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.

Acknowledgments

This work was supported by the projects INTAS-97-1936 and INTAS-OPEN-97-418. V.V.K. gratefully acknowledges the post-doctoral research fellowship at the Department of Physics, NTUA, from the Greek State Scholarship Foundation. Thanks are due to Drs. V. I. Shtompel and A. G. Charnetskaya, and to V. A. Konovalenko for help with WAXS and DSC measurements. Helpful comments by the referee are also highly appreciated.