GEL SPINNING OF POLY(VINYL ALCOHOL) FROM DIMETHYL SULFOXIDE/WATER MIXTURE

Gel spinning of poly(vinyl alcohol) (PVA) was attempted from the PVA dope prepared from the mixture of dimethyl sulfoxide (DMSO) and water. The DMSO/H2O=80/20 (w/w) mixture and methanol were found to be the best solvent for the spinning dope and the coagulant, respectively, to give PVA fiber with the highest drawability. PVA fiber with the highest strength and Young's modulus were obtained from the undrawn gel fibers when subjected to hot two-stage drawing under conditions such as to produce maximum drawability. Furthermore, higher draw ratios of PVA fiber were attained at 6 wt % dope by lowering the coagulating temperature of methanol. In the present work, the highest tensile strength (2.8 GPa) and the highest Young's modulus,(64 GPa) were realized, when the spinning dope was prepared from PVA with DP of 5,000 and the DMSO/H2O (80/20) mixed solvent to have the PVA concentration of 6 wt %, the coagulating temperature of methanol was -20 degrees C, and the two-stage drawing was carried out at 160 (first) and 200 degrees C (second). The PVA fiber prepared under this gel spinning condition could be elongated to 45 times draw ratio. The very high drawability of PVA fibers obtained from the DMSO/H2O (80/20) mixture dope was ascribed to the ability of the DMSO/H2O mixture to promote gelation. (C) 1994 John Wiley and Sons, Inc.