Variation of photoelastic behavior with temperature for some polymers

Publisher Website
Google Scholar
Abstract
The variations of photoelastic behavior for styrenedivinylbenzene copolymers and a diallyl phthalate polymer were studied between 20 and about 190°C. The birefringences for constant stresses were measured. With suitably crosslinked polymers the transition from the glassy state to the rubber‐like state was observed distincitly. In the higher temperature region the photoelastic behavior was in agreement with the statistical theory for ideal rubbers. The photoelastic coefficient in the entropy elasticity range varied linearly with increasing degree of crosslinkage. The extrapolated value of Δn/σ for styrene copolymers to zero content of the crosslinking agent coincides with the value for polystyrene itself. With the very highly crosslinked polymer the transition was observed not to be distinct.