Ultra High Molecular Weight Poly ethylene

Ultra High Molecular Weight Poly(ethylene) 

Ultra high molecular weight poly(ethylene)s (UHMWPE)s are a special form of poly(ethylene) (PE). Due to the exceptional properties in comparison to ordinary PE types, UHMWPEs deserve to be dealt with in a separate chapter. The polymerization of UHMWPE was commercialized in the 1955 by Ruhrchemie AG (1). 

The essential and only monomer for UHMWPE per definition is ethene, also addressed as ethylene. However, this should not taken too seriously. In special cases, some other comonomers are used. 

Initially, ethylene was obtained by the dehydration reaction of ethanol. Nowadays, ethylene is obtained by steam cracking from naphtha as a basic chemical. Steam cracking degrades longer aliphatic chains and introduces the double bond. Steam cracking is done at temperatures up to 900°C and leaves a wide variety of products behind. Ethylene is recovered by distillation processes. 

The production of ethylene by gas crackers, mostly from C2, C3, and some C4 feeds, amounts to about 40% of the world ethylene capacity. This results in a small coproduction of benzene compared to benzene co-produced in naphtha and gas oil crackers, which account for 60% of the world s ethylene production capacity. A typical overall benzene yield from ethane cracking is on the order of only 0.6% of the ethane feed, and the yield of benzene from propane cracking is on the order of 3% of the propane feed. In contrast, the 

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Ultra High Molecular Weight Poly (ethylene) 77... 

UHMWPE ultra-high-molecular-weight poly(ethylene)... 

The effect of ultra-high molecular weight poly-(ethylene) (UHMWPE) the on mechanical and solid particle erosive wear behavior of aramid fabric reinforced-epoxy composites has been investigated [64]. A siUca sand of a size of 150-280 fim was used as an erodent. The erosive wear rate of UHMWPE in aramid-epoxy composite exhibits a lower value in comparison to neat composites. A maximum erosion rate was observed at an impingement angle 60 , and the material behaves in a semiductile manner. 

By virtue of our modem lifestyle, more than one-third of the readers of this article will likely experience the failure of their native hip joint(s)—sooner or later [1], Fortunately, hip-joint arthroplasty is on hand to deal with this condition. A major unsolved problem, however, is the mechanical wear of the artificial joint, which hmits the fifetime to about 10-15 years [2]. While most lubrication of the healthy natural joint relies on a film of synovial fluid (SF), the artificial joint consists of synthetic materials and is mainly lubricated in the mixed and boundary regimes [3]. In a widely used arthroplastic design [4], the acetabular cup consists of a linear of ultra-high-molecular-weight poly(ethylene)... 

Wang A, Manley MT, Serekian P 2003. Wear and structural fatigue simulation of crosslinked ultra-high molecular weight poly ethylene for hip and knee bearing applications ASTM International STP 1445. 

UHMWPE Ultra-High Molecular Weight poly(ethylene) PS poly(styrene)... 

Tate S, Watanabe Y and Chiba A (1993) S50ithesis of ultra-high molecular weight poly(ethylene terephthalate) by swollen-state pol5rmerization, Polymer 34 4974-4977. 

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