Kinetic model for short‐cycle bulk styrene polymerization through bifunctional initiators

Abstract

A model describing the kinetics of bulk styrene polymerization through bifunctional initiators has been developed. The diffusion-controlled propagation and termination reactions at high monomer conversions are modeled with the free volume theory for polymer solutions. Three different commercially available bifunctional initiators were experimentally evaluated for a wide range of polymerization conditions to study the effect of the reaction rate on the molecular weight and molecular weight distribution. The model predictions for the same polymerization conditions show excellent agreement with the experimental data, for the whole range of conversions, for both reaction rate and molecular weight distribution development, under all the conditions tested. It is demonstrated throughout this study that high molecular weights, very high reaction rates, and narrow molecular weight distributions can be achieved simultaneously by using bifunctional initiators. A comparison between monofunctionally initiated systems with the bifunctionally initiated ones shows that shortcycle reactions with reductions in polymerization time of up to 75% may be achieved with the bifunctional initiators for a wider range of conditions without significantly affecting the molecular weight and molecular weight distribution of the final product.

Kinetic modeling of free radical polymerization of styrene initiated by the bifunctional initiator 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxy)hexane

“…• The concentration of polymeric diradical species S n is three orders of magnitude smaller than the polymeric monoradicals P n and Q n [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The diradical species S n could then be neglected [3,4,6,8,10] (Fig.…”

“…The diradical species S n could then be neglected [3,4,6,8,10] (Fig. 3) leading to the simplified model used for all our simulations.…”

“…The problem can be overcome by using multifunctional initiators and by controlling the decomposition rate of the labile groups [2]. Comparison of monofunctional systems with bifunctional can be found in the literature [3][4][5][6][7][8]. The presence of a second radical generating function distributed in the growing and dead polymer can be engaged in further initiation, propagation, chain transfer and termination reaction during the course of polymerization.…”

Dinamička simulacija rada šaržnog polimerizacijskog reaktora i parametarska analiza homopolimerizacije stirena

“…[24][25][26][27][28][29][30] U tu svrhu provedena je dinamička simulacija rada polimerizacijskog šaržnog reaktora primjenom programskog sustava Chem-CAD v. 5.4. (2004.…”

Use of Cyclic Di- and Triperoxides as Initiators of Styrene Polymerization at High Temperature with a View to Their Use in Industrial Applications

“…In the production of polystyrene (PS) various synthetic methods [1][2][3] such as cationic, anionic or free radical mechanisms have been applied the latter being the most important from an industrial point of view. Industrial free radical processes for the synthesis of PS generally use three reactors connected in series and the temperature is increased from 90 to 180°C reaching 60-80% of conversion.…”