AbstractTensile creep of unplasticized and plasticized PVC and toughened polystyrene compounds were recorded as a function of the temperature with the UNIRELAX device developed in our laboratory and produced by Tetrahedron Associates, San Diego, California, U.S.A. The thermomechanical curves obtained this way were found to be governed by the creep process as well as by the recovery of the elastic deformation frozen‐in by processing. Using small stress levels (10 g/mm2) the thermomechanical curve was mainly determined by the recovery of the frozen‐in deformation. Effects of thermal history on the creep thermomechanical curves were studied and interpreted. Using a mathematical formalism derived earlier for amorphous polymers, the curves were computer‐processed in order to separate creep from the recovery of the frozen‐in deformation and to obtain isothermal kinetic