Yeo J H, Demura M, Asakura T, Fujito T, Imanari M, Nicholson L K, Cross T A
Department of Biotechnology, Faculty of Technology, Tokyo University of Agriculture and Technology, Japan.
Solid State Nucl Magn Reson. 1994 Aug;3(4):209-18. doi: 10.1016/0926-2040(94)90041-8.
The structure of an aromatic polyamide, poly(p-phenylene-terephthalamide) (PPTA), was studied in the solid state using 15N nuclear magnetic resonance (NMR) spectroscopy. Spectra of uniaxially aligned molecules placed with the axis of alignment both parallel with and perpendicular to the applied magnetic field were analyzed to yield the orientations of specific molecular bonds with respect to the fiber axis. The 15N chemical shift tensor was characterized by simulating powder pattern spectra of both PPTA and a model compound, benzanilide. Chemical shift and dipolar coupled chemical shift line shapes were calculated through Euler angle transformations from the principal axis system (PAS) reference frame to the fiber axis system (FAS) frame. The orientations of NH and NC' bonds in PPTA are determined as well as the orientational distribution of the PPTA fiber axis. The structural parameters determined for PPTA are compared with those obtained by X-ray diffraction.
采用15N核磁共振（NMR）光谱法对固态芳香族聚酰胺聚对苯二甲酰对苯二胺（PPTA）的结构进行了研究。分析了单轴排列分子在排列轴与外加磁场平行和垂直时的光谱，以得出特定分子键相对于纤维轴的取向。通过模拟PPTA和模型化合物苯甲酰苯胺的粉末图案光谱对15N化学位移张量进行了表征。通过从主轴系统（PAS）参考系到纤维轴系统（FAS）参考系的欧拉角变换，计算了化学位移和偶极耦合化学位移线形。确定了PPTA中NH键和NC'键的取向以及PPTA纤维轴的取向分布。将PPTA确定的结构参数与通过X射线衍射获得的参数进行了比较。
