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

Gel spinning of poly(vinyl alcohol) (PVA) was attempted from the PVA d ope 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 bes t solvent for the spinning dope and the coagulant, respectively, to gi ve 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 p roduce maximum drawability. Furthermore, higher draw ratios of PVA fib er were attained at 6 wt % dope by lowering the coagulating temperatur e 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 coa gulating 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 elongat ed to 45 times draw ratio. The very high drawability of PVA fibers obt ained from the DMSO/H2O (80/20) mixture dope was ascribed to the abili ty of the DMSO/H2O mixture to promote gelation. (C) 1994 John Wiley an d Sons, Inc.