Abstract The pressure-specific volume-temperature (pvT) diagram is well established in science and industry for plastics injection molding purposes. However, the exact specific volume during the process cannot be measured and the help of a pvT model is necessary. The pvT model is based on the data measured under standard conditions and might not reflect the specific volume at process level. In order to know the exact variation of the specific volume, a pvT testing device was used to simulate the injection molding process. Four parameters (starting temperature, holding pressure, holding-end temperature and cooling rate) corresponding to injection temperature, holding pressure, holding time and cooling time were considered. The semi-crystalline polypropylene (PP) and the amorphous acrylonitrile-butadiene-styrene (ABS) were employed. The design of experiments (DoE) method was applied to analyze the influences of these parameters on the changes of the specific volume during the simulated injection molding cycles. The results demonstrated that the specific volume especially at the phase transition and shrinkage stages is significantly influenced by the complicated injection molding process. The starting temperature has a great effect on the specific volume but has little effect on the shrinkage. The specific volume decreases non-linearly with decreasing cooling rate during the shrinkage stage.

中文翻译：

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在模拟注塑过程中测量聚合物的比容

摘要 压力-比体积-温度 (pvT) 图在科学和工业中已经很好地用于塑料注射成型。然而，在此过程中无法测量确切的比容，因此需要 pvT 模型的帮助。pvT 模型基于在标准条件下测量的数据，可能无法反映过程级别的比容。为了了解比容的准确变化，使用 pvT 测试设备来模拟注塑过程。考虑与注射温度、保压压力、保压时间和冷却时间相对应的四个参数（起始温度、保压压力、保压结束温度和冷却速度）。采用半结晶聚丙烯（PP）和无定形丙烯腈-丁二烯-苯乙烯（ABS）。应用实验设计（DoE）方法来分析这些参数对模拟注塑循环过程中比容变化的影响。结果表明，复杂的注射成型工艺显着影响了比容，尤其是在相变和收缩阶段。起始温度对比容影响很大，但对收缩率影响不大。在收缩阶段，比容随着冷却速率的降低而非线性地降低。结果表明，复杂的注射成型工艺显着影响了比容，尤其是在相变和收缩阶段。起始温度对比容影响很大，但对收缩率影响不大。在收缩阶段，比容随着冷却速率的降低而非线性地降低。结果表明，复杂的注射成型工艺显着影响了比容，尤其是在相变和收缩阶段。起始温度对比容影响很大，但对收缩率影响不大。在收缩阶段，比容随着冷却速率的降低而非线性地降低。