Alms Jonathan, Hopmann Christian, Wang Jian, Hohlweck Tobias
Institute for Plastics Processing (IKV), RWTH Aachen University, 52074 Aachen, Germany.
College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Polymers (Basel). 2020 Jul 8;12(7):1515. doi: 10.3390/polym12071515.
The modelling of the correlation between pressure, specific volume and temperature (pvT) of polymers is highly important for applications in the polymer processing of semi-crystalline thermoplastics, especially in injection moulding. In injection moulding, the polymer experiences a wide range of cooling rates, for example, 60 °C/min near the centre of the part and up to 3000 °C/min near the mould walls. The cooling rate has a high influence on the pvT behaviour, as was shown in the continuous two-domain pvT model (CTD). This work examined the Hoffman-Lauritzen nucleation and growth theory used in the modified Hammami model for extremely high cooling rates (up to 300,000 °C/min) by means of Flash differential scanning calorimeter (DSC) measurements. The results were compared to those of the empirical continuous two-domain pvT model. It is shown that the Hammami model is not suitable to predict the crystallisation kinetics of polypropylene at cooling rates above 600 °C/min, but that the continuous two-domain pvT model is well able to predict crystallisation temperatures at high cooling rates.
聚合物压力、比容和温度（pvT）之间相关性的建模对于半结晶热塑性塑料的聚合物加工应用非常重要，尤其是在注塑成型中。在注塑成型过程中，聚合物经历广泛的冷却速率，例如，在部件中心附近为60℃/分钟，在模具壁附近高达3000℃/分钟。如连续双域pvT模型（CTD）所示，冷却速率对pvT行为有很大影响。这项工作通过快速差示扫描量热仪（DSC）测量，研究了修正的哈马米模型中用于极高冷却速率（高达300,000℃/分钟）的霍夫曼-劳里岑成核和生长理论。将结果与经验连续双域pvT模型的结果进行了比较。结果表明，哈马米模型不适用于预测冷却速率高于600℃/分钟时聚丙烯的结晶动力学，但连续双域pvT模型能够很好地预测高冷却速率下的结晶温度。
