FIBER SPINNING STUDIES FOR THE CELLULOSE/AMMONIA/AMMONIUM-THIOCYANATE SYSTEM (COAGULATION, DIFFUSION, MASS TRANSFER, SOLVENT-SPUN RAYON).

摘要

The coagulation process of the fiber spinning of cellulose solutions in a mixture of liquid ammonia (NH(,3)) and ammonium thiocyanate (NH(,4)SCN) was studied. The influence of coagulation variables on the resulting fiber structure and tensile properties is reported.; Model experiments were performed on gelled solutions of cellulose/NH(,3)/NH(,4)SCN in a coagulation bath to determine the coagulation rate, (xi)/SQRT.(t, and mass transfer rate difference between the solvent and the coagulant, (DELTA)k, as a function of molecular volumes of coagulant, bath temperatures, bath compositions and cellulose concentrations. The data were analyzed by means of a one-dimensional linear diffusion model based on Fick's second law, thereby depicting the mechanism of the coagulation process and the effects of major coagulation variables on the cellulose/NH(,3)/NH(,4)SCN fiber formation system.; The importance of the coagulation rate and mass transfer rate difference has been demonstrated in the relationship between coagulation variables and fiber structure, and consequently the fiber properties. The results of this work eventually provided an elucidation of the effects of the coagulation variables upon the physical properties of a solvent-spun cellulosic fiber.