The Polymerization of Vinyl Monomers in Natural-Rubber Latex

Abstract

Practical methods are described for polymerizing methacrylic esters, styrene, and other vinyl monomers in natural-rubber latex. The larger rubber particles require an appreciable time to attain equilibrium with the monomer diffusing into them from a liquid monomer phase dispersed in the serum. Provided that substantial proportions of added surface-active substances are avoided, rubber-soluble monomers can be polymerized almost entirely within the rubber particles, and the modified latex then contains no separately emulsified free polymer. Such conditions favor combination of polymer with rubber. The addition of a sufficiently large amount of dispersing agent favors polymerization of emulsified monomer, with less involvement of the rubber. In this way there can be obtained mixtures of rubber and polymer from monomers whose polymerization is otherwise inhibited by the presence of polyisoprene hydrocarbons.