For an accurate simulation of a high‐pressure injection molding process by using the CAE software, it is important to understand the pressure sensitivity of a polymer's melt viscosity. The current work describes a method for the determination of the pressure dependence parameter D₃ of the Cross‐WLF model. It uses a combined rheological technique using both dynamic and capillary rheometers. Three grades of polycarbonate homopolymers were studied in this work and their complex viscosities were measured using a dynamic shear rheometer. The dynamic data were used to obtain six out of the seven parameters of the Cross‐WLF, except D₃. A capillary rheometer fitted with a counter pressure chamber was further used to characterize the pressure dependence of the zero shear viscosity and to determine the D₃ parameter. Finally, the derived parameters were validated by carrying out injection molding with a box tool and comparing the actual pressure profiles with simulation results using the Autodesk® MoldFlow® software. The validation results indicated that actual pressure profiles from the simulation were found to be less than 10% than that of injection molding. POLYM. ENG. SCI., 60:517–523, 2020. © 2019 Society of Plastics Engineers

中文翻译：

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使用振荡流变仪和毛细管流变仪组合测定聚合物熔体粘度的压力依赖性

为了使用CAE软件精确模拟高压注射成型过程，重要的是要了解聚合物熔体粘度的压力敏感性。当前的工作描述了一种确定Cross-WLF模型的压力依赖性参数D ₃的方法。它使用了结合流变技术的动态流变仪和毛细管流变仪。在这项工作中研究了三种等级的聚碳酸酯均聚物，并使用动态剪切流变仪测量了它们的复数粘度。动态数据用于获取Cross-WLF七个参数中的六个，D ₃除外。。配有背压室的毛细管流变仪还用于表征零剪切粘度的压力依赖性并确定D ₃参数。最后，通过使用箱形工具进行注塑成型并使用Autodesk®MoldFlow®软件将实际压力曲线与仿真结果进行比较，来验证所导出的参数。验证结果表明，从仿真中得出的实际压力曲线比注塑成型的曲线要小10％。POLYM。ENG。SCI。，60：517–523，2020.©2019塑料工程师协会