Dissolution and regeneration of cellulose in NaOH/thiourea aqueous solution

Abstract

A novel cellulose solvent, 1.5 M NaOH/0.65 M thiourea aqueous solution, was used to dissolve cotton linters having a molecular weight of 10.1 × 104 to prepare cellulose solution. Regenerated cellulose (RC) films were obtained from the cellulose solution by coagulating with sulfuric acid (H2SO4) aqueous solution with a concentration from 2 to 30 wt %. Solubility of cellulose, structure, and mechanical properties of the RC films were examined by infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, 13C NMR, and tensile tests. 13C NMR analysis indicated that the novel solvent of cellulose is a nonderivative aqueous solution system. The presence of thiourea enhanced significantly the solubility of cellulose in NaOH aqueous solution and reduced the formation of cellulose gel; as a result, thiourea prevented the association between cellulose molecules, leading to the solvation of cellulose. The RC film obtained by coagulating with 5 wt % H2SO4 aqueous solution for 5 min exhibited higher mechanical properties than that with other H2SO4 concentrations and a homogenous porous structure with a mean pore size of 186 nm for free surface in the wet state. The RC film plasticized with 10% glycerin for 5 min had a tensile strength of 107 MPa and breaking elongation of 10%, and about 1% glycerin in the RC film plays an important role in the enhancement of the mechanical properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1521–1529, 2002

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

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Cellulose modification and shaping – a review

“…For instance, Chen et al [76] have showed the effects of addition of urea, where a cotton linter pulp was dissolved and wet-spun into fibers, which reached comparable crystal orientation as rayon viscose fibers. Addition of thiourea in NaOH has also been shown to be a solvent of cellulose useful for fiber production [15]. Fibers produced from this solvent reached similar values for the mechanical properties as commercial fibers.…”

“…These include sodium hydroxide (NaOH) at low temperatures without or with additives, such as urea, thiourea, and polyethylene glycol [13][14][15][16].…”

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