A Vapor-Phase Technique for Radiation-Induced Grafting of Vinyl Monomers to Fibers

Abstract

A technique for the radiation grafting of volatile vinyl monomers to fiber substrates is described. The monomer is applied from the vapor phase while the samples are exposed to gamma radiation from Cobalt-60. The fibrous materials that are relatively unstable toward radiation are the ones that add the vinyl compounds the most readily. These are the cellulosics (cotton and rayon), cellulose esters (acetate), polyamides (nylon 66), and polypropylene fibers. The polyesters and the acrylics show little tendency to undergo graft polymerization. The monomers that have been studied are methyl acrylate, ethyl acrylate, acrylonitrile, butadiene, vinyl acetate, methyl methacrylate, vinyl chloride, styrene, ethylene, propylene, and divinyl sulfone. The most successful experiments have been conducted with the first five of these monomers, and acetate and polypropylene fibers take part in the grafting process most readily. The rate of grafting of the monomers to many of the substrates can be materially increased by the addition of a third material to the system. Water, methanol, and acetic acid vapors accelerate the rate of grafting to cotton, rayon, and nylon. The modification of cotton by the radiation addition of acrylonitrile results in a fiber almost completely resistant to microorganisms. This effect can be achieved by the deposition of only 3.5% of the monomer (as polymer), and the fiber retains the appearance and feel of untreated cotton. The product is superior in these respects to that made by the addition of acrylonitrile from the iron-peroxide catalyst system.