Emulsion copolymerization of tribromophenyl maleimide with styrene

Emulsion copolymerization of Tribromophenyl Maleimide (TBPMI) and styrene was conducted by semi-batch and batch processes. The effects of monomer composition and copolymerization method on copolymerization rate, molecular weight and molecular weight distribution, latex particle size and size distribution, glass transition temperature (T_g), thermal stability and mechanical properties were investigated. A kinetic study has shown that the rate of copolymerization in the batch process increased with increasing TBPMI content in the monomer feed. For the semi-batch polymerized samples, molecular weight decreased and molecular weight distribution increased with increasing TBPMI content in the monomer feed. For the batch polymerized samples, molecular weight also decreased but no obvious tendency was observed for the molecular weight distribution when TBPMI content increased. Compared with the batch copolymers, the semi-batch copolymers have a higher molecular weight at the same initial monomer mixture composition. Latex particle size decreased, while particle size distribution slightly increased with increasing TBPMI content in both semi-batch and batch latices. The semi-batch samples exhibit only a single T_g, the value of which increses linearly with increasing TBPMI content. For the batch copolymers, two T_gs were found, reflecting a mixture of styrene-rich and TBPMI-rich copolymer chains. TGA results indicate that the thermal stability of the semi-batch copolymers increased with increasing TBPMI concentration. Young's and flexural moduli increased, while tensile and flexural strengths decreased by increasing the TBPMI content for both the semi-batch and batch specimens. The semi-batch specimens have higher tensile and flexural strenghts than the batch ones.