Birefringence of amorphous polymers. 1. Dynamic measurement on polystyrene
Birefringence of amorphous polymers. 1. Dynamic measurement on polystyrene
复制标题
无定形聚合物的双折射。
DOI：
10.1021/ma00020a029
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发表时间：
1991
期刊：
影响因子：
5.5
通讯作者：
K. Osaki
中科院分区：
文献类型：
--
作者：
Tadashi Inoue;H. Okamoto;K. Osaki
开发了一种测量聚合物薄膜的动态复数模量和双折射的装置。在 1-130 Hz 的频率范围和 100-176 C 的温度下对聚苯乙烯薄膜进行了测量。TJie 对应于复杨氏模量的复应变光学系数在玻璃到橡胶转变区域的高频端改变了符号。应力-光学定律仅在对应于橡胶高原区域的相对较低频率下才有效。在使用减少变量的方法进行的初步分析中，杨氏模量和应变光学系数表现出彼此不同的温度依赖性。由呈现双折射的复合主曲线计算出的弛豫光谱由短时间的负盒型部分和长时间的正楔形部分组成。每个区域的弛豫谱的形状与机械弛豫谱的形状非常相似，除了它改变符号的时间之外。使用关于弛豫谱的修改后的应力光学规则对数据进行分析：假设机械弛豫谱是两个分量的总和，并且应力光学规则对于每个分量都有效，但具有不同的应力光学系数。光谱中位于较短弛豫时间的一个分量，其随温度的变化比处于较长时间的另一分量更强烈。后者的位移因子 ot 与粘度成正比。该组件可以用珠弹簧段模型来表示，每个段由大约 10 个单体单元组成。
An apparatus was developed to measure the dynamic complex modulus and the birefringence of polymeric films. Measurements were performed for a polystyrene film over the frequency range of 1-130 Hz and the temperature of 100-176 C. TJie complex strain-optical coefficient corresponding to the complex Young’s modulus changed sign at the high-frequency end of the glass-to-rubber transition region. The stress-optical law held valid only at relatively low frequencies corresponding to the rubbery plateau zone. In a preliminary analysis with the method of the reduced variables, the Young’s modulus and the strain-optical coefficient exhibited different temperature dependences from each other. The relaxation spectrum calculated from the composite master curve presenting the birefringence was composed of a negative box-type section at short times and a positive wedge-type section at long times. The shape of the relaxation spectrum in each region was very similar to that for the mechanical relaxation spectrum except around the time where it changed sign. The data were analyzed with a modified stress-optical rule with regards to the relaxation spectrum: the mechanical relaxation spectrum is assumed to be a sum of two components, and the stress-optical rule holds valid for each component butwith different stress-optical coefficients. One component of the spectrum, located at short relaxation times, varied more strongly with temperature than the other at longer times. The shift factor, ot, for the latter was proportional to the viscosity. This component could be represented by a bead-spring segment model, with each segment composed of about 10 monomer units.