The Thermodynamics of Rubber at Small Extensions

Abstract

On analyzing their own data, Meyer and Ferri have concluded that at small extensions, rubber is an ideal elastomer according to the definition that (∂E/∂L)P,T=0. Further analysis of Meyer and Ferri's data does not sustain their conclusion. If, however, (∂E/∂L)V,T=0 is taken as a new criterion for an ideal elastomer, Meyer and Ferri's data do indicate that rubber is ideal, at least for extensions up to 166 percent. The new criterion implies that the valence angles do not store an appreciable amount of energy when the rubber is stretched. However, both the molecular orientation and the interatomic displacements do influence the energy required for extension.