PACKING ENERGY CALCULATIONS OF POLYETHYLE NE-POLYPROPYLENE COPOLYMER CRYSTAL-STRUCTURE

For the copolymers of polyethylene (PE) with similar to 13 mol% propyl ene (PP) components, the increase in the unit cell dimension of polyet hylene crystal structure is observed by the X-ray diffraction method, but their crystal structures are not analyzed. These copolymer crystal structures were calculated by means of the packing energy minimizatio n method. The variation in the unit cell dimensions observed by the X- ray method was reproduced in these calculations. It was, moreover, ana lyzed that the methyl group of the PP component does not destroy the c rystal structure, but packs into crystal unit cell of PE.