Post-Irradiation Grafted Vinyl-Cellulose Copolymers

Abstract

Purified cotton cellulose fibers, yarns, and fabrics were grafted with vinyl acetate, acrylonitrile, and methyl methacrylate, using a post-irradiation grafting technique. The cottons were irradiated dry and in nitrogen with gamma rays from a cobalt-60 source to a dosage of 10⁶ roentgens (R) and treated at about 23°C with a 15% monomer solution in 70, 75, or 80% aqueous zinc chloride. The rates of graft polymerization of these vinyl monomers onto cotton fibers were studied, and the radiochemical yields obtained were 6400 to 75,000 molecular actions per 100 ev. The rate of reaction and maximum yield were also dependent on the physical state of the cotton. Yarns and fabrics con taining approximately 50 and 25% grafted polymer, respectively, were prepared for property evaluations. Grafted yarns showed a marked increase in elongation-at-break and a decrease in average stiffness, Polyacrylonitrile-cotton yarns exhibited significant rot resistance. The vinyl grafted yarns were thermoplastic. Two different distribu tions of the vinyl polymers were observed on examination of cross sections of grafted fibers. The molecular weights of the vinyl polymers were very high (1-3 X 10⁶). Both the polyvinyl acetate- and the polyacrylonitrile-cotton fabrics exhibited marked improve ments in abrasion resistance.