Thermal decomposition kinetics of polypropylene peroxides in the polymer matrix followed by ESR

Ozonization creates peroxidic species, peroxides and hydroperoxides, in the bulk of polypropylene powder. Their characterization and chemical determination is delicate (135 °C in decalin). Moreover, the thermal decomposition kinetics of the reactive groups at various temperatures cannot be easily followed by usual methods. In order to follow the thermally induced radicals in the polymer matrix, we used the “spin trapping technique” in E S R. Concurrently we looked at the peroxidic decomposition exothermicity using a differential mode technique in D S C. The E S R data show that the spin trap technique can be used successfully to follow the thermal decomposition kinetics. The activation energy (100 kJ/mol) and rate constant values obtained with this technique are in good agreement with those found in the literature by other techniques. The relative thermogram technique in D S C allows to get information about peroxidic decomposition exothermicity.