Abstract
Simultaneous measurements of optical activity and birefringence have been made for the first time on poly-L-lactic acid (PLLA), which is a well-known piezoelectric and biodegradable polymer. Optical gyration of PLLA films, one stretched 2.5 times the other 6 times as long as the original ones, displayed different temperature dependence in the higher and lower temperature regions and changed the sign in the lower one. These facts suggest a conformational change to take place in PLLA at some temperature in the lower one.