Abstract
Stress—temperature coefficients have been measured for a high‐molecular‐weight ethylene—propylene copolymer, containing 45 mole‐% of ethylene, chlorinated and vulcanized with a cure system based on sulphur and accelerators. From the relationships: the thermodynamic functions [∂E/∂L]T and — T [∂S/∂L]T have been determined in a range of the extension ratio up to α=6.9. A good agreement has been found between the experimental data and the stress—strain theoretical curve obtained for a non‐Gaussian type network.