Copolymerization of ethylene and non-conjugated dienes with Cp2ZrCl2/MAO catalyst system: effect of polymerization temperature on the copolymer structure

Ethylene was copolymerized with linear, non-conjugated dienes by the metall ocene catalyst system Cp2ZrCl2/MAO at several temperatures from 20 to 80 de grees C. The dienes were 1,5-hexadiene (HD), 1,7-octadiene (OD) and 7-methy l-1,6-octadiene (MOD). Incorporation of the dienes was studied by H-1 and C -13 NMR and FTIR. Polymerization conditions had a dramatic effect on the de gree of crosslinking of the product. At polymerization temperatures from 20 to 65 degrees C the copolymers of ethylene and HD or OD were nearly totall y crosslinked, whereas at 80 degrees C the degree of crosslinking was consi stently under 10%. When MOD was used as comonomer the degree of crosslinkin g did not increase above 40% even for copolymer produced at 20 degrees C. ( C) 1999 Elsevier Science Ltd. All rights reserved.