Pyrolysis and Combustion of Polystyrene and Polypropylene with Different Molecular Weights

We studied the thermal decomposition of polyolefins and other similar polymers, generally contained in plastic materials to overcome the problem of flammability. There are different patterns of thermal decomposition of these polymeric compounds such as, random decomposition of the main chain, or the formation of a trimer like compound at the polymer chain end that leads to depolymerization. The relationship between flammability and the type of thermal decomposition for polystyrene and polypropylene components was investigated. We observed that the thermal decomposition occurs through cleavage of a particular part in the polymeric chain as well as simultaneous random cleavage. Also, we found that the thermal decomposition products depend on the molecular weight of the polymers, which affects the flammability significantly. The combustion state of a polymer may vary owing to differences in molecular weight. The molecular weight distribution is different for low and high molecular weight samples and there is no combustion of a particular molecular weight under certain conditions. Finally, we found a specific polyolefin and polystyrene structure that does not burn easily, which is a significant finding to develop nonflammable materials for a safe and secure society.