Determination of the Accessibility of N-H Groups of Kevlar 49 Fibres by Photoacoustic FTi.r. Spectroscopy

摘要

Fourier transform infrared (FTi.r.) photoacoustic spectroscopy in combination with deuterium exchange was used to determine the accessibility of the N-H groups of Kevlar 49 fibres. The spectra were corrected for the dependence of the photoacoustic signal on the frequency and the integrated intensities of the N-H and N-D stretching bands were used to calculate the fraction of accessible N-H groups. Exposure of the deuterated fibers to saturated water vapour showed a residual N-D stretching absorption, in agreement with the improved molecular packaging expected after heat-treatment at high temperature.