Thermoplastic polymer composition for skeletal replacements and process for preparing thereof

摘要

The present invention relates to a thermoplastic polymer composition for skeletal replacements and a method of its preparation. The composition according to the invention consists of 12 to 91 percent by weight of a polyolefin with the glass transition temperature higher than 320 K, which is an ethylene - bicyclo[2.2.1]hept-2-ene copolymer with molar concentration of the latter at least 25 percent and 75 percent at the most, of 2 to 72 percent by weight of a polyolefin with the glass transition temperature lower than 250 K, which is (i) ethylene homopolymer of density at least 0.92 g.cme-3 and 0.97 g.cme-3 at the most or (ii) copolymer of ethylene with an {alpha}-olefin selected from a group consisting of propylene, but-1-ene, hex-1-ene, oct-1-ene and dec-1-ene, with density of at least 0.85 g.cme-3 and 0.96 g.cme-3 at the most or a mixture of ethylene homopolymer (i) and ethylene - {alpha}-olefin copolymer (ii) in any arbitrary ratio, and of 5 to 50 percent by weight of carbon fibers with the carbon content of at least 94 percent by weight, a density of at least 1.80 g.cme-3 and 1.92 g.cme-3 at the most and with the fiber diameter of at least 4 microns and 9 microns at the most. The above-described composition is prepared by mixing in the melt a polyolefin with the glass transition temperature higher than 320 K and a polyolefin with the glass transition temperature lower than 250 K at a melt temperature of the stirred mixture of at least 430 K. The so formed thermoplastic polymer composition is then irradiated with gamma rays or accelerated electrons at a dose of at least 20 kGy and 250 kGy at the most, preferably in an inert atmosphere, whereupon the irradiated material is mixed in the melt with carbon fibers at a temperature of at least 430 K. The material can be stabilized against oxidative degradation by admixture of at least 0.1 percent by weight of {alpha}-tocopherol.