Radial crystallization difference of melt-spun polypropylene fiber along spinning line

The radial crystallization difference of polypropylene (PP) fiber along spinning line was investigated via synchrotron radiation microbeam X-ray diffraction (mu-XRD) analysis for the first time. Running fibers were collected at different spinning line positions to study its radial crystallization difference. The distribution of crystallinity, crystal form, and crystal size of PP fiber were obtained based on peak deconvolution. The relation between radial crystallization difference and processing condition was also investigated. The results indicate that the crystallinity of PP in the center region is found higher than the surface due to the radial temperature gradient during melt spinning, and the structure of fiber is highly sensitive to the radial temperature gradient. The crystallinity increased along spinning line and reaches a steady rate after 50 cm of spinning line position. The crystallite size increased before 50 cm of spinning line position and has a slight decrease after 50 cm due to the growth and splitting of crystal. These results display a 2D view of crystallization development of fiber during the melt spinning and give us a basic knowledge about the relation between structure evolution and processing conditions both in axis and radial directions. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47175.