title: Structure study of cellulose fibers wet-spun from environmentally friendly NaOH/urea aqueous solutions.
abstract: In this study, structure changes of regenerated cellulose fibers wet-spun from a cotton linter pulp (degree of polymerization approximately 620) solution in an NaOH/urea solvent under different conditions were investigated by simultaneous synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). WAXD results indicated that the increase in flow rate during spinning produced a better crystal orientation and a higher degree of crystallinity, whereas a 2-fold increase in draw ratio only affected the crystal orientation. When coagulated in a H2SO4/Na2SO4 aqueous solution at 15 degrees C, the regenerated fibers exhibited the highest crystallinity and a crystal orientation comparable to that of commercial rayon fibers by the viscose method. SAXS patterns exhibited a pair of meridional maxima in all regenerated cellulose fibers, indicating the existence of a lamellar structure. A fibrillar superstructure was observed only at higher flow rates (>20 m/min). The conformation of cellulose molecules in NaOH/urea aqueous solution was also investigated by static and dynamic light scattering. It was found that cellulose chains formed aggregates with a radius of gyration, Rg, of about 232 nm and an apparent hydrodynamic radius, Rh, of about 172 nm. The NaOH/urea solvent system is low-cost and environmentally friendly, which may offer an alternative route to replace more hazardous existing methods for the production of regenerated cellulose fibers.
authors.affiliation: Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, USA.
authors.forename: Xuming
authors.initials: X
authors.lastname: Chen
authors.forename: Christian
authors.initials: C
authors.lastname: Burger
authors.forename: Fen
authors.initials: F
authors.lastname: Wan
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Lixia
authors.initials: L
authors.lastname: Rong
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Hsiao
authors.forename: Benjamin
authors.initials: B
authors.lastname: Chu
authors.forename: Jie
authors.initials: J
authors.lastname: Cai
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
mesh_terms: D001704:Biopolymers / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D003460:Crystallization; D004777:Environment; D008027:Light; D008968:Molecular Conformation; D008970:Molecular Weight; D011108:Polymers / Q000737:chemistry; D012542:Scattering, Radiation; D012972:Sodium Hydroxide / Q000737:chemistry*; D012995:Solubility; D013696:Temperature; D014508:Urea / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D001704:Biopolymers; D011108:Polymers; D014867:Water; D012972:Sodium Hydroxide; D014508:Urea; D002482:Cellulose