Simulation of Free Radical Bulk/Solution Homopolymerization Using Mono- and Bi-functional Initiators

Abstract

Monofunctional and bifunctional peroxides are extensively utilized in the production of polystyrene. However, their decomposition kinetics is still an important area to investigate. A computer package developed previously by Gao and Penlidis (1996), which was based on mono-functionally initiated polymerization, is extended in this study to cover homopolymerization of styrene using bifunctional initiators. A database of a wide variety of bifunctional peroxides used in polystyrene production is developed along with a database for twelve new monofunctional initiators. The package handles several different scenarios of styrene polymerization, whether it is in bulk I solution or isothermal I non-isothermal medium. The model is tested with a wide range of conversion and average molecular weight data either from the literature or available from industry. Simulation results agree with the data trends, which makes the simulator a very powerful tool in aid of initiator selection and evaluation. At the end of the paper, results on homopolymerizations of acrylates and methacrylates are also discussed. 299

Comparison of two algorithms for calculation of the apparent rate constant in the kinetic modelling of diallyl terephthalate bulk polymerization

“…It is the most widely used algorithm for calculating the apparent rate constants, though it is not completely correct and its kinetic parameters do not have a clear physical meaning [7,8]. Both, the apparent propagation and the apparent termination kinetic rate constants are the sum of the inversed values of the chemically controlled constants (k pc , k tc ) and of the diffusion-controlled constants (k pd , k td ), which yield [1,[7][8] …”

“…It enables the calculation of the dependence of diffusion coefficient on conversion from the physical properties of pure DAT monomer and polymer. Due to its simplicity, free-volume theory is widely used in the kinetic modelling of various radical polymerizations [7][8][9][10][11][12][13], although other theories may be used, too [7]. All necessary parameters used in free-volume theory were calculated as it was proposed by Zielinski and Duda [18].…”

“…Some of them are semi-empirical [1,8], others are based on parameters with clear physico-chemical meanings [2,7]. Several studies may be found in the literature on the comparison of different algorithms used for apparent rate constant calculation.…”

“…Nevertheless, comparison of two most widely used algorithms such as CCS [1] and S [2] cannot be found in the available literature. In addition, due to a lack of physicochemical parameters used for kinetic modelling of multifunctional monomers authors usually compare different algorithms for apparent rate constant calculation in the kinetic modelling of monomers such as MMA, styrene and others [7][8][9][10]. Only few studies were done so far on the kinetic modelling of more complicated multifunctional monomers [3][4][5][6][11][12][13].…”

“…Kinetic modelling of free-radical polymerization is well understood and various algorithms for apparent rate constant calculation were developed in the past [2,[7][8][9][10]. Some of them are semi-empirical [1,8], others are based on parameters with clear physico-chemical meanings [2,7].…”