【作者】 王树成；

【导师】 王利霞；

【作者基本信息】 郑州大学 ， 材料加工工程， 2010， 硕士

【摘要】 结晶过程是结晶性聚合物在成型加工过程中结构演化的主要形式之一,是影响制品性能的关键因素。随着科技的发展,通过数值模拟研究聚合物结晶形态演化过程已越来越受到关注,而可靠的结晶参数是获得精确结晶演化模拟结果的前提。因此通过实验手段对半结晶聚合物结晶演化过程及结晶动力学进行研究,并基于实验数据,对结晶形态演化模型参数进行识别,获得精确的结晶模型,提高结晶过程预测的准确性有着重要的意义。本文对静态条件下iPP的等温和非等温结晶过程进行实验研究,分析不同结晶条件对结晶演化过程的影响,并在实验的基础上,基于微分形式的结晶形态演化模型,分别用物理分析方法和遗传算法对模型参数进行优化,最终获得优化的参数。应用优化参数的模拟结果与实验结果比较吻合,验证了模型参数的可靠性。主要工作包括：1对静态条件下iPP的等温和非等温结晶过程进行实验研究。对不同温度下的等温结晶过程进行实验研究,结果表明,随着温度条件的升高,结晶速率下降,体系中晶体数量减少,晶体尺寸随之增大。采用不同的等速降温形式对非等温结晶过程进行实验研究,结果表明,随着降温速率的增大,结晶速率升高,体系中晶体数量增多,但晶体尺寸随之减小。2基于微分形式的结晶形态演化模型,对iPP等温、非等温结晶形态演化过程进行分析,基于实验结果,采用最小二乘法获得结晶模型参数。对等温条件下的模拟结果与解析解和实验结果进行对比,结果非常吻合,验证了模型参数的可靠性。3基于实验数据和结晶演化模拟结果,运用实数编码的遗传算法,建立了结晶形态演化模型参数优化理论和算法。采用该方法对结晶模型参数进行优化,获得优化的结晶模型参数。将优化参数用于结晶形态演化模拟,并将体积转化分数及晶体数目的模拟结果与实验结果进行对比,结果非常吻合。表明采用遗传算法识别获得的模型参数,可以更好地描述结晶形态演化过程。更多还原

【Abstract】 Crystallization, as the key factor affecting product quality, is one of the major structure evolutions in polymer fabrication. Nowadays, numerical simulation has aroused intense attention throughout the world. The reliable crystallization parameters are the premise of getting precise simulation results of crystallization morphology evolution. Thus, exploring semi-crystallization procedure and crystallization dynamics is meaningful for crystallization evolution model reorganization and optimization.iPP crystallization under quiescent isothermal and non-isothermal condition has been investigated. Based on the experimental results, a differential system of crystallization evolution has been optimized by physical analysis methods and genetic algorithms. Simulation result using the optimum parameters has a good agreement with the experimental result. The reliability of the crystallization parameters was verified. The main works and achievements are as following:1. iPP crystallization under quiescent isothermal and non-isothermal condition has been investigated. Quiescent isothermal crystallization processes under different temperature were studied, and the results indicate the crystallization rate decreases, the number of crystals reduces and the size of crystals increases with the temperature increasing. Quiescent non-isothermal crystallization experiments under different cooling rate were conducted, and the results show that the crystallization rate and the number of crystals increases while the size of crystals decreases with the cooling rate increasing.2. The processes of crystallization morphology evolution of iPP under isothermal and non-isothermal conditions were investigated based on a differential system model. The model parameters were acquired using the least square method based on the experimental results. Comparison results indicate there is a perfect agreement between simulation and analytical calculations under isothermal conditions, and simulations have consistent results with the experimental results under non-isothermal conditions. The reliability of the model parameters was verified.3. Based on the experiment and simulation result, the theories and algorithms are developed to identify the parameters of crystallization evolution model using real-code Genetic-Algorithms. The parameters of crystallization model were optimized. The optimum parameters were used in the crystallization model, and the crystallization processes were implemented. Comparison of the simulation results with the experimental results shows the simulation results have better consistency with the experiments results. The model using the optimum parameters can describe the crystallization evolution more accurately.更多还原