Abstract:

Two kinds of vinyl monomers, namely methyl methacrylate （MMA） and styrene （St）, were grafted onto chloroprene latex （CRL） via emulsion polymerization under the action of redox initiator. The effects of the emulsification system, the initiation system, the mass ratio of monomer to polymer, the monomer composition and the reaction temperature on the monomer conversion and the grafting efficiency were then investigated. Moreover, the mechanism of emulsion grafting was analyzed. The results indicate that, in the optimal grafting conditions, that is, a polymerization temperature of 50 ℃, a reaction time of 5.5 h, an initiator （ tea-butyl hydroperoxide/tetraethylenepen- tamine） dosage of O. 5% （based on the dry weight of CRL）, a mass ratio of monomer to polymer of 3： 5, a mass ratio of methyl methacrylate to styrene of 3： 2, and a emulsifier （ sodium dodecylbenzenesulfonate） dosage of 1.5 % （ based on the dry weight of monomers）, the monomer conversion and grafting efficiency of the polymerization with dropwise-added monomers respectively reach 99.6% and 54. 9%. FFIR and gel content analysis confirm that MMA and St are successfully grafted onto the main chain of CRL. The results also show that the adhesive obtained from the graft eopolymer prepared in the optimal conditions is of excellent adhesion properties for PVC leatheroid, SBS rubber and sponge, that the active points of the polymerization locate on the surface of latex particles, and that the grafting process is surface-controlled.

Key words: chloroprene latex, emulsion graft polymerization, surface control, methyl methacrylate, styrene