Effects of Beta Irradiation,Copolymers, and Blends on the Transformation Rate of Polybutene-1

The beta irradiation of polybutene-1 (PB-1) and its random copolymers with ethylene results in sample degradation without chain cross-linking. The crystal structures of both homopolymer and ethylene copolymers were phase I (I), except that for samples of short time irradiation, after melting, where phase II (II) was also present. The sample crystallinity decreased from 64% to a low of 45% in the irradiated samples for the condition used. The crystal size/perfection of the transformed I was slightly lower than that of parent II. The beta irradiation increased the transformation rate of II → I but to a lower extent than did the amount of ethylene in the copolymers. IR analysis confirmed that electron irradiation resulted in chain scission and a decrease of ?CH₂? and ?CH₃ groups. The mechanical properties decreased with increasing ethylene content and irradiation dose.