Molecular weight distribution of poly(methyl methacrylate) produced in a starved feed reactor
作者：Gui-Ping Cao, Zhong-Nan Zhu, Ming-Hua Zhang, Hui-hui Le
關鍵字：molecular weight distribution，radical polymerization，a starved feed reactor，methylmethacrylate，termination
論文來源：期刊
發(fā)表時間：2001年
A starved feed reactor (SFR) is a semi-batch polymerization reactor where initiator and monomer are fed slowly into a fixed amount of solvent. The polymerization is carried out isothermally at elevated temperatures. The added initiator decomposes instantaneously and the added monomer polymerizes immediately. The molecular weight (MW) and the molecular weight distribution(MWD) of the polymer can be effectively controlled by the feed ratio of monomer to initiator.This paper presents a study on the MWD of methyl methacrylate (MMA) polymerization in a SFR. The MWD model parameters are regressed with experimental data. Although the solids fraction in the SFR is high (higher than 50%)，viscosity is not high and the "gel effect"is weak due to the low molecular weight of the products. It is found that the termination rate constant is a power function of the polymer concentration in the system; radicals terminate via disproportionation and combination. The fraction of disproportionation is about 0.9-0.96 at temperatures in the range of 100℃-170℃. The initiation efficiency f is about 0.82-0.55，and it decreases with increasing reaction temperature.