The analysis of the chemiluminescence (CL) kinetic parameters (induction time, oxidation rate, and activation energy) after the UV irradiation and outdoor exposure of isotactic polypropylene (i-PP) films have been studied. The initial CL emission intensity increased with increasing photodegradation time of i-PP films. On photodegradation, the activation energies were found to decrease linearly with time of UV-irradiation and outdoor exposure. The slopes of these linear dependences were used to indicate the degree of photodegradation of the polymer and also for the characterization of the stabilizing effect of the additive. (c) 2006 Wiley Periodicals, Inc.