On thermomechanics of polymers in the transition and rubber regions

A nonisothermal theory of viscoelastic media, motivated by thermomechanical behaviour of polymeric materials in the transition zone between the rubber and glassy states, was developed previously by Crochet and Naghdi (1974) and included as a special case a theory with small deformation suitable for thermorheologically simple materials. The object of the present paper is to modify the form of the previous constitutive equations slightly in order to extend the validity of the theory to the rubber region in which the medium behaves elastically.