MISCIBILITY AND DIELECTRIC ALPHA-RELAXATION OF PECH/PVME POLYMER BLENDS

A study of the alpha-relaxation in the poly(epichlorohydrine)(PECH)/poly(vinyl methyl ether)(PVME) system by means of dielectric spectroscopy is reported. This is a particular system in the sense that the glass transition temperatures, T-g, of the pure components are virtually coincident. Moreover, the dielectric relaxation strength of pure PVME is about three times lower than the dielectric relaxation strength of pure PECH. This leads to the fact that the dielectric relaxation emphasizes the contribution to the spectra of the PECH dynamics. Calorimetric measurements indicate that the blends are miscible over all the composition range. In addition, it is observed that the T-g values of the blends are higher than the T-g values of the pure components. This behaviour could be related to the existence of specific interactions between PECH and PVME chains. The alpha-relaxation of this system shows an anomalous behaviour in the sense that opposite to the usual findings throughout all the composition range the dielectric relaxation can be fitted by the Kohlrausch-Williams-Watts law and the time-temperature superposition principle remains applicable.