SYNOPSISAqueous NMMO solutions containing NMMO above 50% are good solvents for syndiotacticity-rich poly(viny1 alcohol) (s-PVA). Although water is not a good solvent and dissolves s-PVA at temperatures above 100°C, the mixtures dissolve it at temperatures below 100°C. s-PVA fibers were prepared through gel-spinning of s-PVA/NMMO/water (NMMO : water = 70 : 30) mixtures in cold water and wet-spinning of the solution in methanol. The mechanical properties and fine structure of the drawn fibers were examined based on the results of measurements of tensile properties, thermal properties, birefringence, and optical and electron microscopic observations. The strength and Young's modulus of the drawn fibers were approximately to 2.0 and 45 GPa, respectively. The reason why the fibers with theoretical mechanical properties could not be prepared was surmised to be related to the structure of the amorphous regions.

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Aqueous NMMO solutions containing NMMO above 50% are good solvents for syndiotacticity‐rich poly(vinyl alcohol) (s‐PVA). Although water is not a good solvent and dissolves s‐PVA at temperatures above 100°C, the mixtures dissolve it at temperatures below 100°C. s‐PVA fibers were prepared through gel‐spinning of s‐PVA/NMMO/water (NMMO: water = 70 : 30) mixtures in cold water and wet‐spinning of the solution in methanol. The mechanical properties and fine structure of the drawn fibers were examined based on the results of measurements of tensile properties, thermal properties, birefringence, and optical and electron microscopic observations. The strength and Young's modulus of the drawn fibers were approximately to 2.0 and 45 GPa, respectively. The reason why the fibers with theoretical mechanical properties could not be prepared was surmised to be related to the structure of the amorphous regions. © 1993 John Wiley & Sons, Inc.