RADIATION POLYMERIZATION OF STYRENE IN HI GHLY CONCENTRATED (GEL-LIKE) EMULSIONS

Radiation-initiated polymerization of styrene in very concentrated (ge llike) emulsions containing 82-90 wt % of styrene was studied. It was found that the rate of polymerization initially grows to reach a maxim um at a conversion less than 12% (stage I) and then decreases with con version (stage II). After the completion of polymerization, the reacti on mixture can be easily diluted by water yielding a PS latex with par ticle dimensions about 100 nm. Apparently, the polymerization occurs i n the microscopic droplets (with dimensions similar to 100 nm) of the monomer, which are formed when the initial emulsion is prepared. Initi ally (first stage), the polymerization is initiated in these microscop ic droplets (formation of latex particles); during the second stage, t he depletion of monomer in latex particles takes place.