Inhibition of polyethylene and polypropylene oxidation by nitro compounds reacting with alkyl and peroxy radicals

The kinetics of chain termination in polypropylene and polyethylene oxidation inhibited by 2,4-dinitrololuene is studied. 2,4-Dinitrololuene inhibits the oxidation of polyethylene and polypropylene lacking hydroperoxide groups by terminating chains in the reaction with alkyl macroradicals. In oxidized polypropylene containing hydroperoxide groups, chain termination on 2,4-dinitrololuene involves both alkyl and peroxy radicals. A cyclic mechanism is proposed for chain termination in partially oxidized polypropylene involving HO2. and nitroxyl radicals formed from 2,4-dinitrololuene.