Ultra high molecular weight polyethylene, Catalysts

High density conditions and application of special catalysts allow one to get ultra high molecular weight polyethylene of molecular weight 4x10 g moP. Using the method of hot pressure, slabs can be obtained which serve as the initial material for the preparation of the elements of endoprosthesis. Such a treatment results in the excellent properties of polyethylene which basically depend on temperature. Tables 4 and 5 collect PE parameters as they depend on molecular weight whereas Table 5 also shows comparative properties of polyethylene and of bone cement. 

Weiser, M.S., Wesolek, M., and Mulhaupt, R. (2006b) The synthesis and X-ray structure of a phenoxyimine catalyst tailored for living olefin polymerization and the synthesis of ultra-high molecular weight polyethylene and atactic polypropylene. Journal of Organometallic Chemistry, 691,2945-2952. 

Table 5.8 lists propylene polymerization data for some of the complexes shown in Figure 5.12. Varieties of other polymer products have been prepared using the D/A-bridged complexes. For example the (Flu)(Cp)ZrCl2 complexes (22a-b) produce ultra-high molecular weight (UHMW) polyethylene with intrinsic viscosities as high as 13.5 d/g. The D/A metallocenes are also effective catalysts for the copolymerization of a-olefins with ethylene to produce medium to ultta-low density polyethylene products. ... 

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