Nanostructure Changes in Nylon 5,6 Fibers under Tension owing to Hydrogen Bond Formation

We investigated the effect of tension on the stable α-phase formation of nylon 5,6 fibers with two different drawing speeds using two-dimensional transmission wide angle X-ray scattering (2D WAXS) measurement. In an ex-situ condition, i.e., after releasing the applied tension and temperature, the relative amount of the α-phase in the fibers was higher at a higher drawing speed (57 mm/min). On the contrary, the development of the α-phase seemed faster and stronger during in-situ elongation of the fiber at a lower drawing speed (38 mm/min). The γ-phase, rather than the α-phase, played a key role in this complex behavior. The mechanical properties of the nylon fibers elongated under slow drawing speed (38 mm/min) were better than those elongated under a higher drawing speed (57 mm/min). The mechanical properties were more consistent in the case of α-phase formation in an in-situ condition under applied tension on the nylon fibers. Detailed structural information was obtained by quantitative analysis of the 2D WAXS data using an in-situ fiber drawing device.