Ultra-high molecular-weight plastics

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... 

Major markets for LDPE are in packaging and sheeting, whereas HDPE is used mainly in blow-molded products (milk bottles, household and cosmetic bottles, fuel tanks), and in pipe, wire, and cable applications. Ultra-high-molecular-weight polyethylene materials (see later), which are the toughest of plastics, are doing an unusual job in the textile machinery field. 

The blood bag case study illustrates the use of polymeric film as a flexible container. It considers the permeability of polymers, plus processes for fabricating plastics film. Plasticised PVC has dominated the market for years, but there could be a changeover to flexible polyolefin films. The case study on replacement joints for implanting in the body illustrates wear and the effects of wear debris. Research continues on improving the wear resistance of the ultra high molecular weight polyethylene (UHMWPE) and mitigating the effects of sterilisation on the implant properties. 

Another version of PE, the ultra-high molecular weight polyethylene is used as a specialty plastic (in artificial hip, knee and shoulder joints), mainly due to its exceptional impact strength, low wear, good stress-crack resistance, durability, and excellent energy absorption characteristics. 

Chubberley A.H. 1965. Ultra-high molecular weight polyethylenes. In Modern plastics encyclopaedia. New York McGraw-Hill. 

Kurtz S.M., L. Pruitt, C.W. Jewett, et al. 1998. The yielding, plastic flow, and fracture behavior of ultra-high molecular weight polyethylene used in total joint replacements. Biomaterials 19 1989-2003. 

Artificial joints. 2. Polyethylene—Therapeutic use. 3. Plastics in medicine. I. Title Ultra-high molecular weight polyethylene in total joint replacement. II. Title. 

Poly Hi Solidur Plastics India Limited [4] developed products for use on the Indian Railways based on ultra-high molecular weight PE (UHMWPE Hoechst s Hostalen GUR). The base polymer is mixed with patented additives and uses a computer controlled sintering process and sophisticated fabrication methods to produce a material which is claimed to have much higher values for a number of technically important properties such as wear, chemical and water resistance, impact strength and dynamic coefficient of friction. The growth of the market for UHMWPE products is briefly discussed, and the applications targeted by Poly Hi Solidur Plastics are discussed. 

Hy-Pact Polymer, Ultra-high-molecular-weight polyethylene. King Plastic Corp. 

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. 

Stabilite, Antioxidant, Arizona Chemical Stabilux, Ultra-high-molecular-weight PBT, Westlake Plastics Co. 

It has been most successful with semicrystalline polymers that can be post-heated for a sufficient time at a temperature within the crystalline endotherm of the polymer. Examples of such polymers are polyphenylene oxide, polytetrafluoroethylene, and ultra-high-molecular-weight polyethylene. (Strong AB (2000) Plastics materials and processing. Prentice Hall, Columbus, OH)... 

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