TG and DSC studies of natural and artificial aging of polypropylene

We study the evolution of thermal degradation of samples of polypropylene (PP), during their aging for two periods of 60 and 80 days. The study, using thermogravimetric analysis (TG) and differential scanning calorimetric (DSC) analyses, focused on two types of aging: the natural one under the impact of the solar environment and the artificial one which was carried out by exposing the sample to radiations of a 100 W commercial lamp. The comparative study of these two types of aging shows that the thermal degradation of the PP increases as a function of time of aging. Indeed, for a same duration, this thermal degradation is more important in the artificial aging case than it is in the natural one and is an increasing function of aging. The prolonged and continuous thermal effect produced by the lamp, in the case of the artificial aging, weakened the polymer and implies very important acceleration of the process of degradation. The results obtained during heating and cooling of the samples, using the DSC, show an evolution of the phase transition temperatures and the corresponding enthalpies of melting and crystallization.