Tensile Rupture of Rubber

Abstract The dependence of tensile strength of a number of vulcanizates on temperature has heen studied. A critical temperature θc is found for natural rubber at which an abrupt change in strength occurs. This temperature depends on degree of crosslinking and also on the nature of the vulcanizing system. The presence of carbon black filler increases the strength above θc but has little influence on the value of θc or the strength at temperatures below it. The behavior can be explained qualitatively in terms of a change in mechanism of rupture from essentially a tear process above θc to a crack growth process below it. The influence of vulcanizing system is mainly due to changes in the nature of the crosslink rather than changes in regularity of the main chain as shown by the rate of low temperature crystallization.