C of irradiated and non-irradiated HDPE/HA was investigated. Also the thermal behavior of HDPE/HA were studied. In this study, the effects of gamma irradiation on the tensile viscoelastic behavior (storage modulus (E') and Loss modulus (E")) at 25°C examined for HDPE/HA nanocomposites at different frequencies using Dynamic Mechanical Analysis (DMA). The DMA was also used to analyze creep-recovery and relaxation properties of the nanocomposites. To analyze the thermal behavior of the HDPE/HA nanocomposite, Differential Scanning Calorimetry (DSC) was used. The microscopic examination of the cryogenically fractured surface revealed a reasonable distribution of HA nanoparticles in the HDPE matrix. The DMA showed that the tensile storage and loss modulus increases with increasing the HA nanoparticles ratio and the test frequency. The creep-recovery behavior improves with increasing the HA nanoparticle content. Finally, the results indicated that the crystallinity, viscoelastic, creep recovery and relaxation behavior of HDPE nanocomposite improved due to gamma irradiation. Based on the experimental results, it is found that prepared HDPE nanocomposite properties improved due to the addition of HA nanoparticles and irradiation. So, the prepared HDPE/HA nanocomposite appears to

21 CFR 172.260 - Oxidized polyethylene.

Code of Federal Regulations, 2013 CFR

2013-04-01

... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.260 Oxidized polyethylene. Oxidized polyethylene may... by high temperature vapor pressure osmometry; contains a maximum of 5 percent by weight of total...

21 CFR 172.260 - Oxidized polyethylene.

Code of Federal Regulations, 2011 CFR

2011-04-01

... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.260 Oxidized polyethylene. Oxidized polyethylene may... by high temperature vapor pressure osmometry; contains a maximum of 5 percent by weight of total...

21 CFR 172.260 - Oxidized polyethylene.

Code of Federal Regulations, 2012 CFR

2012-04-01

... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.260 Oxidized polyethylene. Oxidized polyethylene may... by high temperature vapor pressure osmometry; contains a maximum of 5 percent by weight of total...

Distinctive electrical properties in sandwich-structured Al2O3/low density polyethylene nanocomposites

NASA Astrophysics Data System (ADS)

Wang, Si-Jiao; Zha, Jun-Wei; Li, Wei-Kang; Dang, Zhi-Min

2016-02-01

The sandwich-structured Al2O3/low density polyethylene (Al2O3/LDPE) nanocomposite dielectrics consisting of layer-by-layer with different concentration Al2O3 loading were prepared by melt-blending and following hot pressing method. The space charge distribution from pulsed electro-acoustic method and breakdown strength of the nanocomposites were investigated. Compared with the single-layer Al2O3/LDPE nanocomposites, the sandwich-structured nanocomposites remarkably suppressed the space charge accumulation and presented higher breakdown strength. The charges in the sandwich-structured nanocomposites decayed much faster than that in the single-layer nanocomposites, which was attributed to an effective electric field caused by the formation of the interfacial space charges. The energy depth of shallow and deep traps was estimated as 0.73 eV and 1.17 eV in the sandwich-structured nanocomposites, respectively, according to the thermal excitation theoretical model we proposed. This work provides an attractive strategy of design and fabrication of polymer nanocomposites with excellent space charge suppression.

Pyrolysis of low density polyethylene waste in subcritical water optimized by response surface methodology.

PubMed

Wong, S L; Ngadi, N; Amin, N A S; Abdullah, T A T; Inuwa, I M

2016-01-01

Pyrolysis of low density polyethylene (LDPE) waste from local waste separation company in subcritical water was conducted to investigate the effect of reaction time, temperature, as well as the mass ratio of water to polymer on the liquid yield. The data obtained from the study were used to optimize the liquid yield using response surface methodology. The range of reaction temperature used was 162-338°C, while the reaction time ranged from 37 min to 143 min, and the ratio of water to polymer ranged from 1.9 to 7.1. It was found that pyrolysis of LDPE waste in subcritical water produced hydrogen, methane, carbon monoxide and carbon dioxide, while the liquid product contained alkanes and alkenes with 10-50 carbons atoms, as well as heptadecanone, dichloroacetic acid and heptadecyl ester. The optimized conditions were 152.3°C, reaction time of 1.2 min and ratio of water solution to polymer of 32.7, with the optimum liquid yield of 13.6 wt% and gases yield of 2.6 wt%.

Biomarker responses in zebrafish (Danio rerio) larvae exposed to pristine low-density polyethylene fragments.

PubMed

Karami, Ali; Groman, David B; Wilson, Scott P; Ismail, Patimah; Neela, Vasantha K

2017-04-01

There are serious concerns over the adverse impacts of microplastics (MPs) on living organisms. The main objective of this study was to test the effects of MPs on the total length, weight, condition factor (CF), transcriptional level of antioxidant, anti and pro-apoptotic, and neurotransmitter genes, and the histopathology of the gill, liver, brain, kidney, and intestine in the larvae of zebrafish (Danio rerio). Fish were exposed to one of three levels of pristine low-density polyethylene (LDPE) fragments (5, 50, or 500 μg/L) for 10 or 20 days. No significant changes were observed in any of the selected biomarkers across MP concentrations at days 10 or 20. The expression of casp9 (caspase 9, apoptosis-related cysteine protease), casp3a (caspase 3, apoptosis-related cysteine protease a) and cat (catalase), however, were significantly lower in the larvae sampled at day 20 than day 10. We provide evidence that virgin short-term exposure to LDPE fragments has minimal impact on biomarker responses in D. rerio larvae. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of high energy electron beam (10MeV) on specific heat capacity of low-density polyethylene/hydroxyapatite nano-composite.

PubMed

Soltani, Z; Ziaie, F; Ghaffari, M; Beigzadeh, A M

2017-02-01

In the present work, thermal properties of low density polyethylene (LDPE) and its nano composites are investigated. For this purpose LDPE reinforced with different weight percents of hydroxyapatite (HAP) powder which was synthesized via hydrolysis method are produced. The samples were irradiated with 10MeV electron beam at doses of 75 to 250kGy. Specific heat capacity measurement have been carried out at different temperatures, i.e. 25, 50, 75 and 100°C using modulated temperature differential scanning calorimetry (MTDSC) apparatus and the effect of three parameters include of temperature, irradiation dose and the amount of HAP nano particles as additives on the specific heat capacity of PE/HAP have been investigated precisely. The MTDSC results indicate that the specific heat capacity have decreased by addition of nano sized HAP as reinforcement for LDPE. On the other hand, the effect of radiation dose is reduction in the specific heat capacity in all materials including LDPE and its nano composites. The HAP nano particles along with cross-link junctions due to radiation restrain the movement of the polymer chains in the vicinity of each particle and improve the immobility of polymer chains and consequently lead to reduction in specific heat capacity. Also, the obtained results confirm that the radiation effect on the specific heat capacity is more efficient than the reinforcing effect of nano-sized hydroxyapatite. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluating Performance and Stability of Polyethylene Terephthalate (PET) and Cellulose Polymer as Soilless Mix Components

USDA-ARS?s Scientific Manuscript database

In the U.S., concerns over the long-term sustainability of peat, perlite, and other media components have led to searches for alternative materials. FiberFill, a synthetic fiber made of recyclable polyethylene terephthalate, and Tencel, a cellulose fiber, are new materials with potential as substra...

Tissue response to intraperitoneal implants of polyethylene oxide-modified polyethylene terephthalate.

PubMed

Desai, N P; Hubbell, J A

1992-01-01

Polyethylene terephthalate films surface modified with polyethylene oxide of mol wt 18,500 g/mol (18.5 k) by a previously described technique, were implanted in the peritoneal cavity of mice, along with their respective untreated controls, for periods of 1-28 d. The implants were retrieved and examined for tissue reactivity and cellular adherence. The control polyethylene terephthalate surfaces showed an initial inflammatory reaction followed by an extensive fibrotic response with a mean thickness of 60 microns at 28 d. By contrast, polyethylene oxide-modified polyethylene terephthalate showed only a mild inflammatory response and no fibrotic encapsulation throughout the implantation period: at 28 d a cellular monolayer was observed. Apparently either the polyethylene oxide-modified surface was stimulating less inflammation, which was in turn stimulating less fibroblastic overgrowth, or the cellular adhesion to the polyethylene oxide-modified surface was too weak to support cellular multilayers.

Formation and decomposition of CO2-filled ice.

PubMed

Massani, B; Mitterdorfer, C; Loerting, T

2017-10-07

Recently it was shown that CO 2 -filled ice is formed upon compression of CO 2 -clathrate hydrate. Here we show two alternative routes of its formation, namely, by decompression of CO 2 /ice VI mixtures at 250 K and by isobaric heating of CO 2 /high-density amorphous ice mixtures at 0.5-1.0 GPa above 200 K. Furthermore, we show that filled ice may either transform into the clathrate at an elevated pressure or decompose to "empty" hexagonal ice at ambient pressure and low temperature. This complements the literature studies in which decomposition to ice VI was favoured at high pressures and low temperatures.

Formation and decomposition of CO2-filled ice

NASA Astrophysics Data System (ADS)

Massani, B.; Mitterdorfer, C.; Loerting, T.

2017-10-01

Recently it was shown that CO2-filled ice is formed upon compression of CO2-clathrate hydrate. Here we show two alternative routes of its formation, namely, by decompression of CO2/ice VI mixtures at 250 K and by isobaric heating of CO2/high-density amorphous ice mixtures at 0.5-1.0 GPa above 200 K. Furthermore, we show that filled ice may either transform into the clathrate at an elevated pressure or decompose to "empty" hexagonal ice at ambient pressure and low temperature. This complements the literature studies in which decomposition to ice VI was favoured at high pressures and low temperatures.

Five-year performance monitoring of a high-density polyethylene (HDPE) cover system at a reclaimed mine waste rock pile in the Sydney Coalfield (Nova Scotia, Canada).

PubMed

Power, Christopher; Ramasamy, Murugan; MacAskill, Devin; Shea, Joseph; MacPhee, Joseph; Mayich, David; Baechler, Fred; Mkandawire, Martin

2017-12-01

Cover systems are commonly placed over waste rock piles (WRPs) to limit atmospheric water and oxygen ingress and control the generation and release of acid mine drainage (AMD) to the receiving environment. Although covers containing geomembranes such as high-density polyethylene (HDPE) exhibit the attributes to be highly effective, there are few, if any, published studies monitoring their performance at full-scale WRPs. In 2011, a HDPE cover was installed over the Scotchtown Summit WRP in Nova Scotia, Canada, and extensive field performance monitoring was conducted over the next five years. A range of parameters within the atmosphere, cover, waste rock, groundwater and surface water, were monitored and integrated into a comprehensive hydrogeochemical conceptual model to assess (i) atmospheric ingress to the waste rock, (ii) waste rock acidity and depletion and (iii) evolution of groundwater and surface water quality. Results demonstrate that the cover is effective and meeting site closure objectives. Depletion in oxygen influx resulted in slower sulphide oxidation and AMD generation, while a significant reduction in water influx (i.e. 512 to 50 mm/year) resulted in diminished AMD release. Consistent improvements in groundwater quality (decrease in sulphate and metals; increase in pH) beneath and downgradient of the WRP were observed. Protection and/or significant improvement in surface water quality was evident in all surrounding watercourses due to the improved groundwater plume and elimination of contaminated runoff over previously exposed waste rock. A variably saturated flow and contaminant transport model is currently being developed to predict long-term cover system performance.

Reflective Polyethylene Mulch Reduces Mexican Bean Beetle (Coleoptera: Coccinellidae) Densities and Damage in Snap Beans.

PubMed

Nottingham, L B; Kuhar, T P

2016-08-01

Mexican bean beetle, Epilachna varivestis Mulsant, is a serious pest of snap beans, Phaseolus vulgaris L., in the eastern United States. These beetles are intolerant to direct sunlight, explaining why individuals are typically found on the undersides of leaves and in the lower portion of the plant canopy. We hypothesized that snap beans grown on reflective, agricultural polyethylene (plastic mulch) would have fewer Mexican bean beetles and less injury than those grown on black plastic or bare soil. In 2014 and 2015, beans were seeded into beds of metallized, white, and black plastic, and bare soil, in field plots near Blacksburg, VA. Mexican bean beetle density, feeding injury, predatory arthropods, and snap bean yield were sampled. Reflected light intensity, temperature, and humidity were monitored using data loggers. Pyranometer readings showed that reflected light intensity was highest over metallized plastic and second highest over white plastic; black plastic and bare soil were similarly low. Temperature and humidity were unaffected by treatments. Significant reductions in Mexican bean beetle densities and feeding injury were observed in both metallized and white plastic plots compared to black plastic and bare soil, with metallized plastic having the fewest Mexican bean beetle life stages and injury. Predatory arthropod densities were not reduced by reflective plastic. Metallized plots produced the highest yields, followed by white. The results of this study suggest that growing snap beans on reflective plastic mulch can suppress the incidence and damage of Mexican bean beetle, and increase yield in snap beans. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Radiation cross-linking in ultra-high molecular weight polyethylene for orthopaedic applications

NASA Astrophysics Data System (ADS)

Oral, Ebru; Muratoglu, Orhun K.

2007-12-01

The motivation for radiation cross-linking of ultra-high molecular weight polyethylene (UHMWPE) is to increase its wear resistance to be used as bearing surfaces for total joint arthroplasty. However, radiation also leaves behind long-lived residual free radicals in this polymer, the reactions of which can detrimentally affect mechanical properties. In this review, we focus on the radiation cross-linking and oxidative stability of first and second generation highly cross-linked UHMWPEs developed in our laboratory.

Study of the Auger line shape of polyethylene and diamond

NASA Technical Reports Server (NTRS)

Dayan, M.; Pepper, S. V.

1984-01-01

The KVV Auger electron line shapes of carbon in polyethylene and diamond have been studied. The spectra were obtained in derivative form by electron beam excitation. They were treated by background subtraction, integration and deconvolution to produce the intrinsic Auger line shape. Electron energy loss spectra provided the response function in the deconvolution procedure. The line shape from polyethylene is compared with spectra from linear alkanes and with a previous spectrum of Kelber et al. Both spectra are compared with the self-convolution of their full valence band densities of states and of their p-projected densities. The experimental spectra could not be understood in terms of existing theories. This is so even when correlation effects are qualitatively taken into account account to the theories of Cini and Sawatzky and Lenselink.

Facile Fabrication of Electrically Conductive Low-Density Polyethylene/Carbon Fiber Tubes for Novel Smart Materials via Multiaxial Orientation.

PubMed

Li, Yijun; Nie, Min; Wang, Qi

2018-01-10

Electromechanical sensors are indispensable components in functional devices and robotics application. However, the fabrication of the sensors still maintains a challenging issue that high percolation threshold and easy failure of conductive network are derived from uniaxial orientation of conductive fillers in practical melt processing. Herein, we reported a facile fabrication method to prepare a multiaxial low-density polyethylene (LDPE)/carbon fibers (CFs) tube with bidirectional controllable electrical conductivity and sensitive strain-responsive performance via rotation extrusion technology. The multidimensional helical flow is confirmed in the reverse rotation extrusion, and the CFs readily respond to the flow field leading to a multiaxial orientation in the LDPE matrix. In contrast to uniaxial LDPE/CF composites, which perform a "head to head" conjunction, multiaxial-orientated CF networks exhibit a unique multilayer structure in which the CFs with distinct orientation direction intersect in the interface, endowing the LDPE/CF composites with a low percolation threshold (15 wt %) to those of the uniaxial ones (∼35 wt %). The angles between two axes play a vital role in determining the density of the conductive networks in the interface, which is predominant in tuning the bending-responsive behaviors with a gauge factor range from 12.5 to 56.3 and the corresponding linear respond region from ∼15 to ∼1%. Such a superior performance of conductive LDPE/CF tube confirms that the design of multiaxial orientation paves a novel way to facile fabrication of advanced cost-effective CF-based smart materials, shedding light on promising applications such as smart materials and intelligent engineering monitoring.

Changes in wood flour/HDPE composites after accelerated weathering with and without water spray

Treesearch

Nicole M. Stark

2005-01-01

Wood-plastic lumber is promoted as a low-maintenance high-durability product. After weathering, however, wood-plasticcomposites (WPCs) often fide and lose mechanical properties. In the first part ofthis study, 50%wood-flour-filled high-density polyethylene (HDPE) composite samples were injection molded or extruded. Composites were exposed to two accelerated weathering...

Study of mechanical and morphological properties of bio-based polyethylene (HDPE) and sponge-gourds (Luffa-cylindrica) agroresidue composites

NASA Astrophysics Data System (ADS)

Escocio, Viviane A.; Visconte, Leila L. Y.; Cavalcante, Andre de P.; Furtado, Ana Maria S.; Pacheco, Elen B. A. V.

2015-05-01

Brazil has a remarkable position in the use of renewable energy. The potential of natural resources in Brazil has motivated the use of these renewable resources to make technologies more sustainable. From the large variety of commercially available High Density Polyethylene (HDPE) from different sources, two were chosen for investigation: one produced from sugarcane ethanol, and the other one, a conventional polyethylene, produced from fossil resources. In the preparation of the composites, sponge-gourds also called Luffa cylindrica were selectec. The main application of this product is as bath sponge, whose production generates scraps that are generally burnt. In this work, the composites were prepared by blending the sponge scrap at different proportions (10, 20, 30 and 40% wt/wt) with high density polyethylene (HDPE) from renewable source by extrusion. The melt flow index analysis of the composites was determined and specimens were obtained by injection molding for the assessment of mechanical properties such as tensile (elasticity modulus), flexural and Izod impact strengths. The microstructure of the impact fractured surface of the specimen also was determined. The results showed that the addition of sponge scrap affects positively all the properties studied as compared to HDPE. The results of tensile strength, elasticity modulus and flexural strength were similar to those observed in the literature for composites of HDPE from fossil source. The microstructure corroborates the results of mechanical properties. It was shown that the sponge scrap has potential to be applied as cellulosic filler for renewable polyethylene, providing a totally renewable material with good mechanical properties.

Physiological and behavioral responses of poultry exposed to gas-filled high expansion foam.

PubMed

McKeegan, D E F; Reimert, H G M; Hindle, V A; Boulcott, P; Sparrey, J M; Wathes, C M; Demmers, T G M; Gerritzen, M A

2013-05-01

Disease control measures require poultry to be killed on farms to minimize the risk of disease being transmitted to other poultry and, in some cases, to protect public health. We assessed the welfare implications for poultry of the use of high-expansion gas-filled foam as a potentially humane, emergency killing method. In laboratory trials, broiler chickens, adult laying hens, ducks, and turkeys were exposed to air-, N2-, or CO2-filled high expansion foam (expansion ratio 300:1) under standardized conditions. Birds were equipped with sensors to measure cardiac and brain activity, and measurements of oxygen concentration in the foam were carried out. Initial behavioral responses to foam were not pronounced but included headshakes and brief bouts of wing flapping. Both N2- and CO2-filled foam rapidly induced ataxia/loss of posture and vigorous wing flapping in all species, characteristic of anoxic death. Immersion in air-filled, high expansion foam had little effect on physiology or behavior. Physiological responses to both N2- and CO2-filled foam were characterized by a pronounced bradyarrythymia and a series of consistent changes in the appearance of the electroencephalogram. These were used to determine an unequivocal time to loss of consciousness in relation to submersion. Mean time to loss of consciousness was 30 s in hens and 18 s in broilers exposed to N2-filled foam, and 16 s in broilers, 1 s in ducks, and 15 s in turkeys exposed to CO2-filled foam. Euthanasia achieved with anoxic foam was particularly rapid, which is explained by the very low oxygen concentrations (below 1%) inside the foam. Physiological observations and postmortem examination showed that the mode of action of high expansion, gas-filled foam is anoxia, not occlusion of the airway. These trials provide proof-of-principle that submersion in gas-filled, high expansion foam provides a rapid and highly effective method of euthanasia, which may have potential to provide humane emergency killing

Graphite/Ultra-High Modulus Polyethylene Hybrid Fiber Composites with Epoxy and Polyethylene Matrices for Cosmic Radiation Shielding

NASA Technical Reports Server (NTRS)

2003-01-01

One of the most significant technical challenges in long-duration space missions is that of protecting the crew from harmful radiation. Protection against such radiation on a manned Mars mission will be of vital importance both during transit and while on the surface of the planet. The development of multifunctional materials that serve as integral structural members of the space vehicle and provide the necessary radiation shielding for the crew would be both mission enabling and cost effective. Additionally, combining shielding and structure could reduce total vehicle mass. Hybrid laminated composite materials having both ultramodulus polyethylene (PE) and graphite fibers in epoxy and PE matrices could meet such mission requirements. PE fibers have excellent physical properties, including the highest specific strength of any known fiber. Moreover, the high hydrogen (H) content of polyethylene makes the material an excellent shielding material for cosmic radiation. When such materials are incorporated into an epoxy or PE matrix a very effective shielding material is expected. Boron (B) may be added to the matrix resin or used as a coating to further increase the shielding effectiveness due to B s ability to slow thermal neutrons. These materials may also serve as micrometeorites shields due to PE s high impact energy absorption properties. It should be noted that such materials can be fabricated by existing equipment and methods. It is the objective of this work therefore to: (a) perform preliminary analysis of the radiation transport within these materials; (b) fabricate panels for mechanical property testing before and after radiation exposure. Preliminary determination on the effectiveness of the combinations of material components on both shielding and structural efficiency will be made.

Investigation of space charge distribution of low-density polyethylene/GO-GNF (graphene oxide from graphite nanofiber) nanocomposite for HVDC application.

PubMed

Kim, Yoon Jin; Ha, Son-Tung; Lee, Gun Joo; Nam, Jin Ho; Ryu, Ik Hyun; Nam, Su Hyun; Park, Cheol Min; In, Insik; Kim, Jiwan; Han, Chul Jong

2013-05-01

This paper reported a research on space charge distribution in low-density polyethylene (LDPE) nanocomposites with different types of graphene and graphene oxide (GO) at low filler content (0.05 wt%) under high DC electric field. Effect of addition of graphene oxide or graphene, its dispersion in LDPE polymer matrix on the ability to suppress space charge generation will be investigated and compared with MgO/LDPE nanocomposite at the same filler concentration. At an applied electric field of 80 kV/mm, a positive packet-like charge was observed in both neat LDPE, MgO/LDPE, and graphene/LDPE nanocomposites, whereas only little homogenous space charge was observed in GO/LDPE nanocomposites, especially with GO synthesized from graphite nano fiber (GNF) which is only -100 nm in diameter. Our research also suggests that dispersion of graphene oxide particles on the polymer matrix plays a significant role to the performance of nanocomposites on suppressing packet-like space charge. From these results, it is expected that nano-sized GO synthesized from GNF can be a promising filler material to LDPE composite for HVDC applications.

Biological evaluation of the copper/low-density polyethylene nanocomposite intrauterine device.

PubMed

Hu, Li-Xia; He, Jing; Hou, Li; Wang, Hong; Li, Jun; Xie, Changsheng; Duan, Zhuo; Sun, Li-Kui; Wang, Xin; Zhu, Changhong

2013-01-01

Devices and materials intended for clinical applications as medical and implant devices should be evaluated to determine their biocompatibility in physiological systems. This article presents results from cytotoxicity assay of L929 mouse fibroblasts culture, tests for skin irritation, intracutaneous reactivity and sensitization, and material implantation tests for the novel copper/low-density polyethylene nanocomposite intrauterine device (nano-Cu/LDPE IUD) with potential for future clinical utilization. Cytotoxicity test in vitro was conducted to evaluate the change in morphology, growth and proliferation of cultured L929 mouse fibroblasts, which in vivo examination for skin irritation (n = 6) and intracutaneous reactivity (n = 6) were carried out to explore the irritant behavior in New Zealand White rabbits. Skin sensitization was implemented to evaluate the potential skin sensitizing in Hartley guinea pigs (n = 35). The materials were implanted into the spinal muscle of rabbits (n = 9). The cytotoxicity grade of the nano-Cu/LDPE IUD was 0-1, suggested that the composite was nontoxic or mildly cytotoxic; no irritation reaction and skin sensitization were identified in any animals of specific extracts prepared from the material under test; similarly to the control sides, the inflammatory reaction was observed in the rabbits living tissue of the implanted material in intramuscular implantation assay. They indicated that the novel composite intrauterine device presented potential for this type of application because they meet the requirements of the standard practices recommended for evaluating the biological reactivity. The nano-Cu/LDPE IUD has good biocompatibility, which is biologically safe for the clinical research as a novel contraceptive device.

Effect of γ-aminopropyltriethoxy silane (γ-APS) coupling agent on mechanical and morphological properties of high density polyethylene (HDPE)/acrylonitrile butadiene rubber (NBR)/palm pressed fibre (PPF) composites

NASA Astrophysics Data System (ADS)

Norizan, Nabila Najwa; Santiagoo, Ragunathan; Ismail, Hanafi

2017-07-01

The fabrication of High Density Polyethylene (HDPE)/ Acrylonitrile-butadiene rubber (NBR)/ Palm Pressed Fibre (PPF) composite were investigated. The effect of γ-Aminopropyltriethoxy Silane (APS) as coupling agent on the properties of HDPE/ NBR/ PPF composite were studied. The composites were melt mixed using heated two roll mill at 180°C and speed of 15rpm with six different loading (100/0/10, 80/20/10, 70/30/10, 60/40/10, 50/50/10, and 40/60/10). The effects of γ-APS silane on mechanical, and morphological properties were examined using universal tensile machine (UTM) and scanning electron microscopy (SEM), respectively. Tensile strength and Young's modulus of HDPE/ NBR/ PPF composites decrease with increasing of NBR loading, whilst increasing the elongation at break. However, treated composites have resulted 3% to 29%, and 9% to 19%, higher in tensile strength and young's modulus compared to untreated composites. This was due to the better adhesion between HDPE/ NBR matrices and PPF filler with the presence of silanol moieties. From the morphological study, the micrograph of treated composites has proved the well bonded and good attachment of PPF filler with HDPE/ NBR matrices which resulted to better tensile strength to the HDPE/ NBR/ PPF composites.

Suppression of space charge in crosslinked polyethylene filled with poly(stearyl methacrylate)-grafted SiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Ling; Khani, Mohammad M.; Krentz, Timothy M.; Huang, Yanhui; Zhou, Yuanxiang; Benicewicz, Brian C.; Nelson, J. Keith; Schadler, Linda S.

2017-03-01

Incorporating inorganic nanoparticles (NPs) into polymer matrices provides a promising solution for suppressing space charge effects that can lead to premature failure of electrical insulation used in high voltage direct current engineering. However, realizing homogeneous NP dispersion is a great challenge especially in high-molecular-weight polymers. Here, we address this issue in crosslinked polyethylene by grafting matrix-compatible polymer brushes onto spherical colloidal SiO2 NPs (10-15 nm diameter) to obtain a uniform NP dispersion, thus achieving enhanced space charge suppression, improved DC breakdown strength, and restricted internal field distortion (≤10.6%) over a wide range of external DC fields from -30 kV/mm to -100 kV/mm at room temperature. The NP dispersion state is the key to ensuring an optimized distribution of deep trapping sites. A well-dispersed system provides sufficient charge trapping sites and shows better performance compared to ones with large aggregates. This surface ligand strategy is attractive for future nano-modification of many engineering insulating polymers.

High-density plasma deposition manufacturing productivity improvement

NASA Astrophysics Data System (ADS)

Olmer, Leonard J.; Hudson, Chris P.

1999-09-01

High Density Plasma (HDP) deposition provides a means to deposit high quality dielectrics meeting submicron gap fill requirements. But, compared to traditional PECVD processing, HDP is relatively expensive due to the higher capital cost of the equipment. In order to keep processing costs low, it became necessary to maximize the wafer throughput of HDP processing without degrading the film properties. The approach taken was to optimize the post deposition microwave in-situ clean efficiency. A regression model, based on actual data, indicated that number of wafers processed before a chamber clean was the dominant factor. Furthermore, a design change in the ceramic hardware, surrounding the electrostatic chuck, provided thermal isolation resulting in an enhanced clean rate of the chamber process kit. An infra-red detector located in the chamber exhaust line provided a means to endpoint the clean and in-film particle data confirmed the infra-red results. The combination of increased chamber clean frequency, optimized clean time and improved process.

1 μm-thickness ultra-flexible and high electrode-density surface electromyogram measurement sheet with 2 V organic transistors for prosthetic hand control.

PubMed

Fuketa, Hiroshi; Yoshioka, Kazuaki; Shinozuka, Yasuhiro; Ishida, Koichi; Yokota, Tomoyuki; Matsuhisa, Naoji; Inoue, Yusuke; Sekino, Masaki; Sekitani, Tsuyoshi; Takamiya, Makoto; Someya, Takao; Sakurai, Takayasu

2014-12-01

A 64-channel surface electromyogram (EMG) measurement sheet (SEMS) with 2 V organic transistors on a 1 μm-thick ultra-flexible polyethylene naphthalate (PEN) film is developed for prosthetic hand control. The surface EMG electrodes must satisfy the following three requirements; high mechanical flexibility, high electrode density and high signal integrity. To achieve high electrode density and high signal integrity, a distributed and shared amplifier (DSA) architecture is proposed, which enables an in-situ amplification of the myoelectric signal with a fourfold increase in EMG electrode density. In addition, a post-fabrication select-and-connect (SAC) method is proposed to cope with the large mismatch of organic transistors. The proposed SAC method reduces the area and the power overhead by 96% and 98.2%, respectively, compared with the use of conventional parallel transistors to reduce the transistor mismatch by a factor of 10.

Small-Scale Production of High-Density Dry Ice: A Variant Combination of Two Classic Demonstrations

ERIC Educational Resources Information Center

Flowers, Paul A.

2009-01-01

Easily recoverable, thumb-sized pieces of high-density dry ice are conveniently produced by deposition of carbon dioxide within a test tube submerged in liquid nitrogen. A carbon dioxide-filled balloon sealed over the mouth of the test tube serves as a gas reservoir, and further permits a dramatic demonstration of both the gas-to-solid phase…

High-power-density, high-energy-density fluorinated graphene for primary lithium batteries

NASA Astrophysics Data System (ADS)

Zhong, Guiming; Chen, Huixin; Huang, Xingkang; Yue, Hongjun; Lu, Canzhong

2018-03-01

Li/CFx is one of the highest-energy-density primary batteries; however, poor rate capability hinders its practical applications in high-power devices. Here we report a preparation of fluorinated graphene (GFx) with superior performance through a direct gas fluorination. We find that the so-called “semi-ionic” C-F bond content in all C-F bonds presents a more critical impact on rate performance of the GFx in comparison with sp2 C content in the GFx, morphology, structure, and specific surface area of the materials. The rate capability remains excellent before the semi-ionic C-F bond proportion in the GFx decreases. Thus, by optimizing semi-ionic C-F content in our GFx, we obtain the optimal x of 0.8, with which the GF0.8 exhibits a very high energy density of 1073 Wh kg-1 and an excellent power density of 21460 W kg-1 at a high current density of 10 A g-1. More importantly, our approach opens a new avenue to obtain fluorinated carbon with high energy densities without compromising high power densities.

High-Energy-Density Capacitors

NASA Technical Reports Server (NTRS)

Slenes, Kirk

2003-01-01

Capacitors capable of storing energy at high densities are being developed for use in pulse-power circuits in such diverse systems as defibrillators, particle- beam accelerators, microwave sources, and weapons. Like typical previously developed energy-storage capacitors, these capacitors are made from pairs of metal/solid-dielectric laminated sheets that are wound and pressed into compact shapes to fit into cans, which are then filled with dielectric fluids. Indeed, these capacitors can be fabricated largely by conventional fabrication techniques. The main features that distinguish these capacitors from previously developed ones are improvements in (1) the selection of laminate materials, (2) the fabrication of the laminated sheets from these materials, and (3) the selection of dielectric fluids. In simplest terms, a high-performance laminated sheet of the type used in these capacitors is made by casting a dielectric polymer onto a sheet of aluminized kraft paper. The dielectric polymer is a siloxane polymer that has been modified with polar pendant groups to increase its permittivity and dielectric strength. Potentially, this polymer is capable of withstanding an energy density of 7.5 J/cm3, which is four times that of the previous state-of-the-art-capacitor dielectric film material. However, the full potential of this polymer cannot be realized at present because (1) at thicknesses needed for optimum performance (.8.0 m), the mechanical strength of a film of this polymer is insufficient for incorporation into a wound capacitor and (2) at greater thickness, the achievable energy density decreases because of a logarithmic decrease in dielectric strength with increasing thickness. The aluminized kraft paper provides the mechanical strength needed for processing of the laminate and fabrication of the capacitor, and the aluminum film serves as an electrode layer. Because part of the thickness of the dielectric is not occupied by the modified siloxane polymer, the

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.

Cross-linked compared with historical polyethylene in THA: an 8-year clinical study.

PubMed

Geerdink, Carel H; Grimm, Bernd; Vencken, Wendy; Heyligers, Ide C; Tonino, Alphons J

2009-04-01

Wear particle-induced osteolysis is a major cause of aseptic loosening in THA. Increasing wear resistance of polyethylene (PE) occurs by increasing the cross-link density and early reports document low wear rates with such implants. To confirm longer-term reductions in wear we compared cross-linked polyethylene (irradiation in nitrogen, annealing) with historical polyethylene (irradiation in air) in a prospective, randomized clinical study involving 48 patients who underwent THAs with a minimum followup of 7 years (mean, 8 years; range, 7-9 years). The insert material was the only variable. The Harris hip score, radiographic signs of osteolysis, and polyethylene wear were recorded annually. Twenty-three historical and 17 moderately cross-linked polyethylene inserts were analyzed (five patients died, three were lost to followup). At 8 years, the wear rate was lower for cross-linked polyethylene (0.088 +/- 0.03 mm/year) than for the historical polyethylene (0.142 +/- 0.07 mm/year). This reduction (38%) did not diminish with time (33% at 5 years). Acetabular cyst formation was less frequent (39% versus 12%), affected fewer DeLee and Charnley zones (17% versus 4%), and was less severe for the cross-linked polyethylene. The only revision was for an aseptically loose cup in the historical polyethylene group. Moderately cross-linked polyethylene maintained its wear advantage with time and produced less osteolysis, showing no signs of aging at mid-term followup. Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

High data density temperature measurement for quasi steady-state flows

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.; Rashidnia, Nasser; Creath, Katherine

1995-01-01

A new optical instrument, the liquid crystal point diffraction interferometer (LCPDI), is used to measure the temperature distribution across a heated chamber filled with silicone oil. Data taken using the LCPDI are compared to equivalent measurements made with a traversing thermocouple and the two data sets show excellent agreement This instrument maintains the compact, robust design of Linnik's point diffraction interferometer and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction.

High Data Density Temperature Measurement for Quasi Steady-State Flows

NASA Technical Reports Server (NTRS)

Mercer, C. R.; Rashidnia, N.; Creath, K.

1996-01-01

A new optical instrument, the liquid crystal point diffraction interferometer (LCPDI), is used to measure the temperature distribution across a heated chamber filled with silicone oil. Data taken using the LCPDI are compared to equivalent measurements made with a traversing thermo-couple and the two data sets show excellent agreement. This instrument maintains the compact, robust design of Linniks point diffraction interferometer and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wave-fronts with very high data density and with automated data reduction.

Slip and frictional heating of extruded polyethylene melts

NASA Astrophysics Data System (ADS)

Pérez-González, José; Marín-Santibáñez, Benjamín M.; Zamora-López, Héctor S.; Rodríguez-González, Francisco

2017-05-01

Extrusion of polymer melts with slip at the die generates frictional heating. The relationship between slip flow and frictional heating during the continuous extrusion of a non-slipping linear low-density (LLDPE) and a slipping high-density polyethylene (HDPE), respectively, both pure as well as blended with a fluoropolymer processing aid (PA), was investigated in this work by Rheo-particle image velocimetry and thermal imaging. Significant rises in temperature were measured under slip and no slip conditions, being these much higher than the values predicted by the adiabatic flow assumption. Clear difference was made between viscous and frictional heating before the stick-slip regime for the LLDPE, even though they could not be distinguished from one another at higher stresses. Such a difference, however, could not be made for the slipping HDPE, since overall in the presence of slip, frictional and viscous heating act synergistically to increase the melt temperature.

46 CFR 38.15-1 - Filling of tanks-TB/ALL.

Code of Federal Regulations, 2010 CFR

2010-10-01

... which tank may be loaded. V=volume of tank. d r=density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=density of cargo at the loading temperature and pressure. (b) Nonrefrigerated tanks shall be filled so that their filling densities shall not exceed the...

46 CFR 38.15-1 - Filling of tanks-TB/ALL.

Code of Federal Regulations, 2013 CFR

2013-10-01

... which tank may be loaded. V=volume of tank. d r=density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=density of cargo at the loading temperature and pressure. (b) Nonrefrigerated tanks shall be filled so that their filling densities shall not exceed the...

46 CFR 38.15-1 - Filling of tanks-TB/ALL.

Code of Federal Regulations, 2014 CFR

2014-10-01

... which tank may be loaded. V=volume of tank. d r=density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=density of cargo at the loading temperature and pressure. (b) Nonrefrigerated tanks shall be filled so that their filling densities shall not exceed the...

46 CFR 38.15-1 - Filling of tanks-TB/ALL.

Code of Federal Regulations, 2012 CFR

2012-10-01

... which tank may be loaded. V=volume of tank. d r=density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=density of cargo at the loading temperature and pressure. (b) Nonrefrigerated tanks shall be filled so that their filling densities shall not exceed the...

Properties of soil in the San Fernando hydraulic fill dams

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

Lee, K.L.

1975-08-01

Results are presented of extensive field and laboratory tests on soils from two old hydraulic fill dams that were damaged during the Feb. 9, 1971, San Fernando earthquake. The data include standard penetration, absolute and relative compaction, relative density, static strength, and cyclic triaxial test results for both the hydraulic fill silty sand and the natural silty and gravelly sand alluvium. The relative densities of the hydraulic fills ranged from about 51 to 58 percent and the relative compaction ranged from about 85 to 92 percent of Modified AASHO maximum density. The relative density of the alluvium was about 65more » to 70 percent. Other properties were consistent with previously published data from other similar soils at similar densities.« less

Pie-like electrode design for high-energy density lithium–sulfur batteries

PubMed Central

Li, Zhen; Zhang, Jin Tao; Chen, Yu Ming; Li, Ju; Lou, Xiong Wen (David)

2015-01-01

Owing to the overwhelming advantage in energy density, lithium–sulfur (Li–S) battery is a promising next-generation electrochemical energy storage system. Despite many efforts in pursuing long cycle life, relatively little emphasis has been placed on increasing the areal energy density. Herein, we have designed and developed a ‘pie' structured electrode, which provides an excellent balance between gravimetric and areal energy densities. Combining lotus root-like multichannel carbon nanofibers ‘filling' and amino-functionalized graphene ‘crust', the free-standing paper electrode (S mass loading: 3.6 mg cm−2) delivers high specific capacity of 1,314 mAh g−1 (4.7 mAh cm−2) at 0.1 C (0.6 mA cm−2) accompanied with good cycling stability. Moreover, the areal capacity can be further boosted to more than 8 mAh cm−2 by stacking three layers of paper electrodes with S mass loading of 10.8 mg cm−2. PMID:26608228

Biological Evaluation of the Copper/Low-density Polyethylene Nanocomposite Intrauterine Device

PubMed Central

Wang, Hong; Li, Jun; Xie, Changsheng; Duan, Zhuo; Sun, Li-Kui; Wang, Xin; Zhu, Changhong

2013-01-01

Devices and materials intended for clinical applications as medical and implant devices should be evaluated to determine their biocompatibility in physiological systems. This article presents results from cytotoxicity assay of L929 mouse fibroblasts culture, tests for skin irritation, intracutaneous reactivity and sensitization, and material implantation tests for the novel copper/low-density polyethylene nanocomposite intrauterine device (nano-Cu/LDPE IUD) with potential for future clinical utilization. Cytotoxicity test in vitro was conducted to evaluate the change in morphology, growth and proliferation of cultured L929 mouse fibroblasts, which in vivo examination for skin irritation (n = 6) and intracutaneous reactivity (n = 6) were carried out to explore the irritant behavior in New Zealand White rabbits. Skin sensitization was implemented to evaluate the potential skin sensitizing in Hartley guinea pigs (n = 35). The materials were implanted into the spinal muscle of rabbits (n = 9). The cytotoxicity grade of the nano-Cu/LDPE IUD was 0–1, suggested that the composite was nontoxic or mildly cytotoxic; no irritation reaction and skin sensitization were identified in any animals of specific extracts prepared from the material under test; similarly to the control sides, the inflammatory reaction was observed in the rabbits living tissue of the implanted material in intramuscular implantation assay. They indicated that the novel composite intrauterine device presented potential for this type of application because they meet the requirements of the standard practices recommended for evaluating the biological reactivity. The nano-Cu/LDPE IUD has good biocompatibility, which is biologically safe for the clinical research as a novel contraceptive device. PMID:24058521

Improvement of mechanical and thermal properties of high energy electron beam irradiated HDPE/hydroxyapatite nano-composite

NASA Astrophysics Data System (ADS)

Mohammadi, M.; Ziaie, F.; Majdabadi, A.; Akhavan, A.; Shafaei, M.

2017-01-01

In this research work, the nano-composites of high density polyethylene/hydroxyapatite samples were manufactured via two methods: In the first method, the granules of high density polyethylene and nano-structure hydroxyapatite were processed in an internal mixer to prepare the nano-composite samples with a different weight percentage of the reinforcement phase. As for the second one, high density polyethylene was prepared in nano-powder form in boiling xylene. During this procedure, the hydroxyapatite nano-powder was added with different weight percentages to the solvent to obtain the nano-composite. In both of the procedures, the used hydroxyapatite nano-powder was synthesized via hydrolysis methods. The samples were irradiated under 10 MeV electron beam in 70-200 kGy of doses. Mechanical, thermal and morphological properties of the samples were investigated and compared. The results demonstrate that the nano-composites which we have prepared using nano-polyethylene, show better mechanical and thermal properties than the composites prepared from normal polyethylene granules, due to the better dispersion of nano-particles in the polymer matrix.

Application of laboratory fungal resistance tests to solid wood and wood-plastic composite

Treesearch

Craig Merrill Clemons; Rebecca E. Ibach

2003-01-01

The fungal resistance of high density polyethylene filled with 50% wood flour was investigated using laboratory soil block tests. Modifications to standard test methods were made to increase initial moisture content, increase exposure surface area, and track moisture content, mechanical properties, and weight loss over the exposure period. Mechanical properties...

A Ballistic Material Model for Cross-Plied Unidirectional Ultra-High Molecular-Weight Polyethylene Fiber-Reinforced Armor-Grade Composites

DTIC Science & Technology

2008-01-01

strength polymeric fibers such as aramid (e.g. Kevlar ®, Twaron®, etc.) or oriented polyethy- lene fibers (e.g. Spectra®, Dyneema®, etc.) with an... phenolic -poly-vinyl-butyral resin and on 0◦/90◦ cross- plied oriented polyethylene fiber-reinforced vinyl-ester resin are widely used in hard personnel...are: (a) poly-aramids (e.g. Kevlar ®, Twaron®, Technora®); (b) highly oriented ultra-highmolecular-weight polyethylene, UHMWPE (e.g. Spectra®, Dyneema

Electrospun Polyaniline/Polyethylene Oxide Nanofiber Field Effect Transistor

NASA Technical Reports Server (NTRS)

Pinto, N. J.; Johnson, A. T.; MacDiarmid, A. G.; Mueller, C. H.; Theofylaktos, N.; Robinson, D. C.; Miranda, F. A.

2003-01-01

We report on the observation of field effect transistor (FET) behavior in electrospun camphorsulfonic acid doped polyaniline(PANi)/polyethylene oxide(PE0) nanofibers. Saturation channel currents are observed at surprisingly low source/drain voltages. The hole mobility in the depletion regime is 1.4 x 10(exp -4) sq cm/V s while the 1-D charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating 1-D polymer FET's.

Synthesis of cobalt stearate as oxidant additive for oxo-biodegradable polyethylene

NASA Astrophysics Data System (ADS)

Asriza, Ristika O.; Arcana, I. Made

2015-09-01

Cobalt stearate is an oxidant additives that can initiate a process of degradation in high density polyethylene (HDPE). To determine the effect of cobalt stearate in HDPE, oxo-biodegradable polyethylene film was given an irradiation with UV light or heating at various temperature. After given a heating, the FTIR spectra showed a new absorption peak at wave number 1712 cm-1 indicating the presence of carbonyl groups in polymers, whereas after irradiation with UV light is not visible the presence of this absorption peak. The increase concentration of cobalt stearate added in HDPE and the higher heating temperature, the intensity of the absorption peak of the carbonyl group increased. The increasing intensity of the carbonyl group absorption is caused the presence of damage in the film surface after heating, and this result is supported by analysis the surface properties of the film with using SEM. Biodegradation tests were performed on oxo-biodegradable polyethylene film which has been given heating or UV light with using activated sludge under optimal conditions the growth of microorganisms. After biodegradation, the maximum weight decreased by 23% in the oxo-biodegradable polyethylene film with a cobalt stearate concentration of 0.2% and after heating at a temperature of 75 °C for 10 days, and only 0.69% in the same film after irradiation UV light for 10 days. Based on the results above, cobalt stearate additive is more effective to initiate the oxidative degradation of HDPE when it is initiated by heating compared to irradiation with UV light.

Synthesis of cobalt stearate as oxidant additive for oxo-biodegradable polyethylene

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

Asriza, Ristika O.; Arcana, I Made, E-mail: arcana@chem.itb.ac.id

Cobalt stearate is an oxidant additives that can initiate a process of degradation in high density polyethylene (HDPE). To determine the effect of cobalt stearate in HDPE, oxo-biodegradable polyethylene film was given an irradiation with UV light or heating at various temperature. After given a heating, the FTIR spectra showed a new absorption peak at wave number 1712 cm{sup −1} indicating the presence of carbonyl groups in polymers, whereas after irradiation with UV light is not visible the presence of this absorption peak. The increase concentration of cobalt stearate added in HDPE and the higher heating temperature, the intensity of themore » absorption peak of the carbonyl group increased. The increasing intensity of the carbonyl group absorption is caused the presence of damage in the film surface after heating, and this result is supported by analysis the surface properties of the film with using SEM. Biodegradation tests were performed on oxo-biodegradable polyethylene film which has been given heating or UV light with using activated sludge under optimal conditions the growth of microorganisms. After biodegradation, the maximum weight decreased by 23% in the oxo-biodegradable polyethylene film with a cobalt stearate concentration of 0.2% and after heating at a temperature of 75 °C for 10 days, and only 0.69% in the same film after irradiation UV light for 10 days. Based on the results above, cobalt stearate additive is more effective to initiate the oxidative degradation of HDPE when it is initiated by heating compared to irradiation with UV light.« less

Adhesion and Growth of Vascular Smooth Muscle Cells on Nanostructured and Biofunctionalized Polyethylene

PubMed Central

Novotna, Katarina; Bacakova, Marketa; Kasalkova, Nikola Slepickova; Slepicka, Petr; Lisa, Vera; Svorcik, Vaclav; Bacakova, Lucie

2013-01-01

Cell colonization of synthetic polymers can be regulated by physical and chemical modifications of the polymer surface. High-density and low-density polyethylene (HDPE and LDPE) were therefore activated with Ar+ plasma and grafted with fibronectin (Fn) or bovine serum albumin (BSA). The water drop contact angle usually decreased on the plasma-treated samples, due to the formation of oxidized groups, and this decrease was inversely related to the plasma exposure time (50–300 s). The presence of nitrogen and sulfur on the polymer surface, revealed by X-ray photoelectron spectroscopy (XPS), and also by immunofluorescence staining, showed that Fn and BSA were bound to this surface, particularly to HDPE. Plasma modification and grafting with Fn and BSA increased the nanoscale surface roughness of the polymer. This was mainly manifested on HDPE. Plasma treatment and grafting with Fn or BSA improved the adhesion and growth of vascular smooth muscle cells in a serum-supplemented medium. The final cell population densities on day 6 after seeding were on an average higher on LDPE than on HDPE. In a serum-free medium, BSA grafted to the polymer surface hampered cell adhesion. Thus, the cell behavior on polyethylene can be modulated by its type, intensity of plasma modification, grafting with biomolecules, and composition of the culture medium. PMID:28809234

Parameter analysis on the ultrasonic TSV-filling process and electrochemical characters

NASA Astrophysics Data System (ADS)

Wang, Fuliang; Ren, Xinyu; Wang, Yan; Zeng, Peng; Zhou, Zhaohua; Xiao, Hongbin; Zhu, Wenhui

2017-10-01

As one of the key technologies in 3D packaging, through silicon via (TSV) interconnection technology has become a focus recently. In this paper, an electrodeposition method for TSV filling with the assistance of ultrasound and additives are introduced. Two important parameters i.e. current density and ultrasonic power are studied for TSV filling process and electrochemical properties. It is found that ultrasound can improve the quality of TSV-filling and change the TSV-filling mode. The experimental results also indicate that the filling rate enhances more significantly with decreasing current density under ultrasonic conditions than under silent conditions. In addition, according to the voltammetry curve, the increase of ultrasonic power can significantly increase the current density of cupric reduction, and decrease the thickness of diffusion layer. So that the reduction speed of copper ions is accelerated, resulting in a higher TSV-filling rate.

Effective use of fly ash slurry as fill material.

PubMed

Horiuchi, S; Kawaguchi, M; Yasuhara, K

2000-09-15

A lot of effort has been put into increasing coal ash utilization; however, 50% of total amount is disposed of on land and in the sea. Several attempts have been reported recently concerning slurried coal fly ash use for civil engineering materials, such as for structural fill and backfill. The authors have studied this issue for more than 15 years and reported its potential for (1) underwater fills, (2) light weight backfills, and (3) light weight structural fills, through both laboratory tests and construction works. This paper is an overview of the results obtained for slurry, focusing on the following. (1) Coal fly ash reclaimed by slurry placement shows lower compressibility, higher ground density, and higher strength than by the other methods. This higher strength increases stability against liquefaction during earthquake. (2) Higher stability of the fly ash ground formed by slurry placement is caused by higher density and its self-hardening property. (3) Stability of fly ash reclaimed ground can be increased by increasing density and also by strength enhancement by cement addition. (4) Technical data obtained through a man-made island construction project shows the advantages of fly ash slurry in terms of mechanical properties such as higher stability against sliding failure, sufficient ground strength, and also in terms of cost saving. (5) Concentration in leachates from the placed slurry is lower than the Japanese environmental law. (6) In order to enlarge the fly ash slurry application toward a lightweight fill, mixtures of air foam, cement and fly ash were examined. Test results shows sufficient durability of this material against creep failure. This material was then used as lightweight structural fill around a high-rise building, and showed sufficient quality. From the above data, it can be concluded that coal fly ash slurry can be effectively utilized in civil engineering projects.

Differences in highly cross-linked polyethylene wear between zirconia and cobalt-chromium femoral heads in Japanese patients: a prospective, randomized study.

PubMed

Kawate, Kenji; Ohmura, Tetsuji; Kawahara, Ikuo; Tamai, Katsuya; Ueha, Tomoyuki; Takemura, Kazuo

2009-12-01

The purpose of this study was to compare highly cross-linked polyethylene wear between the zirconia head and the cobalt-chromium head in Japanese patients. A prospective, randomized study was performed to evaluate the outcomes in 32 hips that had zirconia heads and in 30 hips that had cobalt-chromium heads. The mean follow-up periods of both groups were same (5 years). There were no significant differences between the zirconia head and the cobalt-chromium head in the mean polyethylene linear wear per year and the mean volumetric polyethylene wear per year in the steady phase. This study indicates that zirconia head offers no benefits over metal head in terms of wear reduction at 5 years in Japanese patients who have lightweight and thin polyethylene liners.

Effect of Nanoparticles on the Morphology, Thermal, and Electrical Properties of Low-Density Polyethylene after Thermal Aging

PubMed Central

Wang, Youyuan; Zhang, Zhanxi; Xiao, Kun

2017-01-01

This paper investigates the morphology, thermal, and electrical properties of LDPE (low-density polyethylene)-based nanocomposites after thermal aging. The FTIR (Fourier transform infrared spectroscopy) spectra results show that thermo-oxidative reactions occur in neat LDPE and LDPE/SiO2 nanocomposites when the aging time is 35 days and in LDPE/MgO nanocomposites when the aging time is 77 days. Specifically, LDPE/MgO nanocomposites delay the appearance of thermo-oxidative reactions, showing anti-thermal aging ability. Furthermore, nanocomposites present lower onset degradation temperature than neat LDPE, showing better thermal stabilization. With regard to the electrical properties, nanocomposites maintain the ability to suppress space charge accumulation after thermal aging. Additionally, in comparison with SiO2 nanocomposites and neat LDPE, the permittivity of LDPE/MgO nanocomposites changes slightly after thermal aging. It is concluded that LDPE/MgO nanocomposites have better insulation properties than neat LDPE after thermal aging, which may be caused by the interface introduced by the nanoparticles. PMID:29023428

Effect of Nanoparticles on the Morphology, Thermal, and Electrical Properties of Low-Density Polyethylene after Thermal Aging.

PubMed

Wang, Youyuan; Wang, Can; Zhang, Zhanxi; Xiao, Kun

2017-10-12

This paper investigates the morphology, thermal, and electrical properties of LDPE (low-density polyethylene)-based nanocomposites after thermal aging. The FTIR (Fourier transform infrared spectroscopy) spectra results show that thermo-oxidative reactions occur in neat LDPE and LDPE/SiO₂ nanocomposites when the aging time is 35 days and in LDPE/MgO nanocomposites when the aging time is 77 days. Specifically, LDPE/MgO nanocomposites delay the appearance of thermo-oxidative reactions, showing anti-thermal aging ability. Furthermore, nanocomposites present lower onset degradation temperature than neat LDPE, showing better thermal stabilization. With regard to the electrical properties, nanocomposites maintain the ability to suppress space charge accumulation after thermal aging. Additionally, in comparison with SiO₂ nanocomposites and neat LDPE, the permittivity of LDPE/MgO nanocomposites changes slightly after thermal aging. It is concluded that LDPE/MgO nanocomposites have better insulation properties than neat LDPE after thermal aging, which may be caused by the interface introduced by the nanoparticles.

Zosteric acid and salicylic acid bound to a low density polyethylene surface successfully control bacterial biofilm formation.

PubMed

Cattò, C; James, G; Villa, F; Villa, S; Cappitelli, F

2018-05-04

The active moieties of the anti-biofilm natural compounds zosteric (ZA) and salicylic (SA) acids have been covalently immobilized on a low density polyethylene (LDPE) surface. The grafting procedure provided new non-toxic eco-friendly materials (LDPE-CA and LDPE-SA) with anti-biofilm properties superior to the conventional biocide-based approaches and with features suitable for applications in challenging fields where the use of antimicrobial agents is limited. Microbiological investigation proved that LDPE-CA and LDPE-SA: (1) reduced Escherichia coli biofilm biomass by up to 61% with a mechanism that did not affect bacterial viability; (2) significantly affected biofilm morphology, decreasing biofilm thickness, roughness, substratum coverage, cell and matrix polysaccharide bio-volumes by >80% and increasing the surface to bio-volume ratio; (3) made the biofilm more susceptible to ampicillin and ethanol. Since no molecules were leached from the surface, they remained constantly effective and below the lethal level; therefore, the risk of inducing resistance was minimized.

Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

NASA Astrophysics Data System (ADS)

Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

2015-12-01

The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

Magnetorheological response of highly filled magnetoactive elastomers from perspective of mechanical energy density: Fractal aggregates above the nanometer scale?

PubMed

Sorokin, Vladislav V; Belyaeva, Inna A; Shamonin, Mikhail; Kramarenko, Elena Yu

2017-06-01

The dynamic shear modulus of magnetoactive elastomers containing 70 and 80 mass % of carbonyl iron microparticles is measured as a function of strain amplitude via dynamic torsion oscillations in various magnetic fields. The results are presented in terms of the mechanical energy density and considered in the framework of the conventional Kraus model. The form exponent of the Kraus model is further related to a physical model of Huber et al. [Huber et al., J. Phys.: Condens. Matter 8, 409 (1996)10.1088/0953-8984/8/29/003] that uses a realistic representation for the cluster network possessing fractal structure. Two mechanical loading regimes are identified. At small strain amplitudes the exponent β of the Kraus model changes in an externally applied magnetic field due to rearrangement of ferromagnetic-filler particles, while at large strain amplitudes, the exponent β seems to be independent of the magnetic field. The critical mechanical energy characterizing the transition between these two regimes grows with the increasing magnetic field. Similarities between agglomeration and deagglomeration of magnetic filler under simultaneously applied magnetic field and mechanical shear and the concept of jamming transition are discussed. It is proposed that the magnetic field should be considered as an additional parameter to the jamming phase diagram of rubbers filled with magnetic particles.

Dielectric behavior of AC aged polyethylene in humid environment

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

Scarpa, P.C.N.; Das-Gupta, D.K.; Bulinski, A.T.

1996-12-31

The present paper reports the results of a study of electrical aging of low density polyethylene (LDPE) aged in humid environment (0.1M NaCl) at an AC stress of 6kV/mm, 1kHz, at room temperature (RT) and at 65 C, and cross-linked polyethylene (XLPE) AC aged in humid environment (water) at an AC stress of 6kV/mm, 50Hz, at RT, for an extended period of time. For this study the dielectric spectroscopy data in the frequency range of 10{sup {minus}5}Hz to 10{sup 6}Hz and their comparative analysis, have been used to provide electrical analog models of the aging.

Analysis of a GC/MS thermal desorption system with simultaneous sniffing for determination of off-odor compounds and VOCs in fumes formed during extrusion coating of low-density polyethylene.

PubMed

Villberg, K; Veijanen, A

2001-03-01

A thermal desorption equipment introducing volatile organic compounds (VOCs) into the gas chromatographic/ mass spectrometric system (GC/MS) with simultaneous sniffing (SNIFF) is a suitable method for identifying the volatile organic off-odor compounds formed during the extrusion coating process of low-density polyethylene. Fumes emitted during the extrusion coating process of three different plastic materials were collected at two different temperatures (285 and 315 degrees C) from an outgoing pipe and near an extruder. The VOCs of fumes were analyzed by drawing a known volume of air through the adsorbent tube filled with a solid adsorbent (Tenax GR). The air samples were analyzed by using a special thermal desorption device and GC/MS determination. The simultaneous sniffing was carried out to detect off-odors and to assist in the identification of those compounds that contribute to tainting and smelling. The amounts of off-odor carbonyl compounds and the total content of the volatile organic compounds were determined. The most odorous compounds were identified as carboxylic acids while the majority of the volatile compounds were hydrocarbons. The detection and quantification of carboxylic acids were based on the characteristic ions of their mass spectra. The higher the extrusion temperature the more odors were detected. An important observation was that the total concentration of volatiles was dependent not only on the extrusion temperature but also on the plastic material.

Effect of Ar ion on the surface properties of low density polyethylene.

PubMed

Zaki, M F

2016-04-15

In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 10(15) ions/cm(2). The optical, chemical and hardness properties have been investigated using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to the formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for the pristine sample to 2.3 eV for that sample irradiated with the highest fluence of the Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing Ar ion fluences. FTIR spectra showed the formation of new bands of the bombarded polymer samples. Furthermore, polar groups were created on the surface of the irradiated samples which refer to the increase of the hydrophilic nature of the surface of the irradiated samples. The Vicker's hardness increased from 4.9 MPa for the pristine sample to 17.9 MPa for those bombarded at the highest fluence. This increase is attributed to the increase in the crosslinking and alterations of the bombarded surface into hydrogenated amorphous carbon, which improves the hardness of the irradiated samples. The bombarded LDPE surfaces may be used in special applications to the field of the micro-electronic devices and shock absorbers. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of Ar ion on the surface properties of low density polyethylene

NASA Astrophysics Data System (ADS)

Zaki, M. F.

2016-04-01

In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 1015ions/cm2. The optical, chemical and hardness properties have been investigated using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to the formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for the pristine sample to 2.3 eV for that sample irradiated with the highest fluence of the Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing Ar ion fluences. FTIR spectra showed the formation of new bands of the bombarded polymer samples. Furthermore, polar groups were created on the surface of the irradiated samples which refer to the increase of the hydrophilic nature of the surface of the irradiated samples. The Vicker's hardness increased from 4.9 MPa for the pristine sample to 17.9 MPa for those bombarded at the highest fluence. This increase is attributed to the increase in the crosslinking and alterations of the bombarded surface into hydrogenated amorphous carbon, which improves the hardness of the irradiated samples. The bombarded LDPE surfaces may be used in special applications to the field of the micro-electronic devices and shock absorbers.

Kinetic Modeling of RF Breakdown in High-Pressure Gas-filled Cavities

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

Tollestrup, A. V.; Yonehara, K.; Byrd, J. M.

2012-05-01

Recent studies have shown that high gradients can be achieved quickly in high-pressure gas-filled cavities without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this proj ect we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A series of experiments at 805 MHz using hydrogen fill pressures up to 0.01 g/cm3 of H2 have demonstrated high electric field gradientsmore » and scaling with the DC Paschen law limit, up to ~30 MV/m, depending on the choice of electrode material. For higher fi eld stresses, the breakdown characteristics deviate from the Paschen law scaling. Fully-kinetic 0D collisional particle-in-cell (PIC) simulations give breakdown characteristics in H2 and H2/SF6 mixtures in good agreement with the 805 MHz experimental resu lts below this field stress threshold. The impact of these results on gas-filled RF accelerating cavity design will be discussed.« less

The effect of EGDMA on tensile and thermal properties of irradiated low density polyethylene/sepiolite nanocomposites

NASA Astrophysics Data System (ADS)

Ghazali, Siti Nadia Aini; Mohamad, Zurina; Majid, Rohah A.; Appadu, Sivanesan

2017-07-01

This study presents the influence of ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent through electron beam crosslinking process. Therefore, the effects of EGDMA on irradiated low density polyethylene/sepiolite (LDPE/SEP) nanocomposites on the tensile and thermal properties at 4 part per hundred resin (phr) sepiolite were investigated. The LDPE/SEP nanocomposites were prepared by melt mixing using twin screw extruder at 160 ˚C with a screw speed of 50 rpm. The nanocomposites were then undergone injection moulding process followed by irradiated using 2 MeV electron beam machine at doses ranging from 0 to 200 kGy in the air at ambient temperature. It was found that the tensile strength and Young's modulus were slightly increased with the presence of co-agent. The sample containing 4 phr sepiolite at 200 kGy showed 9% increase in tensile strength when EGDMA was added. However, the result of thermogravimetry analysis (TGA) showed some reduction in thermal stability of nanocomposites on 100 kGy irradiation dose. EGDMA had reduced the optimum irradiation dose without having any adverse effect on tensile and thermal properties.

Decay of low-density polyethylene by bacteria extracted from earthworm's guts: A potential for soil restoration.

PubMed

Huerta Lwanga, Esperanza; Thapa, Binita; Yang, Xiaomei; Gertsen, Henny; Salánki, Tamás; Geissen, Violette; Garbeva, Paolina

2018-05-15

Low-density polyethylene (LDPE) is the most abundant source of microplastic pollution worldwide. A recent study found that LDPE decay was increased and the size of the plastic was decreased after passing through the gut of the earthworm Lumbricus terrestris (Oligochaeta). Here, we investigated the involvement of earthworm gut bacteria in the microplastic decay. The bacteria isolated from the earthworm's gut were Gram-positive, belonging to phylum Actinobacteria and Firmicutes. These bacteria were used in a short-term microcosm experiment performed with gamma-sterilized soil with or without LDPE microplastics (MP). We observed that the LDPE-MP particle size was significantly reduced in the presence of bacteria. In addition, the volatile profiles of the treatments were compared and clear differences were detected. Several volatile compounds such as octadecane, eicosane, docosane and tricosane were measured only in the treatments containing both bacteria and LDPE-MP, indicating that these long-chain alkanes are byproducts of bacterial LDPE-MP decay. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Minimum five-year follow-up wear measurement of longevity highly cross-linked polyethylene cup against cobalt-chromium or zirconia heads.

PubMed

Nakahara, Ichiro; Nakamura, Nobuo; Nishii, Takashi; Miki, Hidenobu; Sakai, Takashi; Sugano, Nobuhiko

2010-12-01

We investigated the efficacy of combining highly cross-linked polyethylene with ceramic heads on further reduction in polyethylene wear compared with the combination with cobalt-chromium heads via PolyWare computer-assisted method. A prospective cohort study was performed on 102 cementless total hip arthroplasties using Longevity (Zimmer, Warsaw, Ind) highly cross-linked polyethylene liners. Either 26-mm zirconia heads or 26-mm cobalt-chromium heads were randomly used in 51 hips each. At a mean follow-up of 6.7 years, no significant differences were identified between the groups for total penetration rate and steady-state wear rate. Osteolysis was not observed in any hips in either group. In conclusion, no advantage was seen for the 26-mm zirconia head compared with the 26-mm cobalt-chromium head in this period. Copyright © 2010 Elsevier Inc. All rights reserved.

Note: A high-energy-density Tesla-type pulse generator with novel insulating oil

NASA Astrophysics Data System (ADS)

Liu, Sheng; Su, Jiancang; Fan, Xuliang

2017-09-01

A 10-GW high-energy-density Tesla-type pulse generator is developed with an improved insulating liquid based on a modified Tesla pulser—TPG700, of which the pulse forming line (PFL) is filled with novel insulating oil instead of transformer oil. Properties of insulating oil determining the stored energy density of the PFL are analyzed, and a criterion for appropriate oil is proposed. Midel 7131 is chosen as an application example. The results of insulating property experiment under tens-of-microsecond pulse charging demonstrate that the insulation capability of Midel 7131 is better than that of KI45X transformer oil. The application test in Tesla pulser TPG700 shows that the output power is increased to 10.5 GW with Midel 7131. The output energy density of TPG700 increases for about 60% with Midel 7131.

Note: A high-energy-density Tesla-type pulse generator with novel insulating oil.

PubMed

Liu, Sheng; Su, Jiancang; Fan, Xuliang

2017-09-01

A 10-GW high-energy-density Tesla-type pulse generator is developed with an improved insulating liquid based on a modified Tesla pulser-TPG700, of which the pulse forming line (PFL) is filled with novel insulating oil instead of transformer oil. Properties of insulating oil determining the stored energy density of the PFL are analyzed, and a criterion for appropriate oil is proposed. Midel 7131 is chosen as an application example. The results of insulating property experiment under tens-of-microsecond pulse charging demonstrate that the insulation capability of Midel 7131 is better than that of KI45X transformer oil. The application test in Tesla pulser TPG700 shows that the output power is increased to 10.5 GW with Midel 7131. The output energy density of TPG700 increases for about 60% with Midel 7131.

Stability of an ophthalmic formulation of polyhexamethylene biguanide in gamma-sterilized and ethylene oxide sterilized low density polyethylene multidose eyedroppers

PubMed Central

Wasiak, Mathieu; Jouannet, Mireille; Sautou, Valérie

2018-01-01

Background Polyhexamethylene biguanide (PHMB) eye drops are a frequently used medication to treat Acanthamoeba keratitis. In the absence of marketed PHMB eye drops, pharmacy-compounding units are needed to prepare this much needed treatment, but the lack of validated PHMB stability data severely limits their conservation by imposing short expiration dates after preparation. In this study we aim to assess the physicochemical and microbiological stability of a 0.2 mg/mL PHMB eye drop formulation stored in two kinds of polyethylene bottles at two different temperatures. Methods A liquid chromatography coupled with diode array detector stability-indicating method was validated to quantify PHMB, using a cyanopropyl bonded phase (Agilent Zorbax Eclipse XDB-CN column 4.6 × 75 mm with particle size of 3.5 μm) and isocratic elution consisting of acetonitrile/deionized water (3/97 v/v) at a flow rate of 1.3 mL/min. PHMB eye drops stability was assessed for 90 days of storage at 5 and 25 °C in ethylene oxide sterilized low density polyethylene (EOS-LDPE) and gamma sterilized low density polyethylene (GS-LDPE) bottles. The following analyses were performed: visual inspection, PHMB quantification and breakdown products (BPs) screening, osmolality and pH measurements, and sterility assessment. PHMB quantification and BP screening was also performed on the drops emitted from the multidose eyedroppers to simulate in-use condition. Results The analytical method developed meets all the qualitative and quantitative criteria for validation with an acceptable accuracy and good linearity, and is stability indicating. During 90 days of storage, no significant decrease of PHMB concentration was found compared to initial concentration in all stored PHMB eye drops. However, BP were found at day 30 and at day 90 of monitoring in both kind of bottles, stored at 5 and 25 °C, respectively. Although no significant variation of osmolality was found and sterility was maintained during 90 days

Bipolaronic charge density waves, polaronic spin density waves and high Tc superconductivity

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

Aubry, S.

1992-01-01

At large enough electron phonon coupling, the existence of bipolaronic, polaronic and mixed states is rigorously proven for the adiabatic Holstein model at any dimension and any band filling. The ground-state is one of them which then prove the existence of insulating Bipolaronic Charge Density Waves. The role of the quantum lattice fluctuations is analysed and found to be neglegible in that regime but to become essential in case of phonon softening then favoring the occurence of superconductivity. When a strong Hubbard term is also present, the bipolarons break into polorons and the ground state is expected to be amore » polaronic spin density wave. If the repulsive Hubbard term is comparable to the electron-phonon coupling, the energy for breaking a bipoloron into two polarons can become small and we get instead of these two degenerate structures, a pait of polarons bounded by a spin resonance which we call spin resonant bipolaron''. This resonant bipolaron is still strongly bound, but the role of the quantum lattice fluctuations becomes now very important and yields a sharp broadening of the bandwidth of this resonant bipolarona. Thus, the strong quantum character of these resonant bipolarons could prevent their localization into real space structures which could be insulating bipolaronic CDWs or polaronic SDWS, then favoring the formation of a superconducting coherent state with a possible high {Tc}.« less

Bipolaronic charge density waves, polaronic spin density waves and high {Tc} superconductivity

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

Aubry, S.

1992-09-01

At large enough electron phonon coupling, the existence of bipolaronic, polaronic and mixed states is rigorously proven for the adiabatic Holstein model at any dimension and any band filling. The ground-state is one of them which then prove the existence of insulating Bipolaronic Charge Density Waves. The role of the quantum lattice fluctuations is analysed and found to be neglegible in that regime but to become essential in case of phonon softening then favoring the occurence of superconductivity. When a strong Hubbard term is also present, the bipolarons break into polorons and the ground state is expected to be amore » polaronic spin density wave. If the repulsive Hubbard term is comparable to the electron-phonon coupling, the energy for breaking a bipoloron into two polarons can become small and we get instead of these two degenerate structures, a pait of polarons bounded by a spin resonance which we call ``spin resonant bipolaron``. This resonant bipolaron is still strongly bound, but the role of the quantum lattice fluctuations becomes now very important and yields a sharp broadening of the bandwidth of this resonant bipolarona. Thus, the strong quantum character of these resonant bipolarons could prevent their localization into real space structures which could be insulating bipolaronic CDWs or polaronic SDWS, then favoring the formation of a superconducting coherent state with a possible high {Tc}.« less

Structural and magnetic characterization of copper sulfonated phthalocyanine grafted onto treated polyethylene

NASA Astrophysics Data System (ADS)

Reznickova, A.; Kolska, Z.; Orendac, M.; Cizmar, E.; Sajdl, P.; Svorcik, V.

2016-08-01

This study focuses on high density polyethylene (HDPE) activated by Ar plasma treatment, subsequently grafted with copper sulfonated phthalocyanine (CuPc) especially pointing out to the surface and magnetic properties of those composites. Properties of pristine PE and their plasma treated counterparts were studied by different experimental techniques: X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, zeta potential and by electron spin resonance (ESR). XPS analysis confirmed the successful grafting of phthalocyanine. The highest absorption was found for the sample grafted with bCuPc for 1 h. Electrokinetic analysis also confirmed the plasma treatment and also subsequent CuPc grafting influence significantly the surface chemistry and charge. These results correspond well with XPS determination. ESR studies confirmed the presence of CuPc grafted on HDPE. It was found, that grafting is mediated by magnetically inactive functional groups, rather than radicals. Magnetic properties of CuPc do not seem to change significantly after grafting CuPc on polyethylene surface.

Radiation sterilization of medical devices. Effects of ionizing radiation on ultra-high molecular-weight polyethylene

NASA Astrophysics Data System (ADS)

Buchalla, R.; Schüttler, C.; Bögl, K. W.

1995-02-01

Sterilization by ionizing radiation has become, next to ethylene oxide treament, the most important "cold" sterilization process for medical devices made from plastics. The effects of ionizing radiation on the most important polymer for medical devices, ultra-high molecular-weight polyethylene, are briefly described in this review.

Simulation of Space Charge Dynamic in Polyethylene Under DC Continuous Electrical Stress

NASA Astrophysics Data System (ADS)

Boukhari, Hamed; Rogti, Fatiha

2016-10-01

The space charge dynamic plays a very important role in the aging and breakdown of polymeric insulation materials under high voltage. This is due to the intensification of the local electric field and the attendant chemical-mechanical effects in the vicinity around the trapped charge. In this paper, we have investigated the space charge dynamic in low-density polyethylene under high direct-current voltage, which is evaluated by experimental conditions. The evaluation is on the basis of simulation using a bipolar charge transport model consisting of charge injection, transports, trapping, detrapping, and recombination phenomena. The theoretical formulation of the physical problem is based on the Poisson, the continuity, and the transport equations. Numerical results provide temporal and local distributions of the electric field, the space charge density for the different kinds of charges (net charge density, mobile and trapped of electron density, mobile hole density), conduction and displacement current densities, and the external current. The result shows the appearance of the negative packet-like space charge with a large amount of the bulk under the dc electric field of 100 kV/mm, and the induced distortion of the electric field is largely near to the anode, about 39% higher than the initial electric field applied.

Speckle tracking and speckle content based composite strain imaging for solid and fluid filled lesions.

PubMed

Rabbi, Md Shifat-E; Hasan, Md Kamrul

2017-02-01

Strain imaging though for solid lesions provides an effective way for determining their pathologic condition by displaying the tissue stiffness contrast, for fluid filled lesions such an imaging is yet an open problem. In this paper, we propose a novel speckle content based strain imaging technique for visualization and classification of fluid filled lesions in elastography after automatic identification of the presence of fluid filled lesions. Speckle content based strain, defined as a function of speckle density based on the relationship between strain and speckle density, gives an indirect strain value for fluid filled lesions. To measure the speckle density of the fluid filled lesions, two new criteria based on oscillation count of the windowed radio frequency signal and local variance of the normalized B-mode image are used. An improved speckle tracking technique is also proposed for strain imaging of the solid lesions and background. A wavelet-based integration technique is then proposed for combining the strain images from these two techniques for visualizing both the solid and fluid filled lesions from a common framework. The final output of our algorithm is a high quality composite strain image which can effectively visualize both solid and fluid filled breast lesions in addition to the speckle content of the fluid filled lesions for their discrimination. The performance of our algorithm is evaluated using the in vivo patient data and compared with recently reported techniques. The results show that both the solid and fluid filled lesions can be better visualized using our technique and the fluid filled lesions can be classified with good accuracy. Copyright © 2016 Elsevier B.V. All rights reserved.

Exploring multi potential uses of marine bacteria; an integrated approach for PHB production, PAHs and polyethylene biodegradation.

PubMed

Mohanrasu, K; Premnath, N; Siva Prakash, G; Sudhakar, Muniyasamy; Boobalan, T; Arun, A

2018-05-19

There are copious of bacteria exist in marine environment and it is very important to screen the potential microbes that has the ability to produce biopolymer polyhydroxybutyrate (PHB) as well as polycyclic aromatic hydrocarbons (PAHs) degradation and conventional plastic high density polyethylene (HDPE) biodegradation. Numerous studies have been investigated individually on either one of characteristic feature like PHB production, PAHs and high density polyethylene (HDPE) degradation, but not all together. Hence, in this study, we tried to screen potential marine microbes that have the ability to perform all three features. We have isolated 203 phenotyphicaly different colonies from 19 different sites (marine soil sediments, marine water and oil spilled marine water) which cover the north east to down south seashore regions of Tamilnadu, India. Of the 203 microbial isolates, the best PHB producing (Micrococcus luteus), PAHs degradation (Klebsiella pneumonia) and HDPE degradation (Brevibacillus borstelensis) microorganisms were identified through 16S rRNA sequencing. Analytical studies confirmed PHB production by fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance ( 1 H & 13 C NMR); PAHs degradation by high performance liquid chromatography (HPLC), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM); HDPE degradation by CLSM, FT-IR and SEM which cover the spectroscopy studies on biological systems. Copyright © 2018. Published by Elsevier B.V.

Static viscoelasticity of biomass polyethylene composites

NASA Astrophysics Data System (ADS)

Yang, Keyan; Cai, Hongzhen; Yi, Weiming; Zhang, Qingfa; Zhao, Kunpeng

The biomass polyethylene composites filled with poplar wood flour, rice husk, cotton stalk or corn stalk were prepared by extrusion molding. The static viscoelasticity of composites was investigated by the dynamic thermal mechanical analyzer (DMA). Through the stress-strain scanning, it is found that the linear viscoelasticity interval of composites gradually decreases as the temperature rises, and the critical stress and strain values are 0.8 MPa and 0.03% respectively. The experiment shows that as the temperature rises, the creep compliance of biomass polyethylene composites is increased; under the constant temperature, the creep compliance decreases with the increase of content of biomass and calcium carbonate. The biomass and calcium carbonate used to prepare composites as filler can improve damping vibration attenuation and reduce stress deformation of composites. The stress relaxation modulus of composites is reduced and the relaxation rate increases at the higher temperature. The biomass and calcium carbonate used to prepare composites as filler not only can reduce costs, but also can increase stress relaxation modulus and improve the size thermostability of composites. The corn stalk is a good kind of biomass raw material for composites since it can improve the creep resistance property and the stress relaxation resistance property of composites more effectively than other three kinds of biomass (poplar wood flour, rice husk and cotton stalk).

Use of cotton gin trash and compatibilizers in polyethylene composites

USDA-ARS?s Scientific Manuscript database

The ginning of cotton produces 15-42% of foreign materials, called “cotton gin trash”, including cotton burr, stems, leaf fragment, and dirt. In this work we examined the mechanical properties of composites of low density polyethylene (LDPE) and cotton burr. The burr was ground into powder, and se...

Buoyancy of gas-filled bladders at great depth

NASA Astrophysics Data System (ADS)

Priede, Imants G.

2018-02-01

At high hydrostatic pressures exceeding 20 MPa or 200 bar, equivalent to depths exceeding ca.2000 m, the behaviour of gases deviates significantly from the predictions of standard equations such as Boyle's Law, the Ideal Gas Law and Van der Waals equation. The predictions of these equations are compared with experimental data for nitrogen, oxygen and air at 0 °C and 15 °C, at pressures up to 1100 bar (110 MPa) equivalent to full ocean depth of ca. 11000 m. Owing to reduced compressibility of gases at high pressures, gas-filled bladders at full ocean depth have a density of 847 kg m-3 for Oxygen, 622 kg m-3 for Nitrogen and 660 kg m-3 for air providing potentially useful buoyancy comparable with that available from man-made materials. This helps explain why some of the deepest-living fishes at ca. 7000 m depth (700 bar or 70 MPa) have gas-filled swim bladders. A table is provided of the density and buoyancy of oxygen, nitrogen and air at 0 °C and 15 °C from 100 to 1100 bar.

Slotted Polyimide-Aerogel-Filled-Waveguide Arrays

NASA Technical Reports Server (NTRS)

Rodriguez-Solis, Rafael A.; Pacheco, Hector L.; Miranda, Felix A.; Meador, Mary Ann B.

2013-01-01

This presentation discussed the potential advantages of developing Slotted Waveguide Arrays using polyimide aerogels. Polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aerospace antenna systems. PI aerogels are highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties. For slotted waveguide array applications, there are significant advantages in mass that more than compensate for the slightly higher loss of the aerogel filled waveguide when compared to state of practice commercial waveguide.

Biodegradation of low-density polyethylene (LDPE) by isolated fungi in solid waste medium.

PubMed

Zahra, Sahebnazar; Abbas, Shojaosadati Seyed; Mahsa, Mohammad-Taheri; Mohsen, Nosrati

2010-03-01

In this study, biodegradation of low-density polyethylene (LDPE) by isolated landfill-source fungi was evaluated in a controlled solid waste medium. The fungi, including Aspergillus fumigatus, Aspergillus terreus and Fusarium solani, were isolated from samples taken from an aerobic aged municipal landfill in Tehran. These fungi could degrade LDPE via the formation of a biofilm in a submerged medium. In the sterilized solid waste medium, LPDE films were buried for 100 days in a 1-L flask containing 400 g sterile solid waste raw materials at 28 degrees C. Each fungus was added to a separate flask. The moisture content and pH of the media were maintained at the optimal levels for each fungus. Photo-oxidation (25 days under UV-irradiation) was used as a pretreatment of the LDPE samples. The progress of the process was monitored by measurement of total organic carbon (TOC), pH, temperature and moisture. The results obtained from monitoring the process using isolated fungi under sterile conditions indicate that these fungi are able to grow in solid waste medium. The results of FT-IR and SEM analyses show that A. terreus and A. fumigatus, despite the availability of other organic carbon of materials, could utilize LDPE as carbon source. While there has been much research in the field of LDPE biodegradation under solid conditions, this is the first report of degradation of LDPE by A. fumigatus. Copyright 2009 Elsevier Ltd. All rights reserved.

Biodegradation of low-density polyethylene (LDPE) by isolated fungi in solid waste medium

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

Zahra, Sahebnazar; Abbas, Shojaosadati Seyed, E-mail: sa_shoja@modares.ac.i; Mahsa, Mohammad-Taheri

In this study, biodegradation of low-density polyethylene (LDPE) by isolated landfill-source fungi was evaluated in a controlled solid waste medium. The fungi, including Aspergillus fumigatus, Aspergillus terreus and Fusarium solani, were isolated from samples taken from an aerobic aged municipal landfill in Tehran. These fungi could degrade LDPE via the formation of a biofilm in a submerged medium. In the sterilized solid waste medium, LPDE films were buried for 100 days in a 1-L flask containing 400 g sterile solid waste raw materials at 28 deg. C. Each fungus was added to a separate flask. The moisture content and pHmore » of the media were maintained at the optimal levels for each fungus. Photo-oxidation (25 days under UV-irradiation) was used as a pretreatment of the LDPE samples. The progress of the process was monitored by measurement of total organic carbon (TOC), pH, temperature and moisture. The results obtained from monitoring the process using isolated fungi under sterile conditions indicate that these fungi are able to grow in solid waste medium. The results of FT-IR and SEM analyses show that A. terreus and A. fumigatus, despite the availability of other organic carbon of materials, could utilize LDPE as carbon source. While there has been much research in the field of LDPE biodegradation under solid conditions, this is the first report of degradation of LDPE by A. fumigatus.« less

Characterization of weathered wood-plastic composite surfaces using FTIR spectroscopy, contact angle, and XPS

Treesearch

Nicole M. Stark; Laurent M. Matuana

2007-01-01

Much of the current growth of wood-plastic composites (WPCs) is due to increased penetration into the decking market; therefore it has become imperative to understand the durability of WPCs in outdoor applications. In this study, wood flour filled high-density polyethylene (HDPE) composites were manufactured through either injection molding or extrusion. A set of...

Influence of photostabilizers on wood flour-HDPE composites exposed to xenon-arc radiation with and without water spray

Treesearch

Nicole M. Stark; Laurent M. Matuana

2006-01-01

The weathering of wood-plastic composites changes their appearance and/or mechanical properties. These changes can be slowed through the addition of ultraviolet absorbers and pigments. The first phase of this study examined the effect of incorporating different concentrations of an ultraviolet absorber and/or pigment into wood-flour-filled high-density polyethylene (WF...

The relation between high-density and very-high-density amorphous ice.

PubMed

Loerting, Thomas; Salzmann, Christoph G; Winkel, Katrin; Mayer, Erwin

2006-06-28

The exact nature of the relationship between high-density (HDA) and very-high-density (VHDA) amorphous ice is unknown at present. Here we review the relation between HDA and VHDA, concentrating on experimental aspects and discuss these with respect to the relation between low-density amorphous ice (LDA) and HDA. On compressing LDA at 125 K up to 1.5 GPa, two distinct density steps are observable in the pressure-density curves which correspond to the LDA --> HDA and HDA --> VHDA conversion. This stepwise formation process LDA --> HDA --> VHDA at 125 K is the first unambiguous observation of a stepwise amorphous-amorphous-amorphous transformation sequence. Density values of amorphous ice obtained in situ between 0.3 and 1.9 GPa on isobaric heating up to the temperatures of crystallization show a pronounced change of slope at ca. 0.8 GPa which could indicate formation of a distinct phase. We infer that the relation between HDA and VHDA is very similar to that between LDA and HDA except for a higher activation barrier between the former. We further discuss the two options of thermodynamic phase transition versus kinetic densification for the HDA --> VHDA conversion.

Gap Fill Materials Using Cyclodextrin Derivatives in ArF Lithography

NASA Astrophysics Data System (ADS)

Takei, Satoshi; Shinjo, Tetsuya; Sakaida, Yasushi; Hashimoto, Keisuke

2007-11-01

High planarizing gap fill materials based on β-cyclodextrin in ArF photoresist under-layer materials have been developed for fast etching in CF4 gas. Gap fill materials used in the via-first dual damascene process need to have high etch rates to prevent crowning or fencing on top of the trench after etching and a small thickness bias between the dense and blanket areas to minimize issues observed during trench lithography by narrowing the process latitude. Cyclodextrin is a circular oligomer with a nanoscale porous structure that has a high number of oxygen atoms, as calculated using the Ohnishi parameter, providing high etch rates. Additionally, since gap fill materials using cyclodextrin derivatives have low viscosities and molecular weights, they are expected to exhibit excellent flow properties and minimal thermal shrinkage during baking. In this paper, we describe the composition and basic film properties of gap fill materials; planarization in the via-first dual damascene process and etch rates in CF4 gas compared with dextrin with α-glycoside bonds in polysaccharide, poly(2-hydroxypropyl methacrylate) and poly(4-hydroxystyrene). The β-cyclodextrin used in this study was obtained by esterifying the hydroxyl groups of dextrin resulting in improved wettability on via substrates and solubility in photoresist solvents such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and ethyl lactate. Gap fill materials using cyclodextrin derivatives showed good planarization and via filling performance without observing voids in via holes. In addition to superior via filling performance, the etch rate of gap fill materials using β-cyclodextrin derivatives was 2.8-2.9 times higher than that of an ArF photoresist, evaluated under CF4 gas conditions by reactive ion etching. These results were attributed to the combination of both nanoscale porous structures and a high density of oxygen atoms in our gap fill materials using cyclodextrin

Symmetry control strategies in low gas-fill hohlraum

NASA Astrophysics Data System (ADS)

Goyon, Clement; Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; Meezan, N. B.; Dewald, E.; Ho, D. D.; Weber, C.; Khan, S. F.; Ma, T.; Milovich, J. L.; Moore, A. S.; Benedetti, R.; Pak, A. E.; Ross, J. S.; Nagel, S. R.; Grim, G. P.; Volegov, P.; Biener, J.; Nikroo, A.; Callahan, D. A.; Hurricane, O. A.; Hsing, W. W.; Town, R. P.; Edwards, M. J.

2017-10-01

The primary neutron yield record, to-date, for an ICF implosion on the NIF (1.47*1016) has been achieved using a doped HDC capsule (D =1.82 mm) in an unlined DU hohlraum (D =6.20 mm, L = 11.3 mm) filled with a low He gas-fill (0.3 mg/cc). This platform uses a new ``drooping'' pulse designed to keep high remaining mass and short coasting time. Prior to the high convergence (27x) cryogenic DT implosion, our ability to tune hot spot symmetry using this new pulse was tested at lower convergence (15x) using DD gas-filled capsules. Hot spot symmetry was tuned using beam pointing, gas-fill density, and power balance between outer and inner beams. The main metrics to assess the efficiency of each change are the implosion shape (time resolved X-ray emission of the hot spot) and DD neutron yield. In addition, we will describe the irradiation pattern obtained in each case using X-ray (soft and hard) diagnostics and the laser coupling to the hohlraum. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Development of High-Fill-Factor Large-Aperture Micromirrors for Agile Optical Phased Arrays

DTIC Science & Technology

2010-02-28

Final Project Report Contract/Grant Title: Development of High-Fill-Factor Large-Aperture Micromirrors for Agile Optical Phased Arrays...factor (HFF) micromirror array (MMA) has been proposed, fabricated and tested. Optical-phased-array (OPA) beam steering based on the HFF MMA has also...electrically tuned to multiple 2. 1. Background High-fill-factor (HFF) micromirror arrays (MMAs) can form optical phased arrays (OPAs) for laser beam

Ultra high molecular weight polyethylene: Optical features at millimeter wavelengths

NASA Astrophysics Data System (ADS)

D'Alessandro, G.; Paiella, A.; Coppolecchia, A.; Castellano, M. G.; Colantoni, I.; de Bernardis, P.; Lamagna, L.; Masi, S.

2018-05-01

The next generation of experiments for the measurement of the Cosmic Microwave Background (CMB) requires more and more the use of advanced materials, with specific physical and structural properties. An example is the material used for receiver's cryostat windows and internal lenses. The large throughput of current CMB experiments requires a large diameter (of the order of 0.5 m) of these parts, resulting in heavy structural and optical requirements on the material to be used. Ultra High Molecular Weight (UHMW) polyethylene (PE) features high resistance to traction and good transmissivity in the frequency range of interest. In this paper, we discuss the possibility of using UHMW PE for windows and lenses in experiments working at millimeter wavelengths, by measuring its optical properties: emissivity, transmission and refraction index. Our measurements show that the material is well suited to this purpose.

Enhanced flashover strength in polyethylene nanodielectrics by secondary electron emission modification

NASA Astrophysics Data System (ADS)

Wang, Weiwang; Li, Shengtao; Min, Daomin

2016-04-01

This work studies the correlation between secondary electron emission (SEE) characteristics and impulse surface flashover in polyethylene nanodielectrics both theoretically and experimentally, and illustrates the enhancement of flashover voltage in low-density polyethylene (LDPE) through incorporating Al2O3 nanoparticles. SEE characteristics play key roles in surface charging and gas desorption during surface flashover. This work demonstrates that the presence of Al2O3 nanoparticles decreases the SEE coefficient of LDPE and enhances the impact energy at the equilibrium state of surface charging. These changes can be explained by the increase of surface roughness and of surface ionization energy, and the strong interaction between nanoparticles and the polymer dielectric matrix. The surface charge and flashover voltage are calculated according to the secondary electron emission avalanche (SEEA) model, which reveals that the positive surface charges are reduced near the cathode triple point, while the presence of more nanoparticles in high loading samples enhances the gas desorption. Consequently, the surface flashover performance of LDPE/Al2O3 nanodielectrics is improved.

Enhanced flashover strength in polyethylene nanodielectrics by secondary electron emission modification

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

Wang, Weiwang; Li, Shengtao, E-mail: sli@xjtu.edu.cn; Min, Daomin

2016-04-15

This work studies the correlation between secondary electron emission (SEE) characteristics and impulse surface flashover in polyethylene nanodielectrics both theoretically and experimentally, and illustrates the enhancement of flashover voltage in low-density polyethylene (LDPE) through incorporating Al{sub 2}O{sub 3} nanoparticles. SEE characteristics play key roles in surface charging and gas desorption during surface flashover. This work demonstrates that the presence of Al{sub 2}O{sub 3} nanoparticles decreases the SEE coefficient of LDPE and enhances the impact energy at the equilibrium state of surface charging. These changes can be explained by the increase of surface roughness and of surface ionization energy, and themore » strong interaction between nanoparticles and the polymer dielectric matrix. The surface charge and flashover voltage are calculated according to the secondary electron emission avalanche (SEEA) model, which reveals that the positive surface charges are reduced near the cathode triple point, while the presence of more nanoparticles in high loading samples enhances the gas desorption. Consequently, the surface flashover performance of LDPE/Al{sub 2}O{sub 3} nanodielectrics is improved.« less

Tuning the superstructure of ultrahigh-molecular-weight polyethylene/low-molecular-weight polyethylene blend for artificial joint application.

PubMed

Xu, Ling; Chen, Chen; Zhong, Gan-Ji; Lei, Jun; Xu, Jia-Zhuang; Hsiao, Benjamin S; Li, Zhong-Ming

2012-03-01

An easy approach was reported to achieve high mechanical properties of ultrahigh-molecular-weight polyethylene (UHMWPE)-based polyethylene (PE) blend for artificial joint application without the sacrifice of the original excellent wear and fatigue behavior of UHMWPE. The PE blend with desirable fluidity was obtained by melt mixing UHMWPE and low molecular weight polyethylene (LMWPE), and then was processed by a modified injection molding technology-oscillatory shear injection molding (OSIM). Morphological observation of the OSIM PE blend showed LMWPE contained well-defined interlocking shish-kebab self-reinforced superstructure. Addition of a small amount of long chain polyethylene (2 wt %) to LMWPE greatly induced formation of rich shish-kebabs. The ultimate tensile strength considerably increased from 27.6 MPa for conventional compression molded UHMWPE up to 78.4 MPa for OSIM PE blend along the flow direction and up to 33.5 MPa in its transverse direction. The impact strength of OSIM PE blend was increased by 46% and 7% for OSIM PE blend in the direction parallel and vertical to the shear flow, respectively. Wear and fatigue resistance were comparable to conventional compression molded UHMWPE. The superb performance of the OSIM PE blend was originated from formation of rich interlocking shish-kebab superstructure while maintaining unique properties of UHMWPE. The present results suggested the OSIM PE blend has high potential for artificial joint application. © 2012 American Chemical Society

Enhanced wear performance of ultra high molecular weight polyethylene crosslinked by organosilane.

PubMed

Tang, C Y; Xie, X L; Wu, X C; Li, R K Y; Mai, Y W

2002-11-01

Ultra high molecular weight polyethylene (UHMWPE) crosslinked by organosilane was thermal compression molded. The organosilane used was the tri-ethyloxyl vinyl silane. Its gelation, melting behavior, crystallinity, mechanical and wear-resisting properties were systematically investigated. The results showed that the gel ratio of UHMWPE increases with the incorporation of organosilane. At a low content of organosilane, the melting point and crystallinity of the crosslinked UHMWPE increase, and hence the mechanical and wear-resisting properties are improved. However, at a high content of organosilane, these performances of the crosslinked UHMWPE become worse. At 0.4 phr silane, the wear resistance of crosslinked UHMWPE reaches its optimum value.

Physico-mechanical characteristics of commercially available bulk-fill composites.

PubMed

Leprince, Julian G; Palin, William M; Vanacker, Julie; Sabbagh, Joseph; Devaux, Jacques; Leloup, Gaetane

2014-08-01

Bulk-fill composites have emerged, arguably, as a new "class" of resin-based composites, which are claimed to enable restoration in thick layers, up to 4mm. The objective of this work was to compare, under optimal curing conditions, the physico-mechanical properties of most currently available bulk-fill composites to those of two conventional composite materials chosen as references, one highly filled and one flowable "nano-hybrid" composite. Tetric EvoCeram Bulk Fill (Ivoclar-Vivadent), Venus Bulk Fill (Heraeus-Kulzer), SDR (Dentsply), X-tra Fil (VOCO), X-tra Base (VOCO), Sonic Fill (Kerr), Filtek Bulk Fill (3M-Espe), Xenius (GC) were compared to the two reference materials. The materials were light-cured for 40s in a 2mm×2mm×25mm Teflon mould. Degree of conversion was measured by Raman spectroscopy, Elastic modulus and flexural strength were evaluated by three point bending, surface hardness using Vickers microindentation before and after 24h ethanol storage, and filler weight content by thermogravimetric analysis. The ratio of surface hardness before and after ethanol storage was considered as an evaluation of polymer softening. Data were analyzed by one-way ANOVA and post hoc Tukey's test (p=0.05). The mechanical properties of the bulk-fill composites were mostly lower compared with the conventional high viscosity material, and, at best, comparable to the conventional flowable composite. Linear correlations of the mechanical properties investigated were poor with degree of conversion (0.090.8). Softening in ethanol revealed differences in polymer network density between material types. The reduction of time and improvement of convenience associated with bulk-fill materials is a clear advantage of this particular material class. However, a compromise with mechanical properties compared with more conventional commercially-available nano-hybrid materials was demonstrated by the present work. Given the lower mechanical

The John Charnley Award: an accurate and sensitive method to separate, display, and characterize wear debris: part 1: polyethylene particles.

PubMed

Billi, Fabrizio; Benya, Paul; Kavanaugh, Aaron; Adams, John; Ebramzadeh, Edward; McKellop, Harry

2012-02-01

Numerous studies indicate highly crosslinked polyethylenes reduce the wear debris volume generated by hip arthroplasty acetabular liners. This, in turns, requires new methods to isolate and characterize them. We describe a method for extracting polyethylene wear particles from bovine serum typically used in wear tests and for characterizing their size, distribution, and morphology. Serum proteins were completely digested using an optimized enzymatic digestion method that prevented the loss of the smallest particles and minimized their clumping. Density-gradient ultracentrifugation was designed to remove contaminants and recover the particles without filtration, depositing them directly onto a silicon wafer. This provided uniform distribution of the particles and high contrast against the background, facilitating accurate, automated, morphometric image analysis. The accuracy and precision of the new protocol were assessed by recovering and characterizing particles from wear tests of three types of polyethylene acetabular cups (no crosslinking and 5 Mrads and 7.5 Mrads of gamma irradiation crosslinking). The new method demonstrated important differences in the particle size distributions and morphologic parameters among the three types of polyethylene that could not be detected using prior isolation methods. The new protocol overcomes a number of limitations, such as loss of nanometer-sized particles and artifactual clumping, among others. The analysis of polyethylene wear particles produced in joint simulator wear tests of prosthetic joints is a key tool to identify the wear mechanisms that produce the particles and predict and evaluate their effects on periprosthetic tissues.

Polyethylene Based Materials for Biofilm Carriers Used in Wastewater Treatment

NASA Astrophysics Data System (ADS)

Moga, I. C.; Iordache, O. I.; Petrescu, G.; Pricop, F.; Dumitrescu, I.

2018-06-01

The moving bed biofilm technology is based on biofilm carriers on which consortia of microorganisms attach, develop and grow. Around the world are known many biofilm carrier variants made of varied materials. The most common materials are based on polyethylene since this material has a close to water density. The authors propose a novel biofilm carrier to be used in tertiary treatment for tannery and paper-mill wastewaters. The biological treatment is based on fungal activity. The selected fungal strains will be grown on innovative polyethylene carriers containing cellulose. The carrier will be designed to be exploited in a moving bed bioreactor and to favour fungal growth in the presence of competing bacteria.

Effects of processing method and moisture history on laboratory fungal resistance of wood-HDPE composites.

Treesearch

Craig M. Clemons; Rebecca E. Ibach

2004-01-01

The purpose of this study was to clarify the effects of composite processing and moisture sorption on laboratory fungal resistance of wood-plastic composites. A 2-week water soaking or cyclic boiling-drying procedure was used to infuse moisture into composites made from high-density polyethylene filled with 50 percent wood flour and processed by extrusion, compression...

Mechanical and thermal properties of biocomposites from nonwoven industrial Fique fiber mats with Epoxy Resin and Linear Low Density Polyethylene

NASA Astrophysics Data System (ADS)

Hidalgo-Salazar, Miguel A.; Correa, Juan P.

2018-03-01

In this work Linear Low Density Polyethylene-nonwoven industrial Fique fiber mat (LLDPE-Fique) and Epoxy Resin-nonwoven industrial Fique fiber mat (EP-Fique) biocomposites were prepared using thermocompression and resin film infusion processes. Neat polymeric matrices and its biocomposites were tested following ASTM standards in order to evaluate tensile and flexural mechanical properties. Also, thermal behavior of these materials has been studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Tensile and flexural test revealed that nonwoven Fique reinforced composites exhibited higher modulus and strength but lower deformation capability as compared with LLDPE and EP neat matrices. TG thermograms showed that nonwoven Fique fibers incorporation has an effect on the thermal stability of the composites. On the other hand, Fique fibers did not change the crystallization and melting processes of the LLDPE matrix but restricts the motion of EP macromolecules chains thus increases the Tg of the EP-Fique composite. Finally, this work opens the possibility of considering non-woven Fique fibers as a reinforcement material with a high potential for the manufacture of biocomposites for automotive applications. In addition to the processing test specimens, it was also possible to manufacture a part of LLDPE-Fique, and one part of EP-Fique.

Filling material for a buried cavity in a collapse area using light-weighted foam and active feldspar

NASA Astrophysics Data System (ADS)

Cho, Jin Woo; Lee, Ju-hyoung; Kim, Sung-Wook; Choi, Eun-Kyeong

2017-04-01

Concrete which is generally used as filling material for a buried cavity has very high strength but significantly high self-load is considered its disadvantage. If it is used as filling material, the second collapse due to additional load, causing irreversible damage. If light-weighted foam and active feldspar are used to solve this problem, the second collapse can be prevented by reducing of self-load of filling material. In this study, the specimen was produced by mixing light-weighted foam, active feldspar and cement, and changes in the density, unconfined compressive strength and hydraulic conductivity were analyzed. Using the light-weighted foam could enable the adjustment of density of specimen between 0.5 g/cm3 and 1.7 g/cm3, and if the mixing ratio of the light-weighted foam increases, the specimen has more pores and smaller range of cross-sectional area. It is confirmed that it has direct correlation with the density, and if the specimen has more pores, the density of the specimen is lowered. The density of the specimen influences the unconfined compressive strength and the hydraulic conductivity, and it was also confirmed that the unconfined compressive strength could be adjusted between 0.6 MPa and 8 MPa and the hydraulic conductivity could be adjusted between 10-9cm/sec and 10-3cm/sec. These results indicated that we can adjust unconfined compressive strength and hydraulic conductivity of filling materials by changing the mixing amount of lightweight-weighted foam according to the requirements of the field condition. Keywords: filling material, buried cavity, light-weighted foam, feldspar Acknowledgement This research was supported by a Grant from a Strategic Research Project (Horizontal Drilling and Stabilization Technologies for Urban Search and Rescue (US&R) Operation) funded by the Korea Institute of Civil Engineering and Building Technology.

Raman analysis of polyethylene glycols and polyethylene oxides

NASA Astrophysics Data System (ADS)

Sagitova, E. A.; Prokhorov, K. A.; Nikolaeva, G. Yu; Baimova, A. V.; Pashinin, P. P.; Yarysheva, A. Yu; Mendeleev, D. I.

2018-04-01

We present Raman study of commercial liquids and powders of polyethylene glycols and polyethylene oxides with the average molecular weight from 400 Da to 10000 kDa. The most significant spectral changes were observed for the range of the molecular weights, where the liquid/semisolid transition has occurred. For the powders we revealed increase in the content of the molecules in the helical conformation and in the content of the monoclinic crystalline phase with growth of the molecular weight.

Effect of implanted Cu/low-density polyethylene nanocomposite on the morphology of endometrium in the mouse.

PubMed

Xia, Xianping; Xie, Changsheng; Zhu, Changhong; Cai, Shuizhou; Yang, Xiangliang

2007-08-01

To investigate the damage of endometrium caused by the implanted Cu/low-density polyethylene (LDPE) nanocomposite and the contraceptive effect of this novel copper-containing intrauterine device material. Experimental animal study. TongJi Medical College of Huazhong University of Science and Technology. Sixty healthy female mice. Twenty mice received no implants, 20 mice received the Cu/LDPE nanocomposite, and 20 mice received bulk copper. Morphologic features of the endometrium, contraceptive effect, and surface condition of the implanted implants. The contraceptive effect of both the Cu/LDPE nanocomposite and bulk copper is 100%, the damage of the endometrium caused by the Cu/LDPE nanocomposite is much less than that caused by bulk copper, and the surface of the implanted Cu/LDPE nanocomposite is much smoother and much softer than that of the implanted bulk copper. The contraceptive effect of the Cu/LDPE nanocomposite is comparable with that of bulk copper, and the damage of the endometrium caused by the Cu/LDPE nanocomposite is much less than that caused by bulk copper. The endometrium injury is related to the surface condition of the implanted intrauterine device material.

Use of low density polyethylene membranes for assessment of genotoxicity of PAHs in the Seine River.

PubMed

Vincent-Hubert, Françoise; Uher, Emmanuelle; Di Giorgio, Carole; Michel, Cécile; De Meo, Michel; Gourlay-France, Catherine

2017-03-01

The genotoxicity of river water dissolved contaminants is usually estimated after grab sampling of river water. Water contamination can now be obtained with passive samplers that allow a time-integrated sampling of contaminants. Since it was verified that low density polyethylene membranes (LDPE) accumulate labile hydrophobic compounds, their use was proposed as a passive sampler. This study was designed to test the applicability of passive sampling for combined chemical and genotoxicity measurements. The LDPE extracts were tested with the umu test (TA1535/pSK1002 ± S9) and the Ames assay (TA98, TA100 and YG1041 ± S9). We describe here this new protocol and its application in two field studies on four sites of the Seine River. Field LDPE extracts were negative with the YG1041 and TA100 and weakly positive with the TA98 + S9 and Umu test. Concentrations of labile mutagenic PAHs were higher upstream of Paris than downstream of Paris. Improvement of the method is needed to determine the genotoxicity of low concentrations of labile dissolved organic contaminants.

Polyethylene organo-clay nanocomposites: the role of the interface chemistry on the extent of clay intercalation/exfoliation.

PubMed

Mainil, Michaël; Alexandre, Michaël; Monteverde, Fabien; Dubois, Philippe

2006-02-01

High density polyethylene (HDPE)/clay nanocomposites have been prepared using three different functionalized polyethylene compatibilizers: an ethylene/vinyl acetate copolymer, a polyethylene grafted with maleic anhydride functions and a (styrene-b-ethylene/butylene-b-styrene) block copolymer. The nanocomposites were prepared via two different routes: (1) the dispersion in HDPE of a masterbatch prepared from the compatibilizer and the clay or (2) the direct melt blending of the three components. For each compatibilizer, essentially intercalated nanocomposites were formed as determined by X-ray diffraction and transmission electron microscopy. With the ethylene/vinyl acetate copolymer, a significant delamination of the intercalated clay in thin stacks was observed. This dispersion of thin intercalated stacks within the polymer matrix allowed increasing significantly the stiffness and the flame resistance of the nanocomposite. A positive effect of shear rate and blending time has also been put into evidence, especially for the process based on the masterbatch preparation, improving both the formation of thin stacks of intercalated clay and the mechanical properties and the flame resistance of the formed nanocomposites.

Ultra-High Molecular Weight Polyethylene: Influence of the Chemical, Physical and Mechanical Properties on the Wear Behavior. A Review

PubMed Central

Bellare, Anuj; Bistolfi, Alessandro

2017-01-01

Ultra-high molecular weight polyethylene (UHMWPE) is the most common bearing material in total joint arthroplasty due to its unique combination of superior mechanical properties and wear resistance over other polymers. A great deal of research in recent decades has focused on further improving its performances, in order to provide durable implants in young and active patients. From “historical”, gamma-air sterilized polyethylenes, to the so-called first and second generation of highly crosslinked materials, a variety of different formulations have progressively appeared in the market. This paper reviews the structure–properties relationship of these materials, with a particular emphasis on the in vitro and in vivo wear performances, through an analysis of the existing literature. PMID:28773153

A Long Cycle Life, Self-Healing Zinc-Iodine Flow Battery with High Power Density.

PubMed

Xie, Congxin; Zhang, Huamin; Xu, Wenbin; Wang, Wei; Li, Xianfeng

2018-05-01

A zinc-iodine flow battery (ZIFB) with long cycle life, high energy, high power density, and self-healing behavior is prepared. The long cycle life was achieved by employing a low-cost porous polyolefin membrane and stable electrolytes. The pores in the membrane can be filled with a solution containing I 3 - that can react with zinc dendrite. Therefore, by consuming zinc dendrite, the battery can self-recover from micro-short-circuiting resulting from overcharging. By using KI, ZnBr 2 , and KCl as electrolytes and a high ion-conductivity porous membrane, a very high power density can be achieved. As a result, a ZIFB exhibits an energy efficiency (EE) of 82 % at 80 mA cm -2 , which is 8 times higher than the currently reported ZIFBs. Furthermore, a stack with an output of 700 W was assembled and continuously run for more than 300 cycles. We believe this ZIFB can lead the way to development of new-generation, high-performance flow batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and release study of Triclosan in polyethylene/Triclosan anti-bacterial blend.

PubMed

Kamalipour, Jamshid; Masoomi, Mahmood; Khonakdar, Hossein Ali; Razavi, Seyed Mohammad Reza

2016-09-01

In this study, medium density polyethylene (MDPE) incorporated with Triclosan antibacterial substance has been prepared and Triclosan release rate was investigated. The crystallinity level and matrix polarity, as two significant parameters in antibacterial release control, were studied. Triclosan, a well-established widespread antibacterial agent, was incorporated into medium density polyethylene (MDPE) and Maleic anhydride grafted polyethylene (PE-g-MA) was used to change the polarity of the MDPE matrix. A masterbatch of 10wt% Triclosan incorporated with the MDPE and various PE-g-MA concentrations were prepared using an internal mixer. Then the masterbatch was diluted in the MDPE matrix to produce compounds with 0.1, 0.5, and1wt% Triclosan via twin screw extruder. The compounds were molded by compression molding method and then were cooled in three different cooling rate methods: isothermal cooling (I), quenching (Q),and moderate 5-10°C/min cooling rate (M). Cooling rate effects on crystallinity level were investigated applying sample density measurement. UV-vis absorption spectroscopy was used to probe the release of Triclosan. Antibacterial properties of the compounds against Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus were measured. The results showed that by addition of PE-g-MA, Triclosan release rate was increased. It was confirmed that the sample crystallinity was decreased by the cooling rate enhancement. The results also showed that quenched samples indicated higher release of Triclosan. Cooling rate reduction and raising the polarity increased the release of Triclosan and improved the antibacterial properties of the compounds. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly filled biocomposites based on ethylene-vinyl acetate copolymer and wood flour

NASA Astrophysics Data System (ADS)

Shelenkov, P. G.; Pantyukhov, P. V.; Popov, A. A.

2018-05-01

Recently, there is a great interest in the world to biodegradable materials based on synthetic polymers in a composition with natural fillers. Highly filled polymer composite materials based on various grades of synthetic block copolymer of ethylene vinyl acetate with wood flour were under investigation. Five grades of ethylene-vinyl acetate copolymer differing in the content of vinyl acetate groups and a melt flow index were used in this work in order to find the best one for highly filled biocomposites. Wood flour content in biocomposites was 50, 60, 70 weight %. The rheological and physico-mechanical characteristics of the resulting biocomposites were studied.

High-density carbon capsule experiments on the national ignition facility

DOE PAGES

Ross, J. S.; Ho, D.; Milovich, J.; ...

2015-02-25

Indirect-drive implosions with a high-density carbon (HDC) capsule were conducted on the National Ignition Facility (NIF) to test HDC properties as an ablator material for inertial confinement fusion. In this study, a series of five experiments were completed with 76-μm-thick HDC capsules using a four-shock laser pulse optimized for HDC. The pulse delivered a total energy of 1.3 MJ with a peak power of 360 TW. The experiment demonstrated good laser to target coupling (~90 %) and excellent nuclear performance. Lastly, a deuterium and tritium gas-filled HDC capsule implosion produced a neutron yield of 1.6×10 15 ± 3×10 13, amore » yield over simulated in one dimension of 70%.« less

The influence of malalignment and ageing following sterilisation by gamma irradiation in an inert atmosphere on the wear of ultra-high-molecular-weight polyethylene in patellofemoral replacements

PubMed Central

Maiti, Raman; Cowie, Raelene M; Fisher, John; Jennings, Louise M

2017-01-01

Complications of patellofemoral arthroplasty often occur soon after implantation and, as well as other factors, can be due to the design of the implant or its surgical positioning. A number of studies have previously considered the wear of ultra-high-molecular-weight polyethylene patellae following suboptimal implantation; however, studies have primarily been carried out under a limited number of degrees of freedom. The aim of this study was to develop a protocol to assess the wear of patellae under a malaligned condition in a six-axis patellofemoral joint simulator. The malalignment protocol hindered the tracking of the patella centrally in the trochlear groove and imparted a constant 5° external rotation (tilt) on the patella button. Following 3 million cycles of wear simulation, this condition had no influence on the wear of ultra-high-molecular-weight polyethylene patellae aged for 4 years compared to well-positioned non-aged implants (p > 0.05). However, under the malaligned condition, ultra-high-molecular-weight polyethylene patellae aged 8–10 years after unpacking (following sterilisation by gamma irradiation in an inert atmosphere) and worn ultra-high-molecular-weight polyethylene components also aged 4 years after unpacking (following the same sterilisation process) exhibited a high rate of wear. Fatigue failure due to elevated contact stress led to delamination of the ultra-high-molecular-weight polyethylene and in some cases complete failure of the patellae. The results suggest that suboptimal tracking of the patella in the trochlear groove and tilt of the patella button could have a significant effect on the wear of ultra-high-molecular-weight polyethylene and could lead to implant failure. PMID:28661229

The influence of malalignment and ageing following sterilisation by gamma irradiation in an inert atmosphere on the wear of ultra-high-molecular-weight polyethylene in patellofemoral replacements.

PubMed

Maiti, Raman; Cowie, Raelene M; Fisher, John; Jennings, Louise M

2017-07-01

Complications of patellofemoral arthroplasty often occur soon after implantation and, as well as other factors, can be due to the design of the implant or its surgical positioning. A number of studies have previously considered the wear of ultra-high-molecular-weight polyethylene patellae following suboptimal implantation; however, studies have primarily been carried out under a limited number of degrees of freedom. The aim of this study was to develop a protocol to assess the wear of patellae under a malaligned condition in a six-axis patellofemoral joint simulator. The malalignment protocol hindered the tracking of the patella centrally in the trochlear groove and imparted a constant 5° external rotation (tilt) on the patella button. Following 3 million cycles of wear simulation, this condition had no influence on the wear of ultra-high-molecular-weight polyethylene patellae aged for 4 years compared to well-positioned non-aged implants (p > 0.05). However, under the malaligned condition, ultra-high-molecular-weight polyethylene patellae aged 8-10 years after unpacking (following sterilisation by gamma irradiation in an inert atmosphere) and worn ultra-high-molecular-weight polyethylene components also aged 4 years after unpacking (following the same sterilisation process) exhibited a high rate of wear. Fatigue failure due to elevated contact stress led to delamination of the ultra-high-molecular-weight polyethylene and in some cases complete failure of the patellae. The results suggest that suboptimal tracking of the patella in the trochlear groove and tilt of the patella button could have a significant effect on the wear of ultra-high-molecular-weight polyethylene and could lead to implant failure.

Effect of low-density polyethylene on smoke emissions from burning of simulated debris piles.

PubMed

Hosseini, Seyedehsan; Shrivastava, Manish; Qi, Li; Weise, David R; Cocker, David R; Miller, John W; Jung, Heejung S

2014-06-01

Low-density polyethylene (LDPE) plastic is used to keep piled debris from silvicultural activities--activities associated with development and care of forests--dry to enable efficient disposal by burning. The effects of inclusion of LDPE in this manner on smoke emissions are not well known. In a combustion laboratory experiment, 2-kg mixtures of LDPE and manzanita (Arctostaphylos sp.) wood containing 0, 0.25, and 2.5% LDPE by mass were burned. Gaseous and particulate emissions were sampled in real time during the entire flaming, mixed combustion phase--when the flaming and smoldering phases are present at the same time--and during a portion of the smoldering phase. Analysis of variance was used to test significance of modified combustion efficiency (MCE)--the ratio of concentrations of fire-integrated excess CO2 to CO2 plus CO--and LDPE content on measured individual compounds. MCE ranged between 0.983 and 0.993, indicating that combustion was primarily flaming; MCE was seldom significant as a covariate. Of the 195 compounds identified in the smoke emissions, only the emission factor (EF) of 3M-octane showed an increase with increasing LDPE content. Inclusion of LDPE had an effect on EFs of pyrene and fluoranthene, but no statistical evidence of a linear trend was found. Particulate emission factors showed a marginally significant linear relationship with MCE (0.05 < P-value < 0.10). Based on the results of the current and previous studies and literature reviews, the inclusion of small mass proportions of LDPE in piled silvicultural debris does not appear to change the emissions produced when low-moisture-content wood is burned. In general, combustion of wet piles results in lower MCEs and consequently higher levels of emissions. Current air quality regulations permit the use of burning to dispose of silvicultural piles; however, inclusion of low-density polyethyelene (LDPE) plastic in silvicultural piles can result in a designation of the pile as waste. Waste

Characterization of ecofriendly polyethylene fiber from plastic bag waste

NASA Astrophysics Data System (ADS)

Soekoco, Asril S.; Noerati, Komalasari, Maya; Kurniawan, Hananto, Agus

2017-08-01

This paper presents the characterization of fiber morphology, fiber count and tenacity of polyethylene fiber which is made from plastic bag waste. Recycling plastic bag waste into textile fiber has not developed yet. Plastic bag waste was recycled into fiber by melt spinning using laboratory scale melt spinning equipment with single orifice nozzle and plunger system. The basic principle of melt spinning is by melting materials and then extruding it through small orifice of a spinning nozzle to form fibers. Diameter and cross section shape of Recycled polyethylene fiber were obtained by using scanning electron microscope (SEM) instrumentation. Linear density of the recycled fiber were analyzed by calculation using denier and dTex formulation and The mechanical strength of the fibers was measured in accordance with the ASTM D 3379-75 standard. The cross section of recycled fiber is circular taking the shape of orifice. Fiber count of 303.75 denier has 1.84 g/denier tenacity and fiber count of 32.52 has 3.44 g/denier tenacity. This conditions is affected by the growth of polymer chain alignment when take-up axial velocity become faster. Recycled polyethylene fiber has a great potential application in non-apparel textile.

Synthesis of linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite as an adsorbent for removal of Pb(ΙΙ) from aqueous solutions.

PubMed

Irani, Maryam; Ismail, Hanafi; Ahmad, Zulkifli; Fan, Maohong

2015-01-01

The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy (FTIR), Solid carbon nuclear magnetic resonance spectroscopy (CNMR)), silicon(-29) nuclear magnetic resonance spectroscopy (Si NMR)), and X-ray diffraction spectroscope ((XRD) were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb(II) from the aqueous solution. The Pb(II)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy (FTIR)), scanning electron microscopy (SEM)), and X-ray photoelectron spectroscopy ((XPS)). From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(II). Kinetic studies indicated that the adsorption of Pb(II) followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb(II) ions was 430mg/g. Thus, the waste linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(II) adsorbent. Copyright © 2014. Published by Elsevier B.V.

Effects of Fibers on Color and Translucency Changes of Bulk-Fill and Anterior Composites after Accelerated Aging

PubMed Central

Güven, Mehmet Esad

2018-01-01

The aim of this study was to determine the effects of glass and polyethylene fibers on the color and translucency change of bulk-fill and anterior composites before and after artificial accelerated aging (AAA). Two types of teflon molds were used to fabricate samples which were 13 mm in diameter and, respectively, 2 mm and 4 mm in height. Polyethylene fiber (PF) and glass fiber (GF) were incorporated in the middle of the composite samples. Color and translucency changes of each composite were evaluated before and after AAA with spectrophotometer. ANOVA and Tukey's HSD post hoc statistical analysis were used at a significance level of 0.05. Before AAA (for anterior composites), there were no significant differences in L* and b* parameters among the three groups (p > 0.05); there were no significant differences in L* parameter between PF and GF groups or in TP between GF and control groups (p > 0.05) (for bulk-fill composites). After AAA, there were no significant differences in L* parameter between GF and control groups, in a* parameter between PF and control groups, in b* parameter among all groups, or in TP parameter between GF and control groups (p > 0.05). Fiber reinforcement led to color and TP change in both anterior and bulk-fill resin composites. PMID:29850499

Development of a freeze-tolerant solar water heater using crosslinked polyethylene as a material of construction. Final report, June 18, 1976--October 1, 1977

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

Bradley, J.M.

The feasibility of building a freeze-tolerant absorber for a solar water heater out of carbon-black-reinforced crosslinked polyethylene has been explored. Ten-foot tube specimens made from various crosslinked polyethylene formulations were filled with water at various pressures, and then placed into a deep freeze, then thawed and frozen again for 100 freeze-thaw cycles, or until the tube specimen failed. Tube diameters were measured before and after each freezing to determine how much distention the freezing caused, and how much permanent distention was caused by the strains of repeated freezings. Five tube specimens containing water at as high as 80 psi survivedmore » 100 freeze-thaw cycles. Also, a flat plate collector was fabricated using as absorber surface a single 400 ft tube of carbon-black-reinforced crosslinked polyethylene in the form of a flat spiral coil and this collector was tested for performance at the Los Alamos Scientific Laboratory. The performance test indicates that the absorbancy of such a flat spiral coil to solar radiation is similar to typical black surfaces used on solar absorbers. Thus, it does seem very feasible that domestic water can be directly heated in a solar collector having an absorber made from crosslinked polyethylene, and that this collector can safely withstand at least 100 freeze-thaw cycles.« less

Hybrid Elastin-like Polypeptide–Polyethylene Glycol (ELP-PEG) Hydrogels with Improved Transparency and Independent Control of Matrix Mechanics and Cell Ligand Density

PubMed Central

2015-01-01

Hydrogels have been developed as extracellular matrix (ECM) mimics both for therapeutic applications and basic biological studies. In particular, elastin-like polypeptide (ELP) hydrogels, which can be tuned to mimic several biochemical and physical characteristics of native ECM, have been constructed to encapsulate various types of cells to create in vitro mimics of in vivo tissues. However, ELP hydrogels become opaque at body temperature because of ELP’s lower critical solution temperature behavior. This opacity obstructs light-based observation of the morphology and behavior of encapsulated cells. In order to improve the transparency of ELP hydrogels for better imaging, we have designed a hybrid ELP-polyethylene glycol (PEG) hydrogel system that rapidly cross-links with tris(hydroxymethyl) phosphine (THP) in aqueous solution via Mannich-type condensation. As expected, addition of the hydrophilic PEG component significantly improves the light transmittance. Coherent anti-Stokes Raman scattering (CARS) microscopy reveals that the hybrid ELP-PEG hydrogels have smaller hydrophobic ELP aggregates at 37 °C. Importantly, this hydrogel platform enables independent tuning of adhesion ligand density and matrix stiffness, which is desirable for studies of cell–matrix interactions. Human fibroblasts encapsulated in these hydrogels show high viability (>98%) after 7 days of culture. High-resolution confocal microscopy of encapsulated fibroblasts reveals that the cells adopt a more spread morphology in response to higher RGD ligand concentrations and softer gel mechanics. PMID:25111283

Hybrid elastin-like polypeptide-polyethylene glycol (ELP-PEG) hydrogels with improved transparency and independent control of matrix mechanics and cell ligand density.

PubMed

Wang, Huiyuan; Cai, Lei; Paul, Alexandra; Enejder, Annika; Heilshorn, Sarah C

2014-09-08

Hydrogels have been developed as extracellular matrix (ECM) mimics both for therapeutic applications and basic biological studies. In particular, elastin-like polypeptide (ELP) hydrogels, which can be tuned to mimic several biochemical and physical characteristics of native ECM, have been constructed to encapsulate various types of cells to create in vitro mimics of in vivo tissues. However, ELP hydrogels become opaque at body temperature because of ELP's lower critical solution temperature behavior. This opacity obstructs light-based observation of the morphology and behavior of encapsulated cells. In order to improve the transparency of ELP hydrogels for better imaging, we have designed a hybrid ELP-polyethylene glycol (PEG) hydrogel system that rapidly cross-links with tris(hydroxymethyl) phosphine (THP) in aqueous solution via Mannich-type condensation. As expected, addition of the hydrophilic PEG component significantly improves the light transmittance. Coherent anti-Stokes Raman scattering (CARS) microscopy reveals that the hybrid ELP-PEG hydrogels have smaller hydrophobic ELP aggregates at 37 °C. Importantly, this hydrogel platform enables independent tuning of adhesion ligand density and matrix stiffness, which is desirable for studies of cell-matrix interactions. Human fibroblasts encapsulated in these hydrogels show high viability (>98%) after 7 days of culture. High-resolution confocal microscopy of encapsulated fibroblasts reveals that the cells adopt a more spread morphology in response to higher RGD ligand concentrations and softer gel mechanics.

Experimental investigation on temperature distribution of foamed concrete filled steel tube column under standard fire

NASA Astrophysics Data System (ADS)

Kado, B.; Mohammad, S.; Lee, Y. H.; Shek, P. N.; Kadir, M. A. A.

2018-04-01

Standard fire test was carried out on 3 hollow steel tube and 6 foamed concrete filled steel tube columns. Temperature distribution on the columns was investigated. 1500 kg/m3 and 1800 kg/m3 foamed concrete density at 15%, 20% and 25% load level are the parameters considered. The columns investigated were 2400 mm long, 139.7 mm outer diameter and 6 mm steel tube thickness. The result shows that foamed concrete filled steel tube columns has the highest fire resistance of 43 minutes at 15% load level and low critical temperature of 671 ºC at 25% load level using 1500 kg/m3 foamed concrete density. Fire resistance of foamed concrete filled column increases with lower foamed concrete strength. Foamed concrete can be used to provide more fire resistance to hollow steel column or to replace normal weight concrete in concrete filled columns. Since filling hollow steel with foamed concrete produce column with high fire resistance than unfilled hollow steel column. Therefore normal weight concrete can be substituted with foamed concrete in concrete filled column, it will reduces the self-weight of the structure because of its light weight at the same time providing the desired fire resistance.

Multiscale Modeling of Dewetting Damage in Highly Filled Particulate Composites

NASA Astrophysics Data System (ADS)

Geubelle, P. H.; Inglis, H. M.; Kramer, J. D.; Patel, J. J.; Kumar, N. C.; Tan, H.

2008-02-01

Particle debonding or dewetting constitutes one of the key damage processes in highly filled particulate composites such as solid propellant and other energetic materials. To analyze this failure process, we have developed a multiscale finite element framework that combines, at the microscale, a nonlinear description of the binder response with a cohesive model of the damage process taking place in a representative periodic unit cell (PUC). To relate micro-scale damage to the macroscopic constitutive response of the material, we employ the mathematical theory of homogenization (MTH). After a description of the numerical scheme, we present the results of the damage response of a highly filled particulate composite subjected to a uniaxial macroscopic strain, and show the direct correlation between the complex damage processes taking place in the PUC and the nonlinear macroscopic constitutive response. We also present a detailed study of the PUC size and a comparison between the finite element MTH-based study and a micromechanics model of the dewetting process.

Thermal model development and validation for rapid filling of high pressure hydrogen tanks

DOE PAGES

Johnson, Terry A.; Bozinoski, Radoslav; Ye, Jianjun; ...

2015-06-30

This paper describes the development of thermal models for the filling of high pressure hydrogen tanks with experimental validation. Two models are presented; the first uses a one-dimensional, transient, network flow analysis code developed at Sandia National Labs, and the second uses the commercially available CFD analysis tool Fluent. These models were developed to help assess the safety of Type IV high pressure hydrogen tanks during the filling process. The primary concern for these tanks is due to the increased susceptibility to fatigue failure of the liner caused by the fill process. Thus, a thorough understanding of temperature changes ofmore » the hydrogen gas and the heat transfer to the tank walls is essential. The effects of initial pressure, filling time, and fill procedure were investigated to quantify the temperature change and verify the accuracy of the models. In this paper we show that the predictions of mass averaged gas temperature for the one and three-dimensional models compare well with the experiment and both can be used to make predictions for final mass delivery. Furthermore, due to buoyancy and other three-dimensional effects, however, the maximum wall temperature cannot be predicted using one-dimensional tools alone which means that a three-dimensional analysis is required for a safety assessment of the system.« less

Fast equilibration protocol for million atom systems of highly entangled linear polyethylene chains

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

Sliozberg, Yelena R.; TKC Global, Inc., Aberdeen Proving Ground, Maryland 21005; Kröger, Martin

Equilibrated systems of entangled polymer melts cannot be produced using direct brute force equilibration due to the slow reptation dynamics exhibited by high molecular weight chains. Instead, these dense systems are produced using computational techniques such as Monte Carlo-Molecular Dynamics hybrid algorithms, though the use of soft potentials has also shown promise mainly for coarse-grained polymeric systems. Through the use of soft-potentials, the melt can be equilibrated via molecular dynamics at intermediate and long length scales prior to switching to a Lennard-Jones potential. We will outline two different equilibration protocols, which use various degrees of information to produce the startingmore » configurations. In one protocol, we use only the equilibrium bond angle, bond length, and target density during the construction of the simulation cell, where the information is obtained from available experimental data and extracted from the force field without performing any prior simulation. In the second protocol, we moreover utilize the equilibrium radial distribution function and dihedral angle distribution. This information can be obtained from experimental data or from a simulation of short unentangled chains. Both methods can be used to prepare equilibrated and highly entangled systems, but the second protocol is much more computationally efficient. These systems can be strictly monodisperse or optionally polydisperse depending on the starting chain distribution. Our protocols, which utilize a soft-core harmonic potential, will be applied for the first time to equilibrate a million particle system of polyethylene chains consisting of 1000 united atoms at various temperatures. Calculations of structural and entanglement properties demonstrate that this method can be used as an alternative towards the generation of entangled equilibrium structures.« less

Variational Two-Particle Density Matrix Calculation for the Hubbard Model Below Half Filling Using Spin-Adapted Lifting Conditions

NASA Astrophysics Data System (ADS)

Verstichel, Brecht; van Aggelen, Helen; Poelmans, Ward; Van Neck, Dimitri

2012-05-01

The variational determination of the two-particle density matrix is an interesting, but not yet fully explored technique that allows us to obtain ground-state properties of a quantum many-body system without reference to an N-particle wave function. The one-dimensional fermionic Hubbard model has been studied before with this method, using standard two- and three-index conditions on the density matrix [J. R. Hammond , Phys. Rev. A 73, 062505 (2006)PLRAAN1050-294710.1103/PhysRevA.73.062505], while a more recent study explored so-called subsystem constraints [N. Shenvi , Phys. Rev. Lett. 105, 213003 (2010)PRLTAO0031-900710.1103/PhysRevLett.105.213003]. These studies reported good results even with only standard two-index conditions, but have always been limited to the half-filled lattice. In this Letter, we establish the fact that the two-index approach fails for other fillings. In this case, a subset of three-index conditions is absolutely needed to describe the correct physics in the strong-repulsion limit. We show that applying lifting conditions [J. R. Hammond , Phys. Rev. APLRAAN1050-2947 71, 062503 (2005)10.1103/PhysRevA.71.062503] is the most economical way to achieve this, while still avoiding the computationally much heavier three-index conditions. A further extension to spin-adapted lifting conditions leads to increased accuracy in the intermediate repulsion regime. At the same time, we establish the feasibility of such studies to the more complicated phase diagram in two-dimensional Hubbard models.

Method for shaping polyethylene tubing

NASA Technical Reports Server (NTRS)

Kramer, R. C.

1981-01-01

Method forms polyethylene plastic tubing into configurations previously only possible with metal tubing. By using polyethylene in place of copper or stain less steel tubing inlow pressure systems, fabrication costs are significantly reduced. Polyethylene tubing can be used whenever low pressure tubing is needed in oil operations, aircraft and space applications, powerplants, and testing laboratories.

Highly Conductive and Reliable Copper-Filled Isotropically Conductive Adhesives Using Organic Acids for Oxidation Prevention

NASA Astrophysics Data System (ADS)

Chen, Wenjun; Deng, Dunying; Cheng, Yuanrong; Xiao, Fei

2015-07-01

The easy oxidation of copper is one critical obstacle to high-performance copper-filled isotropically conductive adhesives (ICAs). In this paper, a facile method to prepare highly reliable, highly conductive, and low-cost ICAs is reported. The copper fillers were treated by organic acids for oxidation prevention. Compared with ICA filled with untreated copper flakes, the ICA filled with copper flakes treated by different organic acids exhibited much lower bulk resistivity. The lowest bulk resistivity achieved was 4.5 × 10-5 Ω cm, which is comparable to that of commercially available Ag-filled ICA. After 500 h of 85°C/85% relative humidity (RH) aging, the treated ICAs showed quite stable bulk resistivity and relatively stable contact resistance. Through analyzing the results of x-ray diffraction, x-ray photoelectron spectroscopy, and thermogravimetric analysis, we found that, with the assistance of organic acids, the treated copper flakes exhibited resistance to oxidation, thus guaranteeing good performance.

Effect of organoclay on morphology and properties of linear low density polyethylene and Vietnamese cassava starch biobased blend.

PubMed

Nguyen, D M; Vu, T T; Grillet, Anne-Cécile; Ha Thuc, H; Ha Thuc, C N

2016-01-20

Linear low density polyethylene (LLDPE)/thermal plastic starch (TPS) blend was studied to prepare the biobased nanocomposite material using organoclay nanofil15 (N15) modified by alkilammonium as the reinforced phase. The LLDPE/TPS blend and its nanocomposites were elaborated by melt mixing method at 160 °C for 7 min. And the compounded sample was filmed by blowing method at three different zones of temperature profile which are 160-170-165 °C. The good dispersion of clay in the polymer blend matrix is showed by X-ray diffraction (XRD) and transmission electronic microscopy (TEM), and a semi-exfoliated structure was obtained. The thermal and mechanical properties of materials are enhanced when N15 is added to the mixture. The effect of N15 on morphology and particles size of TPS phase is also investigated. The biodegradation test shows that more than 60% in weight of LLDPE/TPS film is degraded into CO2, H2O, methane and biomass after 5 months in compost soil. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dodecylamine functionalization of carbon nanotubes to improve dispersion, thermal and mechanical properties of polyethylene based nanocomposites

NASA Astrophysics Data System (ADS)

Ferreira, F. V.; Franceschi, W.; Menezes, B. R. C.; Brito, F. S.; Lozano, K.; Coutinho, A. R.; Cividanes, L. S.; Thim, G. P.

2017-07-01

This study presents the effect of dodecylamine (DDA) functionalization of carbon nanotubes (CNTs) on the thermo-physical and mechanical properties of high-density polyethylene (HDPE) based composites. Here, we showed that the functionalization with DDA improved the dispersion of the CNTs as well as the interfacial adhesion with the HDPE matrix via non-covalent interactions. The better dispersion and interaction of CNT in the HDPE matrix as a function of the surface chemistry was correlated with the improved thermo-physical and mechanical properties.

Development and characterisation of chitosan or alginate-coated low density polyethylene films containing Satureja hortensis extract.

PubMed

Rahmani, Bahareh; Hosseini, Hedayat; Khani, Mohammadreza; Farhoodi, Mehdi; Honarvar, Zohreh; Feizollahi, Ehsan; Shokri, Babak; Shojaee-Aliabadi, Saeedeh

2017-12-01

This study aimed to develop novel bilayer films based on alginate, chitosan and low-density polyethylene (LDPE) containing different concentrations of summer savory extract (SSE). The cold atmospheric plasma system was used to increase the surface energy of LDPE. Initially, water contact angle, surface roughness and the functional group of LDPE before and after plasma treatment were investigated. Then physical, mechanical, optical, antioxidant and microstructure properties of plasma-treated and untreated bilayer films and antioxidant films incorporated with SSE were characterized. Results showed that plasma treatment increased oxygen-containing the polar group, surface roughness and decreased water contact angle of LDPE surface (from 90.47° to 48.73°) and in result enhanced adhesion between polysaccharide coating and LDPE. Tensile strength of both alginate and chitosan coated-LDPE increased from 10.096 to 14.372 and 11.513 to 13.459MPa, respectively after plasma pretreatment. However chitosan-based films had lower water solubility. Although, incorporation of SSE into chitosan and alginate coated-LDPE despite slight adverse effects on the physical and mechanical properties of films, it provided antioxidant activity. Chitosan coated-LDPE containing SSE had potential to use as antioxidant food packaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Contamination characteristics and degradation behavior of low-density polyethylene film residues in typical farmland soils of China.

PubMed

Xu, Gang; Wang, Qunhui; Gu, Qingbao; Cao, Yunzhe; DU, Xiaoming; Li, Fasheng

2006-01-01

Low-density polyethylene (LDPE) film residues left in farmlands due to agricultural activities were extensively investigated to evaluate the present pollution situation by selecting the typical areas with LDPE film application, including Harbin, Baoding, and Handan of China. The survey results demonstrated that the film residues were ubiquitous within the investigated areas and the amount reached 2,400-8,200 g ha(-1). Breakage rates of the film residues were almost at the same level in the studied fields. There were relatively small amounts of film residues remaining in neighboring farmland fields without application of LDPE film. The studies showed that the sheets of LDPE residues had the same oxidative deterioration, which was probably due to photodegradation instead of biodegradation. The higher molecular weight components of the LDPE film gradually decreased, which were reflected by the appearance of some small flakes detached from the film bodies. LDPE films in the investigated fields gradually deteriorated and the decomposing levels developed with their left time increasing. The degradation behaviors of LDPE films were confirmed by using Fourier transform infrared (FTIR), scanning electron microscopic (SEM), and gel permeation chromatography analyses.

A New Route of Fucoidan Immobilization on Low Density Polyethylene and Its Blood Compatibility and Anticoagulation Activity

PubMed Central

Ozaltin, Kadir; Lehocký, Marián; Humpolíček, Petr; Pelková, Jana; Sáha, Petr

2016-01-01

Beside biomaterials’ bulk properties, their surface properties are equally important to control interfacial biocompatibility. However, due to the inadequate interaction with tissue, they may cause foreign body reaction. Moreover, surface induced thrombosis can occur when biomaterials are used for blood containing applications. Surface modification of the biomaterials can bring enhanced surface properties in biomedical applications. Sulfated polysaccharide coatings can be used to avoid surface induced thrombosis which may cause vascular occlusion (blocking the blood flow by blood clot), which results in serious health problems. Naturally occurring heparin is one of the sulfated polysaccharides most commonly used as an anticoagulant, but its long term usage causes hemorrhage. Marine sourced sulfated polysaccharide fucoidan is an alternative anticoagulant without the hemorrhage drawback. Heparin and fucoidan immobilization onto a low density polyethylene surface after functionalization by plasma has been studied. Surface energy was demonstrated by water contact angle test and chemical characterizations were carried out by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Surface morphology was monitored by scanning electron microscope and atomic force microscope. Finally, their anticoagulation activity was examined for prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT). PMID:27294915

Polystyrene Foam Products Equation of State as a Function of Porosity and Fill Gas

NASA Astrophysics Data System (ADS)

Mulford, R. N.; Swift, D. C.

2009-12-01

An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam. Differences between air-filled, Ar-blown, and CO2-blown foams are investigated, to estimate the importance of allowing air to react with products of polystyrene decomposition. O2-blown foams are included in some comparisons, to amplify any consequences of reaction with oxygen in air. He-blown foams are included in some comparisons, to provide an extremum of density. Product pressures are slightly higher for oxygen-containing fill gases than for non-oxygen-containing fill gases. Examination of product species indicates that CO2 decomposes at high temperatures.

Grafting of molecularly imprinted polymer to porous polyethylene filtration membranes by plasma polymerization.

PubMed

Cowieson, D; Piletska, E; Moczko, E; Piletsky, S

2013-08-01

An application of plasma-induced grafting of polyethylene membranes with a thin layer of molecularly imprinted polymer (MIP) was presented. High-density polyethylene (HDPE) membranes, "Vyon," were used as a substrate for plasma grafting modification. The herbicide atrazine, one of the most popular targets of the molecular imprinting, was chosen as a template. The parameters of the plasma treatment were optimized in order to achieve a good balance between polymerization and ablation processes. Modified HDPE membranes were characterized, and the presence of the grafted polymeric layer was confirmed based on the observed weight gain, pore size measurements, and infrared spectrometry. Since there was no significant change in the porosity of the modified membranes, it was assumed that only a thin layer of the polymer was introduced on the surface. The experiments on the re-binding of the template atrazine to the membranes modified with MIP and blank polymers were performed. HDPE membranes which were grafted with polymer using continuous plasma polymerization demonstrated the best result which was expressed in an imprinted factor equal to 3, suggesting that molecular imprinting was successfully achieved.

Evaluation of fatigue crack behavior in electron beam irradiated polyethylene pipes

NASA Astrophysics Data System (ADS)

Pokharel, Pashupati; Jian, Wei; Choi, Sunwoong

2016-09-01

A cracked round bar (CRB) fatigue test was employed to determine the slow crack growth (SCG) behavior of samples from high density polyethylene (HDPE) pipes using PE4710 resin. The structure property relationships of fatigue failure of polyethylene CRB specimens which have undergone various degree of electron beam (EB) irradiation were investigated by observing fatigue failure strength and the corresponding fracture surface morphology. Tensile test of these HDPE specimens showed improvements in modulus and yield strength while the failure strain decreased with increasing EB irradiation. The CRB fatigue test of HDPE pipe showed remarkable effect of EB irradiation on number of cycles to failure. The slopes of the stress-cycles to failure curve were similar for 0-100 kGy; however, significantly higher slope was observed for 500 kGy EB irradiated pipe. Also, the cycle to fatigue failure was seen to decrease as with EB irradiation in the high stress range, ∆σ=(16 MPa to 10.8 MPa); however, 500 kGy EB irradiated samples showed longer cycles to failure than the un-irradiated specimens at the stress range below 9.9 MPa and the corresponding initial stress intensity factor (∆KI,0)=0.712 MPa m1/2. The fracture surface morphology indicated that the cross-linked network in 500 kGy EB irradiated PE pipe can endure low dynamic load more effectively than the parent pipe.

Prediction of Liquefaction Potential of Dredge Fill Sand by DCP and Dynamic Probing

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

Alam, Md. Jahangir; Azad, Abul Kalam; Rahman, Ziaur

2008-07-08

From many research it is proved that liquefaction potential of sand is function of mainly relative density and confining pressure. During routine site investigations, high-quality sampling and laboratory testing of sands are not feasible because of inevitable sample disturbance effects and budgetary constraints. On the other hand quality control of sand fill can be done by determining in situ density of sand in layer by layer which is expensive and time consuming. In this paper TRL DCP (Transportation Research Laboratory Dynamic Cone Penetration) and DPL (Dynamic Probing Light) are calibrated to predict the relative density of sand deposit. For thismore » purpose sand of known relative density is prepared in a calibration chamber which is a mild steel cylinder with diameter 0.5 m and height 1.0 m. Relative density of sand is varied by controlling height of fall and diameter of hole of sand discharge bowl. After filling, every time DPL and DCP tests are performed and for every blow the penetration of cone is recorded. N10 is then calculated from penetration records. Thus a database is compiled where N10 and relative densities are known. A correlation is made between N{sub 10} and relative density for two types of sand. A good correlation of N{sub 10} and relative density is found.« less

High-density Two-Dimensional Small Polaron Gas in a Delta-Doped Mott Insulator

PubMed Central

Ouellette, Daniel G.; Moetakef, Pouya; Cain, Tyler A.; Zhang, Jack Y.; Stemmer, Susanne; Emin, David; Allen, S. James

2013-01-01

Heterointerfaces in complex oxide systems open new arenas in which to test models of strongly correlated material, explore the role of dimensionality in metal-insulator-transitions (MITs) and small polaron formation. Close to the quantum critical point Mott MITs depend on band filling controlled by random disordered substitutional doping. Delta-doped Mott insulators are potentially free of random disorder and introduce a new arena in which to explore the effect of electron correlations and dimensionality. Epitaxial films of the prototypical Mott insulator GdTiO3 are delta-doped by substituting a single (GdO)+1 plane with a monolayer of charge neutral SrO to produce a two-dimensional system with high planar doping density. Unlike metallic SrTiO3 quantum wells in GdTiO3 the single SrO delta-doped layer exhibits thermally activated DC and optical conductivity that agree in a quantitative manner with predictions of small polaron transport but with an extremely high two-dimensional density of polarons, ~7 × 1014 cm−2. PMID:24257578

Synergistic effect of calcium stearate and photo treatment on the rate of biodegradation of low density polyethylene spent saline vials.

PubMed

Carol, D; Karpagam, S; Kingsley, S J; Vincent, S

2012-07-01

The biodegradation of spent saline bottles, a low density polyethylene product (LDPE) by two selected Arthrobacter sp. under in vitro conditions is reported. Chemical and UV pretreatment play a vital role in enhancing the rate of biodegradation. Treated LDPE film exhibits a higher weight loss and density when compared to untreated films. Arthrobacter oxydans and Arthrobacter globiformis grew better in medium containing pretreated film than in medium containing untreated film. The decrease in density and weight loss of LDPE was also more for pretreated film when compared to untreated film indicating the affect of abiotic treatment on mechanical properties of LDPE. The decrease in the absorbance corresponding to carbonyl groups and double bonds that were generated during pretreatment suggest that some of the double bonds were cut by Arthrobacter species. Since Arthrobacter sp. are capable of degrading urea, splitting of urea group were also seen in FTIR spectrum indicating the evidence of biodegradation after microbial incubation. The results indicated that biodegradation rate could be enhanced by exposing LDPE to calcium stearate (a pro-oxidant) which acts as an initiator for the oxidation of the polymers leading to a decrease of molecular weight and formation of hydrophilic group. Therefore, the initial step for biodegradation of many inert polymers depends on a photo-oxidation of those polymers. The application in sufficient details with improved procedures utilizing recombinant microorganism with polymer degradation capacity can lead to a better plastic waste management in biomedical field. The present plastic disposal trend of waste accumulation can be minimized with this promising eco-friendly technique.

Surface chemistry changes of weathered HDPE/wood-flour composites studied by XPS and FTIR spectroscopy

Treesearch

Nicole M. Stark; Laurent M. Matuana

2004-01-01

The use of wood-derived fillers by the thermoplastic industry has been growing, fueled in part by the use of wood-fiber–thermoplastic composites by the construction industry. As a result, the durability of wood-fiber– thermoplastic composites after ultraviolet exposure has become a concern. Samples of 100% high-density polyethylene (HDPE) and HDPE filled with 50% wood-...

Photografting of perfluoroalkanes onto polyethylene surfaces via azide/nitrene chemistry

NASA Astrophysics Data System (ADS)

Siegmann, Konstantin; Inauen, Jan; Villamaina, Diego; Winkler, Martin

2017-02-01

The purpose of this study is to render polyethylene surfaces strongly and permanently hydrophobic. Polyethylene is a common plastic and, because of its inertness, difficult to graft. We chose polyethylene as example because of its ubiquity and model character. As graft chains linear perfluoroalkyl residues (-C4F9, -C6F13, -C8F17 and -C10F21) were chosen, and photografting was selected as grafting method. Photolytically generated nitrenes can insert into carbon-hydrogen bonds and are therefore suited for binding to polyethylene. Hydrophobic photo reactive surface modifiers based on azide/nitrene chemistry are designed, synthesized in high yield and characterized. Four new molecules are described. Water contact angles exceeding 110° were achieved on grafted polyethylene. One problem is to demonstrate that the photografted surface modifiers are bound covalently to the polyethylene. Abrasion tests show that all new molecules, when photografted to polyethylene, have a higher abrasion resistance than a polyethylene surface coated with a long-chain perfluoroalkane. Relative abrasion resitances of 1.4, 2.0, 2.1 and 2.5 compared to the fluoroalkane coating were obtained for the four compounds. An abrasion model using ice is developed. Although all four compounds have the same λmax of 266 nm in acetonitrile solution, their molar extincition coefficients increase from 1.6·104 to 2.2·104 with increasing length of the fluorotelomer chain. Exitonic coupling of the chromophores of the surface modifiers is observed for specific molecules in the neat state. A linear correlation of water contact angle with fluorine surface content, as measured by photoelectron spectroscopy, in grafted polyethylene surfaces is established.

Estimating the density of honeybee colonies across their natural range to fill the gap in pollinator decline censuses.

PubMed

Jaffé, Rodolfo; Dietemann, Vincent; Allsopp, Mike H; Costa, Cecilia; Crewe, Robin M; Dall'olio, Raffaele; DE LA Rúa, Pilar; El-Niweiri, Mogbel A A; Fries, Ingemar; Kezic, Nikola; Meusel, Michael S; Paxton, Robert J; Shaibi, Taher; Stolle, Eckart; Moritz, Robin F A

2010-04-01

Although pollinator declines are a global biodiversity threat, the demography of the western honeybee (Apis mellifera) has not been considered by conservationists because it is biased by the activity of beekeepers. To fill this gap in pollinator decline censuses and to provide a broad picture of the current status of honeybees across their natural range, we used microsatellite genetic markers to estimate colony densities and genetic diversity at different locations in Europe, Africa, and central Asia that had different patterns of land use. Genetic diversity and colony densities were highest in South Africa and lowest in Northern Europe and were correlated with mean annual temperature. Confounding factors not related to climate, however, are also likely to influence genetic diversity and colony densities in honeybee populations. Land use showed a significantly negative influence over genetic diversity and the density of honeybee colonies over all sampling locations. In Europe honeybees sampled in nature reserves had genetic diversity and colony densities similar to those sampled in agricultural landscapes, which suggests that the former are not wild but may have come from managed hives. Other results also support this idea: putative wild bees were rare in our European samples, and the mean estimated density of honeybee colonies on the continent closely resembled the reported mean number of managed hives. Current densities of European honeybee populations are in the same range as those found in the adverse climatic conditions of the Kalahari and Saharan deserts, which suggests that beekeeping activities do not compensate for the loss of wild colonies. Our findings highlight the importance of reconsidering the conservation status of honeybees in Europe and of regarding beekeeping not only as a profitable business for producing honey, but also as an essential component of biodiversity conservation.

Neutron diffraction and thermoelectric properties of indium filled In x Co 4 Sb 12 ( x=0.05, 0.2) and indium cerium filled Ce 0.05 In 0.1 Co 4 Sb 12 skutterudites: Neutron diffraction and thermoelectric properties of In/Ce skutterudites

DOE PAGES

Sesselmann, Andreas; Klobes, Benedikt; Dasgupta, Titas; ...

2015-09-25

The thermoelectric properties on polycrystalline single (In) and double filled (Ce, In) skutterudites are characterized between 300 and 700 K. Powder neutron diffraction measurements of the skutterudite compositions In xCo 4Sb 12 (x= 0.05, 0.2) and Ce 0.05In 0.1Co 4Sb 12 as a function of temperature (12- 300 K) were carried out, which gives more insight into the structural data of single and double-filled skutterudites. Our results show that due to the annealing treatment, a Sb deficiency is detectable and thus verifies defects at the Sb lattice site of the skutterudite. Furthermore, we show by electron microprobe analysis that amore » considerable amount of indium is lost during synthesis and post-processing for the single indium filled samples, but not for the double cerium and indium skutterudite sample. The double-filled skutterudite is superior to the single-filled skutterudite composition due to a higher charge carrier density, a comparable lattice thermal resistivity, and a higher density of states effective mass in our experiment. Finally, we obtained a significantly higher Einstein temperature for the double-filled skutterudite composition in comparison to the single-filled species, which reflects the high sensitivity due to filling of the void lattice position within the skutterudite crystal.« less

Pre-oxidation of low-density polyethylene (LDPE) by ultraviolet light (UV) promotes enhanced degradation of LDPE in soil.

PubMed

Tribedi, Prosun; Dey, Samrat

2017-11-09

Polyethylene represents nearly 64% of all the synthetic plastics produced and are mainly used for domestic and industrial applications. Their extensive use poses a serious environmental threat because of their non-biodegradable nature. Among all the polyethylene remediation strategies, in situ bioremediation happens to be the safest and efficient one. In the current study, efforts had been given to compare the extent of LDPE degradation under UV-treated and UV-untreated conditions by soil microcosm. Landfill soil was collected and UV-treated and UV-untreated LDPE were added separately to the soil following incubation under similar conditions. Electron microscopic images as well as the weight loss and the tensile strength results clearly revealed that UV-treated LDPE showed better degradation than the non-treated ones in soil. To elucidate the mechanism of this enhanced biodegradation, the bond spectra of differentially treated LDPE were analyzed by FTIR. The results obtained from bond spectra studies revealed that UV treatment increases both carbonyl and terminal double-bond index of the LDPE, thereby making it highly susceptible for microbial degradation. Moreover, incubation of UV-treated LDPE with soil favors better adherence of metabolically active and significantly higher number of microorganisms on it. Taken together, all these results demonstrate the higher microbial association and their better metabolic potential to the UV-treated LDPE that lead to enhanced degradation of the LDPE by the soil microorganisms.

New developments in the field of high voltage and extra-high voltage cables

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

Jocteur, R.

1990-04-01

In this paper, the author presents the developments in progress at the present time in France concerning the high voltage (HV) and extra-high voltage (EHV) cables with synthetic insulation and their accessories up to the 500 kV range. The authors have adopted a maximum operating field strength approaching 16 kV/mm (405 V/mil) for low density polyethylene (LDPE) insulated cables. The on-going studies should allow to bring the maximum operating field strength for crosslinked polyethylene (XLPE) insulation from 7 to 10 kV/mm (180 to 255 V/mil) and cables could be manufactured more economically with this material.

The morphology of blends of linear and branched polyethylenes in solid state by SANS

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

Wignall, G.D.; Londono, J.D.; Alamo, R.G.

1994-12-31

In a previous paper the authors have shown how small-angle neutron and X-ray scattering (SANS, SAXS) can be used to determine the melt compatibility of different polyolefins, including high-density (HD), low-density (LD), and linear low density (LLD) polyethylene. Such blends have attained widespread commercial applications, though the understanding of the mechanical and melt-flow properties of such blends has hitherto been handicapped by the absence of a consensus concerning the degree of mixing of the components, both in the melt and solid states. Recent SANS data indicate that for HDPE/LDPE blends, the melt is homogeneous for all compositions after proper accountingmore » for H/D isotope effects. In this publication the authors use complementary SANS, DSC, and SAXS to examine the types of morphologies and the different degrees of phase separation which may arise via crystallization effects on cooling from a homogeneous melt.« less

The morphology of blends of linear and branched polyethylenes in solid state by SANS

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

Wignall, G.D.; Londono, J.D.; Alamo, R.G.

1995-03-01

In a previous paper, the authors have shown how small-angle neutron and X-ray scattering (SANS, SAXS) can be used to determine the melt compatibility of different polyolefins, including high-density (HD), low-density (LD), and linear low density (LLD) polyethylene. Such blends have attained widespread commercial applications, though the understanding of the mechanical and melt-flow properties of such blends has hitherto been handicapped by the absence of a consensus concerning the degree of mixing of the components, both in the melt and solid states. Recent SANS data indicate that for HDPE/LDPE blends, the melt is homogeneous for all compositions after proper accountingmore » for H/D isotope effects. In this publication the authors use complementary SANS, DSC, and SAXS to examine the types of morphologies and the different degrees of phase separation which may arise via crystallization effects on cooling from a homogeneous melt.« less

A promising high-energy-density material.

PubMed

Zhang, Wenquan; Zhang, Jiaheng; Deng, Mucong; Qi, Xiujuan; Nie, Fude; Zhang, Qinghua

2017-08-03

High-energy density materials represent a significant class of advanced materials and have been the focus of energetic materials community. The main challenge in this field is to design and synthesize energetic compounds with a highest possible density and a maximum possible chemical stability. Here we show an energetic compound, [2,2'-bi(1,3,4-oxadiazole)]-5,5'-dinitramide, is synthesized through a two-step reaction from commercially available reagents. It exhibits a surprisingly high density (1.99 g cm -3 at 298 K), poor solubility in water and most organic solvents, decent thermal stability, a positive heat of formation and excellent detonation properties. The solid-state structural features of the synthesized compound are also investigated via X-ray diffraction and several theoretical techniques. The energetic and sensitivity properties of the explosive compound are similar to those of 2, 4, 6, 8, 10, 12-(hexanitrohexaaza)cyclododecane (CL-20), and the developed compound shows a great promise for potential applications as a high-energy density material.High energy density materials are of interest, but density is the limiting factor for many organic compounds. Here the authors show the formation of a high density energetic compound from a two-step reaction between commercially available compounds that exhibit good heat thermal stability and detonation properties.

Resistance to densification, tensile strength and capsule-filling performance of some pharmaceutical diluents.

PubMed

Nikolakakis, I; Aragon, O B; Malamataris, S

1998-07-01

The purpose of this study was to compare some indicators of capsule-filling performance, as measured by tapped density under different conditions, and elucidate possible quantitative relationships between variation of capsule fill-weight (%CV) and gravitational and inter-particle forces (attractive or frictional) derived from measurements of particle size, true density, low compression and tensile strength. Five common pharmaceutical diluents (lactose, maize starch, talc, Emcocel and Avicel) were investigated and two capsule-filling methods (pouring powder and dosator nozzle) were employed. It was found that for the pouring-type method the appropriateness of Hausner's ratio (HR), Carr's compressibility index (CC%) and Kawakita's constant (alpha) as indicators of capsule fill-weight variation decreases in the order alpha > CC% > HR; the appropriateness of these indicators also decreases with increasing cylinder size and with impact velocity during tapping. For the dosator-type method the appropriateness of the indicators decreases in the order HR > CC% > alpha, the opposite of that for the pouring-type method; the appropriateness of the indicators increases with decreasing cylinder size and impact velocity. The relationship between %CV and the ratio of inter-particle attractive to gravitational forces calculated from measurements of particle size and true density (Fvdw/Wp) was more significant for the pouring-type capsule-filling method. For the dosator-type method a significant relationship (1% level) was found between %CV and the product of Fvdw/Wp and a function expressing the increase, with packing density (p(f)), in the ratio of frictional to attractive inter-particle forces derived from compression (P) and tensile-strength (T) testing, d(log(P/T))/d(p(f)). The value of tapped density in predictions of capsule-filling performance is affected by the testing conditions in a manner depending on the filling method applied. For the pouring-type method predictions

Statistical mechanics of high-density bond percolation

NASA Astrophysics Data System (ADS)

Timonin, P. N.

2018-05-01

High-density (HD) percolation describes the percolation of specific κ -clusters, which are the compact sets of sites each connected to κ nearest filled sites at least. It takes place in the classical patterns of independently distributed sites or bonds in which the ordinary percolation transition also exists. Hence, the study of series of κ -type HD percolations amounts to the description of classical clusters' structure for which κ -clusters constitute κ -cores nested one into another. Such data are needed for description of a number of physical, biological, and information properties of complex systems on random lattices, graphs, and networks. They range from magnetic properties of semiconductor alloys to anomalies in supercooled water and clustering in biological and social networks. Here we present the statistical mechanics approach to study HD bond percolation on an arbitrary graph. It is shown that the generating function for κ -clusters' size distribution can be obtained from the partition function of the specific q -state Potts-Ising model in the q →1 limit. Using this approach we find exact κ -clusters' size distributions for the Bethe lattice and Erdos-Renyi graph. The application of the method to Euclidean lattices is also discussed.

Utilization of polyethylene terephthalate (PET) in bituminous mixture for improved performance of roads

NASA Astrophysics Data System (ADS)

Ahmad, A. F.; Razali, A. R.; Razelan, I. S. M.; Jalil, S. S. A.; Noh, M. S. M.; Idris, A. A.

2017-05-01

Plastic bottle for recycling can be found from the household waste stream, and most of them are made from Polyethylene Terephthalate. In this research, PET is utilized to explore the potential prospects to upgrade asphalt mixture properties. The objectives include deciding the best measure of PET to be used. For experimental, Marshall mix design was utilized to determine the ideal bitumen binder content and to test the modified mixture properties. The samples were created per the requirement for aggregate course wearing (ACW14) using the Standard Specification of Road Work (SSRW) in Malaysia. 20 samples were utilized to determine the binder content, and 30 samples were used to research the impact of modifying asphalt mixtures. 2%, 5%, 10%, 15% and 20% of PET by weight of the optimum binder content (4.8%) were tested. Optimum PET content is 10%, and the result shows a good stability with 16.824kN, 2.32g/cm3 bulk density, void filled with bitumen (VFB) with 71.35%, flow with 3.2248mm, air void (AV) with 4.53%, and void of mineral aggregate (VMA) with 15.15%. The outcomes showed that PET modifier gives better engineering properties. Therefore, 10% of PET by the weight of binder content was suggested as the best amount of the modifier.

Electric field directed assembly of high-density microbead arrays†

PubMed Central

Barbee, Kristopher D.; Hsiao, Alexander P.; Heller, Michael J.; Huang, Xiaohua

2010-01-01

We report a method for rapid, electric field directed assembly of high-density protein-conjugated microbead arrays. Photolithography is used to fabricate an array of micron to sub-micron-scale wells in an epoxy-based photoresist on a silicon wafer coated with a thin gold film, which serves as the primary electrode. A thin gasket is used to form a microfluidic chamber between the wafer and a glass coverslip coated with indium-tin oxide, which serves as the counter electrode. Streptavidin-conjugated microbeads suspended in a low conductance buffer are introduced into the chamber and directed into the wells via electrophoresis by applying a series of low voltage electrical pulses across the electrodes. Hundreds of millions of microbeads can be permanently assembled on these arrays in as little as 30 seconds and the process can be monitored in real time using epifluorescence microscopy. The binding of the microbeads to the gold film is robust and occurs through electrochemically induced gold-protein interactions, which allows excess beads to be washed away or recycled. The well and bead sizes are chosen such that only one bead can be captured in each well. Filling efficiencies greater than 99.9% have been demonstrated across wafer-scale arrays with densities as high as 69 million beads per cm2. Potential applications for this technology include the assembly of DNA arrays for high-throughput genome sequencing and antibody arrays for proteomic studies. Following array assembly, this device may also be used to enhance the concentration-dependent processes of various assays through the accelerated transport of molecules using electric fields. PMID:19865735

Phase behavior of blends of linear and branched polyethylenes in the molten and solid states by small-angle neutron scattering

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

Alamo, R.G.; Mandelkern, L.; Londono, J.D.

1994-01-17

The state of mixing in blends of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) in the liquid and solid state has been examined by small-angle neutron scattering (SANS) in conjunction with deuterium labeling. In the melt, SANS results indicate that HDPE/LDPE mixtures from a single-phase solution for all concentrations, including blends containing high volume fractions ([phi] > 0.5) of branched polymer, for which multiphase melts have previously been suggested. Proper accounting for isotope effects is essential to avoid artifacts, because the H/D interaction parameter is sufficiently large ([sub [chi]HD] [approximately] 4 [times] 10[sup [minus]4]) to cause phase separation in themore » amorphous state for molecular weights (MW) >150,000. In the solid state, after slow cooling from the melt ([approximately]0.75 C/min), the HDPE/LDPE system shows extensive segregation into separate domains [approximately]100--300 [angstrom] in size. Both the shape and magnitude of the absolute scattering cross section are consistent with the conclusion that the components are extensively segregated into separate lamellae. Two-peak melting curves obtained for such mixtures support the SANS interpretation, and the segregation of components in the solid state is therefore a consequence of crystallization mechanisms rather than incompatibility in the liquid state.« less

High density harp for SSCL linac

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