Mizue EBISAWA, Yukitoshi OTANI, and Norihiro UMEDA

Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan

(Received December 13, 2006; Accepted May 31, 2007)

Some polymer materials under tensile stress provide us interesting information. Internal structure changes of polymer materials must be observed by external stress. Birefringence shows the orientation characteristic in molecular orientation. A microscopic measurement system for birefringence distribution is proposed to analyze the relation between applied stress and birefringence distribution of an internal structure. Birefringence distributions of gelatin such as phase difference and azimuthal angle are shown in cases of loading and unloading stress as a demonstration. The phase difference increased nonlinearly with each process, and change of birefringence in the elastic domain was different from that in the plastic domain.

Key words: birefringence, tensile stress, photoelastic, stress