In this work the radical chain copolymerization of methyl methacrylate and styrene at their azeotropic composition is studied. The propagation and termination reactions for this copolymerization are described by the apparent rate expressions. The apparent rate constants of propagation and termination, kpa and kja, determined at low extent of reaction are 334.0 L mol-1 s-1 and 10.45 X 107 L mol-1 s-1, respectively, and the value obtained is 15. The latter coincides with that obtained when a chemically-controlled termination model is assumed. The relative importance of combination in the termination is evaluated as 68.2%. When the monomer conversion reaches 11 mol %, the monomer conversion vs. reaction time curve predicted with the kpa and kti values mentioned above starts to deviate from the experimental data. The deviation is attributed to a gel effect. Thus, the Hamielec equation is used in correlating kto. We find that kpa = [10.45 X 107/(1 - X)2] exp(0.412X - 12.50X2) and kpa = 334.0 L mol-1 s-1 can satisfactorily describe the reaction course of the conversion vs. reaction time for this copolymerization.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry