Kinetic Parameter Estimation in Peroxide Initiated Degradation of Polypropylene

Abstract

The chain scission rate constant and the initiator decomposition efficiency are very important kinetic parameters in the chemically initiated degradation of polypropylene. These two kinetic parameters have been estimated using both deterministic and stochastic modelling procedures. To relate the chain scission rate constant to measurable properties of this system in a deterministic model, the stationary state hypothesis for the peroxide radical concentration has been relaxed and a new model relating both the overall chain scission rate constant and the peroxide decomposition efficiency to three average molecular weights has been formulated. Using Monte Carlo simulation results, the sensitivity of the kinetic parameter posterior probability surface to the reaction time has been investigated. The results indicate that there is an optimum time for collection of experimental data in the reaction system so that the estimated values of the kinetic parameters are more reliable. Based on simulated data at a reaction time of 30 seconds, the point estimates and the joint confidence region have been obtained for the chain scission rate constant (k 1 ) and the peroxide decomposition efficiency (f) using a Bayesian approach to statistical inference.

Distribution Changes during Thermal Degradation of Poly(styrene peroxide) by Pairing Tree-Based Kinetic Monte Carlo and Artificial Intelligence Tools

“…Promising in tracking molecular distributions are kinetic Monte Carlo (kMC) methods, − as mainly demonstrated for polymerization processes . To a limited extent, the potential of kMC has also been shown for modeling polymer decomposition or thermal degradation, with examples predicting the time evolution of the molar mass distribution (MMD) (or chain length distribution (CLD)) of linear, − cross-linked, ,− star-shaped, and branched , polymers available. Most of these kMC models are based on Gillespie’s stochastic simulation algorithm (SSA). − SSA was initially developed to describe reactions between elemental species.…”

Hydrosilylation of Impact Polypropylene Co-polymer in a Twin-screw Extruder

“…To increase the concentration of the vinylidene group in PP for subsequent modification, peroxide initiated degradation reactions can provide a simple and economical route. The peroxide-induced degradation of PP has been well studied and documented in the literature [6][7][8][9][10][11][12][13] and the reaction mechanism is shown schematically in Figure 1. In addition, peroxide vis-breaking of impact PP copolymers has been explored [14][15][16][17].…”