注射成型聚苯乙烯制品双折射的光弹测试与分析

分析了无定形聚合物注射成型双折射行为及其产生机理，利用光弹法测试了不同工艺条件下聚苯乙烯(PS)平面内双折射分布，考察了熔体温度和保压压力变化对制品双折射和流动残余应力的影响。结果表明，PS制品残余双折射值在流动方向上从浇口附近至流动末端逐渐降低，并且最大双折射值随保压压力增加和熔体温度降低而升高；保压压力对浇口附近双折射分布影响明显。根据双折射的光弹测试结果分析了P制品分子取向和流动残余应力的分布趋势。

Measurement and Analysis of Birefringence Distribution in Injection Molded Polystyrene Parts by Photoelasticity Method

This work explores birefringence behavior for injection molded amorphous polymers. Photoelasticity method was used to measure the gapwise-averaged birefringence of PS plaque parts molded under different process conditions. The effects of melt temperature and packing pressure on the birefringence distribution were investigated. It was found that residual birefringence decreased from the area near the cavity entrance to the end of the part along the melt flow direction, decreased with increasing temperature and decreasing packing pressure. Especially, higher packing pressure exhibited significant effect on birefringence distribution of the area near the gate. Flow-induced residual stress and molecular orientation distribution of injection molded PS part were evaluated from the birefringence distribution measured by photo-elasticity method.