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首页> 外文期刊>Journal of Applied Polymer Science >Toward a viscoelastic modeling of anisotropic shrinkage in injection molding of amorphous polymers
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Toward a viscoelastic modeling of anisotropic shrinkage in injection molding of amorphous polymers

机译：建立无定形聚合物注射成型过程中各向异性收缩的粘弹性模型

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摘要

A novel approach to predict anisotropic shrinkage of amorphous polymers in injection moldings was proposed using the PVT equation of state, frozen-in molecular orientation, and elastic recovery that was not frozen during the process. The anisotropic thermal expansion and compressibility affected by frozen-in molecular orientation were introduced to determine the anisotropy of the length and width shrinkages. Molecular orientation calculations were based on the frozen-in birefringence determined from frozen-in stresses by using the stress-optical rule. To model frozen-in stresses during the molding process, a nonlinear viscoelastic constitutive equation was used with the temperature- and pressure-dependent relaxation time and viscosity. Contribution of elastic recovery that was not frozen during the molding process and calculated from the constitutive equation was used to determine anisotropic shrinkage. Anisotropic shrinkages in moldings were measured at various packing pressures, packing times, melt temperatures, and injection speeds. The experimental results of frozen-in birefringence and anisotropic shrinkage were compared with the simulated data. Experimental and calculated results indicate that shrinkage is highest in the thickness direction, lowest in the width direction, and intermediate in the flow direction. (c) 2005 Wiley Periodicals, Inc.
机译：利用状态，冻结分子取向和过程中未冻结的弹性回复率的PVT方程，提出了一种新的方法来预测注塑成型中非晶聚合物的各向异性收缩。引入了受冻结分子取向影响的各向异性热膨胀和可压缩性，以确定长度和宽度收缩的各向异性。分子取向计算基于通过使用应力-光学法则由冻结应力确定的冻结双折射。为了模拟成型过程中的冻结应力，使用了非线性粘弹性本构方程，其中包括温度和压力相关的松弛时间和粘度。在成型过程中未冻结并根据本构方程计算的弹性回复率的贡献用于确定各向异性收缩率。在各种填充压力，填充时间，熔体温度和注射速度下测量了成型品中的各向异性收缩率。将冻结双折射和各向异性收缩的实验结果与模拟数据进行了比较。实验和计算结果表明，收缩率在厚度方向上最高，在宽度方向上最低，在流动方向上中等。 （c）2005年Wiley Periodicals，Inc.

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