退火对注射成型PC制品力学性能的影响

注射成型的塑料光学制品应用日益广泛,但注射成型加工的聚碳酸酯制品通常有较大的残余应力,会对制品的光学性能、力学性能有负面的影响,而退火可减少/消除制品的残余应力。本文考察了退火对不同工艺条件下注射制品残余应力和力学性能的影响。研究的工艺条件包括三水平的变化的模具温度、熔体温度、保压压力、冷却时间等;残余应力的变化通过光弹实验的应力干涉条纹表示,力学性能的变化以拉伸强度、延伸率的变化表示。实验发现,退火前后,不同工艺条件下注塑PC制品拉伸强度平均提高4.5%,最大达9.0%;同时,断裂延伸率平均降低3%,最多减少14%。

Effects of annealing on mechanical properties of injection mold polycarbonate parts

Residual stresses in transparent injection molded parts may have negative effects on optical and mechanical properties.Annealing is one of the important methods to eliminate or minimize the processing residual stresses.In this paper, the effects of annealing on residual stresses and mechanical properties were investigated and discussed by comparing the photoelastic birefringence results and the tensile properties of the injection molded PC parts before and after annealing treatment.After annealing, it was found that there was no obvious change in birefringence interference pattern while tensile strength and elongation were different at various processing parameters, including mold temperature, melt temperature, injection pressure, packing pressure, cooling time, packing time and injection time.According to the experimental results, after annealing the average tensile strength increased by 4.5% and the maximum value was 9%.And at the same time the average elongation decreased by 3% and maximum reduction reached 14%.