A study of molecular orientation in poly(methyl methacrylate) by means of laser-Raman spectroscopy
A study of molecular orientation in poly(methyl methacrylate) by means of laser-Raman spectroscopy
复制标题
激光拉曼光谱研究聚甲基丙烯酸甲酯分子取向
DOI：
10.1016/0032-3861(74)90055-x
复制
发表时间：
1974
期刊：
影响因子：
4.6
通讯作者：
D. I. Bower
中科院分区：
文献类型：
--
作者：
J. Purvis;D. I. Bower
测量了聚甲基丙烯酸甲酯单轴取向样品的拉曼散射强度与偏振态的关系。研究了波数位移486、562、604和1732 cm-1处的谱线。在使用直角散射几何形状的情况下，可以选择入射光和观察到的散射光的偏振方向的四种组合，并且可以改变拉制方向与入射激光束的方向之间的角度。发现观察到的强度符合在早期出版物中导出的方程。五个参数，这将决定任何散射几何形状和偏振矢量的组合的散射强度。它们被证明包含有关聚合物的结构单元的取向分布的信息，尽管它们的值也表明结构单元的性质或它们之间的相互作用通过绘图被修改。推导出的结构单元的cos 2 θ和cos 4 θ（θ是典型单元的唯一轴与拉伸方向之间的夹角）值与其他作者从宽线NMR测量得到的值吻合得很好。对于双折射率最高的样品，-14.8 × 10− 4，cos 2 θ和cos 4 θ的值分别为0.52±0.03和0.43±0.04。
Measurements have been made of the polarization dependence of the intensity of the Raman scattering from uniaxially oriented samples of poly (methyl methacrylate). Lines at wavenumber shifts 486, 562, 604 and 1732 cm− 1 were studied. With the right-angle scattering geometry used, four combinations of polarization directions of incident and observed scattered light could be chosen and the angle between the draw direction and the direction of the incident laser beam could be varied. The observed intensities were found to fit equations derived in an earlier publication. Five parameters which would determine the scattered intensity for any scattering geometry and combination of polarization vectors were derived. They were shown to contain information about the distribution of orientations of the structural units of the polymer despite the fact that their values also suggest that either the nature of the structural units or the interactions between them are modified by drawing. Values of cos 2 θ and cos 4 θ deduced for the structural units, where θ is the angle between a unique axis in a typical unit and the draw direction, are in good agreement with those obtained by other authors from broadline nmr measurements. For the sample with the highest birefringence,− 14.8× 10− 4, the values of cos 2 θ and cos 4 θ were 0.52±0.03 and 0.43±0.04 respectively.