The Engineering Development And Scale-up Of Emulsion Polymerization Process

Semicontinuous seeded and unseeded emulsion copolymerization of vinyl acetate (VAc) and methyl methacrylate (MMA) were carried out at 70 ℃ with ammonium persulphate as the initiator and sodium dodecyl suphate as the emulsifier The effects of the feed compositions, operation conditions, seeded and unseeded polymerization mode et al. on the system stability, polymerization rate, particles number per unit volume, the copolymer composition and its distribution were investigated experimentally. The relation between the feed rate and the factor of the system stability was given theoretically. On the basis of analyzing the basic process of emulsion copolymerization, the mathematical model on semicontinuous seeded emulsion copolymerization was given. The effect of shear coagulation on VAc/MMA emulsion copolymerization was studied emphatically. The effect of stirrer speed on the copolymerization reaction could be predicted by introducing relative stability factor and relating shear coagulation with the reaction kinetics. Moreover, the stability of different emulsion polymerization system could be compared with quantitatively. The effects of the monomer ratio, the feed rate and emulsifier content on the reaction rates of the VAc/MMA emulsion copolymerization, shear-coagulation-retardant stability , the copolymer composition and its distribution were studied quantitatively by solving the model. Based on the consideration of micell and homogeneous nucleation, nucleation model was developed. The modeling of the experimental results for unseeded emulsion copolymerization was shown by combining the nucleation model with seeded emulsion copolymerization that. In addition, the values of the Mark-Houwink parameters K and a for VAc/MMA emulsion copolymers with different compositions were determined experimentally. The effects of the feed rate, the emulsifier content, the monomer ratio, seeded and unseeded polymerization mode on the molecular weight of the copolymer and its distribution were obtained by the treatment of GPC data. On the basis of the model of seeded and unseeded emulsion copolymerization, the model for calculating molecular weight and its distribution for semicontinuous emulsion copolymer was developed. Comparing the values predicted by the model with experimental results, good agreement was obtained. The experimental results and simulation showed that...