Abstract

The viscoelastic relaxations of four copolymers of ethylene and 1-octadecene, with different comonomer contents, synthesized with a metallocene catalyst, have been analysed and compared to those of the corresponding polyethylene homopolymer. Similar to other ethylene copolymers, the temperature for ? relaxation decreases with the increase in the comonomer content, attributed to the reduction of the crystal size. In fact, a linear relation has been found between the temperature location of ? relaxation and the crystal thickness estimated from the SAXS long spacing. However, the position of ? relaxation experiences very little dependence with the comonomer content and it overlaps to ? relaxation for the higher comonomer contents. As to ? relaxation, there is also a clear effect of the comonomer content on the breadth and on the location of this relaxation. © 2002 Elsevier Science Ltd. All rights reserved.