Thermostimulated creep in amorphous polyolefins. I

The thermostimulated creep of two amorphous polyolefins having the repeating unit ─(CH2)mC(CH3)2─, where m = 2 and 3, was investigated from 77° to 350°. Two relaxation processes are distinguished: a secondary relaxation is observed at 138 and 113°, respectively, for m = 2 and m = 3; a primary relaxation is found around the glass transition. These relaxations have been resolved in their elementary components. From the data acquired, the mechanical losses have been calculated and compared with data from an inverted torsional pendulum. The activation energy found for the secondary relaxation—0.26 eV at 138° K for the amorphous polyolefin with m = 2 and 0.19 eV at 113° K for the polyolefin with m = 3—confirms that this relaxation mode is associated with restricted backbone motion.