Abstract
Recently, Onogi, Keedy and Stein developed a measuring technique of the dynamic birefringence of polymer films. The present paper is concerned with an apparatus similar to theirs but more convenient to measure the phase angle between the birefringence and the strain or stress at temperatures ranging from-40 to 200°C and in the frequency range from 0.005 to 20 cycles per second. This apparatus can also be used for static measurements of the birefringence, strain and strees under a constant strain or constant rate of strain.
Preliminary experiments on valcanized rubber and polyethylene films have showed that this apparatus can give satisfactory Lissajous' figures, and that the phase angles between the birefringence and the strain for these two samples have different signs.
