Combined single particle growth and population balance modeling in stereoregular polymerization of styrene

Abstract

Modeling and experimental analysis for syndiospecific polymerization of styrene over silica-supported metallocene catalyst was carried out. A detail model was developed by coupling the single particle growth model (PGM) with particle population balance equation. The model was employed to predict the effects of intraparticle mass transfer limitations and the initial catalyst particle size on the rate of polymerization and the particle size distribution (PSD) of syndiotactic polystyrene (sPS). The single PGM, based on a modified polymeric multigrain model, was first utilized to calculate the single particle growth rate and polymerization rate under intraparticle mass transfer limitations and different initial catalyst particle sizes. Then, the model was solved simultaneously with particle population balance equation to estimate the PSD of sPS under the same limitations. The single PGM results showed a significant radial distribution of styrene concentration across polymer growth. It was further noticed that the diffusion resistance was most intense at the beginning of the polymerization reaction and the effects of polymerization rate were stronger. Moreover, it appeared that increasing the initial catalyst particle size led to lower rate of polymerization. The PSD simulation results revealed that the mass transfer limitation, as well as the initial catalyst particle size made a strong impact on the PSD of sPS. In addition, the simulation results obtained from this model showed good agreement results with experimental data of sPS.