Molecular Rheology of Polymer Solids: Evaluation of Internal Strain by Birefringence

通过双折射测量来估计聚合物固体的内部应变，以阐明亚松弛的分子起源。在-15 0~1 80℃的温度范围内，同时测量了双酚A聚碳酸酯的动态双折射和动态粘弹性。复数杨氏模数的大色散对于复数应变光学系数是无效的，复数应变光学系数是双折射与应变的比率。结果表明，色散不能归因于任何原子基团的重新取向，而是由于平移运动引起的内部应变的松弛。动态双折射有望成为玻璃态聚合物亚弛豫的一种新的实验方法。

Internal strain of polymer solids were estimated by birefringence measurement to elucidatate molecular origin of sub-relaxations. Dynamic birefringence and dynamic viscoelasticity of bisphenol A polycarbonate were simultaneously measured over a wide range of temperature from - 150 to 180℃. Large dispersion observed for the complex Young's modulus was found to be inactive for the complex strain-optical coefficients, which is the ratio of birefringence to the strain. The present result indicates that dispersion cannot be attributed to the reorientation of any atomic groups, but to the relaxation of internal strain by translational motions. Dynamic birefringence was anticipated to be a new experimental method for the sub relaxation of glassy polymers.