GB838963A - Improvements in or relating to copolymers - Google Patents

Abstract

Copolymers of ethylene, and up to 70% of propylene which may also contain a minor proportion of another unsaturated hydrocarbon are cross-linked by heating the copolymer in the presence of from 0.1 to 20% by weight of the copolymer, of a peroxide of the formula <FORM:0838963/IV (a)/1> where R1 and R6 are aryl groups and R2, R3, R4 and R5 are hydrogen or an alkyl group of less than 4 carbon atoms. The heating is preferably effected within the range of 132 DEG to 190 DEG C. The Specification contains an extensive list of peroxides in accordance with the above formula. p Preferred peroxides are bis (alpha, alpha-dimethylbenzyl) peroxide, bis (alpha, alpha-dimethyl - p - isopropyl - benzyl) peroxide, bis alpha, alpha - dimethyl - p - methylbenzyl) peroxide, and bis (alpha-isopropylbenzyl) peroxide. The third ingredient of the copolymer may be allo-ocimene, vinyl cyclohexane, dipentene, myrcene or isoprene. The polymers may be made using "Zeigler-type" or supported metal oxide type catalysts e.g. in accordance with the processes described in Specifications 748,583 or 804,641. The crosslinking may be effected throughout the whole polymer mass or confined as in the case of films to a surface cross-linking. Wires or filamentary materials may be coated with the cross-linked polymer.