A STUDY OF THE INTERACTION OF MECHANICALLY GENERATED POLYPROPYLENE RADICALS WITH PHENOLIC ANTIOXIDANT IN THE PRESENCE OF OXYGEN BY EPR SPECTROSCOPY

Isotactic polypropylene (iPP) was mechanically degraded in the absence and presence of a phenolic antioxidant at liquid nitrogen temperature in the presence of oxygen. The interaction of the primarily formed iP P macroradicals with oxygen and phenol was studied by EPR spectroscopy in the temperature region between 77 and 303 K at antioxidant concent rations of 0.1, 0.5, and 3.0 wt %. It was found that iPP macroradicals react at low temperature with oxygen, yielding peroxy radicals, and w ith antioxidant, with a simultaneous formation of phenoxy radicals. Th e development and decay of all kinds of radicals was studied. The rate constants for peroxy radical decay were determined and the apparent a ctivation energies for the regions of slow and fast decay were calcula ted.