Molecular segmental distortion in rubbed polystyrene

The rubbing-induced birefringence Δntotal and segmental degree of alignment 〈P2(cos θ)〉av in polystyrene (PS) and their subsequent relaxations at elevated temperatures were studied. The contribution from the alignment of segments Δn0〈P2(cos θ)〉av was found to be less than 11% of the total birefringence Δntotal. The majority contribution (>89%) came from the distortion of the segments. Second, at any given temperature more segmental orientations relaxed than segmental distortion did. The alignments disappeared at a temperature lower than that at which the segmental distortion disappeared. Third, the alignment relaxations of phenyl ring and CH2 bonds were of the same pace with rising temperature, suggesting that the relaxation is due to the orientational relaxation of the backbone, and the phenyl group and the CH2 are always at equilibrium positions relative to their parent backbone.