为了计算聚合物熔体流场的应力分布,文中对传统双折射实验装置进行改进,通过重新合理布置光学元件,提出了一种利用双折射计算流场应力分布的新方法.该方法测量的图像中含有双折射和取向角信息,所得图像在光强最大或最小处的取向角为45,°从而可方便地计算45°等倾线上的剪切应力,克服了传统双折射装置只能用于测量对称流场中对称轴上应力分布的缺陷.文中最后以自制的可视化挤出口模对LDPE1810D材料挤出成型时的流场进行了测量,计算了45°等倾线上的应力分布,结果表明,该方法可以有效测量流场的应力状态.

In order to calculate the stress distribution of the polymer melts in flow field,the conventional equipment of birefringence measurement is improved by reasonably rearrange the optical components in this paper,and a novel method to calculate the stress distribution of polymer melt in flow fields by measuring the flow-induced birefringence is proposed.The image obtained from this method contains both the information of the birefringence and the orientation angle,the orientation angle of the image is 45°where the light intensity gets maximum or minimum,so the shear stress alone the isoclinic line of an angle of 45°can be calculated,the deficiency of the conventional equipment that only used to measure the tensile stress along the axis of symmetry is overcome.In the last,the flow field of LDPE1810D in a self-made visualization die in extrusion condition was measured by using this equipment;the distribution of stress,along the isoclinic lines of an angle of 45°,was calculated.It is proved that this method is capable of the measurement of the birefringence of the flow fields,thus the stress distribution.