Ultra high density molecular weight polyethylene

Polymer Engineering and Science 30,No.l3,Mid-My 1990,p.783-97 LOW DENSITY FOAMS PRODUCED FROM SHEARED ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE GELS Matthews F M Hoffman D M LAWRENCE LIVERMORE NATIONAL LABORATORY... 

Within the family of polyolefins there are many individual families that include low density polyethylenes, linear low density polyethylenes, very low polyethylenes, ultra low polyethylenes, high molecular weight polyethylenes, ultra high molecular weight polyethylenes, polyethylene terephthalates, ethylene-vinyl acetate polyethylenes, chlorinated polyethylenes, crosslinked polyethylenes, polypropylenes, polybutylenes, polyisobutylene, ionomers, polymethylpentene, thermoplastic polyolefin elastomers (polyolefin elastomers, TP), and many others. 

Microcosm size and type 60-cm deep X 17-cm diameter plastic pipe made of ultra-high molecular weight, high density, and nonplasticized polyethylene and containing an intact soil core covered by homogenized topsoil tube sits on a Buchner funnel covered by a thin layer of glass wool... 

Blends of LLDPE/PP = 50 50, with or without compatibilizing ethylene-propylene copolymer, EPR, were studied by Dumouhn et al. [1984]. In spite of the expected immiscibihty, the blends showed additivity of properties with good superposition of the stress growth functions in shear and elongation, as well as with the zero deformation rate Trouton ratio, Rj, = 1. In earlier work, blends of medium density PE (MDPE) with small quantities of ultra-high molecular weight polyethylene (UHMWPE) were studied in shear and extension. Again, SH and Rj, = 1 were observed. 

High density zirconia oxide showed excellent compatibihty with autogenous rhesus monkey bone and was completely nonreactive to the body environment for the duration of the 350 day study [Hentrich et al, 1971]. Zirconia has shown excellent biocompatibihty and good wear and friction when combined with ultra-high molecular weight polyethylene [Kumar et al., 1989 Murakami and Ohtsuki, 1989]. 

Carbon fibers have been incorporated in the high density polyethylene used in total knee replacements (Figure 41.5). The standard ultra high molecular weight polyethylene (UHMWPE) used in these implants... 

High molecular weight HOPE is a special class of linear resins with molecular weights in the 200,000 to 500,000 range. Ultra high density polyethylene has an average molecular weight of over 3 million. 

Y. Chen, H. Zou, M. Liang, P. Liu, Rheological, thermal, and morphological properties of low-density polyethylene/ultra-high-molecular-weight polyethylene and linear low-density polyethylene/ultra-high-molecular-weight polyethylene blends. J. Appl. Polym. Sci. 129, 945-953 (2013)... 

Aramid and ultra-high molecular weight polyethylene are used extensively as base materials for ballistic protection. As discussed earlier (section 7.3.1), these high performance fibres are characterised by high strength, high eneigy absorption, and low density. However, to meet the protection requirements for typical ballistic threats, approximately 13-50 layers of fabric are required, which results in a bulky and stiff armour. The bulk-iness limits its comfort and has resfiicted its appUcation primarily to torso protection. 

Polyethylene, high density, ultra-high m.w.. See Polyethylene, ultrahigh m.w. high-density Polyethylene, high-molecular weight high-density... 

Bellare A., H. Schnablegger, and R.E. Cohen. 1995. A small-angle x-ray scattering study of high-density polyethylene and ultra-high molecular weight polyethylene. Macromolecules 17 2325-2333. 

High-density polyethylene (HDPE)/ultra-high molecular weight polyethylene (UHMWPE) blends are possible by direct compounding, and use of UHMWPE could improve the impact strength or tensile strain of HDPE. The effect of the UHMWPE content on the mechanical properties of the HDPE/UHMWPE blends is improved by compounding due to homogenisation of the mixture [35-39]. 

On the other hand, some polymers show an initial increase in crystallinity, demonstrated by an increase in density. At relatively low doses (< 200 kGy), ultra high molecular weight polyethylene (UHMWPE) appears to show an increase in crystallinity. Since UHMWPE has a... 

UHMWPE Ultra-high-molecular-weight polyethylene VDF-HFA Copolymer of vinylidene fluoride and hexafluoro acetone VDF-TFE Copolymer of vinylidene fluoride and tetrafluoro ethylene VLDPE Very low-density polyethylene compat. Compatibilization, compatibilized, etc. cone. Concentration... 

UHMWPE Ultra high molecular weight polyethylene ULDPE Ultra low-density polyethylene UV Ultraviolet... 

ABS Acrylonitrile-butadiene-styrene HOPE High-density polyethylene LDPE Low-density polyethylene MoS Molybdenum disulfide PA Polyamide(s) PAI Polyamide-imide PBT Polybutylene terephthalate PEEK Polyether ether ketone PEI Polyether imide PET Polyethylene terephthalate PI Polyimide PMMA Polymethylmethacrylate POM Polyoxymethylene PP Polypropylene PPS Polyphenylenesulfide PSU Polysulfone PTEE Polytetrafluoroethylene PU Polyurethane PVDE Polyvinylidine fluoride UHMWPE Ultra-high molecular weight polyethylene UV Ultraviolet XPE Crosslinked polyethylene Source Author s own files ... 

From Figure 8.1 [6] it can be seen that in terms of modulus and tenacity (i.e., the tensile strength divided by the linear density) only the more expensive carbon fibers and some even more expensive, relatively new experimental heat-resistant fibers outperform the p-aramides. It is noteworthy that the oriented fibers of ultra-high molecular weight polyethylene (UHMWPE), e.g., Dyneema , a product of DSM, The Netherlands, display tenacities and moduli in the same range as most p-aramids, however without having their excellent thermal and flame-resistance, as well as insolubility in most organic solvents. 

Volume resistivities are listed in Table 5.2. They range from as low as 2 ohm.cm for epoxy resins to as high as 16-18 ohm.cm for high-density polyethylene, polyether ether ketone, polystyrene, polymethylpentene, polyethylene terephthalate, polyarylates, polyphenylene oxide, polyamide imide, polyimides, polyurethane, polytetrafluoro-ethylene, perfluoroalkoxy ethylene, fluorinated ethylene-propylene copolymer, ultra-high-molecular-weight polyethylene, polysulfones, and polyethersulfones. 

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