Effect of interphase interactions on the dielectric behaviour of polycarbonate/poly(styrene-co-acrylonitrile) blends

Summary

Frequency and temperature dependences of the complex permittivity ɛ^* (=ɛ′−i ɛ″, ɛ′ is the real and ɛ″ imaginary component, respectively) were investigated for blends of polycarbonate/poly(styrene-co-acrylonitrile) (PC/SAN). In the blends, two α-processes corresponding to the main transitions of PC and SAN were found; for SAN at concentrations c _SAN≥ 20 wt% and for PC for c _PC≥ 40 wt%. The Havriliak-Negami shape parameters describing the frequency dependence of ɛ′ and ɛ″ are virtually independent of temperature and composition. Slight shift of temperature or frequency positions of α-processes found for blends from those found for neat polymers with composition of blends indicated partial miscibility of components. The concentration dependences of ɛ′ and ɛ″ at low frequencies and high temperatures could be described with the Böttcher equation from which it followed that percolation threshold takes place for SAN inclusions at c _SAN≈ 30 wt%. Both the reduced dielectric strength ΔɛT and the reduced Onsager term O _t/c _SAN (or O _t/c _PC) in dependence on the blend composition could be qualitatively described by the Böttcher equation as well.