Low‐temperature dielectric relaxation in poly(4,4′‐oxydiphenylene pyromellitimide)

Abstract

AbstractThe effect of end groups on the low‐temperature dielectric relaxation in poly(4,4′‐oxydiphenylene pyromellitimide) has been studied using three kinds of samples with different content of anhydride end groups. The magnitude of the dielectric loss peak, designated here the V peak, which appears near −40°C at 1 kHz, depends on the content of anhydride end groups. If a sample with few anhydride end groups is allowed to absorb water, a loss peak appears near the temperature region of the V peak, but it disappears after subsequent heating. In contrast, a sample having a larger amount of anhydride end groups exhibits a large V peak which remains even after further heating. We conclude that the Oportion of the anhydride end groups is responsible for the V peak, though there may be an additional contribution from absorbed water.