Free radical suspension polymerization kinetics of styrene up to high conversion

Abstract

SUMMARYStyrene was polymerized using different amounts of azoisobutyronitrile as initiator at temperatures of 70 "C, 75 "C and 80 "C in suspension. The course of reaction up to almost complete conversion was modeled within a classical kinetic framework. Optimal simultaneous descriptions of both conversion and average degree of polymerization data were possible using two sets of values for the variation of the overall termination rate coefficient k, with conversion. One explanation for this is that k, is chain length dependent. Evidence for this necessity was derived by considering all kinetic parameters, except the termination rate coefficient, as reliable absolute values.

A Review of Modeling of Diffusion Controlled Polymerization Reactions

“…The model described well available experimental data on the MMA and styrene polymerization under different initial initiator concentrations and temperatures with or without the presence of a chain transfer agent. [147,148] Recently, Nising and Meyer [96] compared the Fleury et al [95] with the Tefera et al [49,147] models in the high temperature polymerization of MMA. They concluded that the first model better describes the experimental data and needs fewer adjustable parameters compared to the second.…”

“…Based on the original Buback model and the three-stage process of radical termination, Tefera et al [49,147,148] published the following free-volume-based model. The apparent termination rate coefficient, k t was expressed as a function of the intrinsic rate constant, k t,R , the translational diffusion coefficient, k TD , and the reaction diffusion coefficient, k RD , in an equation similar to Equation (73), which after some manipulation was converted to the following final equation:…”

A Comprehensive Kinetic Model for the Combined Chemical and Thermal Polymerization of Styrene up to High Conversions

“…Hamielec and coworkers [3,4] investigated, both experimentally and theoretically, the free-radical bulk and solution polymerization of styrene at different temperatures (e.g., 50-75 8C), in the presence of a chemical initiator (2,2 0 -azoisobutyronitrile, AIBN). Tefera et al [5] also investigated, both experimentally and theoretically, the free-radical suspension polymerization of styrene at different temperatures (i.e., 70, 75, and 80 8C) and initiator concentrations (i.e., AIBN: 0.15-0.45 wt.-% of styrene). To simulate their experimental measurements on monomer conversion and molecular-weight averages, they employed two different values for the termination rate constant, k t , one for the monomer conversion and another for the number-and weight-average degrees of polymerization.…”

Free‐Radical Polymerization: Suspension

“…Radical diffusion can depend on solution viscosity, polymer volume fraction and polymer molecular weight. In some cases, the value of f may also depend on polymer content [67]. However, Brooks et al showed that effects of viscosity changes on polymerization rate could be distinguished from the effects of polymer volume fraction [66].…”