Effectiveness of phenol antioxidants and the properties of quinolide peroxides

Abstract

There has been analysis of the kinetics of generation of Quinolide Peroxides (QP) in polymer and other organic compounds during oxidation inhibited by hindered phenols. It is shown that QP linked with the polymer has been formed in the oxidation of solid isotactic polypropylene (PP), in the presence of 2,4,6-tri-tert-butylphenol. Absorption spectra and kinetics of thermal decay have been studied for 13 ortho- and para-QP with formula RO2PhO, where PhO = 2.6-di-tert-butylphenoxyl with substituents in the 4 position: C(CH3)3, CH3, C6H5, OC(CH3)3, and R = C(CH3)3, C(CH3)2CH2CH2CH3, C(CH3)2C6H5, 1,3,5-tri-tert-butylcyclo-hexa-2,5-dienon-4-yl, ▪The kinetics of generation of active radicals in these QP have been also investigated.It is shown that the initiating capacity of QP, especially of o-QP, is of the same order of magnitude as those of conventional radical initiators and greater than those of hydroperoxides, representing the main branching agents in organic oxidation. QP initiate chain oxidation of cumene and PP. The kinetics of inhibited oxidation are discussed considering the QP formed. Some correlation has been found between effectiveness of phenol antioxidant and the QP properties.