Abstract: The birefringence along the thickness direction of PC plate was studied using Wedgemethod. From the distribution of birefringence and molecular orientation with different processing parameters and different positions in the molded plate, an asymmetrical distribution of birefringence on the sideway of the plate was found. On the subsurface near the cold model, there occurred a birefringence peak or a noncontinuous distribution in the thickness direction. The influence of melt temperature and holding pressure on the birefringence was serious, but the annealing had no effect on the birefringence and molecular orientation.

Key words: injection molding, polycarbonate, molecular orientation, birefringence