Chemical structure dependence of the internal energy contribution in rubber elasticity

Conformational elasticity theory recently developed has been used to explor e the internal energy contribution to the elastic force f(e)/f as a functio n of strain for poly(cis-1,4-isoprene) and poly(trans-1,4-isoprene). Calcul ated f(e)/f values are in good agreement with those obtained experimentally . Results show that behavior of f(e)/f is mainly contributed by chemical st ructure, or intramolecular interaction, supporting the experimental observa tions, and that the internal energy contribution is strain dependent.