Structure development in regenerated cellulose fibers wet-spun from environmentally friendly NaOH/Urea aqueous solutions containing cellulose Iβ crystals

Structure development of cellulose crystals in regenerated cellulose fibers wet spun from cotton linters (DP similar to 550), partially dissolved in an environmentally friendly NaOH/urea solution and under varying processing conditions, was studied by synchrotron wide-angle X-ray diffraction (WAXD). The as-prepared cellulose solution contained a small fraction of un-dissolved cellulose I-beta crystals, acting as nanosized fillers instead of crystallization seeds for producing cellulose II crystals during spinning. The crystal size and crystallinity of the cellulose I-beta structure obtained under different spinning conditions remained about constant, whereas those of the cellulose II structure increased notably with flow rate and decreased with draw ratio. Both flow rate and draw ratio enhanced the orientations of cellulose I-beta and cellulose II crystals. The results suggest that to optimize the structure and property of regenerated cellulose fibers spun from NaOH/urea aqueous solutions, one must use very high flow rates to improve the cellulose I-beta orientation.