Structure of thin polyolefin films obtained by quenching of the melt down to 77 K

Abstract

The structure of quenched samples of PE, isotactic PP, copolymers of ethylene with propylene and vinyl acetate and their blends has been investigated by X-ray analysis at 120 and 293 K and by radio thermoluminescence methods. An increase in the rate of cooling of PE and PP melts results in a significant reduction in T g and in the degree of crystallinity. T g values of the copolymers of ethylene with vinyl acetate are relatively slightly dependent on the rate of cooling of the melt if the vinyl acetate concentration exceeds 60 wt.%. The structure of thin films of PPE, PP and some copolymers prepared by quenching of the melts in liquid nitrogen is unstable: heating of the films is accompanied by a rise in T g and by increases in the degrees of crystallinity.