Raman Spectroscopy Of Stressed Samples Of Oriented Poly(Ethylene Terephthalate)
Raman Spectroscopy Of Stressed Samples Of Oriented Poly(Ethylene Terephthalate)
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DOI：
10.1117/12.969595
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发表时间：
1988-12
期刊：
影响因子：
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通讯作者：
L. J. Fina;D. I. Bower;I. Ward
中科院分区：
文献类型：
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作者：
L. J. Fina;D. I. Bower;I. Ward
本文测量了两个中等取向的聚对苯二甲酸乙二酯(PET)样品在0.2 Gpa的拉伸载荷下1616 cm~(-1)拉曼散射峰的位移和形状变化，以及相应的应变。为了获得可重复性的结果，采用了类似于研究粘弹性行为的载荷循环程序。在偏振入射和散射光作用下观察到了拉曼散射，偏振方向均平行于或垂直于样品的拉伸方向。结果表明，两种样品的拉曼频移均与屈服点以下的外加应力呈线性关系。在屈服点之前，线条宽度变化不大，但在屈服点以上，线条宽度显著增加。在相同的应力水平下，观察到两个极化方向的宽度和位移都不同。根据通常的假设对结果进行了讨论，即直线的移动给出了主要导致峰值的那些链中的平均应力的量度，并且直线的宽度和形状给出了关于应力扩散的信息。结果表明，该技术可以提供中等取向聚酯厚样在载荷作用下的分子应力分布的有用信息，包括与拉伸方向成不同角度的不同链上的应力分布信息。
Measurements of the shift and change of shape of the 1616 cm-1 Raman scattering peak of two moderately oriented samples of poly (ethylene terephthalate) (PET) under tensile loads of up to 0.2 GPa are reported, together with the corresponding strains. To obtain reproducible results, load cycling procedures were adopted similar to those established for the study of viscoelastic behaviour. The Raman scattering was observed with polarized incident and scattered light, with the polarization directions either both parallel or both perpendicular to the draw direction in the samples. The results showed that for both samples the Raman shift was linearly related to the applied stress below the yield point. Up to the yield point very little change of line width was observed, but above the yield point the width increased significantly. Differences in both widths and shifts were observed for the two polarization directions at the same stress level. The results are discussed in terms of the usual assumptions that the shift of the line gives a measure of the average stress in those chains which predominantly contribute to the peak and that the width and shape of the line give information about the spread of stresses. It is concluded that the technique can give useful information about the molecular stress distribution in thick samples of moderately oriented PET under load, including information about the different stress distributions on chains at different angles to the draw direction.