GB801399A - Method of enlarging solid cross-linked polymer bodies - Google Patents

Abstract

Slightly cross-linked polymer bodies are enlarged by swelling to between 5 and 30 times their initial volume with at least one monomeric vinylidene compound and polymerizing the monomer present in the swollen polymer while the latter is immersed in a liquid medium which is not a solvent for the monomer or polymer. Optionally the swelling process may be conducted in the presence of the non-solvent. The polymer may be polystyrene cross-linked by electron bombardment; copolymers of styrene, ar-ethylvinylbenzene and divinylbenzene; ar-chlorostyrene, ethylvinylbenzene and divinyl-benzene; ar-vinyltoluene and divinylbenzene; vinyltoluene, ethylvinyl benzene and divinyl-benzene; styrene and butadiene-1,3; styrene and isoprene; vinyltoluene and butadiene; a -methyl styrene, styrene, ethylvinylbenzene and divinylbenzene; or methyl methacrylate, ethyl-vinylbenzene and divinylbenzene. Specified monomers are vinyl acetate, styrene, chloro-styrene, vinyl toluene, methyl methacrylate, acrylonitrile, optionally with minor proportions of a polyolefinic compound, e.g. divinyl benzene or butadiene. Catalysts, e.g. benzoyl and lauroyl peroxides, and a ,a 1-azo-bisisobutyronitrile, dyes, lubricants and plasticisers may be added to the monomers. The swollen polymer bodies may be suspended in water in the presence of starch, methyl cellulose, bentonite, copper sulphate and a water-soluble urea-ethylene oxide-formaldehyde reaction product, and the suspension stirred to prevent bonding. The process may be repeated to further enlarge the bodies.