Thermomechanical studies on natural rubber in torsion and simple extension

Abstract

Thermomechanical heat of deformation studies have been made on crosslinked natural rubber using a Calvet microcalorimeter. Using the Gaussian statistical theory of elasticity to correct for volume changes, torsional experiments gave a value for the relative energy contribution to the retractive force of 0.20₂± 0.01₇(=M_e/M); simple extension experiments gave 0.19 ± 0.02 (=f_e/f). When the data from simple extension experiments were corrected using two empirical dilation equations, values for f_e/f of 0.13 ± 0.02 and 0.14 ± 0.02 were obtained. An assessment was made of the various routes available for studying the energetics of rubber deformation.