聚丙烯气体辅助注射成型冷却过程中温度分布的研究

Temperature Profile of Polypropylene during Cooling Stage in Gas-assisted Injection Molding

通过对聚合物气体辅助注射成型冷却过程进行合理的假设与简化,对聚丙烯(PP)气体辅助注射成型冷却过程进行了实验与数值模拟研究。结果表明,注射氮气后,PP的冷却速度显著加快,并在气-熔界面处出现小范围的结晶平台。采用MATLAB软件对氮气辅助注射成型PP冷却过程中的温度分布进行了数值模拟,将计算所得模拟值与温度采集的实验值进行比较,发现在熔体降温阶段温度分布的模拟值与实验值吻合程度很高;在固相冷却阶段由于聚合物本身复杂特性以及气体的渗透效应,PP的模拟值略高于实验值,而氮气的模拟值低于实验值。

Under reasonable assumptions, the theoretical and experimental temperature distribution of polypropylene （PP） during the cooling stage in gas-assisted injection molding （GAIM） was studied via the numerical simulation coupled with experimental measurement. It showed that the cooling rate of PP was significantly increased after an injection of N2, and a small ＂crystallization platform＂ near the gas-melt interface was observed. The mathematic model was solved through the mathematical software package MATLAB and measurements of temperature profiles of PP and N2 showed good agreement with the numerical prediction during the liquid cooling process. During the solid cooling stage, the values of theoretical predictions of PP were larger than the experimental ones, while the values of theoretical predictions of N2 were lower than the experimental ones.