Process and fiber spinning studies for the cellulose/paraformaldehyde/dimethyl sulfoxide system



A cellulose pulp of about 550 D.P. was readily dissolved in a combination of (CH2O)x/DMSO to afford an initial 6/6/88 cellulose/(CH2O)x/DMSO composition solution. The concentration of formaldehyde was found to be a function of solution heating time and temperature. The solutions were microscopically free of gels and undissolved cellulose fibers. Cellulosic articles such as fibers and films are easily regenerated from these cellulose solutions in the presence of coagulants such as methanol or water. Fibers with high wet modulus, intermediate tenacity, and low elongations were produced from these regenerations systems. Fibers have been spun with conditioned and wet tenacities as high as 2.9 and 2.1 g/d, respectively, with wet modulus (at 5% elongation) as high as 1.3 g/d and solubility in 6.5% NaOH in the low range of 3.0%–15%. In many respects, these fibers are comparable to those produced in the viscose process. However, the low elongations of these fibers probably would not permit normal textile processing. The cellulose/(CH2O)x/DMSO solutions were modified with compounds containing reactive N[BOND]H functional groups which are known to react with excess formaldehyde to yield the corresponding N-methylol derivatives. However, the resulting fiber physical properties were not significantly improved compared to those obtained from unmodified cellulose solutions. Addition of acrylic acid derivatives such as methyl acrylate, butyl methacrylate, or acrylonitrile to the cellulose solutions did not result in the formation of the expected 1,4-type adducts.