Mechanical and dielectric relaxations in alternating block copolymers of dimethylsiloxane and bisphenol a carbonate

Abstract

Alternating block copolymers of bisphenol A carbonate and dimethylsiloxane at three different compositions were studied by mechanical and dielectric measurements. Both sets of data exhibit transitions characteristic of the primary glass transitions of the component polymers. This behavior is characteristic of heterophase polymers. Dielectric data for all three samples cast from methylene chloride solution are presented. In addition, one sample was also cast from the solution of methylene chloride–n-hexane. The resulting morphologic differences among the samples are reflected in the activation energies associated with the low-temperature transitions. The time–temperature superposition principle was invoked to construct master curves for both mechanical and dielectric data. It was found that there exist considerable discrepancies in the respective master curves and the shift factor data. These results indicate that this heterophase block copolymer is thermorheologically complex.