Yielding in amorphous and semi-crystalline polymers: the compensation law

The linear variations of the yield stress of amorphous and semi-crystalline polymers with temperature and hydrostatic pressure (Coulomb-Mohr criteria) is explained in the framework of the cooperative process, when thermally activated, taking into account: (a) the compensation law, the compensation temperature T* being the glass temperature T-g in amorphous polymers and the secondary transition temperature T-alpha c in semi-crystalline polymers; (b) the variation of these mobility temperatures, T-g and T-alpha c, with hydrostatic pressure. (C) 1998 Elsevier Science B.V. All rights reserved.