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通过改进基于构象张量构建的流动诱导结晶理论模型,考虑了流场对结晶生长的影响,对比研究了流场作用对聚丙烯(PP)结晶过程中成核与晶体生长两阶段速率的不同影响程度.理论研究表明,虽然相比成核过程,流场诱导作用对PP晶体生长速率的加速程度有限,但要更为精确地描述流动引起的整个结晶动力学过程,特别是在剪切速率较高且熔体结晶温度较低的情况下,考虑流场对结晶生长速率的影响是十分必要的.研究结果还显示,由于分子链的松弛作用,PP在较低温度下的晶体生长速率受剪切流场的影响要大于较高温度下的影响.本文理论预测结果与实验现象和实验数据的很好吻合亦说明模型改进的合理性和可行性.
The effect of flow field on the growth of crystal was considered by improving the theoretical model of flow induced crystallization based on the conformational tensor. The different effects of the flow field on the two phases of nucleation and crystal growth during the crystallization of polypropylene (PP) The theoretical studies show that although the rate of acceleration induced by the flow field is limited compared to the nucleation process, the whole crystallization kinetics caused by the flow should be described more accurately, especially at a higher shear rate It is necessary to consider the effect of the flow field on the growth rate of crystal.The results also show that the crystal growth rate of PP at lower temperature is influenced by the relaxation of molecular chains The influence of the flow field is larger than the effect of the higher temperature.The good agreement between the theoretical predictions and the experimental and experimental data also shows the rationality and feasibility of the model improvement.