顺序共注射成型工艺参数对iPP制品柱晶生成的影响

Effects of Processing Parameters on Cylindrulite Formationin Isotactic Polypropylene Parts Made by Sequential Co-injection Molding

采用偏光显微镜观察共注射成型制备的等规聚丙烯夹芯制品不同位置处的微观形貌,特别是不同成型工艺条件下复杂温度场和剪切场形成的柱状晶体结构。研究了芯层注射速度、芯层注射温度和延迟时间对选定位置(迟滞线位置处,芯层熔体流动前沿处)柱晶生成数量的影响。结果表明,芯层注射温度为190℃和延迟时间为5 s有利于柱晶的生成,芯层注射速度为20 mm/s时,迟滞线位置处柱晶的数量最多,而芯层熔体流动前沿位置处柱晶数量最少。

Polarized light microscope （PLM） was used to observe the morphology of isotactic polypropylene sandwich parts in different position which were made by sequential co-injection molding,particularly,the cylindritic structures which were caused by the complex temperature field and shear field from different processing parameters. The effects of injection speed of core material, temperature of core material and delay time on cylindritic structures were investigated simultaneously. The results show that core melt temperature 190℃and delay time 5 s are conductive to form cylindritic structures,when the core injection speed is 20 mm/s, the number of cylindrulites in delay line position is maximum while in the core melt flow front position is minimum.