Thermal degradation of polyethylene modeled on tetracontane

The thermal degradation of tetracontane as an idealized monodisperse “polymer” of 40 carbon atoms was modeled based on a detailed reaction mechanism consisting of simultaneous or subsequent H-abstraction, β-scission and backbiting reactions (intramolecular H-shifts). A stiff differential equation solver with a postprocessor program to compute the concentrations of each species and the contribution of each reaction to their production was used. The model correctly predicts degradation at low conversion and indicates objectives for further research to improve accuracy at higher conversions. Rate of production analysis quantifies reaction pathways contributing to the formation and consumption of species and reveals specific H-abstraction and β-scission reactions, the complex impact of backbiting reactions, interdependence between production rates of alkyl and alkenyl radicals, dominant role of small alkyl radicals. The data obtained by the model are compared to the experimental product distribution of the degradation of high density polyethylene measured at 500 °C and 20 s reaction time in a micropyrolizer reactor.