AbstractTranslated from:Vysokomolekuliarnye Soedineniia2, 778–84 (May 1960). A thermomechanical study was made of the softening of crystalline polymers during uniform, uniaxial stretch and also of the effect of the rate of heating upon the softening or amorphous polymers. The effect of the tensile force on the thermo‐mechanical behavior of various polymers was measured over the range 20 to 100 kg/cm2and within wide temperature limits (−150° to 250°C). Ribbons 50 mm long, 2‐4 mm wide and 0.05 to 0.5 mm thick served as