BIREFRINGENCE DISTRIBUTION IN INJECTION MOLDED PARTS WITH WELD LINES

摘要

The effect of processing conditions on the birefringence distribution in Polystyrene injection molded parts with weld lines was investigated. The gapwise averaged birefringence of injection molded parts was measured by photoelasticity method. Birefringence at weldline area generated by different obstacles was also investigated. It was found that melt temperature and packing pressure are the two dominant factors that determine the birefringence development of the molded parts. Birefringence distribution has an appreciable distinction at weldline area, which is attributed to the molecule orientation distribution, local flow behavior and melt meeting angle at the melt front.