Dielectric relaxation of the alternating terpolymers of ethylene, propylene, and carbon monoxide

Abstract

The alternating terpolymers of ethylene, propylene, and carbon monoxide were characterized by wide-angle x-ray scattering (WAXS), differential scanning calorimeter (DSC), thermally stimulated depolarization currents, and dielectric relaxation spectroscopy (DRS). At room temperature, the terpolymers were x-ray amorphous; however, the existence of weak endothermal effects over fairly broad temperature intervals above the glass transition suggested that they should be classified as “microcrystalline” (in a sense that the ultimate level of crystallinity lies beyond the resolution limits of ordinary WAXS instruments). The DRS data in the temperature intervals of α- and sub-glass relaxations were fitted quantitatively to the Havriliak–Negami equation. The characteristic parameters for the α-relaxation were consistent with classification of terpolymers as relatively fragile glass formers; however, their high fragility was attributed to steric constraints to the motion of chain dipoles by the residual network of microcrystals. Strong asymmetry of the dielectric sub-glass relaxation was regarded as additional experimental evidence for the interference of the spatial network of microcrystallites with the motion (in this case, noncooperative) of chain segments.