The influence of some chain-breaking antioxidants on thermal-oxidative decomposition of linolenic acid

Thermoxidation of linolenic acid inhibited by addition of 2,6-di-t-butyl-4-methylphenol and 2,4,6-trimethylphenol at various concentrations was investigated. The measurements were carried out under non-isothermal conditions in an atmosphere of oxygen. DSC curves permitted the determination of onset point and maximum points of the peaks. The influence of inhibitor concentration on temperature of the start of oxidation was noticed. However, no significant changes in temperatures of the maximum heat flow was observed. Measurements and calculations described in this report prove that the assessment of the antioxidant activity of chain-breaking inhibitors can be performed only from the onset temperatures. Calculations of the activation energy of inhibited linolenic acid thermoxidation were performed in order to elucidate the antioxidant activity of the phenolic compounds.