COPOLYMERIZATION AND COPOLYMERS OF 2,4,5-TRIBROMOSTYRENE WITH STYRENEAND ACRYLONITRILE

2,4,5-Tribromostyrene (TBSt) was copolymerized with styrene (St) or ac rylonitrile (AN) in toluene solution using 2,2'-azobisisobutyronitrile as free radical initiator. The copolymerization reactivity ratios wer e found to be for the system TBSt/St r(1) = 1.035 +/- 0.164 (TBSt) and r(2) = 0.150 +/- 0.057 (St), and for the system TBSt/AN r(1) = 2.445 +/- 0.270 (TBSt) and r(2) = 0.133 +/- 0.054 (AN). The e and Q values w ere also calculated. The initial copolymerization rate, R(p), for both systems linearly increases as the content of TBSt in the monomer mixt ure increases. However, these values are somewhat higher when AN was u sed as a comonomer. A similar behavior has also been established for t he course of the copolymerization reactions to high conversion. The re sulting copolymers and TBSt-homopolymer show similar thermal stabiliti es of polystyrene. However, the glass transition temperature increases markedly with increasing TBSt content.