Non-isothermal thermogravimetry, differential scanning calorimetry and chemiluminescence in degradation of polyethylene, polypropylene, polystyrene and poly(methyl methacrylate)

The degradation of pure polymers such as polyethylene, polypropylene, polystyrene and poly(methyl methacrylate) in nitrogen and oxygen was characterized by means of non-isothermal thermogravimetry, chemiluminescence and differential scanning calorimetry. The link between the results of the different methods based on Bolland Gee scheme of polymer oxidation is described. From the set of parameters determined from the thermogravimetry, the rate constants based upon the sum of several temperature dependent first-order processes were calculated and compared with those obtained by an iso-conversional method derived for several heating rates. Competition between propagation of oxidation and depolymerisation to monomer is proposed to explain the differences in kinetic behaviour of the examined polymers.