Calculation Of Reaction Rate Coefficients Research Articles

Modeling Copolymerization of Styrene and Acrylic Acid via the Free-Radical Retrograde-Precipitation Polymerization (FRRPP) Process

The free-radical retrograde-precipitation polymerization (or FRRPP) process is a free-radical-based chain polymerization process that occurs above a lower critical solution temperature (LCST). The unique features of FRRPP have been exploited for the synthesis of novel amphiphilic materials under industrially practicable conditions. In the work described here, the copolymerization of styrene and acrylic acid via FRRPP is modeled and simulated to derive greater understanding behind the polymerization mechanism. The penultimate model is used to calculate the reactivity ratios. These reactivity ratios are used to calculate conversion, composition, and molecular weight distributions using the mole balance equations for the different species in the system and the Achilias Kiparissides model for the calculation of reaction rate coefficients. The results suggest that precipitation and the resulting phase separation and change in diffusivities have a strong impact on the polymerization kinetics. The penultimate model provides a better representation of the reactivities, in comparison to other approaches.

Influence of concentration on the values of recombination and ionization rate coefficients of atoms S and F

In our previous papers we have published theoretical results of recombination and ionization rate coefficients computed by the method of modified diffusion approximation. These values depend on concentrations of electrons, ions and neutral atoms. In first approximation, we have considered the equilibrium concentrations at given temperature and pressure, and used these values of reaction rate coefficients in the model of reaction kinetics to compute the nonequilibrium composition of the SF6 system during are extinction in gas self-blasted high-voltage circuit breakers. In this paper we have improved our calculations of the composition. We have included the calculation of reaction rate coefficients into the chemical kinetics model; in each computational step current values of reaction rate coefficients are computed according to the current concentrations in the system. Results are compared.

State-to-state nonequilibrium reaction rates

The paper studies the strongly nonequilibrium vibrational and chemical kinetics in a reacting gas flow in the state-to-state approach. Considered are exchange reactions, dissociation and recombination. The algorithms for calculation of reaction rate coefficients, depending on vibrational levels of components are developed on the basis of the kinetic theory. Formulas for reaction rate coefficients are obtained taking into account non-maxwellian velocity distributions.