Monte carlo simulation of the thermal degradation of linear polymers by the mechanism of random ruptures in the isothermal and dynamic modes

摘要

The kinetics of the thermal degradation of polymers by the mechanism of random ruptures is simulated using the Monte Carlo method. The modeling is performed for arrays of linear chains with initial degrees of polymerization of 100 to 500 and an initial polydispersity (P _w /P _n) of 1 to 3 at three constant temperatures and five heating rates. The obtained data are processed by means of nonlinear regression within the framework of two different kinetic models (Avrami model and autocatalytic model) and by two isoconversional methods. The kinetics of degradation by the mechanism of random ruptures depends neither on the degree of polymerization nor on the polydispersity. Nonlinear regression makes it possible to correctly determine the activation energy and preexponential factor from the autocatalytic model in both the isothermal and dynamic modes. The simulation data obtained in the dynamic mode are also treated by two isoconversional methods commonly used to analyze TGA thermograms: Flynn-Wall-Ozava (FWO) and Kissinger-Akahire-Sunose (KAS) methods. Of these two methods, KAS provides better results.