A tensile stage for high-stress low-strain fibre studies

Determining the effects of stress on the internal structure of high-performance fibres may provide insight into their structure–property relationships. The deformation of voids inside a poly(p-phenylene terephthalamide) (PPTA) fibre upon application of stress is one such effect which may be observed using in situ small-angle X-ray scattering. For this purpose, a compact in-vacuum stretching device is described here, capable of applying a force of up to 500 N using specially designed fibre clamps. Furthermore, a small radiative heater is placed around the fibre at the measurement position, so that the effects of the application of heat during tensile load can also be determined. Initial results show a slight but significant effect of stress and heating on the internal void structure of PPTA fibres. The effects on the void structure of heating and stress appear to be markedly different.