Ultra high molecular weight polyethylene additives

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. 

Ultra-high molecular weight polyethylene (UHMWPE) can also be considered as sncb an intentional additive, becanse it can be nsed for scratch-resistant coatings, which can... 

At a conceptual level, polyethylene consists only of carbon and hydrogen, as was described in the previous chapter. However, if the discussion of polyethylene is to proceed from ideal abstractions to actual physical implants, three "real world" steps need to occur. First, the ultra-high molecular weight polyethylene (UHMWPE) must be polymerized from ethylene gas. Second, the polymerized UHMWPE, in the form of resin powder, needs to be consolidated into a sheet, rod, or near-net shaped implant (Figure 2.1). Finally, in most instances, tire UHMWPE implant needs to be machined into its final shape (Figure 2.1). A small subset of implants are consolidated into their final form directly, in a process known as direct compression molding (DCM), witiiout need of additional machining. 

Ultra-High-Molecular-Weight Polyethylene. This is extremely difficult to process. Addition of paraffin wax or low-molecular-weight polyethylene wax permits conventional melt processing. 

Lennite, Lennite XL, Ultra-high-molecular-weight polyethylene, Westlake Plastics Co. Leucopure EGM, Fluorescent whitener for polymers, Clariant Corp., BU Additives Levapren, EVA resins, Bayer Corp., Fibers, Additives Rubber Div. 

Silicon-based polymers such as polydimethyl siloxanene (PDMS) have been used as polymer processing aids for many years. Dow Corning has developed ultra-high molecular weight PDMS additives that work as process aids in polyethylene and polypropylene. Because these materials solidify with the polymer, they reportedly... 

Tomita N, Kitakura T, Onmori N, Ikada Y, Aoyama E. Prevention of fatigue cracks in ultra high molecular weight polyethylene joint components by the addition of vitamin E. J Biomed Mater Res (Appl Biomater) 1999 48(1999) 474-8. 

Ranade RA, Wunder SL, Baran GR. Toughening of dimethacrylate resins by addition of ultra high molecular weight polyethylene (UHMWPE) particles. Polymer 2006 May 31 47(12) 4318-27. 

Additive-free film samples of isotactic polypropylene (iPP, 30pm Himont Profax resin) and polyethylenes (LLDPE, 120ym, linear low density DuPont Sclair resin, and UHMW-PE, 120wm, ultra high molecular weight, high density Himont LSR 5641-1B resin) were oxidized by exposure in air to y-radiation (AECL Gamma Cell 220, 1.0... 

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