The Dielectric Property of Polystyrene and Some Ring-substituted Polystyrenes in Glassy State

Measurements of dielectric properties of polystyrene and some substituted polystyrenes containing different substituents (methyl group and halogen atoms) in the phenyl ring are carried out over a temperature range from 93 to 343°K in vacuo (10 -3 mmHg) at 1 and 10 kHz. The temperature dependence of dielectric loss ε '' is mardedly different according to the location of the substituent in the ring. The dielectric behavior of these polymers at temperatures around 150°K at 10 kHz is explained in terms of two modes of phenyl group motions: the hindered rotation of phenyl group around the bond to the main chain and the oscillation or wagging of phenyl rings. The relaxation observed as a shoulder at the foot of the α-loss peak in the ε ''-temperature curve is attributed to the local-mode oscillation of the main chain.