Kinetic modeling of bulk free-radical polymerization of methyl methacrylate

Abstract

The free-radical bulk polymerization of many monomers is characterized by a sudden rise in the rate of polymerization, a phenomenon called autoacceleration. Many mathematical models have been developed to describe this phenomenon. In this paper, the development of a new kinetic model is described. The model very successfully describes experimental data obtained by differential scanning calorimetry of the bulk free-radical polymerization of methyl methacrylate. The proposed model is composed of two contributions to the conversion of the monomer, one originating from polymerization according to the classical theory of radical polymerization and the other originating from polymerization during the autoacceleration. The rate constant of the autoacceleration (second contribution) is about eightfold higher than the rate constant of the first-order reaction (first contribution).

Anchor Effect in Polymerization Kinetics: Case of Monofunctionalized POSS

“…The homopolymerization of neat LM (as other methacrylates with a longer ester group) occurs, with a poorly marked gel effect appearing at higher conversions [25]). Consequently, the polymerization rate at the maximum of this effect is much lower than at the beginning of the polymerization, in contrast to short-chain methacrylates, such as methyl methacrylate MMA (e.g., [26]), butyl methacrylate, or 2-hydroxyethyl methacrylate [7]. Therefore, in our case, the maximum polymerization rate, R p max , is defined as the highest reaction rate, not the rate at the maximum of the gel effect.…”

Use of confocal Raman microscopy to characterise ethyl cyanoacrylate adhesive depth curing

“…Here a piecewise regression method with no priori model assumptions was used to define key polymerisation parameters. Although a mechanistic modelling approach that yields physical meaning is desirable, the empirical regression approach allows a simpler approximation of the overall system and has been used previously in the analysis of other complex reaction mechanisms [29][30][31] .…”

Bulk Free Radical Polymerization of Methyl Methacrylate and Vinyl Acetate: A Comparative Study

“…This autoacceleration is what it is known as the “gel effect” or “Norrish–Smith” effect or “Trommsdorff” effect . Notwithstanding the numerous efforts that have been made to try to understand the autoacceleration phenomenon, this topic remains open to discussion . It is widely accepted that the origin of the autoacceleration has to do with a drastic decrease in the rate of chain termination due to severe diffusion limitations.…”