Fiber Structure Development of Nylon 6 After Necking

Fiber structure development of the continuous neck-drawing process of Nylon 6 (poly ε-caprolactam) fibers was investigated by in situ wide-angle X-ray diffraction and small-angle X-ray scattering measurements using the ultrahigh luminance synchrotron radiation of SPring-8. Feed speeds of 4 and 25 m/min were used with time resolutions of 1.7 and 0.43 ms, respectively. The estimated temperature of the running fiber jumped from 90 to 140­150 ̊C with necking, and reached a maximum temperature of about 185 ̊C. The pseudohexagonal phase was oriented along the fiber axis by necking, and transformed to the α'-crystal from 20 to 110 ms after necking. The ά-crystal transformed to the α-crystal below 130 ̊C. The low-oriented long-period structure of the as-spun fiber disappeared by necking, and a higher oriented long-period structure was reconstructed within 10 ms after necking. The 7.8 nm long-period of the as-spun fiber increased to 9.5 nm with the reconstruction.