Enthalpy relaxation in amorphous and crystalline polymers. Polyaryl ether ether ketone blends

Abstract

The kinetics of enthalpic relaxation in compatible blends of polyether ehter ketone, PEEK and polyetherimide, PEI have been measured by DSC, and interpreted in terms of a broad spectrum of relaxation processes, in that the overall fractional extent of conversion φ(t) at time t obeys the relationship, 1−φ(t)=exp(−t/τ)^β, where τ is the relaxation time and β is a measure of the reciprocal breadth of the relaxation spectrum. Similar analysis has been carried on the dynamic and dielectric response of the blends, but there is little similarity in the β values so determined. Although the 50:50 blend exhibits a single glass transition temperature, the observed value of β, 0.2 for the dielectric relaxation spectra is consistent with some heterogeneity developing at the molecular level.