An experimental study on hulk and solution polymerization of methyl methacrylate with responses to step changes in temperature

Several important polymerizations [e.g., polymethylmethacrylate (PMMA), polystyrene (PS), etc.] exhibit the gel, glass and cage effects during polymerization. These are associated with the decrease of the diffusivities of the macroradicals, monomer molecules and primary radicals with increasing viscosities of the reaction mass. The recent model of Seth and Gupta [ V. Seth, S.K. Gupta, J. Polym. Eng., 15 (1995) 283.] has been used to explain these results. The model parameters are tuned using experimental data on near-isothermal bulk and solution polymerizations of methyl methacrylate (MMA) in a 1-1 stainless steel, computer controlled reactor. A series of bulk and solution polymerizations (at 10%, 20% and 30% solvent concentrations) have been carried out at two different temperatures (50 degrees C and 70 degrees C) using benzoyl peroxide (BPO) as initiator at one initiator concentration (41.5 mol/m(3)). Two important process variables, e.g., monomer conversion and viscosity average molecular weights were measured using gravimetric analysis and dilute solution viscometry, respectively. The results obtained from this study are in excellent agreement with those reported earlier in the literature. Experiments have also been carried out with step changes in temperature. Thus, the present study establishes the applicability of the model for the more general non-isothermal reactor operations with bulk as well as solution polymerizations along with semi-batch reactor operations. (C) 1998 Elsevier Science. All rights reserved.