Open control of kinetics, molecular weight and its distrebution for methyl methacrylate polymerization

The gel effects will bring a violent increase of conversion for methyl methacrylate polymerization. It will be very dangerous for the reactor and causes an increase of molecular weight and broadens the molecular weight distribution. In order to control the kinetics, molecular weight and its distribution of polymerization simultaneously three characteristic parameters for polymerization of methyl methacrylate; the heat load distribution index, the change of molecular weight and molecular weight distribution index, were suggested for consideration. The effects of the flow rate and feeding mode of the monomer, solvent and chain transfer agent on the three parameters were investigated, respectively. The gel effect can not be eliminated by changing the flow rate of monomer. The change of monomer feed mode will result in a multiple violent increase of conversion, and the molecular weight will increase with the appearance of gel effect. So the method based on varying the flow rate and feed mode of monomer can not meet the demand of properly controlling the kinetics, molecular weight and molecular weight distribution of polymerization and its products.The molecular weight of polymers prepared by solution polymerization or by with the participation of chain transfer agent was always lower than that of bulk polymerization. However, by changing the flow rate and feed mode of solvent or chain transfer agent, not only the molecular weight can be equal to that of bulk polymerization, but also the gel effect can be eliminated, and the kinetics, molecular weight and molecular weight distribution of polymerization can be properly controlled simultaneously. The optimum heat load distribution index was even less than 2.0, the change of molecular weight was lower than 10%, and molecular weight distribution index was even in the range of 2.0 - 2.2, respectively. Two open control methods were selected and satisfied with the experimental data.