Influences of Solution State on the Formation of Polyvinyl Alcohol As-spun Fiber during Dry-wet Gel Spinning

The polyvinyl alcohol (PVA) as-spun fibers were prepared by dry-wet gel spinning, with dimethylsulfwdde (DMSO) as solvent and methanol as the cooling medium. The rheological properties of spinning solutions, matter exchanges, sonic orientation factor and entanglement of PVA as-spun fibers were investigated. Solution with lower PVA content at lower temperature has a same viscosity with the more concentrated solution at higher temperature. Solution with lower concentration has a higher G' and a lower Tan delta, which leads to a lower sonic orientation factor for the fiber. The calculating results from the optical microscope show that solution with lower PVA content loses less DMSO due to the weaker gel ability and the possible phase separation during the coagulation. Moreover, solution more closed to the gel point bounds more DMSO, which makes the DMSO exchange difficult to process. The entanglement in the as-spun fiber decreases with the decreasing PVA content in the solution. Suitable crystallization and entanglement can obtain fibers with higher strength.