Quantum-chemical analysis of the mechanism of action of sterically hindered amines in photostabilization of polyolefins

A quantum-chemical study was made of the reaction of sterically hindered amines with the degradation products of polyolefins. The reactivity indices of these compounds and the formation energies of their reaction products were calculated by the semiempirical CNDO/2 and MINDO/3 methods. The mechanism of the photostabilizing action of sterically hindered amines was substantiated theoretically. The criteria by means of which it is possible to determine their relative reactivities were established, and the role of the substituent was determined. The results are compared with experimental data on the photostabilizing effectiveness of these compounds.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 594–597, September–October, 1989.