Influence of water on polyvinyl alcohol sol-gel transition and gel spinning

In order to investigate the effect of water on polyvinyl achohol sol-gel transition in gel spinning, the polyvinyl alcohol (PVA) solutions and their gels were prepared using different weight ratio of dimethylsulfoxide (DMSO) and water as the solvents. The structure and property of the solutions and the corresponding gels were characterized by dynamic viscometer. The viscometer results show that water is a poor solvent of PVA compared with DMSO. Twenty percent water causes hydrogen bond crosslinking in the solution which makes the viscosity higher. More water leads to the transformation from solution to gel. The enhanced gelation ability of solution by water and the microcrystallites in the gel result in a higher modulus. Overall, the reasons why the final fiber with a higher strength can be obtained during the gel spinning of PVA solution with 80 % DMSO and 20 % water are that viscosifying action, reducing entanglement and the mater exchange, the enhancing modulus of gel make the structure of as-spun fiber more homogeneous which can bear a higher stretching ratio.