Fatigue crack growth of elastomers in the swollen state

The values of crack growth rate for styrene-butadiene copolymer (SBR) and a crylonitrile-butadiene copolymer (NBR) under dynamic tearing condition were measured in both dry and swollen conditions. For swollen samples, tearing energy was adjusted by a simple geometrical factor lambda(delta)(2) (where lambda(s) is the linear swelling ratio), in order to take into account the reduction in number of molecular chains per unit fracture plane. The crack growth rate of a swollen elastomer was observed to be significantly increas ed over the measured range of tearing energy compared to that of an unswoll en elastomer. The effects of the type of elastomer, degree of swelling, and crosslinking structure on fatigue crack behaviour of swollen elastomers ar e discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.