Development of Simulation Technique of Flow and Structure Formation for Polymeric Blended Materials

为了弄清形态、分子动力学和流变性能之间的关系，我们开发了用分子动力学方法预测其流变性能的模拟程序，采用珠簧模型和管模型。模拟结果定性地描述了剪切速率与一阶法向应力差和剪切粘度的关系，这与实际聚合物熔体的情况一致。我们只考虑液滴和基质液体的物理性质，建立了单液滴变形和破碎的模拟模型。它成功地模拟了液滴的破裂，这是连续介质力学方法所不能做到的。在简单剪切流场中对牛顿-牛顿系统进行了数值模拟，并与实验结果进行了比较。模拟结果显示了其破碎模式及其对物理性质的依赖关系，详见实验。但是，模拟的变形和破裂的时间过程与实验结果不一致。从宏观处理的角度出发，开发了较好地预测聚合物液体行为的粘弹性本构方程模型参数优化确定的计算机程序，并对各模型的预测精度进行了研究。利用这些本构模型，对不同形状的模具和薄膜铸造过程的挤出物膨胀进行了粘弹性流动分析。得到了一些关于流动机理的新信息，如挤出物膨胀问题中反变形不可逆性的要求或考虑，单轴伸长率或延伸增厚性对平面伸长率的重要性等。开发了包含自由面在内的三维粘弹性流动分析程序，分析了低剪切速率区域方形通道的挤出膨胀性。少

For the purpose of clarification of relation between morphology, molecular dynamics and rheological properties, we developed the simulation program to predict the rheological properties by the molecular dynamics method using the Bead-Spring model and Tube model. The simulation results qualitatively presented the shear-rate dependence on the first normal stress difference and shear viscosity, which was seen for the actual polymer melts.We formulated the simulation model of deformation and breakup or a single droplet using only the physical properties or a droplet and a matrix liquid. It achieved success to represent the breakup of a droplet by the simulation, which has been impossible by means or the method or continuum mechanics. We performed the simulation for Newtonian-Newtonian system in the simple shearing flow field and its results were compared with the experimental observation. The simulation results showed the mode or breakup and the dependence or phisical properties on it, see … More n in the experiment. But the time-course of deformation and breakup in the simulation was not in agreement with experimental one.In the view point or macroscopic treatment, we developed the computer program of optimum determination of model parameters for the viscoelastic constitutive equations which could relatively well predict the behavior or polymer liquids, and studied the prediction accuracy or each model. Using these constitutive models, we carried out the viscoelastic flow analyses for the extrudate swell from the various shaped dies and film casting process. The several new informations on flow mechanism could be obtained, for example, requirement or consideration of irreversibility in reversed deformation for the extrudate swell problem, importance of ratio or extension-thickening nature in the uni-axial elongation to that in the planar elongation, etc. Also, three-dimensional analysis program or viscoelastic flow including the free surface was developed and the extrudate swell from the square channel in the low shear rate region was analyzed. Less