The crystallinity of ethylene/a-olefin copolymers

which was prepared by copolymerization of ethylene and a-olefins with heterogeneous Ziegler-Natta catalyst made by chemical reaction

was studied by WAXD

DSC

and PLM methods.The results of WAXD showed that the crystallite size and degree of crystallinity decrease and the parameters of unit cell increase with increase content of a-olefin in copolymers. On the other hand

the crystallite size and degree of crystallinity of the copolymers after heat treatment obviously increase

while parameters of unit cell decrease. Both the critical crystalline sequence lengthes and the value of k obtained increase in the order of EPe