Stabilization hydroperoxide degradation

Many of the apparently discordant experimental results in the early literature probably resulted from insufficient attention being paid to sample quality. Subsequently, both purification and degradation of PA have received attention. " Exposure to oxygen initially produces an increase in conductivity, but this doping reaction is soon overtaken by degradation, which leads to the formation of carbonyl and hydroperoxide groups and a decrease in conductivity. Incorporation of stabilizers reduces degradation but does not eliminate it. 

One of the more important protective mechanisms is probably the ability of these substances to interact not only with various oxygen-centered radicals but also with hydroperoxides. This ability is supplemented by the formation of associates between the amine light stabilizer and species responsible for polymer degradation. 

Allen, N. S., Edge, M., Mohammadian, M. and Jones, K., UV and thermal hydrolytic degradation of poly (ethylene terephthalate) importance of hydroperoxides and benzophenone end groups, Polym. Degrad. Stabil., 41, 191-196 (1993). 

However, organic peroxides will still form in stored fuel, and their gradual accumulation can contribute to elastomer degradation throughout the fuel storage and distribution system. Hydroperoxide formation and accumulation can be readily controlled by the addition of low levels of traditional fuel oil stabilizers. 

When the alkyl hydroperoxide has been fully formed, only one half of the oxidizing power of the oxygen has been utilized. Alkyl hydroperoxides are therefore unstable, the stability being dependent upon the structure. Tertiary hydroperoxides are the most, and primary hydroperoxides the least, stable. The degradation reaction, which is essentially a second stage in the oxidation, may be either inter- or intramolecular the degradation may be either bi- or monomolecular. The rate of degradation is a function of the temperature and is easily subject to catalysis. 

The complexes [Cu(S2CNEt2]2] and [Cu S2P(OPr )2 2] have been shown to be extremely effective scavengers for peroxy radicals and can be used to inhibit the autoxidation of hydrocarbons.99 Poly(2,6-dimethyl-1,4-phenylene oxide) can be effectively stabilized against thermal degradation by the bistriazene complex (41).100 The stabilizing action is thought to involve quenching of thermally excited states and the decomposition of hydroperoxides by the complex. 

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