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 invest igated. The measurements were carried out under non-isothermal conditions i n an atmosphere of oxygen. DSC curves permitted the determination of onset point and maximum points of the peaks. The influence of inhibitor concentra tion on temperature of the start of oxidation was noticed. However, no sign ificant changes in temperatures of the maximum heat flow was observed. Meas urements and calculations described in this report prove that the assessmen t 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 elucida te the antioxidant activity of the phenolic compounds.