Structural Analysis of Polyamide Fibers by Solid State 15N NMR

The 15N CP NMR spectra of three kinds of polyamide fibers: silk fibroin, poly (p-phenylene-terephthalamide) and poly (m-phenylene-isophthalamide), were observed. The fiber axes were set parallel and perpendicular to the applied magnetic field. The angles of the NH and NC' bonds of the amide groups relative to the fiber axes were determined according to the equations derived from the solid state NMR theory with the 15N chemical shift tensors in the preceding paper. This analytical method is very useful in the structural study of the non-crystalline domains in polyamide fiber.