Abstract
Frontal Polymerization (FP) is a process in which a spatially localized reaction zone propagates into a monomer converting it into a polymer. Two types of frontal polymerization processes have been observed experimentally. One is exothermic FP, which occurs due to diffusion of heat released in the polymerization reactions and which we have previously studied. The other is an isothermal FP process, also referred to as interfacial gel polymerization, which is due to mass diffusion of the species coupled with the gel effect. We propose and study a model of interfacial gel polymerization. We determine, both numerically and analytically, important characteristics of the process including the time-dependent propagation velocity of the reaction zone, the structure of the wave, and the distance traveled by the front before it breaks down due to reactions ahead of the front.
Original language | English (US) |
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Pages (from-to) | 67-73 |
Number of pages | 7 |
Journal | Mathematical and Computer Modelling |
Volume | 30 |
Issue number | 1-2 |
DOIs | |
State | Published - Jul 1999 |
Funding
The mechanism of propagation determines the structure of the wave and the properties of the products. Two distinct processes of interest are exothermic frontal polymerization and isothermal gel polymerization. The propagation mechanism of exothermic polymerization waves is the same as in combustion waves: the polymerization reactions release heat which diffuses ahead and increases the reaction rate in adjacent layers of the reactants, and the process repeats. Isothermal gel polymerization fronts propagate due to the diffusion of species coupled with the so-called gel effect (see [3] and the references therein) which manifests itself in a significant increase in the effective polymerization rate when the degree of monomer conversion exceeds a critical value. The intermolecular bonds between abundant polymer molecules diminish the encounters among, and hence, the termination of, the growing polymer chains. This decrease in the termination rate results in an increase in the effective reaction rate constant. The gel effect increases the +Supportedb y an NSF Graduate Student Research Fellowship. *Supported by NSF Grant DMS-9699103.
Keywords
- Gel effect
- Isothermal polymerization
- Reaction-diffusion systems
ASJC Scopus subject areas
- Modeling and Simulation
- Computer Science Applications