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Abstract

Stretched articles of ultrahigh-molecular-weight polyethylene are prepared by melt-kneading a mixture of ultrahigh-molecular-weight polyethylene with a paraffinic wax having a melting point of 40.degree. to 120.degree. C. and a weight average molecular weight of at least 230 but less than 2000 in a screw extruder while maintaining the temperature of the mixture at 180.degree. to 280.degree. C. The molten mixture is melt-extruded through a die at a temperature of 180.degree. to 300.degree. C. and the resulting unstretched extrudate is cooled to solidify it. The unstretched solidified extrudate is then subjected to a stretching treatment at a temperature of 60.degree. to 140.degree. C. at a particular stretch ratio. Stretch shaped articles of ultrahigh-molecular-weight polyethylene having high tensile strength and modulus of elasticity are produced uniformly and reproducibly. The stretched shaped articles are substantially free from stretching uneveness. Examples of the paraffinic wax include n-alkanes having at least 22 carbon atoms.

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