| abstract |
A polyethylene article such as film or fiber having high strength and high elastic modulus is produced by orienting an ultra-high molecular weight polyethylene having an intrinsic viscosity at 135°C in decalin of 5 to 50 dl/g, said ultra-high molecular weight polyethyelene being prepared by homo- or copolymerizing ethylene in the presence of a catalyst system and hydrogen, said catalyst system comprising (1) a solid catalyst component containing at least magnesium and one or both of titanium and vanadium, (2) an organometallic compound and (3) a compound represented by the following general formula [I] :n where R 1 , R 2 , R 3 and R 4 are each hydrogen or a hydrocarbon residue, with the proviso that any two of R 1 , R 2 , R 3 and R 4 may conjointly form a cyclic hydrocarbon residue. |