Dielectric study on the miscibility of binary polymer blends

Abstract

The α-relaxations of various polymer blends have been measured by broad-band dielectric relaxation spectroscopy (1 Hz to 1 MHz) over a wide temperature range (−50 to 220°C). In all blends under investigation the dipole moment of one polymer was negligible compared with that of its counterpart, which simplified the evaluation of blending effects on the α-relaxation. In mixtures of poly(vinyl methyl ether) (PVME) with polystyrene, which are well known to exhibit lower critical solution temperature behaviour, the α-relaxation of PVME could be measured in the one- and two-phase region. The results are compared with differential scanning calorimetric measurements of this system. The dielectric miscibility criterion ensured for the blend PVME/polystyrene was then used to study miscibility of other polymer blends. In the temperature range under investigation, mixtures ofPVME/poly( p -methylstyrene) andPVME/poly(styrene- block-p -methylstyrene) are incompatible, whereaspoly( o -chlorostyrene) blended with poly(methylphenylsiloxane) is either compatible or semicompatible.