Studies on fibers spun from poly(vinyl alcohol-b-acrylonitrile) emulsions prepared by ultrasonic technique. II. Properties of the fibers

The moisture content of poly(vinyl alcohol-b-acrylonitrile) fibers decrease s with an increasing hydrophobic AN content and crystallinity of the fibers ; however, the copolymer fiber with 26.94% AN, drawn x 5, and heat-treated at 200 degreesC has a moisture content value slightly lower than that of co mmercial PVA fiber, but much higher than that of commercial PAN fiber. The block copolymer fibers have a water-retention value higher than that of com mercial PVA fiber, owing to the presence of voids in these fibers, and have a stronger wicking ability than that of commercial PVA, PAN fibers, and wo ol and cotton mainly due to the grooved surface and bulk porous morphology of the fibers. The tensile strength of the copolymer fibers with an appropr iate AN content are lower than that of commercial PVA fiber, but higher tha n that of commercial PAN fiber and much higher than that of wool and cotton . The melting temperatures of the copolymer fibers increase with increasing heat-treatment temperature. The copolymer fibers possess a lower peak cycl izing temperature than that of the PAN fiber and have a higher thermal stab ility than that of both PVA and PAN fibers. (C) 2001 John Wiley & Sons, Inc .