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Sample records for high density polyethylene

  1. Vacuum Outgassing of High Density Polyethylene

    SciTech Connect

    Dinh, L N; Sze, J; Schildbach, M A; Chinn, S C; Maxwell, R S; Raboin, P; McLean II, W

    2008-08-11

    A combination of thermogravimetric analysis (TGA) and temperature programmed decomposition (TPD) was employed to identify the outgassing species, the total amount of outgassing, and the outgassing kinetics of high density polyethylene (HDPE) in a vacuum environment. The isoconversional kinetic analysis was then used to analyze the outgassing kinetics and to predict the long-term outgassing of HDPE in vacuum applications at ambient temperature. H{sub 2}O and C{sub n}H{sub x} with n as high as 9 and x centering around 2n are the major outgassing species from solid HDPE, but the quantities evolved can be significantly reduced by vacuum baking at 368 K for a few hours prior to device assembly.

  2. THz-Spectroscopy on High Density Polyethylene with Different Crystallinity

    NASA Astrophysics Data System (ADS)

    Sommer, Stefan; Raidt, Thomas; Fischer, Bernd M.; Katzenberg, Frank; Tiller, Jörg C.; Koch, Martin

    2016-02-01

    The different crystallinity states of high density polyethylene (PE-HD) are investigated using THz time-domain spectroscopy by exploiting the complex permittivity at a frequency range from 0.5 up to 3.5 THz. We found that samples with different crystallinity can be distinguished by comparing the material specific refractive index ( n) or rather the linked complex part of the permittivity (∈ ' '). Correlating the calorimetrically determined degrees of crystallinity with the absolute values of the refractive index and the specific absorption peak at 2.18 THz, respectively, suggests in both cases a linear correlation.

  3. Catalytic degradation of high density polyethylene using zeolites.

    PubMed

    Zaggout, F R; al Mughari, A R; Garforth, A

    2001-01-01

    Plastic wastes, which cause a serious environmental problem in urban areas, can serve as sources of energy. Catalytic treatment of High Density Polyethylene (HDPE) has shown that the degradation of HDPE resulted in the production of a stream of gaseous hydrocarbons varied in the range C1-C8. The degradation was carried out using diluted forms of zeolites ZSM-5, USY and Mordenite (MORD) using a fluidized bed reactor (FBR). Effect of coke formation on the activity of the catalysts was screened by thermogravimetric (TGA). ZSM-5 showed a significant resistance to deactivation because of the nature of its small pore size compared with USY and MORD. PMID:11382018

  4. Analyzing and improving viscoelastic properties of high density polyethylene

    NASA Astrophysics Data System (ADS)

    Ahmed, Reaj Uddin

    2011-12-01

    High Density Polyethylene (HDPE) is closely packed, less branched polyethylene having higher mechanical properties, chemical resistance, and heat resistance than Low Density Polyentylene (LDPE). Better properties and cost effectiveness make it an important raw material over LDPE in packaging industries. Stacked containers made of HDPE experience static loading and deformation strain during their storage period in a warehouse. As HDPE is a viscoelastic material, dimensional stability of stacked HDPE containers depends on time dependent properties such as creep and stress relaxation. Now, light weighting is a driving force in packaging industries, which results in lower production costs but performance of the product becomes a challenge. Proper understanding of the viscoelastic properties of HDPE, with relevant FE simulation can facilitate improved designs. This research involves understanding and improving viscoelastic properties, creep behavior, and stress relaxation of HDPE. Different approaches were carried out to meet the objectives. Organic filler CaCO3 was added to HDPE at increasing weight fractions and corresponding property changes were investigated. Annealing heat treatments were also carried out for potential property improvements. The effect of ageing was also investigated on both annealed and non annealed HDPE. The related performance of different water bottles against squeeze pressure was also characterized. Both approaches, incorporation of CaCO3 and annealing, showed improvements in the properties of HDPE over neat HDPE. This research aids finding the optimum solution for improving viscoelastic properties, stress relaxation, and creep behavior of HDPE in manufacturing.

  5. Scoping study. High density polyethylene (HDPE) in salstone service

    SciTech Connect

    Phifer, Mark A.

    2005-02-18

    An evaluation of the use of high density polyethylene (HDPE) geomembranes in Saltstone service has been conducted due to the potential benefits that could be derived from such usage. HDPE is one of the simplest hydrocarbon polymers and one of the most common polymers utilized in the production of geomembranes, which means that its costs are relatively low. Additionally, HDPE geomembranes have an extremely low permeability and an extremely low water vapor diffusional flux, which means that it is a good barrier to contaminant transport. The primary consideration in association with HDPE geomembranes in Saltstone service is the potential impact of Saltstone on the degradation of the HDPE geomembranes. Therefore, the evaluation documented herein has primarily focused upon the potential HDPE degradation in Saltstone service.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  7. Properties of high density polyethylene – Paulownia wood flour composites via injection molding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Paulownia wood (PW) flour is evaluated as a bio-based fiber reinforcement. Composites of high density polyethylene (HDPE), 25% by weight of PW, and either 0% or 5% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding followed by injection molding. Molded test composite...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  10. 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.

  11. 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.

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

    SciTech Connect

    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 from 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.

  13. Wood plastic composites based on microfibrillar blends of high density polyethylene/poly(ethylene terephthalate).

    PubMed

    Lei, Yong; Wu, Qinglin

    2010-05-01

    High-melting-temperature poly(ethylene terephthalate) (PET) was successfully introduced into wood plastic composites through a two-step reactive extrusion technology. Wood flour was added into pre-prepared PET/high density polyethylene (HDPE) microfibrillar blends (MFBs) in the second extrusion at the temperature for processing HDPE. Addition of 25% in situ formed PET microfibers obviously increased the mechanical properties of HDPE, and more significant enhancement by the in situ formed recycled PET microfibers was observed for the recycled HDPE. Adding 2% E-GMA improved the compatibility between matrix and microfibers in MFBs, resulting further enhanced mechanical properties. The subsequent addition of 40% wood flour did not influence the size and morphology of PET microfibers, and improved the comprehensive mechanical properties of MFBs. The wood flour increased the crystallinity level of HDPE in the compatibilized MFB in which PET phase did not crystallize. The storage modulus of MFB was greatly improved by wood flour. PMID:20100654

  14. 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.

  15. 77 FR 13387 - Pipeline Safety: Notice to Operators of Driscopipe® 8000 High Density Polyethylene Pipe of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-06

    ... 8000 High Density Polyethylene Pipe of the Potential for Material Degradation AGENCY: Pipeline and.... SUMMARY: PHMSA is issuing this advisory bulletin to alert operators using Driscopipe 8000 High Density... authorities. II. Advisory Bulletin (ADB-2012-03) To: Operators using Driscopipe 8000 High Density...

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

    USGS Publications Warehouse

    Kazyak, David C.; Zydlewski, Joseph

    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.

  17. Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography.

    PubMed

    Prabhu, K N; Brüll, R; Macko, T; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2015-11-01

    High-temperature two-dimensional liquid chromatography (HT 2D-LC) using HT-HPLC as first dimension and HT-SEC as second dimension holds enormous potential to investigate the distribution according to molar mass and chemical composition of bimodal high density polyethylene (BiHDPE), as it avoids drawbacks of crystallization-based techniques. In this study, we have stepwise optimized the chromatographic parameters of 1D, comprising gradient slope and temperature, using model homo- and copolymers of ethylene with the aim to minimize the impact of molar mass on the compositional separation. Then the HT-HPLC was hyphenated to HT-SEC and optimum conditions for the volume of the sample transfer loop were probed with regard to the resolution of BiHDPE into the individual constituents HDPE and LLDPE. A particular important aspect was the use of infrared (IR) detection, and the demands it puts on the chromatographic aspects: We have shown that IR detection can be successfully applied in HT 2D-LC of BiHDPE, which is broadly distributed with regard to short chain branching and molar mass, only when the separation in 2D is optimized with regard to chromatographic resolution. As final result a bimodality is evident in the contour and the 3D surface plots as well as in both HPLC and SEC projections generated from HT 2D-LC. PMID:26435312

  18. Statistical modeling of crack growth and reliability assessment of high-density polyethylene

    SciTech Connect

    Qureshi, F.S.; Sheikh, A.K.; Khan, Z.; Ahmad, M.

    1999-06-01

    In this work, a statistical evaluation of the crack-growth process in high-density polyethylene (HDPE) was carried out. The specimens were compression molded from virgin, molding-grade HDPE. Edge-notched specimens for replicate fatigue testing were prepared from compression-molded sheets. Fatigue test results were then analyzed, and it is shown that if the crack-growth process can be characterized as a random process following a power-law-type behavior, then the time to reach a critical crack length will be distributed according to an inverted lognormal model.

  19. Determination of Thermal Properties and Morphology of Eucalyptus Wood Residue Filled High Density Polyethylene Composites

    PubMed Central

    Mengeloglu, Fatih; Kabakci, Ayse

    2008-01-01

    Thermal behaviors of eucalyptus wood residue (EWR) filled recycled high density polyethylene (HDPE) composites have been measured applying the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Morphology of the materials was also studied using scanning electron microscope (SEM). Addition of the EWR into the recycled HDPE matrix reduced the starting of degradation temperature. EWR filled recycled HDPE had two main decomposition peaks, one for EWR around 350 °C and one for recycled HDPE around 460 °C. Addition of EWR did not affect the melting temperature of the recycled HDPE. Morphological study showed that addition of coupling agent improved the compatibility between wood residue and recycled HDPE. PMID:19325736

  20. 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.

  1. Comparison between decrosslinking of crosslinked high and low density polyethylenes via ultrasonically aided extrusion

    NASA Astrophysics Data System (ADS)

    Isayev, Avraam I.; Huang, Keyuan

    2016-03-01

    Among various crosslinked plastics, recycling of crosslinked polyethylenes is of a great importance due to the presence of a three-dimensional network. To solve this problem, novel environmentally friendly technologies for decrosslinking of the crosslinked polymers are developed based on ultrasonically assisted single (SSE) and twin screw (TSE) extruders. In particular, decrosslinking of peroxide crosslinked high-density polyethylene (XHDPE) and low-density polyethylene (XLDPE) by means of an ultrasonic SSE and TSE is investigated. Barrel pressure, die pressure and ultrasonic power consumption during extrusion are recorded. Swelling, rheological, thermal analysis and tensile tests are used to elucidate the structure-property relationships of decrosslinked XHDPE and XLDPE. The frequency dependencies of the storage and loss moduli, complex viscosity and tangent loss of XHDPE, XLDPE and their decrosslinked networks are described by the post critical gel model with its parameters correlated with gel fraction and crosslink density. The dynamic, thermal and tensile properties of the decrosslinked XHDPE and XLDPE are greatly affected by the type of preferential bond breakage. It was found that the decrosslinking of XLDPE is more difficult than that of XHDPE. An analysis based on the Horikx function reveals a highly preferential breakage of crosslinks during decrosslinking of XHDPE. In contrast to decrosslinking of XHDPE, the presence of long-chain branching in XLDPE is found to lead to the breakage of its main chains during decrosslinking. An improvement and a reduction in mechanical properties of decrosslinked XHDPE and XLDPE are, respectively, observed in comparison with those of virgin XHDPE and XLDPE.

  2. Product distribution modelling in the thermal pyrolysis of high density polyethylene.

    PubMed

    Elordi, G; Lopez, G; Olazar, M; Aguado, R; Bilbao, J

    2007-06-18

    The thermal fast pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor in the 450-715 degrees C range, and individual products have been monitored with the aim of obtaining kinetic data for the design and simulation of this process at large scale. Kinetic schemes have been proposed in order to explain both the results obtained in the laboratory plant and those obtained in the literature by other authors operating at laboratory and larger scale. Discrimination has been carried out based on the contribution of the variance of model parameters (stepwise regression) to the total variance explained by the model. The models based on that of Westerhout et al. [R.W.J. Westerhout, J. Waanders, W.P.M. Van Swaaij, Recycling of polyethene and polypropene in a novel bench-scale rotating cone reactor by high-temperature pyrolysis. Ind. Eng. Chem. Res. 37 (6) (1998) 2293-2300] do not adequately predict the experimental results, especially those corresponding to aromatics and char, which is probably due to the very short residence times attained in the conical spouted bed and, consequently, to the lower yields of aromatics and char. The model of best fit is the one where polyethylene degrades to give gas, liquid (oil) and wax fractions. Furthermore, the latter undergoes secondary reactions to give liquid and aromatics, which in turn produce more char. PMID:17337118

  3. 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.

  4. Reaction between Steel-Making Slag and Carbonaceous Materials While Mixing with High Density Polyethylene

    NASA Astrophysics Data System (ADS)

    Hong, Lan; Sahajwalla, Veena

    2016-01-01

    Since the beginning of the extensive applications in numerous high temperature processes such as iron- and steel-making, coke-making etc. partly in the place of coke, the investigation into the reaction mechanism of waste plastics has become increasingly necessary. In this paper a fundamental study on the behavior of a typical component of waste plastics, high density polyethylene (HDPE), in a mixture with coke at a 1:1 ratio in mass base was conducted during the reaction with iron oxide in steel-making slag at 1823 K and was compared with coke and graphite. The reaction mechanism of carbonaceous materials was analyzed based on the contents of CO and CO2 in the off-gas monitored by an infrared (IR) gas analyzer. It is clear from the results that the reaction of HDPE and coke mixture with steel-making slag approached equilibrium of the Boudouard reaction more quickly and closely than coke or graphite.

  5. Gasification of biomass/high density polyethylene mixtures in a downdraft gasifier.

    PubMed

    García-Bacaicoa, P; Mastral, J F; Ceamanos, J; Berrueco, C; Serrano, S

    2008-09-01

    In this work, an experimental study of the thermal decomposition of mixtures of wood particles and high density polyethylene in different atmospheres has been carried out in a downdraft gasifier with a nominal processing capacity of 50 kg/h. The main objective was to study the feasibility of the operation of the gasification plant using mixtures and to investigate the characteristics of the gas obtained. In order to do so, experiments with biomass only and with mixtures with up to 15% HDPE have been carried out. The main components of the gas generated are N(2) (50%), H(2) (14%), CO (9-22%) and CO(2) (7-17%) and its relatively high calorific value was adequate for using it in an internal combustion engine generator consisting of a modified diesel engine coupled with a 25 kV A alternator. PMID:18083026

  6. 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.

  7. 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.

  8. A multivariate analysis of the effects of multiple extrusion cycles on high density polyethylene bottle resin

    SciTech Connect

    Zahavich, A.

    1995-10-01

    The recycling of post consumer (PCR) high density polyethylene (HDPE) blow molding resins has increased dramatically over the past 5 years. The focus of research for this product has been on specific performance and processing properties such as tensile or melt strength. Little work has been done on studying the entire range of properties as a whole, particularly in the area of multiple extrusions. This paper describes a designed experiment study where multivariate statistical techniques were used to compare 2 HDPE and 2 HDPE PCR materials, in terms of changes in a number of properties with exposure to multiple extrusions. Virgin homopolymer and copolymer resins and PCR, mixed color bottle and natural, were passed through 4 extrusion cycles. Viscosity, swell, melt strength, crystallinity, polydispersity and ESCR properties were studied using principal component analysis.

  9. Interfacial thermal resistance between high-density polyethylene (HDPE) and sapphire

    NASA Astrophysics Data System (ADS)

    Zheng, Kun; Zhu, Jie; Ma, Yong-Mei; Tang, Da-Wei; Wang, Fo-Song

    2014-10-01

    To improve the thermal conductivity of polymeric composites, the numerous interfacial thermal resistance (ITR) inside is usually considered as a bottle neck, but the direct measurement of the ITR is hardly reported. In this paper, a sandwich structure which consists of transducer/high density polyethylene (HDPE)/sapphire is prepared to study the interface characteristics. Then, the ITRs between HDPE and sapphire of two samples with different HDPE thickness values are measured by time-domain thermoreflectance (TDTR) method and the results are ~ 2 × 10-7 m2·K·W-1. Furthermore, a model is used to evaluate the importance of ITR for the thermal conductivity of composites. The model's analysis indicates that reducing the ITR is an effective way of improving the thermal conductivity of composites. These results will provide valuable guidance for the design and manufacture of polymer-based thermally conductive materials.

  10. The electrical properties of schungite-containing compositions based on polypropylene and high-density polyethylene

    NASA Astrophysics Data System (ADS)

    Rozhkov, S. S.; Kedrina, N. F.; Timofeeva, V. A.; Chmutin, I. A.; Ryvkina, N. G.; Solov'eva, A. B.

    2007-11-01

    Variations in the dc and ac conductivities of schungite-containing compositions based on polypropylene-high-density polyethylene (PP-PE) blends were studied depending on the composition of the polymeric blend, the volume concentration of the filler, and the order of the introduction of the composition components during the preparation of compositions. It was shown that the conductivities of the compositions could depend on the order of the introduction of the components. The structure of initial and schungite-containing PP-PE blends of different compositions was studied by atomic-force microscopy. It was shown that the structure of the compositions depended on the composition of the initial PP-PE blends and the order of the introduction of the components into schungite-filled PP-PE compositions.

  11. Load effect on an SMS fiber structure embedded in a high-density polyethylene

    NASA Astrophysics Data System (ADS)

    Puspita, Ika; Rahmah, Fitri; Hatta, Agus M.; Koentjoro, Sekartedjo

    2015-01-01

    In this paper, a load effect on a singlemode-multimode-singlemode (SMS) fiber structure embedded in a high-density polyethylene (HDPE) was investigated numerically and experimentally. It was modelled that the applied load induces a longitudinal strain on the HDPE and accordingly affects the SMS fiber structure's parameters. It was calculated the output power of the SMS fiber structure using a graded index multimode fiber (MMF) due to the applied strain from 0 to 4000 N. The experimental result shows that for the MMF length of 105 mm, the output power has monotonically increasing for an applied load range from 1700 to 4000 N with a sensitivity of 1.18 x 10-3 dBm/N. This configuration of SMS fiber structure embedded in the HDPE is potential for a load sensor.

  12. Friction and wear of hydroxyapatite reinforced high density polyethylene against the stainless steel counterface.

    PubMed

    Wang, M; Chandrasekaran, M; Bonfield, W

    2002-06-01

    Hydroxyapatite (HA) reinforced high density polyethylene (HDPE) was invented as a biomaterial for skeletal applications. In this investigation, tribological properties (e.g. wear rate and coefficient of friction) of unfilled HDPE and HA/HDPE composites were evaluated against the duplex stainless steel in dry and lubricated conditions, with distilled water or aqueous solutions of proteins (egg albumen or glucose) being lubricants. Wear tests were conducted in a custom-built test rig for HDPE and HA/HDPE containing up to 40 vol % of HA. It was found that HA/HDPE composites had lower coefficients of friction than unfilled HDPE under certain conditions. HA/HDPE also exhibited less severe fatigue failure marks than HDPE. The degradation and fatigue failure of HDPE due to the presence of proteins were severe for low speed wear testing (100 rpm) as compared to high speed wear testing (200 rpm). This was due possibly to the high shear rate at the contact which could remove any degraded film instantaneously at high sliding speed, while with a low sliding speed the build-up of a degraded layer of protein could occur. The degraded protein layer would stay at the contact for a longer time and mechanical activation would induce adverse reactions, weakening the surface layer of HDPE. Both egg albumen and glucose were found to be corrosive to steel and adversely reactive for HDPE and HA/HDPE composites. The wear modes observed were similar to that of ultra-high molecular weight polyethylene. Specimens tested with egg albumen also displayed higher wear rates, which was again attributed to corrosion accelerated wear. PMID:15348592

  13. An investigation on chloroprene-compatibilized acrylonitrile butadiene rubber/high density polyethylene blends

    PubMed Central

    Ahmed, Khalil

    2014-01-01

    Blends of acrylonitrile butadiene rubber/high density polyethylene (NBR/HDPE) compatibilized by Chloroprene rubber (CR) were prepared. A fixed quantity of industrial waste such as marble waste (MW, 40 phr) was also included. The effect of the blend ratio and CR on cure characteristics, mechanical and swelling properties of MW-filled NBR/HDPE blends was investigated. The results showed that the MW-filled NBR/HDPE blends revealed an increase in tensile strength, tear, modulus, hardness and cross-link density for increasing weight ratio of HDPE. The minimum torque (ML) and maximum torque (MH) of blends increased with increasing weight ratio of HDPE while scorch time (ts2) cure time (tc90), compression set and abrasion loss of blends decreased with increasing weight ratio of HDPE. The blends also showed a continuous reduction in elongation at break as well as swelling coefficient with increasing HDPE amount in blends. MW filled blends based on CR provided the most encouraging balance values of overall properties. PMID:26644917

  14. An investigation on chloroprene-compatibilized acrylonitrile butadiene rubber/high density polyethylene blends.

    PubMed

    Ahmed, Khalil

    2015-11-01

    Blends of acrylonitrile butadiene rubber/high density polyethylene (NBR/HDPE) compatibilized by Chloroprene rubber (CR) were prepared. A fixed quantity of industrial waste such as marble waste (MW, 40 phr) was also included. The effect of the blend ratio and CR on cure characteristics, mechanical and swelling properties of MW-filled NBR/HDPE blends was investigated. The results showed that the MW-filled NBR/HDPE blends revealed an increase in tensile strength, tear, modulus, hardness and cross-link density for increasing weight ratio of HDPE. The minimum torque (M L) and maximum torque (M H) of blends increased with increasing weight ratio of HDPE while scorch time (ts2) cure time (tc90), compression set and abrasion loss of blends decreased with increasing weight ratio of HDPE. The blends also showed a continuous reduction in elongation at break as well as swelling coefficient with increasing HDPE amount in blends. MW filled blends based on CR provided the most encouraging balance values of overall properties. PMID:26644917

  15. Current Activities Assessing Butt Fusion Joint Integrity in High Density Polyethylene Piping

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Doctor, Steven R.; Denslow, Kayte M.

    2012-09-01

    The Pacific Northwest National Laboratory (PNNL) in Richland, Washington, conducted initial studies to evaluate the effectiveness of nondestructive examinations (NDE) coupled with mechanical testing for assessing butt fusion joint integrity in high density polyethylene (HDPE) pipe. The work provided insightful information to the United States Nuclear Regulatory Commission (NRC) on the effectiveness of volumetric inspection techniques for detecting lack of fusion (LOF) conditions in the fusion joints. HDPE has been installed on a limited basis in American Society of Mechanical Engineers (ASME) Class 3, buried piping systems at several operating U.S. nuclear power plants and has been proposed for use in new construction. A comparison was made between the results from ultrasonic and microwave nondestructive examinations and the results from mechanical destructive evaluations, specifically the high-speed tensile test and the side-bend test, for determining joint integrity. The data comparison revealed that none of the NDE techniques detected all of the lack-of-fusion conditions that were revealed by the destructive tests. Follow-on work has recently been initiated at PNNL to accurately characterize the NDE responses from machined flaws of varying size and location in PE 4710 materials as well as the LOF condition. This effort is directed at quantifying the ability of volumetric NDE techniques to detect flaws in relation to the critical flaw size associated with joint integrity. A status of these latest investigations is presented.

  16. Catalytic degradation of high-density polyethylene over different zeolitic structures

    SciTech Connect

    Manos, G.; Garforth, A.; Dwyer, J.

    2000-05-01

    The catalytic degradation of high-density polyethylene to hydrocarbons was studied over different zeolites. The product range was typically between C{sub 3} and C{sub 15} hydrocarbons. Distinctive patterns of product distribution were found with different zeolitic structures. Over large-pore ultrastable Y, Y, and {beta} zeolites, alkanes were the main products with less alkenes and aromatics and only very small amounts of cycloalkanes and cycloalkenes. Medium-pore mordenite and ZSM-5 gave significantly more olefins. In the medium-pore zeolites secondary bimolecular reactions were sterically hindered, resulting in higher amounts of alkenes as primary products. The hydrocarbons formed with medium-pore zeolites were lighter than those formed with large-pore zeolites. The following order was found regarding the carbon number distribution: (lighter products) ZSM-5 < mordenite < {beta} < Y < US-Y (heavier products). A similar order was found regarding the bond saturation: (more alkenes) ZSM-5 < mordenite < {beta} < Y < US-Y (more alkanes). Dependent upon the chosen zeolite, a variety of products was obtained with high values as fuel, confirming catalytic degradation of polymers as a promising method of waste plastic recycling.

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

    SciTech Connect

    Mu, Mulan E-mail: m.basheer@qub.ac.uk; Basheer, P. A. M. E-mail: m.basheer@qub.ac.uk; Bai, Yun; McNally, Tony

    2014-05-15

    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 a 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.

  18. The use of high-density porous polyethylene as a custom-made nasal spreader graft.

    PubMed

    Gürlek, Ali; Celik, Mehmet; Fariz, Alpay; Ersöz-Oztürk, Ayşe; Eren, Ahmet T; Tenekeci, Göktekin

    2006-01-01

    The concept and technique of using high-density porous polyethylene (HDPP), a nonresorbable synthetic material, for nasal spreader grafts, are presented. This material is thought to be particularly useful in revision (secondary or tertiary) rhinoplasty, in which internal valve collapse frequently is confronted and septal cartilage often is unavailable because it has been harvested for spreader or other grafts. Sold as a thin plain sheet (0.85 x 38 x 50 mm) that can be cut to an appropriate size for spreader grafts, HDPP is a ready-to-use material commercially available on the market. Because HDPP permits ingrowths of fibrous tissue inside and around, it is a nonabsorbable material that stabilizes the upper lateral cartilages in their new position and maintains the appropriate internal valve angle. The authors used this material for 15 patients undergoing secondary (n = 12) and tertiary (n = 3) rhinoplasty because of valvular collapse. During the mean follow-up period of 16 months (range, 8-30 months), neither complication nor recurrence of airway obstruction occurred. PMID:16411156

  19. 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. PMID:26322761

  20. Photothermal Characterization of Nanocomposites Based on High Density Polyethylene (HDPE) Filled with Expanded Graphite

    NASA Astrophysics Data System (ADS)

    Chirtoc, M.; Horny, N.; Henry, J.-F.; Turgut, A.; Kökey, I.; Tavman, I.; Omastová, M.

    2012-11-01

    The effective thermophysical and optical properties of high density polyethylene (HDPE) filled with 50 μm and 5 μm particle sizes of expanded graphite (EG50, EG5) are characterized. The methods used were front- and back-detection modulated photothermal radiometry (FD-, BD-PTR) and BD-flash IR thermography. Results were interpreted according to one-dimensional heat diffusion models. The absolute thermal diffusivity was determined at low frequency from FD- and BD-PTR spectra, while the volumetric heat capacity, the thermal effusivity, and the optical absorption coefficient were determined from broad-band FD-PTR spectra. The directly obtained diffusivity values compare well with those calculated from the heat capacity and thermal effusivity, and with BD-flash results. The errors caused by the finite absorption coefficient of diluted samples are also evaluated and corrected for. A particle-size effect with the opposite influence on thermal and optical properties has been observed. Heat transport parameters of HDPE/EG composites are significantly enhanced (factor of 3 to 4 in thermal diffusivity) at low particle charge before reaching saturation above a 0.10 particle volume fraction. These features are explained in the framework of effective medium models by strongly non-spherical EG particles.

  1. PORTSMOUTH ON-SITE DISPOSAL CELL HIGH DENSITY POLYETHYLENE GEOMEMBRANE LONGEVITY

    SciTech Connect

    Phifer, M.

    2012-01-31

    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 the 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.

  2. 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. PMID:25981704

  3. Measurements and predictions of outgassing from high density polyethylene (HDPE), PBX9502, and certain silicones by the isoconversional analysis

    SciTech Connect

    Dinh, L N; Glascoe, E A; Schildbach, M A; Chinn, S C; Maxwell, R S; McLean II, W

    2009-07-06

    The techniques of mass spectrometry and temperature programmed decomposition were used to measure outgassing kinetics from high density polyethylene, insensitive high explosive PBX 9502, and silica-filled polysiloxane TR55 and S5370. The isoconversional thermal analysis method was then employed to extract outgassing kinetics and to make kinetic predictions for long term outgassing at lower temperatures. The accuracy, advantages and disadvantages of the isoconversional analysis in terms of kinetic prediction for these materials and some others will be discussed.

  4. Porous high-density polyethylene in functional rhinoplasty: Excellent long-term aesthetic results and safety

    PubMed Central

    Kim, Young Hyo; Jang, Tae Young

    2014-01-01

    BACKGROUND: Experience with the use of porous high-density polyethylene (PHDPE) for reconstruction of the nasal framework has been limited. OBJECTIVE: To confirm the safety and utility of PHDPE by analyzing aesthetic outcomes and assessing the frequency of complication related to PHDPE in a large, population-based, long-term follow-up study. METHODS: A total of 151 patients who had undergone septoplasty and/or functional rhinoplasty using PHDPE were enrolled. PHDPE sheets were used for diverse purposes such as septal extension graft, spreader graft, columellar strut or dorsal augmentation graft. After a long-term follow-up period (mean [± SD] 39.5±27.8 months; range six to 101 months), postoperative aesthetic outcome was evaluated objectively (by independent surgeons) and subjectively (patient self-report). Complications related to PHDPE were estimated through review of medical records. RESULTS: The most common use of the PHDPE graft was for septal extension (n=80 [42.6%]) and spreader graft (n=58 [30.9%]). Results of aesthetic evaluation by surgeons were excellent in 61 cases (40.4%), good in 54 (35.8%) and fair in 34 (22.5%). According to patient self-report, 100 were ‘satisfied’ (66.2%) and 36 rated their new profile as ‘better than the preoperative profile’ (23.8%). Complications were reported in six cases (4.0% [five cases of extrusion and one case of infection]). All complications were resolved after the surgical removal of PHDPE sheets under local anesthesia. CONCLUSION: The present study demonstrated that PHDPE could be used in functional primary rhinoplasty with excellent long-term aesthetic results and safety. PMID:25152641

  5. Perfluorinated carboxylic acids in directly fluorinated high-density polyethylene material.

    PubMed

    Rand, Amy A; Mabury, Scott A

    2011-10-01

    Perfluorinated carboxylic acids (PFCAs) are ubiquitous in the environment and have been detected in human blood worldwide. One potential route is direct exposure to PFCAs through contact with polymers that have been fluorinated through a process referred to as direct fluorination. PFCAs are hypothesized to be reaction byproducts of direct fluorination when trace amounts of oxygen are present. The objective of this research was to investigate whether PFCAs could be measured in directly fluorinated high-density polyethylene (HDPE) bottles. PFCAs were quantified using Soxhlet extraction with methanol, followed by LC-MS/MS analysis. Total concentrations of PFCAs ranged from 8.5 ± 0.53 to 113 ± 2.5 ng/bottle (1 L), with the short-chain PFCAs, perfluoropropanoic, perfluorobutanoic, perfluoropentanoic, and perfluorohexanoic acids, being the dominant congeners observed. Relative PFCA concentrations varied depending on fluorination level. Structural isomers were detected using (19)F NMR and are hypothesized to have formed during the fluorination process; NMR data revealed the linear isomer typically comprised 55% of the examined sample. Internally branched, isopropyl branched, and t-butyl PFCA isomers of varying chain length were also identified. Electrochemical fluorination was previously thought to be the only source of branched PFCA isomers. The observation here of branched isomers suggests direct fluorination may be an additional source of exposure to these chemicals. The purpose of this study was to measure PFCAs in directly fluorinated material, serving as a previously unidentified source contributing to the environmental load of PFCAs, with potential for human exposure. PMID:21688793

  6. The application and progress of high-density porous polyethylene in the repair of orbital wall defect.

    PubMed

    Qian, Zhuyun; Fan, Xianqun

    2014-07-01

    High-density porous polyethylene is a type of polymeric biomaterial. When used to efficiently fill the extensive orbital volume and correct enophthalmos caused by orbital wall defect, it has a significant advantage of biocompatibility, which results in a low rate of postoperative exposure and infection. The major disadvantage of this material is its radiolucency. However, with the development of imaging techniques, it is now possible to use multidetector computed tomography to directly contour the implant and describe its position. The use of tissue engineering involving high-density porous polyethylene will further improve its biocompatibility. At the same time, composite materials will play an important role in the repair of orbital wall defect. PMID:24911609

  7. Wear of the high-density polyethylene socket in total hip arthroplasty and its role in endosteal cavitation.

    PubMed

    Wroblewski, B M

    1997-01-01

    High-density polyethylene (HDP) has been used in clinical practice in total hip replacement since its introduction by Charnley in November 1962. Fears are being expressed that this may be the weakest link and the ultimate cause of failure of the arthroplasty. Long-term clinical experience suggests that loosening may be the primary cause while the presence of HDP wear particles is secondary. Healing of endosteal cavities can take place in the presence of HDP wear particles. PMID:9141896

  8. 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

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

    SciTech Connect

    Aras, Neny Rasnyanti M. Arcana, I Made

    2015-09-30

    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{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 0.2% manganese

  10. Kinetics of Moisture Absorption for Alkali Extracted Steam-Exploded Fiber Filled High-Density Polyethylene Composites

    NASA Astrophysics Data System (ADS)

    Taib, R. M.; Ramarad, S.; Ishak, Z. A. M.; Rozman, H. D.

    2010-03-01

    Acacia mangium wood fiber derived from steam-explosion and fiber fractionation treatment was used as fillers for high-density polyethylene (HDPE). The alkali extracted steam-exploded fibers (AEF) obtained were acetylated to produce acetylated fibers (AAEF) having three different weight percent gain (WPG). Composites of AEF or AAEF and HDPE were prepared via 2-roll mill, compression molded and cut into dumbbell specimens. All samples were immersed in water at room temperature for 30 days. The process of absorption of water by all composites followed the kinetics and mechanisms described by the Fick's theory. Diffusion coefficient (D) values increased with filler loading but decreased with increasing WPG of the AAEF fiber. Further decrease was observed when maleated polyethylene (MAPE) was added to the composite system. This was due to improved fiber-matrix adhesion that restricts movement of water molecules from further penetrate inside the composite structures.

  11. Kinetics of Moisture Absorption for Alkali Extracted Steam-Exploded Fiber Filled High-Density Polyethylene Composites

    SciTech Connect

    Taib, R. M.; Ramarad, S.; Ishak, Z. A. M.; Rozman, H. D.

    2010-03-11

    Acacia mangium wood fiber derived from steam-explosion and fiber fractionation treatment was used as fillers for high-density polyethylene (HDPE). The alkali extracted steam-exploded fibers (AEF) obtained were acetylated to produce acetylated fibers (AAEF) having three different weight percent gain (WPG). Composites of AEF or AAEF and HDPE were prepared via 2-roll mill, compression molded and cut into dumbbell specimens. All samples were immersed in water at room temperature for 30 days. The process of absorption of water by all composites followed the kinetics and mechanisms described by the Fick's theory. Diffusion coefficient (D) values increased with filler loading but decreased with increasing WPG of the AAEF fiber. Further decrease was observed when maleated polyethylene (MAPE) was added to the composite system. This was due to improved fiber-matrix adhesion that restricts movement of water molecules from further penetrate inside the composite structures.

  12. 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. PMID:26994428

  13. A Major Intermediate Component in Drawn High-Density Polyethylene Identified by Solid-State NMR

    NASA Astrophysics Data System (ADS)

    Mowery, Daniel; Schmidt-Rohr, Klaus

    2001-03-01

    In a commercial polyethylene (HDPE) highly drawn at 295 K, a distinct morphological component intermediate to the crystalline and the almost isotropic amorphous phases has been identified by solid-state nuclear magnetic resonance (NMR). This intermediate component accounts for nearly 25% of the material bulk, exceeding the amorphous fraction at the highest draw ratios. In the neat isotropic material examined for reference, the NMR-derived composition shows excellent agreement with other techniques. 13C NMR isotropic chemical shifts of the intermediate component, whose signal was selected using an “inverse T1,C filter”, prove chains of nearly all-trans conformations; the line width indicates significant disorder. Reduction of dipolar couplings and the chemical-shift anisotropy show fast rotations of 30 50 deg. amplitude around the chain axes. The degree of orientation of the chain axes is high. Spin diffusion experiments suggest that the intermediate component consists mostly of extended chain bundles closely associated with the amorphous phase (tie-molecule bundles ?).

  14. The effects of high energy electron beam irradiation on the thermal and structural properties of low density polyethylene

    NASA Astrophysics Data System (ADS)

    Murray, Kieran A.; Kennedy, James E.; McEvoy, Brian; Vrain, Olivier; Ryan, Damien; Higginbotham, Clement L.

    2012-08-01

    Radiation is currently being exploited to modify polyethylene in order to improve properties for various applications such as hip replacements. This paper thoroughly examines the effects of high energy electron beam irradiation (10 MeV) on low density polyethylene (LDPE) material. ASTM (American Society for Testing and Materials) testing specimens were manufactured from LDPE and subjected to a broad range of doses ranging between 25 and 400 kGy at room temperature in an air atmosphere. Extensive characterisation techniques such as modulated differential scanning calorimetry (MDSC) and the Fourier transform infrared spectroscopy (FTIR) were conducted on the non-irradiated and irradiated samples. While considering the semicrystalline nature of LDPE during the MDSC experiment, the melting temperature (Tm) and the temperature crystallinity (Tc) were calculated. This revealed that the Tm and the Tc decreased in temperature as the irradiation dose increased. The FTIR analysis was implemented to evaluate the presence of polar species such as carbonyl groups and trans-vinylene double bond groups. The IR spectra illustrated that the concentration of characteristic bands for trans-vinylene bonds increased with increasing radiation dose indicating the formation of carbonyl bond groups. Furthermore, the results demonstrated an occurrence of oxidative degradation due to the formation of carbonyl groups at 1718 cm-1.

  15. Atomic force microscopic study of the structure of high-density polyethylene deformed in liquid medium by crazing mechanism.

    PubMed

    Bagrov, D V; Yarysheva, A Y; Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2014-02-01

    A procedure has been developed for the direct atomic force microscopic (AFM) examination of the native structure of high-density polyethylene (HDPE) deformed in an adsorption-active liquid medium (AALM) by the crazing mechanism. The AFM investigation has been carried out in the presence of a liquid medium under conditions preventing deformed films from shrinkage. Deformation of HDPE in AALM has been shown to proceed through the delocalized crazing mechanism and result in the development of a fibrillar-porous structure. The structural parameters of the crazed polymer have been determined. The obtained AFM images demonstrate a nanosized nonuniformity of the deformation and enable one to observe the structural rearrangements that take place in the deformed polymer after removal of the liquid medium and stress relaxation. A structural similarity has been revealed between HDPE deformed in the AALM and hard elastic polymers. PMID:24283329

  16. Solidification behavior of high-density polyethylene (HDPE) during injection molding: Correlation between crystallization kinetics and thermal gradient field

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Deng, Yan-Li; Li, Gui-Jing; Miao, Ji-Bin; Xia, Ru; Qian, Jia-Sheng; Chen, Peng; Liu, Jing-Wang

    2015-07-01

    This work mainly investigated the effect of thermal field on the crystallization kinetics of high-density polyethylene (HDPE) during injection molding (IM) process. The thickness X = 0.4 was found to be a crucial location heavily influenced by thermal conduction. The temperature decay tended to be stable, with limited variation of the crystallization rate when X > 0.4. It was observed that the crystallization rate was in good proportion to the cooling rate (ϕ). Our experimental finding showed that the consequence of relative crystallinity (χ) was in agreement with that of the secondary temperature difference (STD). This study is practically significant to the further investigation on the relationship among “processing-structure-property” of polymeric materials.

  17. Thermal, tensile and rheological properties of high density polyethylene (HDPE) processed and irradiated by gamma-ray in different atmospheres

    SciTech Connect

    Ferreto, H. F. R. E-mail: ana-feitoza@yahoo.com.br; Oliveira, A. C. F. E-mail: ana-feitoza@yahoo.com.br; Parra, D. F. E-mail: ablugao@ipen.br; Lugão, A. B. E-mail: ablugao@ipen.br; Gaia, R.

    2014-05-15

    The aim of this paper is to investigate structural changes of high density polyethylene (HDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of {sup 60}Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of HDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.

  18. 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. PMID:19574041

  19. Oxygen-sensitive phosphorescent nanomaterials produced from high-density polyethylene films by local solvent-crazing.

    PubMed

    Toncelli, Claudio; Arzhakova, Olga V; Dolgova, Alla; Volynskii, Aleksandr L; Bakeev, Nikolai F; Kerry, Joe P; Papkovsky, Dmitri B

    2014-02-01

    Discrete solid-state phosphorescent oxygen sensors produced by local solvent-crazing of high density polyethylene films are described. The simple spotting of dye solution followed by tensile drawing of the polymer substrate provides uniform nanostructures with good spatial control, effective encapsulation of dye molecules, and quenchability by O2. The dye-polymer composite sensors prepared using toluene as a solvent and stabilized by annealing at high temperature, show moderate optical signals, near-optimal sensitivity to O2 (RSD at 21 KPa 1.9%), and reproducible phosphorescence lifetime readings. Calibration experiments performed over 0-25 kPa O2 and 10-30 °C temperatures ranges reveal linear Stern-Volmer plots and temperature dependences and minimal effect of humidity on sensor calibration. The high degree of lateral and in-depth homogeneity of these O2-sensitive materials was confirmed by high-resolution atomic force and wide-field optical microscopy, including 2D and 3D phosphorescence lifetime imaging. PMID:24422456

  20. Novel cholesterol feeding strategy enables a high-density cultivation of cholesterol-dependent NS0 cells in linear low-density polyethylene-based disposable bioreactors.

    PubMed

    Tao, Yiwen; Yusuf-Makagiansar, Helena; Shih, Jennifer; Ryll, Thomas; Sinacore, Marty

    2012-08-01

    We have developed a perfusion-based high cell density (HD) cell banking and inoculum expansion procedure for a cholesterol-dependent NS0 myeloma cell line using linear low-density polyethylene-based disposable bioreactors. Challenges associated with cholesterol-polymer interactions, which suppress cholesterol-dependent NS0 myeloma cell growth, were overcome using a novel cholesterol feeding protocol that included a combination of two cholesterol formulations: an ethanol-based formulation and an aqueous formulation. Using a cholesterol feed optimized for HD cell culture in a disposable bioreactor perfusion system, cell densities of >25 × 10(6) viable cells/ml at ≥ 90 % cell viability were achieved. Vials of high density cell banks were created by filling 90-100 × 10(6) viable cells/ml in 5 ml cryotube vials. Implementation of the HD cell banks enabled a significant reduction in the number of step operations in the inoculum expansion phase in a large-scale manufacturing setting. PMID:22481299

  1. 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. PMID:25532672

  2. Impact of using high-density polyethylene geomembrane layer as landfill intermediate cover on landfill gas extraction.

    PubMed

    Chen, Zezhi; Gong, Huijuan; Zhang, Mengqun; Wu, Weili; Liu, Yu; Feng, Jin

    2011-05-01

    Clay is widely used as a traditional cover material for landfills. As clay becomes increasingly costly and scarce, and it also reduces the storage capacity of landfills, alternative materials with low hydraulic conductivity are employed. In developing countries such as China, landfill gas (LFG) is usually extracted for utilization during filling stage, therefore, the intermediate covering system is an important part in a landfill. In this study, a field test of LFG extraction was implemented under the condition of using high-density polyethylene (HDPE) geomembrane layer as the only intermediate cover on the landfill. Results showed that after welding the HDPE geomembranes together to form a whole airtight layer upon a larger area of landfill, the gas flow in the general pipe increased 25% comparing with the design that the HDPE geomembranes were not welded together, which means that the gas extraction ability improved. However as the heat isolation capacity of the HDPE geomembrane layer is low, the gas generation ability of a shallow landfill is likely to be weakened in cold weather. Although using HDPE geomembrane layer as intermediate cover is acceptable in practice, the management and maintenance of it needs to be investigated in order to guarantee its effective operation for a long term. PMID:21232931

  3. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    SciTech Connect

    Xiang, Dong; Harkin-Jones, Eileen; Linton, David

    2015-05-22

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1∼2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites.

  4. Thermal and mechanical properties of e-beam irradiated butt-fusion joint in high-density polyethylene pipes

    NASA Astrophysics Data System (ADS)

    Vijayan, Vipin; Pokharel, Pashupati; Kang, Min Kwan; Choi, Sunwoong

    2016-05-01

    The effects of electron beam irradiation on the thermal and mechanical properties of a butt-fusion joint in high density polyethylene (HDPE) pipes were investigated. Differential scanning calorimetry, X-ray diffraction, and Fourier transform infra-red spectroscopy of welded samples revealed the changes of crystallinity due to the cross linking effect of electron beam irradiation. The suppression of the degree of crystallinity with increasing the irradiation dose from 0 kGy to 500 kGy indicated that the e-beam radiation induced cross-links among the polymer chains at the weld zone. The cross-link junction at the joint of HDPE pipe prevented chain folding and reorganization leading to the formation of imperfect crystallites with smaller size and also less in content. Tensile test of the welded samples with different dose of e-beam irradiation showed the increased values of the yield stress and Young's modulus as a function of irradiation dose. On the other hand, the elongation at break diminished clearly with increasing the irradiation doses.

  5. Influence of γ-ray modified MWCNTs on the structural and thermal properties of high-density polyethylene

    NASA Astrophysics Data System (ADS)

    Ghafoor, Bilal; Mehmood, Malik Sajjad; Shahid, Umair; Baluch, Mansoor A.; Yasin, Tariq

    2016-08-01

    This study aims to investigate the influence of adding 100 kGy γ-irradiated multi wall carbon nano tubes (MWCNTs) on the structural and thermal properties of high-density polyethylene (HDPE). The effects of further γ-irradiation in the presence of γ-MWCNTs on aforementioned properties have also been investigated. FTIR spectroscopic measurements of HDPE and HDPE/γ-MWCNTs composites reveal that modification of MWCNTs with ≤100 kGy of γ-dose reduces its efficiency as free radical quencher. This behavior is found to increase further with the increase in the concentration of γ-MWCNTs. Wide angle X-ray diffraction (WAXD) data shows a decrease in percent crystallinity and shifting of crystalline peaks toward lower values of 2θ angles. This behavior is mainly attributed to the oxidation induced due to residual free radicals. Thermal analysis reveals that addition of γ-MWCNTs decreases the thermal stability as far as onset thermal degradation temperature, percent crystallinity, and melting temperature of UHMWPE/γ-MWCNTs. In addition to this, gel content measurements show that insoluble percentage of UHMWPE is higher with the incorporation γ-MWCNTs and further irradiation. The gel contents are found to improve up to 29% and 60%, respectively with the incorporation of γ-MWCNTs and further irradiation.

  6. 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. PMID:27072033

  7. 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

  8. High density polyethylene (HDPE)/poly(ethylene terephthalate) (PET) polymer blend studies related to recycling co-mingled plastics

    NASA Astrophysics Data System (ADS)

    Tsai, Pang-Yen

    Polymer blends of virgin high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) were studied as an attempt to relate the microstructure to the mechanical properties of the blends. The virgin blends were prepared by extrusion and then injection molded into specimens for characterization. Two of the virgin blends were tested for possible compatibilization using a styrene-ethylene-butylene-styrene (SEBS) block copolymer. In addition, six blends of post-consumer resins (PCRs) of HDPE and PET were included in this work for comparison. The moduli of the virgin blends showed positive deviation from those expected from the rule of mixtures. The synergism of the composite moduli can be explained partly by a Poisson's effect. Yield strengths of the blends molded at low injection chamber temperatures (200sp°, 230sp°, and 250sp°C) followed the rule of mixtures well, because PET filaments found in the composites had very high length to diameter ratios. When the injection chamber temperature was above the PET melting point (˜254sp°C), PET filaments were found to break down into particles, and the yield strengths of the blends coincided with the values expected from the inverse rule of mixtures. Impact strengths of the virgin blends were much less than that of a HDPE homopolymer due to poor interfacial bonding between HDPE and PET. Compatibilization appeared to be advantageous since it dramatically improved the impact strength of the virgin blends. SEM micrographs of impact fractured surfaces revealed that the improved adhesion from compatibilization and the presence of numerous uniaxially aligned PET filaments in the HDPE substrate can account for the significant increases in fracture resistance of the compatibilized blends. Mechanical performance of the PCRs was inferior to that of the virgin blends. Aside from polymer degradation and contamination due to repeated processing and handling, absence of PET filaments and interfacial bonding could be

  9. Herbicide dissipation from low density polyethylene mulch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  10. Methyl bromide emission from fields partially covered with a high-density polyethylene and a virtually impermeable film

    SciTech Connect

    Wang, D.; Yates, S.R.

    1998-09-01

    Recent field studies in the interior valley of southern California have indicated that 56--73% of methyl bromide (MeBr) used in soil fumigation is lost to atmospheric emission when the fields are covered completely with a high-density polyethylene (HDPE) film. The emission can be reduced to less than 5% when a virtually impermeable film or Hytibar is used to cover the fields. This study was conducted to determine MeBr emission from bedded field plots where only the beds were covered with a HDPE or a virtually impermeable plastic film. The results provide an assessment on MeBr emission from field beds partially covered with the HDPE film and the suitability of using a virtually impermeable film for emission reduction. Methyl bromide gas was applied to replicated field beds covered with either a HDPE or the Hytibar film. The films were removed 6 days after MeBr application. Replicated soil cores were taken from different locations of the field beds, 20 days after MeBr application, for the determination of soil bromide ion concentrations. The total amount of MeBr degraded from each plot was calculated from the measured bromide ion concentrations, and the potential emission was determined as the difference between the amount of applied and that of degraded. Results indicated that the potential emission from this bedded system was about 95% for the HDPE treatment and 90% for the Hytibar-covered plots. Regardless of the small improvement with the virtually impermeable film, the experiment clearly indicates that partially covering the field with either a HDPE or a virtually impermeable film would result in unacceptably high emission losses.

  11. Large area neutron detector based on Li6 ionization chamber with integrated body-moderator of high density polyethylene

    SciTech Connect

    Ianakiev, Kiril D.; Swinhoe, Martyn T.; Chung, Kiwhan; Makela, Mark F.

    2009-06-30

    A detector was developed and funded by DHS to be a lower cost alternative to 3He detectors. A 6Li foil-lined ionization chamber was prepared with fill gas at one atmosphere and pulse mode operation. The high-density polyethylene (HOPE) body serves also as a neutron moderator. All electrodes, including high voltage bias supply, are hermetically sealed within the plastic slabs.

  12. 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. PMID:12808590

  13. 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. PMID:26992845

  14. Investigation of the structure of cold-drawn high-density polyethylene using solid-state NMR

    NASA Astrophysics Data System (ADS)

    Mowery, Daniel Michael

    In this dissertation, the cold-drawing response of a commercial high-density polyethylene (HDPE) resin has been studied using solid-state nuclear magnetic resonance (NMR) spectroscopy and variety of other complementary techniques. Melt-crystallized, isotropic samples of the HDPE have been drawn to various extensions at ambient temperature (21°C) and at a relatively slow strain rate (0.0013 s-1). Using solid-state NMR, the first unambiguous evidence for a major morphological component intermediate to the crystalline and amorphous domains in the cold-drawn HDPE microstructure has been found. Employing an 'inverse 13 C T1 filter' and other filtering techniques, signals from the various components have been selected and compared. The intermediate component comprises chains of all-trans conformation but with significant disorder in packing. The chains show fast, intermediate-amplitude motions about their axes and are generally aligned with the draw direction, but with a greater distribution of orientation angles relative to crystalline phase. A quantitative 13C NMR procedure has been utilized in the analysis of morphological component composition during cold drawing. In the undeformed material, the NMR-derived composition shows excellent agreement with other common techniques. The mass fraction of the intermediate component has been measured by NMR to be as high as 35% in the cold-drawn HDPE, greater than the contributions from the amorphous domains and monoclinic crystals. The intermediate component content dramatically increases by 240% just after necking, along with a doubling in the monoclinic crystals. At the same time, decreases of about 25% in the total crystalline and amorphous phases occur. A general re-ordering in the microstructure takes place during neck propagation and strain hardening. The total crystallinity rises by about 8%, with a corresponding decrease in the monoclinic crystals (50%) and amorphous material (30%). Based on 1H spin diffusion data, a

  15. 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. PMID:25563952

  16. Influence of high doses γ-irradiation on oxygen permeability of linear low-density polyethylene and cast polypropylene films

    NASA Astrophysics Data System (ADS)

    Klepac, Damir; Ščetar, Mario; Baranović, Goran; Galić, Kata; Valić, Srećko

    2014-04-01

    Linear low density polyethylene (PE-LLD) and cast polypropylene (PPcast) films were irradiated in a 60Co γ-source. The total irradiation dose varied from 0 kGy (unirradiated samples) to 200 kGy. Oxygen transport was investigated by a manometric method and the structural changes were studied by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Free radicals decay as a function of time was monitored by electron spin resonance (ESR) spectroscopy. The results show that the γ-irradiation reduces oxygen permeability coefficient in both films. The reduction was associated with an increase in crystallinity. DSC thermograms revealed a decrease in PPcast melting point with increasing irradiation dose, indicating higher degradation compared to PE-LLD. The observed peak in FTIR spectra for both samples at 1716 cm-1 corresponds to the stretching of the carbonyl and carboxylic groups which arise from the reaction of oxygen with the free radicals produced in the polymer matrix as a result of irradiation.

  17. 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. PMID:23291406

  18. The effects of high energy electron beam irradiation in air on accelerated aging and on the structure property relationships of low density polyethylene

    NASA Astrophysics Data System (ADS)

    Murray, Kieran A.; Kennedy, James E.; McEvoy, Brian; Vrain, Olivier; Ryan, Damien; Cowman, Richard; Higginbotham, Clement L.

    2013-02-01

    The response of low density polyethylene (LDPE) to high energy electron beam irradiation in air (10 MeV) between 25 and 400 kGy was examined and compared to non-irradiated polyethylene in terms of the mechanical and structural properties. To quantify the degree of crosslinking, swelling studies were performed and from this it was observed that the crosslink density increased as the irradiation dose increased. Furthermore, a reduction was observed in the numerical data for molar mass between adjacent crosslinks and the number of monomeric units between adjacent crosslinks as the irradiation dose was conducted incrementally. Accelerated aging provided evidence that radicals became trapped in the polymer matrix of LDPE and this in turn initiated further reactions to transpire as time elapsed, leading to additional alteration in the structural properties. Fourier transform infrared spectroscopy (FTIR) was implemented to provide insight into this. This technique established that the aging process had increased the oxidative degradation products due to oxygen permeation into the polymer and double bonds within the material. Mechanical testing revealed an increase in the tensile strength and a decrease in the elongation at break. Accelerated aging caused additional modifications to occur in the mechanical properties which are further elucidated throughout this study. Dynamic frequency sweeps investigated the effects of irradiation on the structural properties of LDPE. The effect of varying the irradiation dose concentration was apparent as this controlled the level of crosslinking within the material. Maxwell and Kelvin or Voigt models were employed in this analytical technique to define the reaction procedure of the frequency sweep test with regards to non-crosslinked and crosslinked LDPE.

  19. Estimation of the Environmental Load of High- and Low-Density Polyethylene From South Korea Using a Mass Balance Approach.

    PubMed

    Kim, Mijin; Hyun, Seunghun; Kwon, Jung-Hwan

    2015-10-01

    The accumulation of marine plastic debris is one of the main emerging environmental issues of the twenty first century. Numerous studies in recent decades have reported the level of plastic particles on the beaches and in oceans worldwide. However, it is still unclear how much plastic debris remains in the marine environment because the sampling methods for identifying and quantifying plastics from the environment have not been standardized; moreover, the methods are not guaranteed to find all of the plastics that do remain. The level of identified marine plastic debris may explain only the small portion of remaining plastics. To perform a quantitative estimation of remaining plastics, a mass balance analysis was performed for high- and low-density PE within the borders of South Korea during 1995-2012. Disposal methods such as incineration, land disposal, and recycling accounted for only approximately 40 % of PE use, whereas 60 % remained unaccounted for. The total unaccounted mass of high- and low-density PE to the marine environment during the evaluation period was 28 million tons. The corresponding contribution to marine plastic debris would be approximately 25,000 tons and 70 g km(-2) of the world oceans assuming that the fraction entering the marine environment is 0.001 and that the degradation half-life is 50 years in seawater. Because the observed concentrations of plastics worldwide were much lower than the range expected by extrapolation from this mass balance study, it is considered that there probably is still a huge mass of unidentified plastic debris. Further research is therefore needed to fill this gap between the mass balance approximation and the identified marine plastics including a better estimation of the mass flux to the marine environment. PMID:26153107

  20. Characterization of solidified radioactive waste and container due to the incorporation of high density polyethylene granules and powder in mortar matrices

    SciTech Connect

    Peric, A.D.

    1999-07-01

    Powder and granules of the high density polyethylene (PEHD) were used to prepare mortar based matrices for immobilization of radioactive waste materials containing {sup 137}Cs, as well as containers for solidified radioactive waste form. Seven types of matrices, differ due to the percentage of granules and filler material added, were investigated. PEHD powder and granules 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, as well as mechanical characteristics either of mortar matrix and container. In this paper, only mechanical strength aspect of the investigated mortar and concrete container formulations, is presented. The equivalent diameter of the PEHD granules used was 2.0 mm. PEHD granules were used to replace 100 volume percent of stone granules, sifted size of 2.0 mm, normally used in the matrix preparation, in order to decrease the porosity and density of the mortar matrix and to avoid segregation of the stone particles at the bottom of the immobilized radioactive waste cylindrical form. PEHD powder, particle size of 250 micrometer, was added as filler to the mortar formulation, replacing 5, 8 and 10 wt% of the total cement weight in matrix formulation and 15 and 18 wt% of the total cement weight in container formulation. Cured samples were investigated on mechanical strength, using 150 MPa hydraulic press, in order to determine influence of added polyethylene granules and powder on samples resistance to mechanical forces that solidified waste materials and concrete containers may experience at the disposal site. Results of performed investigations have shown that samples prepared with polyethylene granules, replacing 100 wt% of the stone granules, have almost twice as much mechanical strength than samples prepared with stone aggregate. Samples prepared with PEHD granules and powder have mechanical

  1. Grafting functional antioxidants on highly crosslinked polyethylene

    NASA Astrophysics Data System (ADS)

    Al-Malaika, S.; Riasat, S.; Lewucha, C.

    2016-05-01

    The problem of interference of antioxidants, such as hindered phenols, with peroxide-initiated crosslinking of polyethylene was addressed through the use of functional (reactive) graftable antioxidants (g-AO). Reactive derivatives of hindered phenol and hindered amine antioxidants were synthesised, characterised and used to investigate their grafting reactions in high density polyethylene; both non-crosslinked (PE) and highly peroxide-crosslinked (PEXa). Assessment of the extent of in-situ grafting of the antioxidants, their retention after exhaustive solvent extraction in PE and PEXa, and the stabilising performance of the grafted antioxidants (g-AO) in the polymer were examined and benchmarked against conventionally stabilised crosslinked & non-crosslinked polyethylene. It was shown that the functional antioxidants graft to a high extent in PEXa, and that the level of interference of the g-AOs with the polymer crosslinking process was minimal compared to that of conventional antioxidants which bear the same antioxidant function. The much higher level of retention of the g-AOs in PEXa after exhaustive solvent extraction, compared to that of the corresponding conventional antioxidants, accounts for their superior long-term thermal stabilising performance under severe extractive conditions.

  2. Enhancement of mechanical strength of TiO{sub 2}/high-density polyethylene composites for bone repair with silane-coupling treatment

    SciTech Connect

    Hashimoto, Masami . E-mail: masami@jfcc.or.jp; Takadama, Hiroaki . E-mail: takadama@jfcc.or.jp; Mizuno, Mineo . E-mail: mizuno@jfcc.or.jp; Kokubo, Tadashi . E-mail: kokubo@isc.chubu.ac.jp

    2006-03-09

    Mechanical properties of composites made up of high-density polyethylene (HDPE) and silanated TiO{sub 2} particles for use as a bone-repairing material were investigated in comparison with those of the composites of HDPE with unsilanized TiO{sub 2} particles. The interfacial morphology and interaction between silanated TiO{sub 2} and HDPE were analyzed by means of Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The absorption in spectral bands related to the carboxyl bond in the silane-coupling agent, the vinyl group in the HDPE, and the formation of the ether bond was studied in order to assess the influence of the silane-coupling agent. The SEM micrograph showed that the 'bridging effect' between HDPE and TiO{sub 2} was brought about by the silane-coupling agent. The use of the silane-coupling agent and the increase of the hot-pressing pressure for shaping the composites facilitated the penetration of polymer into cavities between individual TiO{sub 2} particles, which increased the density of the composite. Therefore, mechanical properties such as bending yield strength and Young's modulus increased from 49 MPa and 7.5 GPa to 65 MPa and 10 GPa, respectively, after the silane-coupling treatment and increase in the hot-pressing pressure.

  3. 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.

  4. Heat transfer performance of a phase-change thermal energy storage water heater using cross-linked high density polyethylene pellets

    SciTech Connect

    Jotshi, C.K.; Klausner, J.F.; Goswami, D.Y.; Hsieh, C.K.; Santhosh, M.K.; Colacino, F.

    1996-12-31

    The objective of this investigation was to develop an efficient water heater that stores thermal energy in a mixture of cross-linked high density polyethylene (HDPE) pellets and propylene glycol. Properties of cross-linked HDPE, such as melting and crystallization temperatures, heat of fusion and crystallization, and volume change were measured in the laboratory. The heat transfer coefficient for the mixture was also measured in a laboratory test. A prototype model of a storage water heater using a mixture of cross-linked HDPE pellets and propylene glycol was designed and fabricated. A copper finned heat transfer coil was used to extract the heat from the storage tank by passing water through it. The heat transfer efficiency (heat extracted by water/heat stored) was measured to be about 70%. To increase the efficiency, the storage unit was modified. In the modified unit, the length of the heat transfer coil was increased and coil spacing optimized. With the modification, the heat transfer efficiency was measured to be about 90%. In addition, a variable heat flux heating element, having high heat flux at the bottom and low heat flux at top, was used to reduce thermal stratification of the propylene glycol/HDPE pellet mixture.

  5. Efficacy of alphacypermethrin-treated high density polyethylene mesh applied to jet stalls housing horses against Culicoides biting midges in South Africa.

    PubMed

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

    2015-05-30

    The efficacy of alphacypermethrin-treated high density polyethylene (HDPE) mesh applied to jet stalls against Culicoides biting midges (Diptera: Ceratopogonidae) was determined by mechanical aspiration of midges from horses and using Onderstepoort 220 V downdraught black light traps in four blocks of a 3 × 2 randomised design under South African field conditions. The alphacypermethrin-treated HDPE mesh applied to the stall significantly (P = 0.008) reduced the number of Culicoides midges, predominantly Culicoides (Avaritia) imicola Kieffer, mechanically aspirated from horses housed in the stall. The mesh reduced the Culicoides midge attack rate in the treated stall compared to the untreated stall and a sentinel horse by 6 times and 14 times, respectively. The number of Culicoides midges and C. imicola collected in light traps from the untreated and alphacypermethrin HDPE mesh-treated stalls did not differ significantly (P = 0.82). Alphacypermethrin-treated HDPE mesh could be used to reduce exposure of horses in jet stalls to Culicoides midges, specifically C. imicola, and the risk of midge-borne Orbivirus transmission. PMID:25794942

  6. 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. PMID:20127544

  7. Creep behavior of 6 micrometer linear low density polyethylene film

    NASA Technical Reports Server (NTRS)

    Simpson, J. M.; Schur, W. W.

    1993-01-01

    Creep tests were performed to provide material characteristics for a 6.4-micron polyethylene film used to construct high altitude balloons. Results suggest simple power law relationships are adequate for stresses below about 4.83 MPa.

  8. Method for assessing lead, cadmium, mercury and arsenic in high-density polyethylene packaging and study of the migration into yoghurt and simulant.

    PubMed

    Kiyataka, Paulo Henrique M; Dantas, Sílvia T; Pallone, Juliana Azevedo Lima

    2014-01-01

    The purpose of this paper was to assess the concentration of lead (Pb), cadmium (Cd), mercury (Hg) and arsenic (As) in high-density polyethylene (HDPE) packaging intended for contact with yoghurt and the migration of these elements using the food itself and 3% acetic acid as a food simulant in accordance to ANVISA, the Brazilian Health Surveillance Agency. In order to perform this study, it was necessary to develop and validate a method by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. For method validation, the parameters linearity, limits of detection (LODs) and quantification (LOQs), accuracy and precision were determined. Fifteen commercial samples of yoghurt, marketed in Campinas - São Paulo (Brazil), were used for the analysis. The packaging and yoghurt were digested in high-pressure ashing equipment (HPA) and the migration of the elements into simulant were determined directly in the solution. The validated method proved adequate and the results obtained showed that all the packaging had levels of Hg and Cd below the LOQ, corresponding to 1.0 and 1.5 μg l(-1), respectively. The highest levels of As and Pb were 0.87 and 462.3 mg kg(-1), respectively. The migration of these elements to the yoghurt after 45 days of contact at 4ºC was below the LOQ for all the samples assessed. The results of specific migration into 3% acetic acid simulant showed the concentrations of Cd, Hg and As below 5, 5 and 10 µg kg(-1), respectively, which are the maximum limits set by ANVISA. However, for three samples the packaging lid showed migration of Pb into simulant ranging from 30.6 to 40.2 μg kg(-1), exceeding the limit set by ANVISA of 10 μg kg(-1). PMID:24444394

  9. Herbicide dissipation from low density polyethylene mulch utilizing analytical techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Georgia, most of the low density polyethylene mulch (LDPM) is laid for spring vegetable production followed by a second crop in the autumn, with a potential third crop the following spring. Between these vegetable plantings, farmers often use contact and residual herbicides to control weeds that ...

  10. 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

  11. Criticality Evaluation of Plutonium-239 Moderated by High-Density Polyethylene in Stainless Steel and Aluminum Containers Suitable for Non-Exclusive Use Transport

    SciTech Connect

    Watson, T T

    2007-08-10

    Research is conducted at the Joint Actinide Shock Physics Experimental Facility (JASPER) on the effects of high pressure and temperature environments on plutonium-239, in support of the stockpile stewardship program. Once an experiment has been completed, it is necessary to transport the end products for interim storage or final disposition. Federal shipping regulations for nonexclusive use transportation require that no more than 180 grams of fissile material are present in at least 360 kilograms of contiguous non-fissile material. To evaluate the conservatism of these regulatory requirements, a worst-case scenario of 180g {sup 239}Pu and a more realistic scenario of 100g {sup 239}Pu were modeled using one of Lawrence Livermore National Laboratory's Monte Carlo transport codes known as COG 10. The geometry consisted of {sup 239}Pu spheres homogeneously mixed with high-density polyethylene surrounded by a cube of either stainless steel 304 or aluminum. An optimized geometry for both cube materials and hydrogen-to-fissile isotope (H/X) ratio were determined for a single unit. Infinite and finite 3D arrays of these optimized units were then simulated to determine if the systems would exceed criticality. Completion of these simulations showed that the optimal H/X ratio for the most reactive units ranged from 800 to 1600. A single unit of either cube type for either scenario would not reach criticality. An infinite array was determined to reach criticality only for the 180g case. The offsetting of spheres in their respective cubes was also considered and showed a considerable decrease in the number of close-packed units needed to reach criticality. These results call into question the current regulations for fissile material transport, which under certain circumstances may not be sufficient in preventing the development of a critical system. However, a conservative, theoretical approach was taken in all assumptions and such idealized configurations may not be likely to

  12. Mechanical and electrical properties of low density polyethylene filled with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sabet, Maziyar; Soleimani, Hassan

    2014-08-01

    Carbon nanotubes (CNTs) reveal outstanding electrical and mechanical properties in addition to nanometer scale diameter and high aspect ratio, consequently, making it an ideal reinforcing agent for high strength polymer composites. Low density polyethylene (LDPE)/CNT composites were prepared via melt compounding. Mechanical and electrical properties of (LDPE)/CNT composites with different CNT contents were studied in this research.

  13. DSC melting behavior of irradiated low density polyethylenes containing antioxidants

    NASA Astrophysics Data System (ADS)

    Gal, O.; Kostoski, D.; Babić, D.; Stannett, V. T.

    The effect of antioxidants (0.5 wt% content) on the melting behaviour of low density polyethylenes, one branched and one linear, was examined with data obtained by DSC. The two polyethylenes exhibit noticeable differences in pure form; LLDPE has a higher melting point, lower heat of fusion and a more complex fusion endotherm than LDPE. The addition of antioxidants has a scarcely noticeable influence on the melting behaviour of LDPE whether irradiated or not, while in the case of LLDPE the effect is more visible. However, a careful analysis of the observed characteristics, peak temperatures and lamellae thickness distribution as well as heat of fusion, show that the observed effects are appearing as the consequence of chemical processes, scission and crosslinking, which occur in PE under either thermomechanical action (mixing in the course of the sample preparation), or radiation.

  14. Reduced Water Density in a Poly(ethylene oxide) Brush

    SciTech Connect

    Lee, Hoyoung; Kim, Dae Hwan; Park, Hae-Woong; Mahynski, Nathan A.; Kim, Kyungil; Meron, Mati; Lin, Binhua; Won, You-Yeon

    2012-09-05

    A model poly(ethylene oxide) (PEO) brush system, prepared by spreading a poly(ethylene oxide)-poly(n-butyl acrylate) (PEO-PnBA) amphiphilic diblock copolymer onto an air-water interface, was investigated under various grafting density conditions by using the X-ray reflectivity (XR) technique. The overall electron density profiles of the PEO-PnBA monolayer in the direction normal to the air-water interface were determined from the XR data. From this analysis, it was found that inside of the PEO brush, the water density is significantly lower than that of bulk water, in particular, in the region close to the PnBA-water interface. Separate XR measurements with a PnBA homopolymer monolayer confirm that the reduced water density within the PEO-PnBA monolayer is not due to unfavorable contacts between the PnBA surface and water. The above result, therefore, lends support to the notion that PEO chains provide a hydrophobic environment for the surrounding water molecules when they exist as polymer brush chains.

  15. 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.

  16. Morphology Effects on Space Charge Characteristics of Low Density Polyethylene

    NASA Astrophysics Data System (ADS)

    Zhou; Yuanxiang; Wang; Yunshan; Zahn, Markus; Wang; Ninghua; Sun; Qinghua; Liang; Xidong; Guan; Zhichen

    2011-01-01

    Low density polyethylene (LDPE) film samples with different morphology were prepared by three kinds of annealing methods which were different in cooling rates in this study. A pulsed electro-acoustic (PEA) space charge measurement system was improved to solve the surface discharge problems for small samples applied with a high voltage. Negative direct current (DC) fields from 50 to above 220 kV/mm were applied to the samples. The influences of morphologies on space charge and space charge packet characteristics were measured by the improved high voltage withstand (HVW) PEA system. Mobility and trap depth of released charges were calculated by space charge decay. It was found that there is a different probability of space charge packet initiation under applied field from -60 to -100 kV/mm. Average velocity and mobility of the space charge packets were calculated by space charge packet dynamics. It was found that the lower cooling rate samples have higher crystallinity, more homo-charge accumulation, lower mobility and deeper trap depth. The mechanism of morphological effects on space charge phenomena have been presumed to give a plausible explanation for their inherent relationships. The morphology in the metal-dielectric interface and in the bulk is convincingly suggested to be responsible for the injection and propagation processes of space charge. A model of positive space charge initiation in LDPE samples was also suggested and analyzed. The mechanism of morphological effects and the charge injection model are well fit with the injection and propagation processes of space charge. The different effects of morphology in the metal-dielectric interface and in the bulk of polymers are stressed.

  17. 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

    2016-05-01

    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. PMID:26876998

  18. Cavitation erosion of low-density polyethylene coatings for pipe liners

    NASA Astrophysics Data System (ADS)

    Hattori, S.; Benitani, E.; Ruan, W.; Suda, Y.; Takeuchi, R.; Iwata, T.

    2015-12-01

    The relationship between mechanical properties and the erosion rate was examined for chloroprene rubber and a number of polyethylene materials produced by different methods. As electric power plants are in operation over long periods of time, the effect of aging was also examined by testing material intended for use in pipes in electric power plants. Cavitation erosion tests were carried out by using a flowing apparatus as specified in the American Society for Testing Materials G134-95 standard. A flow velocity of 150 m/s and a test time of 24hours, were the experimental conditions used for a cavitating liquid jet test on polyethylene. The maximum depth of erosion rate (MaxDER) of polyethylene was found to decrease with the increase in hardness. Among all the tested materials, the relatively high molecular weight polyethylene with low density (m-LLDPE-H), showed the best resistance to cavitation erosion in terms of MaxDER. The effect of aging on the erosion rate of polyethylene was limited.

  19. Medium density polyethylene composites with functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pulikkathara, Merlyn X.; Kuznetsov, Oleksandr V.; Peralta, Ivana R. G.; Wei, Xin; Khabashesku, Valery N.

    2009-05-01

    A strong interface between the single-walled carbon nanotubes (SWNTs) and polymer matrix is necessary to achieve enhanced mechanical properties of composites. In this work a series of sidewall-functionalized SWNTs have been investigated in order to evaluate the effect of functionalization on SWNT aspect ratio and composite interfacial chemistry and their role on mechanical properties of a medium density polyethylene (MDPE) matrix. Fluorinated nanotubes (F-SWNTs) were used as precursors for subsequent sidewall functionalization with long chain alkyl groups to produce an F-SWNT- C11H23 derivative. The latter was refluorinated to yield a new perfluorinated derivative, F-SWNT- C11FxHy. The functionalized SWNTs as well as the pristine SWNTs were integrated into an MDPE matrix at a 1 wt% loading. The nanotubes and composite materials were characterized with FTIR, Raman spectroscopy, NMR, XPS, AFM, SEM, TGA, DSC and tensile tests. When incorporated into polyethylene, the new perfluorinated derivative, F-SWNT- C11FxHy, yielded the highest tensile strength value among all nanotube/MDPE composite samples, showing a 52% enhancement in comparison with the neat MDPE. The 1 wt% SWNT/MDPE composite contained nanotubes with a larger aspect ratio but, due to a lack of interfacial chemistry, it resulted in less improvement in mechanical properties compared to the composites made with the fluorinated SWNT derivatives.

  20. Medium density polyethylene composites with functionalized carbon nanotubes.

    PubMed

    Pulikkathara, Merlyn X; Kuznetsov, Oleksandr V; Peralta, Ivana R G; Wei, Xin; Khabashesku, Valery N

    2009-05-13

    A strong interface between the single-walled carbon nanotubes (SWNTs) and polymer matrix is necessary to achieve enhanced mechanical properties of composites. In this work a series of sidewall-functionalized SWNTs have been investigated in order to evaluate the effect of functionalization on SWNT aspect ratio and composite interfacial chemistry and their role on mechanical properties of a medium density polyethylene (MDPE) matrix. Fluorinated nanotubes (F-SWNTs) were used as precursors for subsequent sidewall functionalization with long chain alkyl groups to produce an F-SWNT- C(11)H(23) derivative. The latter was refluorinated to yield a new perfluorinated derivative, F-SWNT- C(11)F(x)H(y). The functionalized SWNTs as well as the pristine SWNTs were integrated into an MDPE matrix at a 1 wt% loading. The nanotubes and composite materials were characterized with FTIR, Raman spectroscopy, NMR, XPS, AFM, SEM, TGA, DSC and tensile tests. When incorporated into polyethylene, the new perfluorinated derivative, F-SWNT- C(11)F(x)H(y), yielded the highest tensile strength value among all nanotube/MDPE composite samples, showing a 52% enhancement in comparison with the neat MDPE. The 1 wt% SWNT/MDPE composite contained nanotubes with a larger aspect ratio but, due to a lack of interfacial chemistry, it resulted in less improvement in mechanical properties compared to the composites made with the fluorinated SWNT derivatives. PMID:19420641

  1. Polyethylene nanofibres with very high thermal conductivities.

    PubMed

    Shen, Sheng; Henry, Asegun; Tong, Jonathan; Zheng, Ruiting; Chen, Gang

    2010-04-01

    Bulk polymers are generally regarded as thermal insulators, and typically have thermal conductivities on the order of 0.1 W m(-1) K(-1). However, recent work suggests that individual chains of polyethylene--the simplest and most widely used polymer--can have extremely high thermal conductivity. Practical applications of these polymers may also require that the individual chains form fibres or films. Here, we report the fabrication of high-quality ultra-drawn polyethylene nanofibres with diameters of 50-500 nm and lengths up to tens of millimetres. The thermal conductivity of the nanofibres was found to be as high as approximately 104 W m(-1) K(-1), which is larger than the conductivities of about half of the pure metals. The high thermal conductivity is attributed to the restructuring of the polymer chains by stretching, which improves the fibre quality toward an 'ideal' single crystalline fibre. Such thermally conductive polymers are potentially useful as heat spreaders and could supplement conventional metallic heat-transfer materials, which are used in applications such as solar hot-water collectors, heat exchangers and electronic packaging. PMID:20208547

  2. Electrical conduction in irradiated low-density polyethylene

    NASA Astrophysics Data System (ADS)

    Banford, H. M.; Fouracre, R. A.; Chen, G.; Tedford, D. J.

    A programme of experiments has been undertaken to examine transient charging/discharging currents and steady state currents in low-density polyethylene (LDPE) under the application of direct fields. This has been undertaken for pristine material and for material which has received doses of radiation between 10 4 and 10 6 Gy from either a 60Co γ-source or a research reactor. The material was irradiated in ambient air or dry nitrogen. Measurements were made for applied fields in the range 6.7 × 10 5-5.3 × 10 7 V m -1 and temperatures between ambient and 90°C. With pristine material at low fields, transient charging/discharging currents decreased monotonically with time. However, the mechanism changed at higher fields with a peak occurring in the charging transient indicating a space-charge limited process. Substantial charge injection was also in evidence as demonstrated by anomalous discharging currents. This transient response was echoed by the current/voltage characteristics of steady state behaviour. Gamma and neutron irradiation brought about a change in this situation and the charge transport mechanism altered gradually from space-charge-limited conduction to an ohmic process with increasing dose. The role played by charge traps appears to be significant.

  3. Waste form development/test. [Low-density polyethylene and modified sulfur cement as solidification agents

    SciTech Connect

    Kalb, P.D.; Colombo, P.

    1983-01-01

    The main objective of this study is to investigate new solidification agents relative to their potential application to wastes generated by advanced high volume reduction technologies, e.g., incinerator ash, dry solids, and ion exchange resins. Candidate materials selected for the solidification of these wastes include a modified sulfur cement and low-density polyethylene, neither of which are currently employed commerically for the solidification of low-level waste (LLW). As both the modified sulfur cement and the polyethylene are thermoplastic materials, a heated screw type extruder is utilized in the production of waste form samples for testing and evaluation. In this regard, work is being conducted to determine the range of conditions under which these solidification agents can be satisfactorily applied to the specific LLW streams and to provide information relevant to operating parameters and process control.

  4. Melt index of low-density polyethylene and its effect on rotational molding

    NASA Astrophysics Data System (ADS)

    Yuldashev, A. Kh.; Negmatov, S. S.; Abed-Negmatova, N. S.; Abdurakhmanov, A. G.; Bozorov, Sh. A.; Eminov, Sh. Sh.; Aripova, A.; Khodjikariev, D. M.

    2012-07-01

    The melt index of low density polyethylene is directly correlated to the "in service" strength. This correlation together with other chemical properties allowed us to select the best material for rotational molding process.

  5. Catalytic degradation of high-density polyethylene on an ultrastable-Y zeolite. Nature of initial polymer reactions, pattern of formation of gas and liquid products, and temperature effects

    SciTech Connect

    Manos, G.; Garforth, A.; Dwyer, J.

    2000-05-01

    The catalytic degradation of high-density polyethylene (hdPE) over ultrastable Y zeolite in a semibatch reactor was studied at different heating rates and reaction temperatures. Catalytic degradation of the polymer occurred at much lower temperatures than pure thermal degradation. When gel permeation chromatography was used to determine the molar mass distribution, it was found that solid state reactions occur only in the presence of a catalyst. These reactions change the polymer structure well before the formation of significant amounts of volatile products. The pattern of formation of gaseous and liquid products was studied and found to follow the temperature increase. After the system reached its final temperature, the reaction rate of formation of volatile products decreased rapidly. The product range was typically between C{sub 3} and C{sub 15}. Isobutane and isopentane were the main gaseous products. The liquid product fraction was alkane-rich, as alkenes rapidly undergo bimolecular hydrogen transfer reactions to give alkanes as secondary products.

  6. Wear of highly crosslinked polyethylene acetabular components

    PubMed Central

    Callary, Stuart A; Solomon, Lucian B; Holubowycz, Oksana T; Campbell, David G; Munn, Zachary; Howie, Donald W

    2015-01-01

    Background and purpose Wear rates of highly crosslinked polyethylene (XLPE) acetabular components have varied considerably between different published studies. This variation is in part due to the different techniques used to measure wear and to the errors inherent in measuring the relatively low amounts of wear in XLPE bearings. We undertook a scoping review of studies that have examined the in vivo wear of XLPE acetabular components using the most sensitive method available, radiostereometric analysis (RSA). Methods A systematic search of the PubMed, Scopus, and Cochrane databases was performed to identify published studies in which RSA was used to measure wear of XLPE components in primary total hip arthroplasty (THA). Results 18 publications examined 12 primary THA cohorts, comprising only 260 THAs at 2–10 years of follow-up. The mean or median proximal wear rate reported ranged from 0.00 to 0.06 mm/year. However, differences in the manner in which wear was determined made it difficult to compare some studies. Furthermore, differences in RSA methodology between studies, such as the use of supine or standing radiographs and the use of beaded or unbeaded reference segments, may limit future meta-analyses examining the effect of patient and implant variables on wear rates. Interpretation This scoping review confirmed the low wear rates of XLPE in THA, as measured by RSA. We make recommendations to enhance the standardization of reporting of RSA wear results, which will facilitate early identification of poorly performing implants and enable a better understanding of the effects of surgical and patient factors on wear. PMID:25301435

  7. Fatigue crack propagation resistance of highly crosslinked polyethylene.

    PubMed

    Bradford, Letitia; Baker, David; Ries, Michael D; Pruitt, Lisa A

    2004-12-01

    A higher degree of cross-linking has been shown to improve wear properties of ultra-high molecular weight polyethylene in laboratory studies. However, cross-linking can also affect the mechanical properties of ultra-high molecular weight polyethylene. Fatigue crack propagation resistance was determined for electron beam cross-linked ultra-high molecular weight polyethylene and compared with gamma irradiation cross-linked and noncross-linked polyethylene fatigue specimens. Crosslinking was done with different dosages of irradiation followed by melting. For one irradiation dose (50 kGy) extrusion and molding processes were compared. A fracture mechanics approach was used to determine how the degree of cross-linking affects resistance to crack propagation in ultra-high molecular weight polyethylene. Fatigue crack propagation resistance was reduced in proportion to the irradiation dose. The type of irradiation (gamma or electron beam) or manufacturing method (extrusion or molding) did not affect fatigue crack propagation resistance. The reduced fatigue strength of highly cross-linked ultra-high molecular weight polyethylene could lead to mechanical failure in conditions that are associated with cyclic local tensile stresses. PMID:15577468

  8. Mechanical, rheological, and bioactivity properties of ultra high-molecular-weight polyethylene bioactive composites containing polyethylene glycol and hydroxyapatite.

    PubMed

    Ahmad, Mazatusziha; Uzir Wahit, Mat; 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

  9. 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

  10. Autumn vegetable response to residual herbicides applied the previous spring under low density polyethylene mulch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field studies were conducted in 2002 and 2005 to evaluate autumn vegetable tolerance to residual herbicides applied the previous spring under low density polyethylene (LDPE) mulch. Spring applications of 1.12 kg/ha S-metolachlor, 0.027 kg/ha halosulfuron, 0.28 kg/ha sulfentrazone, and 1.12 kg/ha S...

  11. Residual herbicide dissipation for bare soil versus soil under low density polyethylene mulch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yellow nutsedge and purple nutsedge are the most common and troublesome vegetable weeds in the Southern US. Herbicides in low density polyethylene (LDPE) mulch systems are potential methyl bromide alternatives for nutsedge control. Halosulfuron-methyl, sulfentrazone, and s-metolachlor all have nutse...

  12. An atomistic description of the high-field degradation of dielectric polyethylene

    SciTech Connect

    Bealing, Clive R.; Ramprasad, R.

    2013-11-07

    A microscopic mechanism governing the initiating step in the high-field aging of crystalline polyethylene is proposed, based on density functional calculations and ab initio molecular dynamics simulations. It is assumed that electrons, holes, and excitons are present in the system. While the additional individual electrons or holes are not expected to lead to significant degradation, the presence of triplet excitons are concluded to be rather damaging. The electron and hole states of the exciton localize on a distorted region of polyethylene, significantly weakening nearby C–H bonds and facilitating C–H bond scission. The barrier to cleavage of the weakened C–H bonds is estimated and is comparable to the thermal energy, suggesting that this mechanism may be responsible for the degradation of polyethylene when placed under electrical stress, e.g., in high-voltage cables.

  13. An atomistic description of the high-field degradation of dielectric polyethylene

    NASA Astrophysics Data System (ADS)

    Bealing, Clive R.; Ramprasad, R.

    2013-11-01

    A microscopic mechanism governing the initiating step in the high-field aging of crystalline polyethylene is proposed, based on density functional calculations and ab initio molecular dynamics simulations. It is assumed that electrons, holes, and excitons are present in the system. While the additional individual electrons or holes are not expected to lead to significant degradation, the presence of triplet excitons are concluded to be rather damaging. The electron and hole states of the exciton localize on a distorted region of polyethylene, significantly weakening nearby C-H bonds and facilitating C-H bond scission. The barrier to cleavage of the weakened C-H bonds is estimated and is comparable to the thermal energy, suggesting that this mechanism may be responsible for the degradation of polyethylene when placed under electrical stress, e.g., in high-voltage cables.

  14. High Thermal Conductivity Aligned Polyethylene-Graphene Nanocomposites

    NASA Astrophysics Data System (ADS)

    Garg, Jivtesh; Saeidijavash, Mortaza

    We investigate enhancement of thermal conductivity in polyethylene-graphene nanocomposites. The effect of alignment of both the polymer chains and the dispersed graphene flakes on thermal conductivity enhancement will be reported. In this work nanocomposites are prepared through microextrusion of polyethylene pellets and graphene nanopowder. Alignment is achieved through mechanical stretching of the nanocomposites. Thermal conductivity is measured using both Angstrom method and Laser flash. Variables involved in the study are the draw ratio and the weight percentage of graphene nanopowder. Results will shed light on the role of alignment of graphene flakes on enhancing thermal transport and provide new avenues to achieve ultra-high thermal conductivity in polymeric materials.

  15. 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. PMID:24210946

  16. 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. PMID:24679750

  17. 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.

  18. 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.

  19. High-temperature thermal degradation of polyethylene from reactive molecular dynamics

    NASA Astrophysics Data System (ADS)

    Lane, J. Matthew D.; Moore, Nathan W.

    Thermal degradation of polyethylene is studied under extremely high-rate temperature ramp rates from 1014 to 1010 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. These results are used to parameterize a kinetic rate model for the dissociation and coalescence of hydrocarbons as a function of temperature, temperature ramp rate, and density. The results are contrasted to first-order random-scission macrokinetic models often assumed for pyrolysis of linear polyethylene under ambient conditions. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04- 94AL85000.

  20. 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. PMID:24275347

  1. Space Charge Trapping and Conduction in Low-Density Polyethylene/Silica Nanocomposite

    NASA Astrophysics Data System (ADS)

    Wu; Jiandong; Yin; Yi; Lan; Li; Wang; Qiaohua; Li; Xuguang; Xiao; Dengming

    2012-04-01

    The high field conduction and space charge distribution were investigated in low-density polyethylene (LDPE) and LDPE/silica nanocomposites filled with various concentrations of nanosilica. The results indicate that nanosilica could effectively suppress space charge accumulation at nanofiller concentrations from 0.1 to 5.0 wt %. However, the conduction current at a high field significantly increases at low concentrations from 0.1 to 0.5 wt % and remarkably reduces at high concentrations from 0.5 to 5.0 wt %. It is shown that the trap depth corresponding to the time from 2 to 3600 s significantly decreases at low nanofiller concentrations from 0.1 to 0.5 wt %. However, the depth of deep traps corresponding to the time from 100 to 3600 s increases with the increase in nanofiller concentration from 0.5 to 5.0 wt %. Moreover, the depth of shallow traps corresponding to the time from 2 to 100 s increases at concentrations from 0.5 to 2.0 wt %, and then it decreases at concentrations from 2.0 to 5.0 wt %. In addition, the apparent mobility varies with the modification of trap depth caused by the introduction of nanofiller. The threshold field EΩ-t for remarkable charge injection and Et-c proportional to the total trap density H are significantly lower in the nanocomposite with a low nanosilica concentration, i.e., 0.1 and 0.5 wt %, while both of them increase at concentrations from 0.5 to 5.0 wt %. It is considered that the impurity effect is greater than the nanofiller effect at a low nanofiller concentration. The deep trap is speculated as the chemical trap in the interface of the nanofiller bonding strongly with the polymer chain, while the shallow trap may be related to the chemical trap in the weakly bonded interface. It is clear that the space charge behavior and conduction are significantly affected by modification of the trap depth and density distribution owing to the introduction of nanofiller.

  2. High power density targets

    NASA Astrophysics Data System (ADS)

    Pellemoine, Frederique

    2013-12-01

    In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material. This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

  3. RAPID COMMUNICATION: Influence of temperature treatment on the electrical properties of low-density polyethylene

    NASA Astrophysics Data System (ADS)

    Boudou, L.; Guastavino, J.

    2000-11-01

    The influence of temperature from 298 K to 353 K on the electrical conduction of low-density polyethylene is reported. Conduction current and differential scanning calorimetry (DSC) measurements show a correlation between the structural change due to the temperature treatment and the change in the activation energy of the conduction mechanism involved. When the temperature is greater than 318 K, an activation energy decrease from 0.94 eV to 0.68 eV and a DSC exothermic peak are observed. This temperature threshold is correlated with a facilitated detrapping of charges stored during polarization.

  4. 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. PMID:15902864

  5. Field calibration of low density polyethylene passive samplers for gaseous POPs.

    PubMed

    Khairy, Mohammed A; Lohmann, Rainer

    2014-03-01

    A field calibration study of low density polyethylene (LDPE) for measuring atmospheric concentrations of persistent organic pollutants (POPs) was performed in East Providence (RI), USA. LDPE samplers were collected after 3, 7, 10, 14, 17 and 21 days of exposure along with samples from a co-deployed high volume sampler. Uptake kinetics of POPs by LDPEs were confirmed both by using an uptake study over time and the inclusion of performance reference compounds (PRCs). Results indicated that only POPs with log sampler-air partitioning coefficient (KPE-A) ≤ 7.6 were approaching equilibrium by the end of the deployment period, whereas all the other POPs were still in the linear uptake rate. Sampling rates (1.0-80 m(3) per day) were higher for some POPs when compared to literature values possibly due to the open sampler housing design used. Derived KPE-As for the detected POPs in field calibration study were correlated against the compounds' octanol-air partitioning coefficients (log KOA): [log KPE-A = 0.88 ± 0.02 × log KOA + 0.40 ± 0.21 (R(2) = 0.96; n = 59; SE = 0.23)], and their subcooled liquid vapour pressures (log PL/Pa): [log KPE-A = -0.82 ± 0.02 × log PL + 6.22 ± 0.05 (R(2) = 0.96; n = 59; SE = 0.22)] to predict values for all POPs. PL was generally found to be a better predictor of KPE-A for all POPs. PMID:24270460

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

    SciTech Connect

    Sanchez-Nacher, L.; Garcia-Sanoguera, D.; Fenollar, O.; Balart, J.; Fombuena, V.

    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 increase 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.

  7. Radiation grafting of acrylamide onto starch-filled low density polyethylene

    NASA Astrophysics Data System (ADS)

    Bagheri, Rouhallah; Naimian, Franak; Sheikh, Nassrin

    1997-04-01

    Acrylamide (AAm) was grafted on the surface of starch-filled low density polyethylene (SLDPE) and low density polyethylene (LDPE) films by the mutual irradiation technique at doses from 0.75 to 5 kGy. The effect of dose, solvents and dihydroxybenzoquinone on the degree of grafting was studied by Fourier transform infrared spectroscopy and the weight measurement method of extracted films at a constant monomer concentration (10% w/w). An ultraviolet spectrophotometer was also used to elucidate the results of the above methods. Grafting on SLDPE and LDPE samples reaches a maximum followed by a slight decrease with increasing dose. A higher degree of grafting was obtained on SLDPE samples compared with that on LDPE. An induction period was observed in the case of the samples prepared in tetrahdyrfuran (THF) as the solvent compared with those in chloroform. Addition of benzene to chloroform and THF (50% v/v) accelerates the rate of AAm grafting on the samples. Dihydroxybenzoquinone inhibits the grafting reactions of the samples especially in the THF solutions. The water uptake measurement of the samples correlates with the degree of grafting.

  8. Conformation and electronic structure of polyethylene: A density-functional approach

    NASA Astrophysics Data System (ADS)

    Miao, M. S.; van Camp, P. E.; van Doren, V. E.; Ladik, J. J.; Mintmire, J. W.

    1996-10-01

    Two different local-density approximations, the Gáspár-Kohn-Sham and the Perdew-Zunger approximations, of the density-functional method have been used to calculate structural and electronic properties of polyethylene systems with several different dihedral angles. For each system, the CC bond lengths and the CCC and HCH bond angles are optimized simultaneously. All the parameters appear to be strongly coupled with torsional freedom and vary with the change in dihedral angle in a pattern similar to that of the total energy. The total energy has an absolute minimum for the planar zigzag conformation but a distinct local minimum for the quasistable helical conformation. Another minimum occurs in the energy curve close to this gauche minimum. The calculated valence and conduction bands are discussed and compared with other theoretical calculations and experiment.

  9. Optimizing the surface density of polyethylene glycol chains by grafting from binary solvent mixtures

    NASA Astrophysics Data System (ADS)

    Arcot, Lokanathan; Ogaki, Ryosuke; Zhang, Shuai; Meyer, Rikke L.; Kingshott, Peter

    2015-06-01

    Polyethylene glycol (PEG) brushes are very effective at controlling non-specific deposition of biological material onto surfaces, which is of paramount importance to obtaining successful outcomes in biomaterials, tissue engineered scaffolds, biosensors, filtration membranes and drug delivery devices. We report on a simple 'grafting to' approach involving binary solvent mixtures that are chosen based on Hansen's solubility parameters to optimize the solubility of PEG thereby enabling control over the graft density. The PEG thiol-gold model system enabled a thorough characterization of PEG films formed, while studies on a PEG silane-silicon system examined the versatility to be applied to any substrate-head group system by choosing an appropriate solvent pair. The ability of PEG films to resist non-specific adsorption of proteins was quantitatively assessed by full serum exposure studies and the binary solvent strategy was found to produce PEG films with optimal graft density to efficiently resist protein adsorption.

  10. High Energy Density Microwaves

    SciTech Connect

    Phillips, R.M.

    1999-04-01

    These proceedings represent papers presented at the RF98 Workshop entitled `High Energy Density Microwaves` held in California in October, 1998. The topics discussed were predominantly accelerator{minus}related. The Workshop dealt, for the most part, with the generation and control of electron beams, the amplification of RF signals, the design of mode converters, and the effect of very high RF field gradients. This Workshop was designed to address the concerns of the microwave tube industry worldwide, the plasma physicists who deal with very high beam currents and gigawatts of RF power, and researchers in accelerator centers around the world. Papers were presented on multibeam klystrons, gyrotron development, plasmas in microwave tubes, RF breakdown, and alternatives to conventional linear coliders at 1 TeV and above. The Workshop was partially sponsored by the US Department of Energy. There were 46 papers presented at the conference,out of which 19 have been abstracted for the Energy,Science and Technology database.(AIP)

  11. The effect of size and content of jackfruit seed flour on the properties of low density polyethylene

    NASA Astrophysics Data System (ADS)

    Santhiya, P.; Sam, S. T.; Ragunathan, S.; Noriman, N. Z.; Voon, C. H.

    2015-05-01

    The effect of jackfruit seed flour content on the tensile properties of low density polyethylene (LDPE) was investigated. A polysaccharides-based natural polymer, jackfruit seed flour, was melt blended with low density polyethylene (LDPE). LDPE/ jackfruit seed blends were prepared by using internal mixer (brabender) at 150°C. The jackfruit seed flour content ranged from 0 to 20 wt%. The tensile properties were tested by using a universal testing machine (UTM) according to ASTM D638. The Young's modulus increased with jackfruit seed blends content up to 20 wt% and decreased thereafter.

  12. 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.

  13. Chitosan filled recycled low density polyethylene composite: Melt flow behaviour and thermal degradation properties

    NASA Astrophysics Data System (ADS)

    Lim, B. Y.; Voon, C. H.; Salmah, H.; Nordin, H.

    2016-07-01

    An environmentally friendly composite was fabricated from chitosan and recycled low density polyethylene (rLDPE) with the means of melt mixing at 180 °C. The composites were prepared in different loading (10, 20, 30 and 40 php) of chitosan. Due to the incompatibility between filler and matrix, a coupling agent, Ultraplus TP01, was added into the composites. The melt flow index (MFI) values of rLDPE/chitosan composites decreased with chitosan loading but increased with rise of temperature. With the presence of Ultraplus TP01, MFI values of composites were decreased. The thermal stability of rLDPE/chitosan was reduced with increase of chitosan loading but increased with addition of Ultraplus TP01. It was believed that Ultraplus TP01 had provided better interfacial bonding between chitosan and rLDPE, thus enhanced the thermal stability of rLDPE/chitosan composites.

  14. Mechanical properties of low-density polyethylene filled by graphite nanoplatelets.

    PubMed

    Carotenuto, G; De Nicola, S; Palomba, M; Pullini, D; Horsewell, A; Hansen, T W; Nicolais, L

    2012-12-01

    The mechanical properties of GNP/LDPE nanocomposites (graphite nanoplatelets/low density polyethylene) have been investigated, in order to establish the effect of nanoscale reinforcement within the polymer matrix. Results show that the presence of the filler does not involve a change in the microscopic structure of the polymer. However, on a macroscopic scale, GNPs limit the mobility of the polymer chains, resulting in an increase in stiffness for the final composite. Orientation of GNPs within the LDPE matrix is also an important issue that affects mechanical properties and it has been evaluated by testing nanocomposites made by different manufacturing techniques (compression moulding and blown extrusion). The comparison between the experimental data and the Halpin-Tsai model shows that the orientation of GNPs due to the extrusion process leads to values of tensile modulus higher than that obtained with the randomly oriented disposition resulting from the compression moulding technique. PMID:23128320

  15. Improvement of impact strength in linear low density polyethylene (LLDPE) by blending with amorphous polymers

    SciTech Connect

    Mirabella, F.M. Jr.

    1996-12-31

    The objective of the current work was to improve the film impact strength of commercial linear low density polyethylene (LLDPE) resins, while maintaining or improving other desirable properties. The approach used was to blend rubber-like (i.e. essentially noncrystalline) polymer resins with the base resin LLDPE. The choice of the rubber-like components was largely dictated by their commercial availability. The rubber-like polymers chosen were poly (ethylene-vinyl acetate) [EVA], poly (ethylene-n-butyl acrylate) [EnBA], and poly (ethylene-propylene) rubber [EPR]. The weight percent range of addition of the rubber-like component was restricted to 5% - 20%. The preferred range was only up to 10%. The structure of the base LLDPE resin, rubber-like components and the blends thereof was characterized. The physical and mechanical properties of the blown films of the resin blends were measured and correlations between structure and properties were determined.

  16. 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.

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

    SciTech Connect

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

    2010-12-23

    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.

  18. 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.

  19. 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. PMID:26275857

  20. 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. PMID:27341891

  1. Durability of highly cross-linked polyethylene in total hip and total knee arthroplasty.

    PubMed

    Dion, Neil T; Bragdon, Charles; Muratoglu, Orhun; Freiberg, Andrew A

    2015-07-01

    This article reviews the history of the development of highly cross-linked polyethylene and provides an in-depth review of the clinical results regarding the durability of highly cross-linked polyethylene (HXLPE) used in total hip arthroplasty (THA) and total knee arthroplasty (TKA). The use of polyethylene as a bearing surface has contributed to the success of THA and TKA; however, polyethylene wear and osteolysis can lead to failure. Ongoing clinical and retrieval studies are required to analyze outcomes at longer-term follow-up. PMID:26043046

  2. High Power Density Motors

    NASA Technical Reports Server (NTRS)

    Kascak, Daniel J.

    2004-01-01

    With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

  3. Structural changes in the low-density polyethylene/natural rubber composites in the aqueous and soil media

    NASA Astrophysics Data System (ADS)

    Mastalygina, Elena E.; Varyan, Ivetta A.; Kolesnikova, Natalya N.; Popov, Anatoly A.

    2016-05-01

    The novel biodegradable materials based on polyethylene with different content of natural rubber have been developed. In this paper the regularities of changes in structure and properties of the composites under the influence of biological and non-biological factors have been investigated. High levels of biodegradability and satisfied mechanical properties of biocomposites, as well as the significant modification of the polyethylene crystalline phase in the composites affected by moisture and environmental factors have been determined.

  4. High sensitivity of positron annihilation to thermal oxidation of polyethylene

    NASA Astrophysics Data System (ADS)

    Ito, Kenji; Kobayashi, Yoshinori; Nanasawa, Atsushi

    2003-01-01

    We demonstrate the high sensitivity of positron annihilation to compositional changes related to the thermal degradation of polyethylene (PE). Positron annihilation γ-ray and lifetime measurements were conducted for PE films with and without antioxidant (1000-ppm Ciba® IRGANOX® 1076), subjected to heat treatment at 100 °C for different periods, to a maximum of 30 days. For the film without antioxidant, the positron Doppler parameter (S) and ortho-positronium formation probability (Io-Ps) appreciably decreased with increased heat treatment times, whereas they barely changed for the film with antioxidant. This, together with the Fourier transform infrared measurements, demonstrated that the variations of S and Io-Ps are caused by the thermal oxidation of PE. The S parameter was found to be sensitive to the early stage of degradation, where the carbonyl concentration is inferred to be lower than 100 ppm. The high sensitivity results from the large positron mobility in PE and from the high positron affinity of oxygen-containing polar groups. This work provides the basis for an application of positron annihilation to sensitive detection of the initial degradation of PE and other nonpolar polymers.

  5. Ultra High Molecular Weight Polyethylene: Mechanics, Morphology, and Clinical Behavior

    PubMed Central

    Sobieraj, MC; Rimnac, CM

    2013-01-01

    Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been used for over four decades as a bearing surface in total joint replacements. The mechanical properties and wear properties of UHMWPE are of interest with respect to the in vivo performance of UHMWPE joint replacement components. The mechanical properties of the polymer are dependent on both its crystalline and amorphous phases. Altering either phase (i.e., changing overall crystallinity, crystalline morphology, or crosslinking the amorphous phase) can affect the mechanical behavior of the material. There is also evidence that the morphology of UHMWPE, and, hence, its mechanical properties evolve with loading. UHMWPE has also been shown to be susceptible to oxidative degradation following gamma radiation sterilization with subsequent loss of mechanical properties. Contemporary UHMWPE sterilization methods have been developed to reduce or eliminate oxidative degradation. Also, crosslinking of UHMWPE has been pursued to improve the wear resistance of UHMWPE joint components. The 1st generation of highly crosslinked UHMWPEs have resulted in clinically reduced wear; however, the mechanical properties of these materials, such as ductility and fracture toughness, are reduced when compared to the virgin material. Therefore, a 2nd generation of highly crosslinked UHMWPEs are being introduced to preserve the wear resistance of the 1st generation while also seeking to provide oxidative stability and improved mechanical properties. PMID:19627849

  6. Quantifying the Coverage Density of Poly(ethylene glycol) Chains on the Surface of Gold Nanostructures

    PubMed Central

    Xia, Xiaohu; Yang, Miaoxin; Wang, Yucai; Zheng, Yiqun; Li, Qingge; Chen, Jingyi; Xia, Younan

    2011-01-01

    The coverage density of poly(ethylene glycol) (PEG) is a key parameter in determining the efficiency of PEGylation, a process pivotal to in vivo delivery and targeting of nanomaterials. Here we report four complementary methods for quantifying the coverage density of PEG chains on various types of Au nanostructures by using a model system based on HS-PEG-NH2 with different molecular weights. Specifically, the methods involve reactions with fluorescamine and ninhydrin, as well as labeling with fluorescein isothiocyanate (FITC) and Cu2+ ions. The first two methods use conventional amine assays to measure the number of unreacted HS-PEG-NH2 molecules left behind in the solution after incubation with the Au nanostructures. The other two methods involve coupling between the terminal –NH2 groups of adsorbed -S-PEG-NH2 chains and FITC or a ligand for Cu2+ ion, and thus pertain to the “active” –NH2 groups on the surface of a Au nanostructure. We found that the coverage density decreased as the length of PEG chains increased. A stronger binding affinity of the initial capping ligand to the Au surface tended to reduce the PEGylation efficiency by slowing down the ligand exchange process. For the Au nanostructures and capping ligands we have tested, the PEGylation efficiency decreased in the order of citrate-capped nanoparticles > PVP-capped nanocages ≈ CTAC-capped nanoparticles ≫ CTAB-capped nanorods, where PVP, CTAC, and CTAB stand for poly(vinyl pyrrolidone), cetyltrimethylammonium chloride, and cetyltrimethylammonium bromide, respectively. PMID:22148912

  7. Inducing the migration behavior of endothelial cells by tuning the ligand density on a density-gradient poly(ethylene glycol) surface.

    PubMed

    Li, Tiantian; Xu, Kui; Fu, Ya; Cai, Kaiyong

    2016-07-01

    The migration of endothelial cells (ECs) is crucially important for many biological processes, including early embryonic vasculogenesis, wound healing and angiogenesis. To investigate the effect of the surface poly(ethylene glycol) (mPEG-CHO) density on the migration of ECs, we developed a convenient and effective method to fabricate a series of silicon slides with graded PEG densities on their surfaces based on gradual treatment with 3-glycidoxypropyltrimethoxysilane (GPTMS), backfilling with 3-aminopropyltriethoxysilane (APTES) and subsequent conjugation of m-PEG. The PEG gradient was confirmed by X-ray photoelectron spectrometry (XPS), contact angle measurement and spectroscopic ellipsometry and determined to range from 0.56 to 0.75chains/nm(2). The impact of the PEG gradient on the EC migration was evaluated by real-time observation via a time-lapse phase-contrast microscope. ECs adhered to the silicon surfaces with high and modest PEG densities displayed a higher tendency of migration than those on corresponding non-graded samples. The results suggest that the motility of ECs could be modulated by the PEG gradient. This study would be helpful for understanding cell-substrate interactions. PMID:27058513

  8. High Energy Density Capacitors

    SciTech Connect

    2010-07-01

    BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.

  9. 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.

  10. Implications of observed PBDE diffusion coefficients in low density polyethylene and silicone rubber.

    PubMed

    Narváez Valderrama, Jhon F; Baek, Kine; Molina, Francisco J; Allan, Ian J

    2016-01-01

    A film-stacking technique was used to estimate diffusion coefficients of polybrominated diphenyl ethers (PBDEs) in low density polyethylene (LDPE) and silicone rubber. Substantially higher PBDE diffusion coefficients were observed for silicone rubber (AlteSil™) than for LDPE. A much steeper decrease in LDPE diffusion coefficients was found with increasing PBDE molecular weight than that for silicone rubber. From a passive sampling point-of-view, this means that for equivalent polymer-water partition coefficients for these two materials, the mass transfer resistance for these substances in the LDPE will be significantly higher than that for silicone rubber. Boundary layer control of the uptake process for silicone rubber can be expected for PBDEs. With a microplastic perspective, the low diffusion coefficients of PBDEs and in particular of decabromo diphenyl ether (BDE 209) in LDPE imply that the polymer diffusion coefficients for these plastic additives used as flame retardants need to be taken into account when considering the risk posed by microplastic particle ingestion by marine organisms. PMID:26678428

  11. 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%. PMID:26150081

  12. Biodegradation of low-density polyethylene (LDPE) by isolated fungi in solid waste medium

    SciTech Connect

    Zahra, Sahebnazar; Abbas, Shojaosadati Seyed; Mahsa, Mohammad-Taheri; Mohsen, Nosrati

    2010-03-15

    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 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.

  13. Estimation of membrane diffusion coefficients and equilibration times for low-density polyethylene passive diffusion samplers.

    PubMed

    Divine, Craig E; McCray, John E

    2004-03-15

    Passive diffusion (PD) samplers offer several potential technical and cost-related advantages, particularly for measuring dissolved gases and volatile organic compounds (VOCs) in groundwater at contaminated sites. Sampler equilibration is a diffusion-type process; therefore, equilibration time is dependent on sampler dimensions, membrane thickness, and the temperature-dependent membrane diffusion coefficient (Dm) for the analyte of interest. Diffusion coefficients for low-density polyethylene membranes were measured for He, Ne, H2, O2, and N2 in laboratory experiments and ranged from 1.1 to 1.9 x 10(-7) cm2 sec(-1) (21 degrees C). Additionally, Dm values for several commonly occurring VOCs were estimated from empirical experimental data previously presented by others (Vroblesky, D. A.; Campbell, T. R. Adv. Environ. Res. 2001, 5(1), 1.), and estimated values ranged from 1.7 to 4.4 x 10(-7) cm2 sec(-1) (21 degrees C). On the basis of these Dm ranges, PD sampler equilibration time is predicted for various sampler dimensions, including dimensions consistent with simple constructed samplers used in this study and commercially available samplers. Additionally, a numerical model is presented that can be used to evaluate PD sampler concentration "lag time" for conditions in which in situ concentrations are temporally variable. The model adequately predicted lag time for laboratory experiments and is used to show that data obtained from appropriately designed PD samplers represent near-instantaneous measurement of in situ concentrations for most field conditions. PMID:15074699

  14. Comparative fatigue behavior and toughness of remelted and annealed highly crosslinked polyethylenes.

    PubMed

    Medel, Francisco J; Peña, P; Cegoñino, José; Gómez-Barrena, E; Puértolas, J A

    2007-11-01

    Highly cross-linked polyethylenes (HXLPEs) have been incorporated into the hip replacement armamentarium based on their improved wear resistance. However, two different methods of thermal treatment separate the orthopedic community as strategies to control potential long-term oxidation, and controversy remains with problems in the long-term use of acetabular liners (long-term oxidation, rim fracture after impingement, etc.). Meanwhile, the mechanical properties of HXLPEs that may alleviate these problems are still unclear. On the other hand, HXLPEs are scarcely used in knee replacements, as there exists concern about the probably reduced fatigue and fracture performances of these materials. Thus, our aim was to compare the effects of both thermal treatment regimes on mechanical properties and to associate these findings with the material microstructure. The fatigue behavior of annealed and remelted HXLPEs was characterized using short-term cyclic stress-strain, long-term fatigue, and fatigue crack propagation tests. On the other hand, impact tests, tensile experiments, and the J-integral multispecimen method allowed us to assess toughness. Microstructure features such as crosslink density, crystallinity percentage, and lamellar thickness were investigated by swelling measurements, differential scanning calorimetry, and transmission electron microscopy, respectively. This study confirms that annealing preserves mechanical properties better than remelting from both fatigue and fracture resistance points of view, and it remarks that a suitable selection of irradiation and stabilization conditions is needed to achieve optimal mechanical performances of ultra high molecular weight polyethylenes for each specific total joint replacement. PMID:17680670

  15. 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.

  16. High density circuit technology

    NASA Technical Reports Server (NTRS)

    Wade, T. E.

    1979-01-01

    Polyimide dielectric materials were acquired for comparative and evaluative studies in double layer metal processes. Preliminary experiments were performed. Also, the literature indicates that sputtered aluminum films may be successfully patterned using the left-off technique provided the substrate temperature remains low and the argon pressure in the chamber is relatively high at the time of sputtering. Vendors associated with dry processing equipment are identified. A literature search relative to future trends in VLSI fabrication techniques is described.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26552843

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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.

  19. Improving the Transparency of Ultra-Drawn Melt-Crystallized Polyethylenes: Toward High-Modulus/High-Strength Window Application.

    PubMed

    Shen, Lihua; Nickmans, Koen; Severn, John; Bastiaansen, Cees W M

    2016-07-13

    Highly transparent, ultradrawn high-density polyethylene (HDPE) films were successfully prepared using compression molding and solid-state drawing techniques. The low optical transmittance (<50%) of the pure drawn HDPE films can be drastically improved (>90%) by incorporating a small amount (>1 wt %/wt) of specific additives to HDPE materials prior to drawing. It is shown that additives with relatively high refractive index result in an increased optical transmittance in the visible light wavelength which illustrates that the improvement in optical characteristics probably originates from refractive index matching between the crystalline and noncrystalline regions in the drawn films. Moreover, the optically transparent drawn HDPE films containing additives maintain their physical and mechanical properties, especially their high modulus and high strength, which make these films potentially useful in a variety of applications, such as high-impact windows. PMID:27314927

  20. High density associative memory

    NASA Technical Reports Server (NTRS)

    Moopenn, Alexander W. (Inventor); Thakoor, Anilkumar P. (Inventor); Daud, Taher (Inventor); Lambe, John J. (Inventor)

    1989-01-01

    A multi-layered, thin-film, digital memory having associative recall. There is a first memory matrix and a second memory matrix. Each memory matrix comprises, a first layer comprising a plurality of electrically separated row conductors; a second layer comprising a plurality of electrically separated column conductors intersecting but electrically separated from the row conductors; and, a plurality of resistance elements electrically connected between the row condutors and the column conductors at respective intersections of the row conductors and the column conductors, each resistance element comprising, in series, a first resistor of sufficiently high ohmage to conduct a sensible element current therethrough with virtually no heat-generating power consumption when a low voltage as employed in thin-film applications is applied thereacross and a second resistor of sufficiently high ohmage to conduct no sensible current therethrough when a low voltage as employed in thin-film applications is applied thereacross, the second resistor having the quality of breaking down to create a short therethrough upon the application of a breakdown level voltage across the first and second resistors.

  1. 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. PMID:26845585

  2. 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.

  3. Equipment evaluation for low density polyethylene encapsulated nitrate salt waste at the Rocky Flats Plant

    SciTech Connect

    Yamada, W.I.; Faucette, A.M.; Jantzen, R.C.; Logsdon, B.W.; Oldham, J.H.; Saiki, D.M.; Yudnich, R.J.

    1993-08-30

    Mixed wastes at the Rocky Flats Plant (RFP) are subject to regulation by the Resource Conservation and Recovery Act (RCRA). Polymer solidification is being developed as a final treatment technology for several of these mixed wastes, including nitrate salts. Encapsulation nitrate salts with low density polyethylene (LDPE) has been the preliminary focus of the RFP polymer solidification effort. Literature reviews, industry surveys, and lab-scale and pilot-scale tests have been conducted to evaluate several options for encapsulating nitrate salts with LDPE. Most of the effort has focused on identifying compatible drying and extrusion technologies. Other processing options, specifically meltration and non-heated compounding machines, were also investigated. The best approach appears to be pretreatment of the nitrate salt waste brine in either a vertical or horizontal thin film evaporator followed by compounding of the dried waste with LDPE in an intermeshing, co-rotating, twin-screw extruder. Additional pilot-scale tests planned for the fall of 1993 should further support this recommendation. Preliminary evaluation work indicates that meltration is not possible at atmospheric pressure with the LDPE (Chevron PE-1409) provided by RFP. However, meltration should be possible at atmospheric pressure using another LDPE formulation with altered physical and rheological properties: Lower molecular weight and lower viscosity (Epoline C-15). Contract modifications are now in process to allow a follow-on pilot scale demonstration. Questions regarding changed safety and physical properties of the resultant LDPE waste form due to use of the Epoline C-15 will be addressed. No additional work with non-heated mixer compounder machines is planned at this time.

  4. A theory for accelerated slow crack growth in medium-density polyethylene fuel-gas pipes

    SciTech Connect

    Chaoui, K.

    1989-01-01

    In the present work, a new testing procedure is developed for medium density polyethylene (MDPE) fuel gas pipes to produce brittle fracture at laboratory scale within a shorter period of time as compared to existing procedures. In the proposed procedure, the intrinsic resistance of (MDPE) pipes is studied under fatigue mode and ambient environment. Because of the lack of theoretical foundations in the existing procedures, brittle fracture in such structural components is addressed using the crack layer formalism in order to assess the controlling damage mechanisms and extract characteristic parameters representative of the phenomena occurring as a result of failure. It is found that crack propagation behavior is split into a brittle regime which extends up to half of the specimen width and a ductile regime which controls most of the second half. Damage analysis revealed that the brittle regime is led by a craze zone which becomes diffuse and larger as ductility increases. Crack and its surrounding damage are treated as a single macroscopic entity called a crack layer (CL). The portion where damage accumulates under the effects of the stress field at the crack tip is defined as the active zone. This zone is a major energy sink and thus, controls the crack propagation rate. The driving force and the instability conditions for CL propagation are commonly given in terms of the energy available and the energy required for propagation which is expressed as the product of the resistance moment R{sub 1} and the specific enthalpy of damage. In the present case, the analysis is limited to the brittle regime which is of a great interest in the long-term failure of MDPE pipes under service conditions. Also, the analysis uses the entire brittle fracture history to evaluate the resistance moment for the crazing mechanism and to extract the specific enthalpy of damage {Psi}*.

  5. High energy density electrochemical cell

    NASA Technical Reports Server (NTRS)

    Byrne, J. J.; Williams, D. L.

    1970-01-01

    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density.

  6. 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. PMID:26572348

  7. Treatment with orthophosphoric acid enhances the thermal stability of the piezoelectricity in low-density polyethylene ferroelectrets

    NASA Astrophysics Data System (ADS)

    Rychkov, Dmitry; Alberto Pisani Altafim, Ruy; Qiu, Xunlin; Gerhard, Reimund

    2012-06-01

    Ferroelectrets have been fabricated from low-density polyethylene (LDPE) films by means of a template-based lamination. The temperature dependence of the piezoelectric d33 coefficient has been investigated. It was found that low-density polyethylene ferroelectrets have rather low thermal stability with the piezoelectric coefficient decaying almost to zero already at 100 °C. This behavior is attributed to the poor electret properties of the polyethylene films used for the fabrication of the ferroelectrets. In order to improve the charge trapping and the thermal stability of electret charge and piezoelectricity, LDPE ferroelectrets were treated with orthophosphoric acid. The treatment resulted in considerable improvements of the charge stability in LDPE films and in ferroelectret systems made from them. For example, the charge and piezoelectric-coefficient decay curves shifted to higher temperatures by 60 K and 40 K, respectively. It is shown that the decay of the piezoelectric coefficient in LDPE ferroelectrets is governed by the relaxation of less stable positive charges. The treatment also leads to noticeable changes in the chemical composition of the LDPE surface. Infrared spectroscopy reveals absorption bands attributed to phosphorus-containing structures, while scanning electron microscopy shows new island-like structures, 50-200 nm in diameter, on the modified surface.

  8. High density modular avionics packaging

    NASA Astrophysics Data System (ADS)

    Poradish, F.

    Requirements and design configurations for high density modular avionics packaging are examined, with particular attention given to new hardware trends, the design of high-density standard modules (HDSM's), and HDSM requirements. The discussion of the HDSM's covers thermal management, system testability, power supply, and performance specifications. The general design of an integrated HDSM demonstration system currently under construction is briefly described, and some test data are presented.

  9. Laminated thermoplastic composite material from recycled high density polyethylene

    NASA Technical Reports Server (NTRS)

    Liu, Ping; Waskom, Tommy L.

    1994-01-01

    The design of a materials-science, educational experiment is presented. The student should understand the fundamentals of polymer processing and mechanical property testing of materials. The ability to use American Society for Testing and Materials (ASTM) standards is also necessary for designing material test specimens and testing procedures. The objectives of the experiment are (1) to understand the concept of laminated composite materials, processing, testing, and quality assurance of thermoplastic composites and (2) to observe an application example of recycled plastics.

  10. Development of an extremely wear-resistant ultra high molecular weight polyethylene for total hip replacements.

    PubMed

    McKellop, H; Shen, F W; Lu, B; Campbell, P; Salovey, R

    1999-03-01

    Osteolysis induced by ultra high molecular weight polyethylene wear debris is one of the primary factors limiting the lifespan of total hip replacements. Crosslinking polyethylene is known to improve its wear resistance in certain industrial applications, and crosslinked polyethylene acetabular cups have shown improved wear resistance in two clinical studies. In the present study, crosslinked polyethylene cups were produced by two methods. Chemically crosslinked cups were produced by mixing a peroxide with ultra high molecular weight polyethylene powder and then molding the cups directly to shape. Radiation-crosslinked cups were produced by exposing conventional extruded ultra high molecular weight polyethylene bar stock to gamma radiation at various doses from 3.3 to 100 Mrad (1 Mrad = 10 kGy), remelting the bars to extinguish residual free radicals (i.e., to minimize long-term oxidation), and then machining the cups by conventional techniques. In hip-joint simulator tests lasting as long as 5 million cycles, both types of cross-linked cups exhibited dramatically improved resistance to wear. Artificial aging of the cups by heating for 30 days in air at 80 degrees C induced oxidation of the chemically crosslinked cups. However, a chemically crosslinked cup that was aged 2.7 years at room temperature had very little oxidation. Thus, whether substantial oxidation of chemically crosslinked polyethylene would occur at body temperature remains unclear. The radiation-crosslinked remelted cups exhibited excellent resistance to oxidation. Because crosslinking can reduce the ultimate tensile strength, fatigue strength, and elongation to failure of ultra high molecular weight polyethylene, the optimal crosslinking dose provides a balance between these physical properties and the wear resistance of the implant and might substantially reduce the incidence of wear-induced osteolysis with total hip replacements. PMID:10221831

  11. Preparation of hydroxylated polyethylene surfaces.

    PubMed

    Zand, A; Walter, N; Bahu, M; Ketterer, S; Sanders, M; Sikorski, Y; Cunningham, R; Beholz, L

    2008-01-01

    The surfaces of high-density or ultra-high-molecular-weight polyethylenes were hydroxylated using a two-step process. The wetting and wear properties of the untreated (virgin) and surface hydroxylated polyethylenes were compared. The introduction of hydroxyl groups provided an increase in surface hydrophilicity resulting in reduced wear. Hydrophilicity was analyzed by optical analysis of water contact angle. Wear was determined by weight loss under conditions of a reciprocating pin-on-plate apparatus with the panels immersed in water or calf serum. These results suggest that hydroxylation of polyethylene friction-bearing orthopedic surfaces may lead to a longer joint life. PMID:18318959

  12. High performance protein microarrays based on glycidyl methacrylate-modified polyethylene terephthalate plastic substrate.

    PubMed

    Liu, Yingshuai; Li, Chang Ming; Hu, Weihua; Lu, Zhisong

    2009-01-15

    There is a great challenge to immobilize high density of probe molecules for high performance protein microarrays, and this is achieved in this work by using polyethylene terephthalate (PET) plastic substrate onto which glycidyl methacrylate (GMA) photopolymer is grafted under mild conditions to introduce high density of epoxy groups for covalent immobilization of proteins. The poly(GMA)-grafted PET (PGMA-PET) surface was characterized with atomic force microscope (AFM) and attenuated total reflectance Fourier transform infra-red (ATR-FTIR) spectroscopy. For high density of protein immobilization and good quality of microspots, experiments were conducted to optimize the printing buffer, and an optimal buffer was found out to be PBS with 10% glycerol+0.003% triton X-100. According to the studies of loading capacity and immobilization kinetics, the optimal protein probe concentration and incubation time for the efficient immobilization are 200 microg mL(-1) and 8h, respectively. The performance of the PGMA-PET-based protein microarrays is evaluated with sandwich immunoassay using rat IgG and anti-rat IgG as model proteins, demonstrating a limit of detection (LOD) of 10 pg mL(-1) and a dynamic range of five orders of magnitude which are better than or very comparable with the reported or commercially available immunoassays, while providing a high-throughput approach. The work renders a simple and economic method to manufacture high performance protein microarrays and is expected to have great potentials in broad applications related to clinic diagnosis, drug discovery and proteomic research. PMID:19064107

  13. Photoionization and High Density Gas

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

  14. 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.

  15. 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.

  16. Development of a low-density polyethylene-containing passive sampler for measuring dissolved hydrophobic organic compounds in open waters.

    PubMed

    Bao, Lian-Jun; Xu, Shi-Ping; Liang, Yan; Zeng, Eddy Y

    2012-05-01

    A passive water sampler with low-density polyethylene (LDPE) as the sorbent phase was built and field-tested for sensing freely dissolved concentrations of hydrophobic organic compounds (HOCs) in fresh and coastal water. Based on the measured LDPE-water partition coefficients (K(pew)) of 12 polycyclic aromatic hydrocarbons (PAHs) and dichlorodiphenyltrichloroethane (DDT) and its seven metabolites, the detection limits with the passive sampler containing 10-g LDPE ranged from 0.04 to 56.9 pg/L in the equilibrium sampling mode. Furthermore, the utility of the passive sampler in measuring dissolved HOC concentrations in open waters was examined through a comparison with solid-phase extraction combined with liquid-liquid extraction (SPE-LLE) and poly(dimethyl)siloxane (PDMS) coated fiber samplers. The total concentrations of PAHs (3.8-16 ng/L) obtained by the passive sampler were lower than those (87.7-115.5 ng/L) obtained through SPE-LLE. This large difference was probably attributable to slower water exchange in and out of the passive sampler as time progressed because of blockage by algae in eutrophia reservoirs and high dissolved organic carbon contents resulting in higher-than-expected PAH concentrations by SPE-LLE. Furthermore, the concentrations and compositional profiles of DDXs (sum of p,p'-DDT, p,p'-DDD, p,p'-DDE, o,p'-DDT, o,p'-DDD, o,p'-DDE, and p,p'-DDMU) at site A obtained by the passive sampler agreed with the results obtained with the PDMS-coated fibers, suggesting that the passive sampler was able to reasonably quantify dissolved HOCs in seawater. PMID:22388779

  17. Influence of Polyethylene Glycol Density and Surface Lipid on Pharmacokinetics and Biodistribution of Lipid-Calcium-Phosphate Nanoparticles

    PubMed Central

    Liu, Yang; Hu, Yunxia; Huang, Leaf

    2014-01-01

    The pharmacokinetics (PK) and biodistribution of nanoparticles (NPs) are controlled by a complex array of interrelated, physicochemical and biological factors of NPs. The lipid-bilayer core structure of the Lipid-Calcium-Phosphate (LCP) NPs allows us to examine the effects of the density of polyethylene glycol (PEG) and the incorporation of various lipids onto the surface on their fate in vivo. Fluorescence quantification estimated that up to 20% (molar percent of outer leaflet lipids) could be grafted on the surface of LCP NPs. Contrary to the common belief that high level of PEGylation could prevent the uptake of NPs by the reticuloendothelial system (RES) organs such as liver and spleen, a significant amount of the injected dose was observed in the liver. Confocal microscopy revealed that LCP NPs were largely localized in hepatocytes not Kupffer cells. It was further demonstrated that the delivery to hepatocytes was dependent on both the concentration of PEG and the surface lipids. LCP NPs could be directed from hepatocytes to Kupffer cells by decreasing PEG concentration on the particle surface. In addition, LCP NPs with 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) exhibited higher accumulation in the hepatocytes than LCP NPs with dioleoylphosphatidylcholine (DOPC). Analysis of the proteins bound to NPs suggested that apolipoprotein E (apoE) might serve as an endogenous targeting ligand for LCP-DOTAP NPs, but not LCP-DOPC NPs. The significant uptake of NPs by the hepatocytes is of great interest to formulation design for oncologic and hepatic drug deliveries. PMID:24388798

  18. High Energy Density Laboratory Astrophysics

    SciTech Connect

    Remington, B A

    2004-11-11

    High-energy-density (HED) physics refers broadly to the study of macroscopic collections of matter under extreme conditions of temperature and density. The experimental facilities most widely used for these studies are high-power lasers and magnetic-pinch generators. The HED physics pursued on these facilities is still in its infancy, yet new regimes of experimental science are emerging. Examples from astrophysics include work relevant to planetary interiors, supernovae, astrophysical jets, and accreting compact objects (such as neutron stars and black holes). In this paper, we will review a selection of recent results in this new field of HED laboratory astrophysics and provide a brief look ahead to the coming decade.

  19. Spatially revolved high density electroencephalography

    NASA Astrophysics Data System (ADS)

    Wu, Jerry; Szu, Harold; Chen, Yuechen; Guo, Ran; Gu, Xixi

    2015-05-01

    Electroencephalography (EEG) measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In practice, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, several tens of minutes, as recorded from multiple electrodes placed on the scalp. In order to improve the resolution and the distortion cause by the hair and scalp, large array magnetoencephalography (MEG) systems are introduced. The major challenge is to systematically compare the accuracy of epileptic source localization with high electrode density to that obtained with sparser electrode setups. In this report, we demonstrate a two dimension (2D) image Fast Fourier Transform (FFT) analysis along with utilization of Peano (space-filling) curve to further reduce the hardware requirement for high density EEG and improve the accuracy and performance of the high density EEG analysis. The brain-computer interfaces (BCIs) in this work is enhanced by A field-programmable gate array (FPGA) board with optimized two dimension (2D) image Fast Fourier Transform (FFT) analysis.

  20. Sensory stability of ultra-high temperature milk in polyethylene bottle.

    PubMed

    Petrus, R R; Walter, E H M; Faria, J A F; Abreu, L F

    2009-01-01

    The objective of this study was to evaluate the sensory stability of ultra-high temperature (UHT) milk subjected to different heat treatments and stored at room temperature in white high density polyethylene bottles (HDPE) pigmented with titanium dioxide. Two lots of 300 units each were processed, respectively, at 135 and 141 degrees C/10 s using indirect heating and subsequently aseptically filled in an ISO class 7 clean room. These experimental lots were evaluated for appearance, aroma, flavor, and overall appreciation and compared to samples of commercial UHT milk purchased from local commercial stores. The time-temperature combinations investigated did not affect either the acceptability or the shelf life of the milk. Despite the limited light barrier properties of HDPE bottles, the product contained in the package tested exhibited good stability, with a shelf life ranging from 4 to 11 wk. Within this time period, the acceptability of the experimental lots was similar to that of the commercial products. The results achieved in this study contribute to turn the low-cost UHT system investigated into a technically viable option for small-size dairy processing plants. PMID:19200121

  1. Equal channel angular extrusion of ultra-high molecular weight polyethylene.

    PubMed

    Reinitz, Steven D; Engler, Alexander J; Carlson, Evan M; Van Citters, Douglas W

    2016-10-01

    Ultra-high molecular weight polyethylene (UHMWPE), a common bearing surface in total joint arthroplasty, is subject to material property tradeoffs associated with conventional processing techniques. For orthopaedic applications, radiation-induced cross-linking is used to enhance the wear resistance of the material, but cross-linking also restricts relative chain movement in the amorphous regions and hence decreases toughness. Equal Channel Angular Extrusion (ECAE) is proposed as a novel mechanism by which entanglements can be introduced to the polymer bulk during consolidation, with the aim of imparting the same tribological benefits of conventional processing without complete inhibition of chain motion. ECAE processing at temperatures near the crystalline melt for UHMWPE produces (1) increased entanglements compared to control materials; (2) increasing entanglements with increasing temperature; and (3) mechanical properties between values for untreated polyethylene and for cross-linked polyethylene. These results support additional research in ECAE-processed UHMWPE for joint arthroplasty applications. PMID:27287161

  2. High-pressure crystalline polyethylene studied by x-ray diffraction and ab initio simulations

    SciTech Connect

    Fontana, L.; Vinh, Diep Q.; Santoro, M.; Gorelli, F. A.; Hanfland, M.

    2007-05-01

    Crystalline polyethylene was investigated under pressure between 0 and 40 GPa, up to 280 deg. C, by means of synchrotron x-ray powder diffraction and ab initio calculations. A rich polymorphism was unveiled, consisting of two new high-pressure monoclinic phases, in addition to the well-known orthorhombic one, which appear reversibly, although with strong hysteresis, upon increasing pressure above 6 GPa (P2{sub 1}/m, Z{sub chain}=1) and 14-16 GPa (A2/m, Z{sub chain}=2), respectively. The equation of state was determined for the three solid phases. We find that polyethylene is characterized by a sharp separation between strong covalent intrachain and weaker interchain interactions up to the maximum investigated pressure, which, in turn, places the ultimate chemical stability limit of polyethylene far beyond these thermodynamic conditions.

  3. 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

  4. Low-pressure plasma enhanced immobilization of chitosan on low-density polyethylene for bio-medical applications

    NASA Astrophysics Data System (ADS)

    Pandiyaraj, K. Navaneetha; Ferraria, Ana Maria; Rego, Ana Maria Botelho do; Deshmukh, Rajendra. R.; Su, Pi-Guey; Halleluyah Mercy, Jr.; Halim, Ahmad Sukari

    2015-02-01

    With the aim of improving blood compatibility of low density polyethylene (LDPE) films, an effective low-pressure plasma technology was employed to functionalize the LDPE film surfaces through in-situ grafting of acrylic acid (AAc). Subsequently, the molecules of poly(ethylene glycol) (PEG) and chitosan (CHI) were immobilized on the surface of grafted LDPE films. The unmodified and modified LDPE films were analyzed using various characterization techniques such as contact angle, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) to understand the changes in surface properties such as hydrophilicity, surface topography and chemical composition, respectively. Furthermore, LDPE films have been subjected to an ageing process to determine the durability of the plasma assisted surface modification. The blood compatibility of the surface modified LDPE films was confirmed by in vitro tests. It was found that surface modified LDPE films show better hydrophilic behavior compared with the unmodified one. FTIR and XPS results confirm the successful immobilization of CHI on the surface of LDPE films. LDPE films showed marked morphological changes after grafting of AAc, PEG and CHI which were confirmed through AFM imaging. The in vitro blood compatibility tests have clearly demonstrated that CHI immobilized LDPE films exhibit remarkable anti thrombogenic nature compared with other modified films. Surface modified LDPE films through low-pressure plasma technique could be adequate for biomedical implants such as artificial skin substrates, urethral catheters or cardiac stents, among others.

  5. QCD AT HIGH PARTON DENSITY

    SciTech Connect

    KOVCHEGOV,Y.V.

    2000-04-25

    The authors derive an equation determining the small-x evolution of the F{sub 2} structure function of a large nucleus which resumes a cascade of gluons in the leading logarithmic approximation using Mueller's color dipole model. In the traditional language it corresponds to resummation of the pomeron fan diagrams, originally conjectured in the GLR equation. The authors show that the solution of the equation describes the physics of structure functions at high partonic densities, thus allowing them to gain some understanding of the most interesting and challenging phenomena in small-x physics--saturation.

  6. High-density digital recording

    NASA Technical Reports Server (NTRS)

    Kalil, F. (Editor); Buschman, A. (Editor)

    1985-01-01

    The problems associated with high-density digital recording (HDDR) are discussed. Five independent users of HDDR systems and their problems, solutions, and insights are provided as guidance for other users of HDDR systems. Various pulse code modulation coding techniques are reviewed. An introduction to error detection and correction head optimization theory and perpendicular recording are provided. Competitive tape recorder manufacturers apply all of the above theories and techniques and present their offerings. The methodology used by the HDDR Users Subcommittee of THIC to evaluate parallel HDDR systems is presented.

  7. The activation energy of oxidative thermal degradation of radiation- and peroxide-crosslinked low-density polyethylene

    SciTech Connect

    Matusevich, Yu.I.; Butovskaya, G.V.; Krul, L.P.

    1994-11-01

    The parameters of thermal degradation (kinetic order of the reaction, preexponential factor logA, and activation energy E{sub d}) of low-density polyethylene crosslinked by radiation or by dicumyl peroxide were determined from thermogravimetric data processed using the complementarity-based method of {open_quotes}supercorrelations.{close_quotes} The degradation of the polymer was found to obey a first-order rate equation. At mass losses of 10-20%, the parameters logA and E{sub d} were shown to decrease with an increasing degree of crosslinking because of the evolution of low-molecular radiolysis products and the low probability of chain radical processes. In the region of more intense destruction, E{sub d} (as well as logA) increases because the degradation of crosslinked polymer macromolecules requires greater energy consumption.

  8. 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

  9. Medium Osmolarity and Pericellular Matrix Development Improves Chondrocyte Survival When Photoencapsulated in Poly(Ethylene Glycol) Hydrogels at Low Densities

    PubMed Central

    Villanueva, Idalis; Bishop, Nikki L.

    2009-01-01

    The ability to encapsulate cells over a range of cell densities is important toward mimicking cell densities of native tissues and rationally designing strategies where cell source and/or cell numbers are clinically limited. Our preliminary findings demonstrate that survival of freshly isolated adult bovine chondrocytes dramatically decreases when photoencapsulated in poly(ethylene glycol) hydrogels at low densities (4 million cells/mL). During enzymatic digestion of cartilage, chondrocytes undergo a harsh change in their microenvironment. We hypothesize that the absence of exogenous antioxidants, the hyposmotic environment, and the loss of a protective pericellular matrix (PCM) increase chondrocytes' susceptibility to free radical damage during photoencapsulation. Incorporation of antioxidants and serum into the encapsulation medium improved cell survival twofold compared to phosphate-buffered saline. Increasing medium osmolarity from 330 to 400 mOsm (physiological) improved cell survival by 40% and resulted in ∼2-fold increase in adenosine triphosphate (ATP) production 24 h postencapsulation. However, cell survival was only temporary. Allowing cells to reproduce some PCM before photoencapsulation in 400 mOsm medium resulted in superior cell survival during and postencapsulation for up to 15 days. In summary, the combination of antioxidants, physiological osmolarity, and the development of some PCM result in an improved robustness against free radical damage during photoencapsulation. PMID:19331581

  10. High density tape casting system

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr. (Inventor)

    1989-01-01

    A system is provided for casting thin sheets (or tapes) of particles bound together, that are used for oxygen membranes and other applications, which enables the particles to be cast at a high packing density in a tape of uniform thickness. A slurry contains the particles, a binder, and a solvent, and is cast against the inside walls of a rotating chamber. Prior to spraying the slurry against the chamber walls, a solvent is applied to a container. The solvent evaporates to saturate the chamber with solvent vapor. Only then is the slurry cast. As a result, the slurry remains fluid long enough to spread evenly over the casting surface formed by the chamber, and for the slurry particles to become densely packed. Only then is the chamber vented to remove solvent, so the slurry can dry. The major novel feature is applying solvent vapor to a rotating chamber before casting slurry against the chamber walls.

  11. High power density spray cooling

    NASA Astrophysics Data System (ADS)

    Tilton, Donald E.; Pais, Martin R.; Chow, Louis C.

    1989-07-01

    The research reported describes experimental and theoretical investigations of high power density evaporative spray cooling. Preliminary experiments demonstrating heat fluxes greater than 1,000 W/sq cm were conducted. Extensive laser phase Doppler measurements of spray characteristics were also taken. These measurements provided valuable insight into the heat transfer process. An in-depth analysis was conducted to determine the mechanisms responsible for critical heat flux. Theoretical modeling was also conducted to determine the most desirable heat transfer conditions. After analysis of these results, an improved experimental apparatus was designed and fabricated. The new apparatus provided greater experimental control and improve accuracy. New tests were conducted in which the critical heat flux was increased, and the heat transfer efficiency was greatly improved. These results are compared to those of previous researchers, and indicated substantial improvement.

  12. Oxides having high energy densities

    DOEpatents

    Ceder, Gerbrand; Kang, Kisuk

    2013-09-10

    Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.

  13. 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. PMID:26970299

  14. Fast equilibration protocol for million atom systems of highly entangled linear polyethylene chains

    NASA Astrophysics Data System (ADS)

    Sliozberg, Yelena R.; Kröger, Martin; Chantawansri, Tanya L.

    2016-04-01

    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 starting 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.

  15. Study On Temperature Distribution In T Fittings - Polyethylene Natural Gas Pipes Assemblies

    NASA Astrophysics Data System (ADS)

    Avrigean, Eugen

    2015-09-01

    The present paper intends to approach theoretically and experimentally an important topic concerning the operational safety of the polyethylene pipes used in natural gas distribution. We discuss the influence of temperature in the high density polyethylene elbows during welding to the polyethylene pipes.

  16. Properties and Microstructural Characteristic of Kaolin Geopolymer Ceramics with Addition of Ultra High Molecular Weight Polyethylene

    NASA Astrophysics Data System (ADS)

    Ahmad, Romisuhani; Bakri Abdullah, Mohd Mustafa Al; Hussin, Kamarudin; Sandu, Andrei Victor; Binhussain, Mohammed; Ain Jaya, Nur

    2016-06-01

    In this paper, the mechanical properties and microstructure of kaolin geopolymer ceramics with addition of Ultra High Molecular Weight Polyethylene were studied. Inorganic polymers based on alumina and silica polysialate units were synthesized at room temperature from kaolin and sodium silicate in a highly alkaline medium, followed by curing and drying at 80 °C. Alkaline activator was formed by mixing the 12 M NaOH solution with sodium silicate at a ratio of 0.24. Addition of Ultra High Molecular Weight Polyethylene to the kaolin geopolymer are fabricated with Ultra High Molecular Weight Polyethylene content of 2, 4, 6 and 8 (wt. %) by using powder metallurgy method. The samples were heated at 1200 °C and the strength and morphological were tested. It was found that the flexural strength for the kaolin geopolymer ceramics with addition of UHMWPE were improved and generally increased with the increasing of UHMWPE loading. The result revealed that the optimum flexural strength was obtained at UHMWPE loading of 4 wt. % (92.1 MPa) and the flexural strength started to decrease. Microstructural analysis showed the samples appeared to have more number of pores and connected of pores increased with the increasing of UHMWPE content.

  17. Increasing the wear resistance of ultra-high molecular weight polyethylene by adding solid lubricating fillers

    SciTech Connect

    Panin, S. V.; Kornienko, L. A.; Poltaranin, M. A.; Ivanova, L. R.; Suan, T. Nguen

    2014-11-14

    In order to compare effectiveness of adding solid lubricating fillers for polymeric composites based on ultra-high molecular weight polyethylene (UHMWPE) with graphite, molybdenum disulfide and polytetrafluoroethylene, their tribotechnical characteristics under dry friction, boundary lubrication and abrasive wearing were investigated. The optimal weight fractions of fillers in terms of improving wear resistance have been determined. The supramolecular structure and topography of wear track surfaces of UHMWPE-based composites with different content of fillers have been studied.

  18. Density limits investigation and high density operation in EAST tokamak

    NASA Astrophysics Data System (ADS)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  19. Highly cross-linked, electron-beam-irradiated, melted polyethylene: some pros.

    PubMed

    Harris, William H

    2004-12-01

    Extensive new evidence generated within the past the year provides strong support for the use of electron-beam highly cross-linked, subsequently melted ultra-high molecular weight polyethylene in total hip replacement arthroplasty. In terms of wear reduction, three studies involving three different demographic groups and two different measurement techniques have found that the femoral head penetration with this type of polyethylene after bedding in has finished taking place is less than 10 micra per year. This wear rate is similar to the wear rate of metal-on-metal and ceramic-on-ceramic articulations. Retrieval specimens up to 3 years after insertion confirmed the minimal wear by exhibiting persisting machine marks throughout the inside diameter of the liner. Extensive studies show no evidence of oxidation, confirming the absence of residual free radicals. No evidence of fatigue failure exists except three known cases out of 150,000, in which malposition of the acetabular component produced abnormally high contact stresses on unsupported polyethylene. The in vivo wear, oxidation resistance, and mechanical properties of this alternative bearing material are excellent, with in vivo durations now exceeding five years. The other major advantages over hard-on-hard bearings including familiarity, adaptability, forgiveness, and cost seem to be compelling. PMID:15577467

  20. The yield behavior of polyethylene tubes subjected to biaxial loadings

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    High-density polyethylene is subjected to biaxial states of stress to examine the yield behavior of the semicrystalline thermoplastic under constant octahedral shear-stress rates. Combinations of internal pressures and axial loads are applied to thin-walled tubes of polyethylene, and the strain response in the axial and hoop directions are measured. The polyethylene specimens are found to be anisotropic, and the experimental measurements are compared to yield criteria that are applicable to isotropic and anisotropic materials.

  1. High Energy Density Electrolytic Capacitor

    NASA Technical Reports Server (NTRS)

    Evans, David A.

    1996-01-01

    A new type of electrolytic capacitor which combines an electrolytic capacitor anode with an electrochemical capacitor cathode was developed. The resulting capacitor has a four time higher energy density than standard electrolytic capacitors, with comparable electric performance. The prototype, a 480 microFarad, 200 V device, has an energy density exceeding 4 J/cc. Now a 680 microFarad 50 V, MIL-style all tantalum device has been constructed and is undergoing qualification testing. Pending a favorable outcome, work will begin on other ratings. The potential for commercially significant development exists in applying this technology to aluminum-based electrolytic capacitors. It is possible to at least double the energy density of aluminum electrolytics, while using existing manufacturing methods, and without adding material expense. Data presented include electrical characteristics and performance measurements of the 200 V and 50 V hybrid capacitors and results from ongoing qualification testing of the MIL-style tantalum capacitors.

  2. High energy density electrolytic capacitor

    NASA Technical Reports Server (NTRS)

    Evans, David A.

    1995-01-01

    Recently a new type of electrolytic capacitor was developed. This capacitor, the Evans Hybrid, combines an electrolytic capacitor anode with an electrochemical capacitors cathode. The resulting capacitor has four times the energy density of other electrolytic capacitors, with comparable electrical performance. The prototype, a 480 micro F, 200 V device, had an energy density exceeding 4 J/cc. Now, a 680 micro F, 50 V, MIL-style all tantalum device has been constructed and is undergoing qualification testing. Pending a favorable outcome, work will begin on other ratings. Potential for commercially significant development exists in applying this technology to aluminum-based electrolytic capacitors. It is possible to at least double the energy density of aluminum electrolytics, while using existing manufacturing methods, and without adding material expense. Data presented include electrical characteristics and performance measurements of the 200 V and 50 V Hybrid capacitors and results of ongolng qualification status of the MJL-style tantalum.

  3. 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

  4. Effect of stearic acid-grafted starch compatibilizer on properties of linear low density polyethylene/thermoplastic starch blown film.

    PubMed

    Khanoonkon, Nattaporn; Yoksan, Rangrong; Ogale, Amod A

    2016-02-10

    The present work aims to investigate the effect of stearic acid-grafted starch (ST-SA) on the rheological, thermal, optical, dynamic mechanical thermal, and tensile properties of linear low density polyethylene/thermoplastic starch (LLDPE/TPS) blends, as well as on their water vapor and oxygen barrier properties. Blends consisting of LLDPE and TPS in a weight ratio of 60:40 and ST-SA at different concentrations, i.e. 1, 3 and 5%, were prepared using a twin-screw extruder. The obtained resins were subsequently converted into films via blown film extrusion. Incorporation of ST-SA resulted in a decreased degree of shear thinning, reduced ambient temperature elasticity, and improved tensile strength, secant modulus, extensibility, and UV absorption, as well as diminished water vapor and oxygen permeabilities of the LLDPE/TPS blend. These effects are attributed to the enhanced interfacial adhesion between LLDPE and TPS phases through the compatibilizing effect induced by ST-SA, and the good dispersion of the TPS phase in the LLDPE matrix. The results confirmed that ST-SA could potentially be used as a compatibilizer for the LLDPE/TPS blend system. PMID:26686117

  5. A New Route of Fucoidan Immobilization on Low Density Polyethylene and Its Blood Compatibility and Anticoagulation Activity.

    PubMed

    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

  6. Efficacy of two acidic sanitizers for microbial reduction on metal cans and low-density polyethylene film surfaces.

    PubMed

    Lee, J; Gupta, M J; Lopes, J; Pascall, M A

    2007-10-01

    This study investigated 2 sanitizer formulations and compared them with hydrogen peroxide (H(2)O(2)). Formulation number 1 contained citric acid and sodium dodecylbenzene sulfonate (SDBS). Formulation number 2 contained SDBS, citric, lactic, phosphoric acids, and benzoic acid. Low concentration levels of the sanitizers (1.0% for formulation 1 and 0.5% for formulation 2) were compared with 35% H(2)O(2) for their efficacies on Escherichia coli, Listeria innocua, and Saccharomyces cerevisiae inoculated onto low-density polyethylene (LDPE) films and metal cans at room temperature (23 +/- 1 degrees C) and 40 degrees C. The results showed that both formulations 1 and 2 required >120 s to sanitize both materials from microbial populations at room temperature, while <15 s was needed for the H(2)O(2). Except for formulation 1 on the E. coli inoculated LDPE film surface, the sanitizers completely eliminated the bacterial populations on both materials in 60 s at 40 degrees C. In general, the formulations were more effective for reduction of the microbial numbers on the can material when compared with the LDPE film. The E. coli showed greater tolerance for the sanitizers when exposed to the process conditions in this study. All sanitizers completely eliminated the test organisms in

  7. 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. PMID:26572342

  8. Effect of Xylopia aethiopica aqueous extract on antioxidant properties of refrigerated Roma tomato variety packaged in low density polyethylene bags.

    PubMed

    Babarinde, Grace Oluwakemi; Adegoke, Gabriel O

    2015-03-01

    Effects of Xylopia aethiopica (Dunal) A. Richard aqueous extract on the antioxidants of matured tomato fruits at red stage were investigated at 13 ± 2 °C and 80 ± 5 % relative humidity. A sample treated with sodium bicarbonate and untreated samples were included. Samples packaged in low density polyethylene (30 μm thickness) bags were analysed at intervals of 5 days. The treatments revealed statistically significant differences in ascorbic acid content of stored tomato fruits. Fruits treated with 5 % X. aethiopica on day 5 of storage had 21.0 mg/100 g which was significantly (p < 0.05) higher than 18.2 mg/100 g in untreated control samples. At 15th day of storage, ascorbic acid was 10.0 and 14.2 mg/100 g in tomato fruits treated with sodium bicarbonate and 5 % X. aethiopica respectively. The carotenoid and lycopene contents were lower in sodium bicarbonate-treated and the untreated control samples than in X. aethiopica-treated sample. The total phenolic contents were better retained in X. aethiopica-treated tomato than in control. Treatment of tomato fruits with X. aethiopica at 4 & 5 % levels significantly retained the qualities evaluated. PMID:25745258

  9. High performance, high density hydrocarbon fuels

    NASA Technical Reports Server (NTRS)

    Frankenfeld, J. W.; Hastings, T. W.; Lieberman, M.; Taylor, W. F.

    1978-01-01

    The fuels were selected from 77 original candidates on the basis of estimated merit index and cost effectiveness. The ten candidates consisted of 3 pure compounds, 4 chemical plant streams and 3 refinery streams. Critical physical and chemical properties of the candidate fuels were measured including heat of combustion, density, and viscosity as a function of temperature, freezing points, vapor pressure, boiling point, thermal stability. The best all around candidate was found to be a chemical plant olefin stream rich in dicyclopentadiene. This material has a high merit index and is available at low cost. Possible problem areas were identified as low temperature flow properties and thermal stability. An economic analysis was carried out to determine the production costs of top candidates. The chemical plant and refinery streams were all less than 44 cent/kg while the pure compounds were greater than 44 cent/kg. A literature survey was conducted on the state of the art of advanced hydrocarbon fuel technology as applied to high energy propellents. Several areas for additional research were identified.

  10. Profiles in garbage: Polyethylene terephthalate

    SciTech Connect

    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.

  11. SECURING CONTAINERIZED HAZARDOUS WASTES WITH POLYETHYLENE RESIN AND FIBERGLASS ENCAPSULATES

    EPA Science Inventory

    This study investigates the fabrication and use of polyethylene resin and fiberglass to encapsulate and secure containerized hazardous wastes. Laboratory-scale encapsulates of composite structure were made from powdered, high-density polyethylene (HDPE) and epoxy-resin-wetted fib...

  12. Total Hip Arthroplasty Using Metal Head on a Highly Cross-linked Polyethylene Liner

    PubMed Central

    Kim, Min-Yook; Park, Ji-Hoon; Lee, Jung-Ho

    2015-01-01

    Purpose This retrospective study was performed to evaluate the clinical results and measure polyethylene liner wear in total hip arthroplasty (THA) with highly cross-linked polyethylene. Materials and Methods Except for patients who had died or were unable to have follow-up at least 2 years, 60 of 78 hips that underwent THA were included this study. The mean age was 64.5 years (range, 25-81 years) and the mean body mass index (BMI) was 23.0 kg/m2 (18.1-32.3 kg/m2). Diagnosis at the time of the operation was osteonecrois of the femoral head in 28 hips, primary osteoarthritis in 14, hip fracture in 13, and other diseases in 5. The mean follow-up period was 3.8 years (2.1-7.1 years). Harris hip score (HHS) was reviewed before THA and at the last follow-up. On the anteroposterior pelvic radiographs, acetabular cup inclination and ante-version were also measured. The annual linear wear rate was measured using Livermore's method on the radiographs. Results The mean HHS was 60.1 (28-94) before operation and 90.4 (47-100) at the last follow-up. In the immediate post-operation, the average inclination and anteversion angles of the acetabular cups were 46.3° (standard deviation, ±6.7°) and, 21.4°(±10.1°) respectively. The mean of the annual linear polyethylene wear was 0.079 mm/year (0.001-0.291 mm/year). Age, gender and BMI were not statistically related to linear polyethylene wear but the period of follow-up and the acetabular cup's inclination showed significant negative and positive correlation respectively. Conclusion The wear rate of a highly cross-linked polyethylene was shown to correlate negatively with duration of follow-up. However, our study was based on a short-term follow-up, so a long-term follow-up study is necessary in the future. PMID:27536629

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

    PubMed Central

    Oral, Ebru; Muratoglu, Orhun K.

    2007-01-01

    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. PMID:19050735

  14. Scratching vulnerability of conventional vs highly cross-linked polyethylene liners because of large embedded third-body particles.

    PubMed

    Heiner, Anneliese D; Galvin, Alison L; Fisher, John; Callaghan, John J; Brown, Thomas D

    2012-05-01

    The hypothesis of this study was that acetabular liner vulnerability to scratching from femoral heads, roughened by third bodies embedded in the liner, is not significantly lower for highly cross-linked polyethylene (HXPE) than for conventional polyethylene (CPE). Six CPE and 6 HXPE acetabular liners were each reproducibly embedded with 5 cobalt-chromium-molybdenum (CoCrMo) beads then run for 10,000 cycles in a joint simulator. By visual rank ordering, there was low association between liner scratch severity and polyethylene type. The CPE and HXPE liner scratches were not significantly different in scratch peak-valley height or width or in liner roughness in the vicinity of the embedded beads. This model indicated that high cross-linking of polyethylene does not offer appreciable protection against severe scratching induced by large embedded third-body particles. PMID:22115764

  15. Influence of Hemp Fibers Pre-processing on Low Density Polyethylene Matrix Composites Properties

    NASA Astrophysics Data System (ADS)

    Kukle, S.; Vidzickis, R.; Zelca, Z.; Belakova, D.; Kajaks, J.

    2016-04-01

    In present research with short hemp fibres reinforced LLDPE matrix composites with fibres content in a range from 30 to 50 wt% subjected to four different pre-processing technologies were produced and such their properties as tensile strength and elongation at break, tensile modulus, melt flow index, micro hardness and water absorption dynamics were investigated. Capillary viscosimetry was used for fluidity evaluation and melt flow index (MFI) evaluated for all variants. MFI of fibres of two pre-processing variants were high enough to increase hemp fibres content from 30 to 50 wt% with moderate increase of water sorption capability.

  16. High Density Fuel Development for Research Reactors

    SciTech Connect

    Daniel Wachs; Dennis Keiser; Mitchell Meyer; Douglas Burkes; Curtis Clark; Glenn Moore; Jan-Fong Jue; Totju Totev; Gerard Hofman; Tom Wiencek; Yeon So Kim; Jim Snelgrove

    2007-09-01

    An international effort to develop, qualify, and license high and very high density fuels has been underway for several years within the framework of multi-national RERTR programs. The current development status is the result of significant contributions from many laboratories, specifically CNEA in Argentina, AECL in Canada, CEA in France, TUM in Germany, KAERI in Korea, VNIIM, RDIPE, IPPE, NCCP and RIARR in Russia, INL, ANL and Y-12 in USA. These programs are mainly engaged with UMo dispersion fuels with densities from 6 to 8 gU/cm3 (high density fuel) and UMo monolithic fuel with density as high as 16 gU/cm3 (very high density fuel). This paper, mainly focused on the French & US programs, gives the status of high density UMo fuel development and perspectives on their qualification.

  17. Aerodynamic Focusing Of High-Density Aerosols

    SciTech Connect

    Ruiz, D. E.; Fisch, Nathaniel

    2014-02-24

    High-density micron-sized particle aerosols might form the basis for a number of applications in which a material target with a particular shape might be quickly ionized to form a cylindrical or sheet shaped plasma. A simple experimental device was built in order to study the properties of high-density aerosol focusing for 1 m silica spheres. Preliminary results recover previous findings on aerodynamic focusing at low densities. At higher densities, it is demonstrated that the focusing properties change in a way which is consistent with a density dependent Stokes number.

  18. 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

    2014-09-01

    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

  19. 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

  20. Determination of the surface density of polyethylene glycol on gold nanoparticles by use of microscale thermogravimetric analysis.

    PubMed

    Sebby, K B; Mansfield, E

    2015-04-01

    The widespread integration of nanoparticle technologies into biomedicine will depend on the ability to repeatedly create particles with well-defined properties and predictable behaviors. For this to happen, fast, reliable, inexpensive, and widely available techniques to characterize nanomaterials are needed. Characterization of the surface molecules is particularly important since the surface, including the surface molecule density, plays a dominant role in determining how nanoparticles interact with their surroundings. Here, 10 and 30 nm gold nanoparticle NIST Standard Reference Materials were functionalized with fluorescently labeled polyethylene glycol (PEG) with either thiolate or lipoic acid anchoring groups to evaluate analytical techniques for determining surface coverage. The coating of the nanoparticles was confirmed with dynamic light scattering, microscale thermogravimetric analysis (μ-TGA), and ultraviolet-visible (UV-vis) spectroscopy. A UV-vis method for determining gold nanoparticle concentrations that takes into account spectral broadening upon functionalization was developed. The amount of bound PEG was quantified with μ-TGA, a technique analogous to thermogravimetric analysis that uses quartz crystal microbalances, and fluorescence spectroscopy of displaced ligands. It is shown that μ-TGA is a convenient technique for the quantification of ligands bound to inorganic particles while sacrificing a minimal amount of sample, and the treatment of the functionalized nanoparticle dispersions with dithiothreitol may be insufficient to achieve complete displacement of the surface ligands for quantification by fluorescence measurements. The μ-TGA and fluorescence results were used to determine ligand footprint sizes-average areas occupied by each ligand on the particles' surface. The lipoic acid bound ligands had footprint sizes of 0.21 and 0.25 nm(2) on 10 and 30 nm particles, respectively while the thiolate ligands had footprint sizes of 0.085 and 0

  1. Determination of silicone rubber and low-density polyethylene diffusion and polymer/water partition coefficients for emerging contaminants.

    PubMed

    Pintado-Herrera, Marina G; Lara-Martín, Pablo A; González-Mazo, Eduardo; Allan, Ian J

    2016-09-01

    There is a growing interest in assessing the concentration and distribution of new nonregulated organic compounds (emerging contaminants) in the environment. The measurement of freely dissolved concentrations using conventional approaches is challenging because of the low concentrations that may be encountered and their temporally variable emissions. Absorption-based passive sampling enables the estimation of freely dissolved concentrations of hydrophobic contaminants of emerging concern in water. In the present study, calibration was undertaken for 2 polymers, low-density polyethylene (LDPE) and silicone rubber for 11 fragrances, 5 endocrine-disrupting compounds, 7 ultraviolet (UV) filters, and 8 organophosphate flame retardant compounds. Batch experiments were performed to estimate contaminant diffusion coefficients in the polymers (Dp ), which in general decreased with increasing molecular weight. The values for fragrances, endocrine-disrupting compounds, and UV filters were in ranges similar to those previously reported for polycyclic aromatic hydrocarbons, but were 1 order of magnitude lower for organophosphate flame retardant compounds. Silicone rubber had higher Dp values than LDPE and was therefore selected for further experiments to calculate polymer/water partition coefficients (KPW ). The authors observed a positive correlation between log KPW and log octanol/water partition coefficient values. Field testing of silicone rubber passive samplers was undertaken though exposure in the River Alna (Norway) for an exposure time of 21 d to estimate freely dissolved concentration. Some fragrances and UV filters were predominant over other emerging and regulated contaminants, at levels up to 1600 ng L(-1) for galaxolide and 448 ng L(-1) for octocrylene. Environ Toxicol Chem 2016;35:2162-2172. © 2016 SETAC. PMID:26833936

  2. Determination of Vocs in groundwater at an industrial contamination site using a homemade low-density polyethylene passive diffusion sampler.

    PubMed

    Ma, Xu; Tan, Zhiqiang; Pang, Long; Liu, Jingfu

    2013-11-01

    A home-made inexpensive passive diffusion bag (PDB) sampler, prepared by filling deionized water in low-density polyethylene (LDPE) tubes, was evaluated for volatile organic compounds (VOC) sampling in groundwater at industrial contamination sites. Impacts of environmentally relevant conditions on the sampling equilibration time and partitioning of VOCs between the sampler and the water sample were investigated. Sample salinity, agitation and temperature can influence the equilibration time, but generally sampling equilibration was obtained in 14 days under real field sampling of VOCs in groundwater. Both laboratory study and field testing in a contaminated site showed that the VOC concentrations in the developed sampler were equal to those in the water samples at equilibrium. Coupled with a purge and trap concentrator-gas chromatograph-mass spectrometer (P&T-GC-MS), the developed PDB sampler provided a low-cost sampling device for routine monitoring of VOCs in groundwater in wells, with LODs in the range of 2.9-10 microg/L. The proposed PDB was applied to determine VOCs in groundwater at an industrial contamination site, and the present results agreed well with those determined using conventional pump-and-sample monitoring. All the studied 13 VOCs were tested in the four wells in the industrial contamination sites, with their concentrations in the range of 12-73660 microg/L. In addition, while benzene and toluene were heavily contaminated up to a maximum concentration of 74000 tg/L and 6000 microg/L, respectively, 1,2,3-trichlorobenzene and bromobenzene had relatively low contamination levels (below 25 microg/L). PMID:24552064

  3. 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.

  4. Surfing the High Density Universe

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1998-01-01

    The central theme of the proposed research is to link what we know about galaxy clusters and large-scale structure in the local Universe at z less than 0.1 to what we know about the original fluctuations that led to this structure as observed in the cosmic microwave background. The simple-minded approach to this question (the kind I always take) is to took at structure in the regime 0.1 less than z less than 1000. We have a unique resource to help us in this task in the form of the VLA FIRST radio survey in which, to date, we have completed mapping nearly 5000 deg2 of the northern sky to a 20 cm flux density limit of 1.0 mJy. The 435,000 radio sources detected all have positions accurate to better than 1. As this report is written, we are obtaining the next - 1000 deg 2 of data; the goal of the survey is to complete the full 10,000 deg 2 to be covered in the Sloan Digital Sky Survey.

  5. High density harp for SSCL linac

    SciTech Connect

    Fritsche, C.T.; Krogh, M.L.; Crist, C.E.

    1993-05-01

    AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities.

  6. Separation of polyethylene glycols and amino-terminated polyethylene glycols by high-performance liquid chromatography under near critical conditions.

    PubMed

    Wei, Y-Z; Zhuo, R-X; Jiang, X-L

    2016-05-20

    The separation and characterization of polyethylene glycols (PEGs) and amino-substituted derivatives on common silica-based reversed-phase packing columns using isocratic elution is described. This separation is achieved by liquid chromatography under the near critical conditions (LCCC), based on the number of amino functional end groups without obvious effect of molar mass for PEGs. The mobile phase is acetonitrile in water with an optimal ammonium acetate buffer. The separation mechanism of PEG and amino-substituted PEG under the near LCCC on silica-based packing columns is confirmed to be ion-exchange interaction. Under the LCCC of PEG backbone, with fine tune of buffer concentration, the retention factor ratios for benzylamine and phenol in buffered mobile phases, α(benzylamine/phenol)-values, were used to assess the ion-exchange capacity on silica-based reversed-phase packing columns. To the best of our knowledge, this is the first report on separation of amino-functional PEGs independent of the molar mass by isocratic elution using common C18 or phenyl reversed-phase packing columns. PMID:27102303

  7. High bandwidth vapor density diagnostic system

    DOEpatents

    Globig, Michael A.; Story, Thomas W.

    1992-01-01

    A high bandwidth vapor density diagnostic system for measuring the density of an atomic vapor during one or more photoionization events. The system translates the measurements from a low frequency region to a high frequency, relatively noise-free region in the spectrum to provide improved signal to noise ratio.

  8. 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.

  9. The Incidence of Acetabular Osteolysis in Young Patients With Conventional versus Highly Crosslinked Polyethylene

    PubMed Central

    Mall, Nathan A.; Nunley, Ryan M.; Zhu, Jin Jun; Maloney, William J.; Barrack, Robert L.

    2010-01-01

    Background Osteolysis is a major mode of hip implant failure. Previous literature has focused on the amount of polyethylene wear comparing highly crosslinked polyethylene (HXPLE) with conventional liners but has not clarified the relative incidence of osteolysis with these two liners. Questions/purposes We determined (1) the incidence of osteolysis in HXLPE versus conventional polyethylene (CPE), (2) the ability to detect and evaluate the size of lytic lesions using radiographs compared with CT scans, (3) head penetration in hips without and with lysis, and (4) determined whether acetabular position, head size, and UCLA activity score contributed to lysis. Methods We compared head penetration and osteolysis on plain radiographs and presence and volume of osteolysis on CT scans in 48 patients with HXLPE (mean, 46.5 years) and 50 patients with CPE (mean, 43.2 years). The minimum followup was 5 years (average, 7.2 years; range, 5.1–10.9 years), Results Osteolysis was apparent on CT in a larger number of patients with CPE liners than HXLPE liners: 12 of 50 (24%) versus one of 48 (2%), respectively. We found no correlation between head penetration and volume of osteolytic lesions. Head penetration was greater in patients with osteolysis. Smaller head sizes were associated with greater wear and those with osteolysis had smaller head sizes; however, there was no difference in acetabular component position or UCLA activity in those with lysis compared with those without. Conclusions HXLPE diminished the incidence of osteolysis, but the lack of correlation between penetration and volume of osteolysis suggests other factors other than wear contribute to the development of osteolysis. Level of Evidence Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence. PMID:20824407

  10. 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.

  11. THE EFFECTS OF HIGH DOSE IRRADIATION ON THE CROSS-LINKING OF VITAMIN E-BLENDED ULTRAHIGH MOLECULAR WEIGHT POLYETHYLENE

    PubMed Central

    Oral, Ebru; Beckos, Christine Godleski; Malhi, Arnaz S.; Muratoglu, Orhun K.

    2008-01-01

    Vitamin E-stabilized, highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is a promising oxidation and wear resistant UHMWPE with improved mechanical strength in comparison with the first generation, irradiated and melted UHMWPE. One approach of incorporating vitamin E in UHMWPE is through blending of vitamin E in UHMWPE powder followed by consolidation and radiation crosslinking. However radiation crosslinking efficiency of UHMWPE decreases in the presence of vitamin E. Therefore an optimum vitamin E concentration and radiation dose level needs to be determined to achieve a cross-link density comparable to 100-kGy irradiated and melted UHMWPE, which has shown excellent wear properties in vivo. We investigated the cross-link density and mechanical properties of vitamin E-blended UHMWPEs as a function of vitamin E concentration in the blend and gamma irradiation doses up to 200 kGy. We found that 0.3 wt% vitamin E-blended UHMWPE could not be cross-linked above a cross-link density achieved at a radiation dose of 65 kGy for virgin UHMWPE and 1.0 wt% vitamin E-blended UHMWPE could not be cross-linked above a cross-link density achieved at a radiation dose of 25 kGy for virgin UHMWPE even when the former were irradiated to a radiation dose of 200 kGy. In addition, higher plasticity at vitamin E concentrations at and above 0.3 wt% indicated that increased chain scissioning may be prevalent. Since the wear resistance of this irradiated UHMWPE would be expected to be low, vitamin E concentrations equal to or above 0.3 wt% are not recommended for subsequent irradiation to achieve a wear resistant cross-linked UHMWPE. The long–term oxidative stability of irradiated blends with low vitamin E concentrations has yet to be studied to determine an optimum between cross-link density and long-term oxidative stability. PMID:18514813

  12. Combined Chemical Activation and Fenton Degradation to Convert Waste Polyethylene into High-Value Fine Chemicals.

    PubMed

    Chow, Cheuk-Fai; Wong, Wing-Leung; Ho, Keith Yat-Fung; Chan, Chung-Sum; Gong, Cheng-Bin

    2016-07-01

    Plastic waste is a valuable organic resource. However, proper technologies to recover usable materials from plastic are still very rare. Although the conversion/cracking/degradation of certain plastics into chemicals has drawn much attention, effective and selective cracking of the major waste plastic polyethylene is extremely difficult, with degradation of C-C/C-H bonds identified as the bottleneck. Pyrolysis, for example, is a nonselective degradation method used to crack plastics, but it requires a very high energy input. To solve the current plastic pollution crisis, more effective technologies are needed for converting plastic waste into useful substances that can be fed into the energy cycle or used to produce fine chemicals for industry. In this study, we demonstrate a new and effective chemical approach by using the Fenton reaction to convert polyethylene plastic waste into carboxylic acids under ambient conditions. Understanding the fundamentals of this new chemical process provides a possible protocol to solve global plastic-waste problems. PMID:27168079

  13. Biological reaction to polyethylene particles in a murine calvarial model is highly influenced by age.

    PubMed

    Langlois, Jean; Zaoui, Amine; Bichara, David A; Nich, Christophe; Bensidhoum, Morad; Petite, Hervé; Muratoglu, Orhun K; Hamadouche, Moussa

    2016-04-01

    Particle-induced osteolysis is driven by multiple factors including bone metabolism, inflammation, and age. The objective of this study was to determine the influence of age on polyethylene (PE) particle-induced osteolysis in a murine calvarial model comparing 2-month-old (young) versus 24-month-old (old) mice. After PE particle implantation, calvaria were assessed at days (D) 3, D7, D14, and D21 via chemoluminescent imaging for inflammation (L-012 probe). In addition micro-computed tomography (micro-CT) and histomorphometry end points addressed the bone reaction. Inflammation peaked at D7 in young mice and D14 in old mice. Using micro-CT, a nadir of mature bone was recorded at D7 for young mice, versus D21 for old mice. Besides, regenerating bone peaked at distinct timepoints: D7 for young mice versus D21 for old mice. In the young mice group, the histomorphometric findings correlated with micro-CT regenerating bone findings at D7, associated with ample osteoïd deposition. No osteoïd could be histologically quantified in the old mice group at D7. This study demonstrated that the biological reaction to polyethylene particles is highly influenced by age. PMID:26375608

  14. Assessment of the migration potential of nanosilver from nanoparticle-coated low-density polyethylene food packaging into food simulants.

    PubMed

    Hannon, Joseph Christopher; Kerry, Joseph P; Cruz-Romero, Malco; Azlin-Hasim, Shafrina; Morris, Michael; Cummins, Enda

    2016-01-01

    An experimental nanosilver-coated low-density polyethylene (LDPE) food packaging was incubated with food simulants using a conventional oven and tested for migration according to European Commission Regulation No. 10/2011. The commercial LDPE films were coated using a layer-by-layer (LbL) technique and three levels of silver (Ag) precursor concentration (0.5%, 2% and 5% silver nitrate (AgNO3), respectively) were used to attach antimicrobial Ag. The experimental migration study conditions (time, temperature and food simulant) under conventional oven heating (10 days at 60°C, 2 h at 70°C, 2 h at 60°C or 10 days at 70°C) were chosen to simulate the worst-case storage period of over 6 months. In addition, migration was quantified under microwave heating. The total Ag migrant levels in the food simulants were quantified by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Mean migration levels obtained by ICP-AES for oven heating were in the range 0.01-1.75 mg l(-1). Migration observed for microwave heating was found to be significantly higher when compared with oven heating for similar temperatures (100°C) and identical exposure times (2 min). In each of the packaging materials and food simulants tested, the presence of nanoparticles (NPs) was confirmed by scanning electron microscopy (SEM). On inspection of the migration observed under conventional oven heating, an important finding was the significant reduction in migration resulting from the increased Ag precursor concentration used to attach Ag on the LDPE LbL-coated films. This observation merits further investigation into the LbL coating process used, as it suggests potential for process modifications to reduce migration. In turn, any reduction in NP migration below regulatory limits could greatly support the antimicrobial silver nanoparticle (AgNP)-LDPE LbL-coated films being used as a food packaging material. PMID:26523861

  15. Friction, wear, transfer and wear surface morphology of ultra-high-molecular-weight polyethylene

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1983-01-01

    Tribological studies at 25 C in a 50-percent-relative-humidity air atmosphere were conducted using hemispherically tipped 440 C HT (high temperature) stainless steel pins sliding against ultra-high-molecular-weight polyethylene (UHMWPE) disks. The results indicate that sliding speed, sliding distance, contact stress and specimen geometry can markedly affect friction, UHMWPE wear, UHMWPE transfer and the type of wear mechanisms that occur. Adhesion appears to be the predominant wear mechanism; but after long sliding distances at slow speeds, heavy ridges of transfer result which can induce fatigue-like wear on the UHMWPE disk wear track. In one instance, abrasive wear to the metallic pin was observed. This was caused by a hard particle embedded in the UHMWPE disk wear track.

  16. Modification of polyethylene terephthalate under high-energy heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhu, Zhiyong; Liu, Changlong; Sun, Youmei; Liu, Jie; Tang, Yuhua; Jin, Yunfan; Du, Junli

    2002-05-01

    Polyethylene terephthalate films were irradiated with high-energy heavy ions to fluences ranging from 9×10 9 to 5.5×10 12 ions/cm 2. The radiation-induced changes in molecular and crystalline structures were investigated by the Fourier-transform infrared (FTIR) spectroscopy and the X-ray diffraction measurement. FTIR spectra measurements reveal that the material suffers serious degradation through bond breaking. The absorbance of the typical infrared bands decays exponentially with increase of ion fluence and the bond-disruption cross-section shows a sigmoid variation with the electronic energy loss. The semi-crystalline structure of the material is destroyed by the irradiation with processes that are electronic energy loss dependent. At lower electronic energy loss values the amorphization is closely related to the destruction of the trans-configuration of the ethylene glycol residue. At high electronic energy loss, however, other processes determine the amorphization.

  17. High density load bearing insulation peg

    DOEpatents

    Nowobilski, J.J.; Owens, W.J.

    1985-01-29

    A high density peg is disclosed which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure. 4 figs.

  18. High density load bearing insulation peg

    DOEpatents

    Nowobilski, Jeffert J.; Owens, William J.

    1985-01-01

    A high density peg which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure.

  19. In vivo biological response to highly cross-linked and vitamin e-doped polyethylene--a particle-Induced osteolysis animal study.

    PubMed

    Huang, Chang-Hung; Lu, Yung-Chang; Chang, Ting-Kuo; Hsiao, I-Lin; Su, Yi-Ching; Yeh, Shu-Ting; Fang, Hsu-Wei; Huang, Chun-Hsiung

    2016-04-01

    Polyethylene particle-induced osteolysis is the primary limitation in the long-term success of total joint replacement with conventional ultra high molecular weight polyethylene (UHMWPE). Highly cross-linked polyethylene (HXLPE) and vitamin E-doped cross-linked polyethylene (VE-HXLPE) have been developed to increase the wear resistance of joint surfaces. However, very few studies have reported on the incidence of particle-induced osteolysis for these novel materials. The aim of this study was to use a particle-induced osteolysis animal model to compare the in vivo biological response to different polymer particles. Three commercially available polymers (UHMWPE, HXLPE, and VE-HXLPE) were compared. Osseous properties including the bone volume relative to the tissue volume (BV/TV), trabecular thickness (Tb. Th), and bone mineral density (BMD) were examined using micro computed tomography. Histological analysis was used to observe tissue inflammation in each group. This study demonstrated that the osseous properties and noticeable inflammatory reactions were obviously decreased in the HXLPE group. When compared with the sham group, a decrease of 12.7% was found in BV/TV, 9.6% in BMD and 8.3% in Tb.Th for the HXLPE group. The heightened inflammatory response in the HXLPE group could be due to its smaller size and greater amount of implanted particles. Vitamin E diffused in vivo may not affect the inflammatory and osteolytic responses in this model. The morphological size and total cumulative amount of implanted particles could be critical factors in determining the biological response. PMID:25952769

  20. High density tape/head interface study

    NASA Technical Reports Server (NTRS)

    Csengery, L. C.

    1983-01-01

    The high energy (H sub c approximately or = to 650 oersteds) tapes and high track density (84 tracks per inch) heads investigated had, as its goal, the definition of optimum combinations of head and tape, including the control required of their interfacial dynamics that would enable the manufacture of high rate (150 Mbps) digital tape recorders for unattended space flight.

  1. Physicochemical and mechanical properties of experimental coextruded food-packaging films containing a buried layer of recycled low-density polyethylene.

    PubMed

    Badeka, Anastasia; Goulas, Antonios E; Adamantiadi, Antigoni; Kontominas, Michael G

    2003-04-01

    Migrational, permeation, and tensile properties of experimental five- and eight-layer coextruded and laminated films containing a middle buried layer of recycled low-density polyethylene (LDPE) comprising 40-50% bw of the multilayer structure were determined. Respective films containing 100% virgin LDPE as the buried layer were taken as controls. Results showed that the percentage of recycled LDPE in the multilayer structure did not affect overall migration values to distilled water, 3% acetic acid, and iso-octane. In all cases, overall migration values were lower than the upper acceptable limit (10 mg/dm(2)) set by the European Union. Transmission rate values to O(2), CO(2), and water vapor were also not affected by the percentage of recycled LDPE in the multilayer structure. On the basis of O(2) transmission rates, low-barrier, barrier, and high-barrier multilayer structures were produced. Likewise, tensile properties (tensile strength, percent elongation at break, and Young's modulus) were not affected by the percentage of recycled material in the multilayer structure. Finally, all experimental films produced no adverse effects in taste or odor of the food-contacting phase tested. The above findings are discussed in relation to the high quality of the primary LDPE scrap used throughout this work in combination with the functional barrier hypothesis. On the basis of the present results it is proposed that primary LDPE scrap may be used as a middle layer comprising 40-50% bw of multilayer food-packaging films without any compromise in migrational, barrier, mechanical, and organoleptic properties. PMID:12670192

  2. Resistance to moist conditions of whey protein isolate and pea starch biodegradable films and low density polyethylene nondegradable films: a comparative study

    NASA Astrophysics Data System (ADS)

    Mehyar, G. F.; Bawab, A. Al

    2015-10-01

    Biodegradable packaging materials are degraded under the natural environmental conditions. Therefore using them could alleviate the problem of plastics accumulation in nature. For effective replacement of plastics, with biodegradable materials, biodegradable packages should keep their properties under the high relative humidity (RH) conditions. Therefore the objectives of the study were to develop biodegradable packaging material based on whey protein isolate (WPI) and pea starch (PS). To study their mechanical, oxygen barrier and solubility properties under different RHs compared with those of low density polyethylene (LDPE), the most used plastic in packaging. Films of WPI and PS were prepared separately and conditioned at different RH (30-90%) then their properties were studied. At low RHs (<50%), WPI films had 2-3 times lower elongation at break (E or stretchability) than PS and LDPE. Increasing RH to 90% significantly (P<0.01) increased the elongation of PS but not WPI and LDPE films. LDPE and WPI films kept significantly (P<0.01) higher tensile strength (TS) than PS films at high RH (90%). Oxygen permeability (OP) of all films was very low (<0.5 cm3 μm m-2 d-1 kPa-1) below 40% RH but increased for PS films and became significantly (P<0.01) different than that of LDPE and WPI at > 40% RH. Oxygen permeability of WPI and LDPE did not adversely affected by increasing RH to 65%. Furthermore, WPI and LDPE films had lower degree of hydration at 50% and 90% RH and total soluble matter than PS films. These results suggest that WPI could be successfully replacing LDPE in packaging of moist products.

  3. 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

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

    PubMed

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

    2016-08-01

    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

  5. High-frequency fusion of Streptomyces parvulus or Streptomyces antibioticus protoplasts induced by polyethylene glycol.

    PubMed Central

    Ochi, K; Hitchcock, M J; Katz, E

    1979-01-01

    Conditions were established for the regeneration of protoplasts of Streptomyces parvulus and Streptomyces antibioticus to the mycelial form. Regeneration was accomplished with a hypertonic medium that contained sucrose, CaCl2, MgCl2, and low levels of phosphate. High-frequency fusion of protoplasts derived from auxotrophic strains of S. parvulus or S. antibioticus was induced by polyethylene glycol 4,000 (42%, wt/vol). The frequency of genetic transfer by the fusogenic procedure varied with the auxotrophic strains examined. Fusion with auxotrophic strains of S. parvulus resulted in the formation of true prototrophic recombinants. Similar studies with S. antibioticus revealed that both stable prototrophic recombinants and heterokaryons were formed. PMID:479112

  6. Tribological behavior of ultra-high molecular weight polyethylene in a hip joint simulator

    NASA Astrophysics Data System (ADS)

    Mohamad Raffi, N.; Kanagarajan, D.; Srinivasan, V.

    2012-12-01

    In this paper effects of various injection molding parameters on tribological properties of ultra-high molecular weight polyethylene (UHMWPE) were investigated. The tribological properties like coefficient of friction and wear rate were obtained from the experimental results of hip simulator which was designed and fabricated in the laboratory. Bovine serum was used as a lubricant in this study. In addition, the hardness of the specimen was also investigated as well. The injection molding parameters that varied for this study are melt temperature, injection velocity and compaction time. The results show that contact loads and melt temperature were mostly influenced the tribological behavior of UHMWPE. A wear mechanism map was developed to study the dominant wear mechanism that influences the wear behavior of UHMWPE. SEM was employed to study the worn out morphologies of UHMWPE. The dominant wear mechanisms that are dominated through our study are ironing, scratching, ploughing, plastic deformation, and fatigue wear.

  7. [Determination of isophthalic acid in polyethylene glycol terephthalate fiber by high performance liquid chromatography].

    PubMed

    Wang, R; Wang, X Y; Tang, C J; Li, L P

    2001-07-01

    The isophthalic acid(IPA) is present in polyethylene glycol terephthalate(PET) at small level, but plays an important role for the properties of polyester fiber. Thus the PET sample was hydrolysated by 100 g/L of sodium hydrate in methanol at 70 degrees C during 10 h and finally assayed by HPLC. A reversed-phase high performance liquid chromatographic method for the separation of isophthalic acid from terephthalic acid(TPA) has been developed. The operating conditions were Novapak C18 column, methanol-water(15:85, V/V)(pH3) as mobile phase with the flow rate of 1.0 mL/min and UV detection wavelength at 254 nm. PMID:12545507

  8. Once Annealed Highly Cross-Linked Polyethylene Exhibits Low Wear at 9 to 15 Years.

    PubMed

    D'Antonio, James; Capello, William N; Ramakrishnan, Rama

    2016-05-01

    A once annealed highly cross-linked polyethylene (HXLPE) was introduced in 1998. Concerns regarding its long-term performance and oxidative resistance exist because of the presence of retained free radicals. The authors studied 48 patients with 50 hip implants having an average age of 62 years. They were followed for 9 to 15 years. The purpose of this study was to determine linear wear rate and the incidence of osteolysis and/or mechanical failure. At an average follow-up of 12.2 years, the annual linear wear rate was 0.018 mm (SD, 0.024 mm). No mechanical failures or osteolysis have been found to date. The clinical performance of this HXLPE continues to meet expectations despite the presence of free radicals. [Orthopedics. 2016; 39(3):e565-e571.]. PMID:27088350

  9. Detection of peroxy species in ultra-high-molecular-weight polyethylene by Raman spectroscopy.

    PubMed

    Chenery, D H

    1997-03-01

    Samples of gamma-sterilized ultra-high-molecular-weight polyethylene (UHMWPE) have been examined using infrared and Raman spectroscopies. Infrared spectra of microtomed sections of a thick segment of material exhibited carbonyl bands whose intensity was consistent with published data. Raman spectroscopy has been used for the first time to detect oxidized precursors to the commonly found carbonyl species. Gamma-sterilized plates examined as soon as possible after sterilization exhibited bands consistent with epoxide, alcohol and three different peroxy-containing species. The detection of these species in irradiated UHMWPE is reported for the first time and demonstrates that oxidation of this material proceeds via a gamma-induced free radical mechanism, as has been widely assumed. PMID:9061182

  10. Electrical Capacitance of Polyethylene under Application of High DC Electric Field

    NASA Astrophysics Data System (ADS)

    Sakamoto, Hidenobu; Yahagi, Kichinosuke

    1980-02-01

    An increase in the electrical capacitance of polyethylene is detected when a high dc electric field is applied with a variable-frequency oscillator. The increment of capacitance increases in proportion to the square of the applied field and changes reversibly below about 30 MV/m for gold electrodes. This change in capacitance is due to the effect of electromechanical compressive stress. Above 30 MV/m, the capacitance undergoes an irreversible change and the increase in capacitance is discussed in terms of the polarization of trapped electronic space charges injected from the electrode. In the region above about 90 MV/m, where the conduction current obeys Child’s law, the increment of capacitance with field again becomes proportional to the square of the applied field and may be explained by free carrier polarization.