Ultra high molecular weight polyethylene processing

Lemstra, P.J. Bastiaansen, C.W.M. Peijs, T. Jacobs, M.J.N. Fibres based on ultra-high molecular weight polyethylene—processing and applications. In Solid Phase Processing of Polymers, Ward, I.M., Coates, P.D., Dumolin, M.M., Eds. Hanser Gardner Publications, Inc. Cincinnati, Ohio, 2000 Section 5.3, 173 pp. 

Lemstra PJ, Bastiaansen CWM, Peijs T, Jacobs MJN (2000) Fibres based on ultra-high molecular weight polyethylene - processing and applications. In Ward IM, Coates PD, Dumoulin MM (eds) Solid phase processing of polymers. Carl Hanser Verlag, Munich, p 172... 

Bimkraut, W. H., Braun, G., and Falbe, J., Ultra high molecular weight polyethylene processing and properties, App/. Polym. Sympos., 36, 79-88 (1981). 

Ultra-high molecular weight polyethylene (UHMWPE) has been used in orthopaedic prosthetic surgery for many years due to its excellent mechanical properties and frictional resistance. A large number of studies on both retrieved prostheses and raw material have, however, been necessary in order to understand and prevent degradation of the prostheses. The shape of the prostheses and the compression moulded blocks from which they are cut is usually not suitable for examination. In a number of studies microtomy has therefore been used in order to produce pieces suitable for further studies [112, 113, 114, 115, 116, 117, 118, 119, 120]. However, very often when microtomy is used, it is without any consideration of the fact that the process... 

The ultra-high molecular weight polyethylene fiber is a highly crystalline fiber with very high stiffness and strength. All of this results from some innovative processing and control of structure of polyethylene. 

Figure 4.11 Flow diagram of the gel-spinning process of making ultra high molecular weight polyethylene fiber.

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. 

Kurtz S.M., O.K. Muratoglu, M. Evans, A.A. Edidin. 1999. Advances in the processing, sterilization, and crossUnking of ultra-high molecular weight polyethylene for total joint arthroplasty Biomaterials 20 1659-1688. 

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. 

HaUdin G.W., and I.L. Kamel. 1977a. Powder processing of ultra-high molecular weight polyethylene. I. Powder characterization and compaction. Poly Eng Sci 17 21-26. 

Wang X.Y., S.Y. Li, and R. Salovey. 1988. Processing of ultra-high molecular weight polyethylene. ] Appl Poly Sci 35 2165-2171. 

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