Stress relaxation studies of scission in rubber vulcanizates

Abstract The method of stress relaxation has been used to study oxidative scission in crosslinked rubbers of five different chain structures. Each chain structure was crosslinked by sulfur and by a nonsulfur‐containing agent. Among the sulfur‐cured vuleanizates the rate of scission varied very significantly with chain structure in spite of the presence of sulfur crosslinks in each. On the contrary, for natural rubber, GR‐S, and butyl rubber, the rates of scission of the sulfur cures were not very different from the corresponding sulfurless cures. It was concluded that in these three cases the scission reactions occur predominantly along the network chains as opposed to scission at the crosslinked site.