Kevlar 49 fibres: Thermal expansion coefficients from high temperature X-ray data

Axial and basal plane coefficients of thermal expansion (alpha) have been e stimated for Kevlar 49 fibres using high temperature X-ray diffraction data . The monoclinic unit cell exhibits an anisotropic behaviour. Whereas the a xial dimension contracts with heating, the basal plane expands. The unit ce ll, however, registers an overall increase in volume.