Dielectric relaxation of poly(chlorostyrenes) and their copolymers in the primary transition region

Abstract

Dielectric relaxation measurements were carried out on a series of bulk poly(chlorostyrene) homopolymers and random copolymers over the frequency range from 50 to 100 kHz and at temperatures in the neighbourhood of the glass transitions of the polymers thus encompassing the α relaxation. Homopolymers examined were polystyrene (PS), poly(2-chlorostyrene) (P2CS), poly(3-chlorostyrene) (P3CS), and poly(4-chlorostyrene) (P4CS). Copolymers were poly(styrene-co-2-chlorostyrene) (PS2CS), poly(styrene-co-4-chlorostyrene) (PS4CS), and poly(2-chlorostyrene-co-4-chlorostyrene) (P2CS4CS). The dielectric data were analysed to yield dipole moments and Kirkwood—Fröhlich correlation parameters. The shapes of the dielectric loss curves were also taken into account. Glass transition temperatures were determined by differential scanning calorimetry (d.s.c.). It was concluded that the phenyl ring rotates freely in the α relaxation regions of PS, P4CS, and P3CS, but not in P2CS. The dipole moments of the copolymers are correlated with dyad distributions calculated from reactivity ratios.