Experimental Examination of the Statistical Theory of Rubber Elasticity. Low Extension Studies

Abstract

An experimental study was made of the behavior of two rubbers, Butyl (GR-I-18) and Paracril-35, in the low extension region (0 to 15 percent), at temperatures ranging from −40°C to +60°C. The results have been compared with the Guth-James theory of rubber elasticity. In general, good agreement with theory was observed. Two effects predicted by the theory have been confirmed, namely, the nonlinear dependence of stress upon temperature at constant extended length, and the shift of the thermoelastic inversion extension to higher values with increasing temperature. Small deviations, which increased with increasing extension and with decreasing temperature, were observed.