| Abstract: | A method of separation of polyvinyl side chains from grafted polyacrylonitrile–cotton copolymers was developed in order to study the effect of length of side chain on copolymer properties. The method consists of dispersion of the copolymer (1 g.) containing 20% polyacrylonitrile in 75% aq. ZnCl2 (100 ml.), addition of 6N HCl (100 ml.), heating for 1 hr. at 100°C., and precipitation and purification of the resulting vinyl polymer. The effect of hydrolysis on the intrinsic viscosity, the nitrogen content, and the infrared absorption spectra of the polyacrylonitrile polymers was investigated. It was concluded that this method of separation of the grafted polymers permitted a comparison of samples grafted by various techniques. A series of grafted copolymers was hydrolyzed, and the molecular weights of the isolated products were determined by measurements of intrinsic viscosity. Copolymer samples prepared by a post-irradiation grafting technique had the longest polyacrylonitrile side chains (molecular weight, 1 × 106). Samples grafted by a simultaneous irradiation technique varied in side-chain length, depending upon the monomer-solvent system used in the preparation of the copolymer (molecular weight, 3 × 104?5 × 105). Chemically initiated grafting to cotton resulted in a copolymer containing relatively short side chains (molecular weight, 9 × 104). |
