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.
The molar excess enthalpies of binary mixtures of pyridine with C6–C9n-alkanes have been measured at 313.15 K in the entire composition range. The measuredHE values were compared with those calculated by means of the Prigogine-Flory-Patterson theory and by the ERAS method.
The thermooxidative decompositions of some edible oils were investigated. Isothermal measurements of convention were made with a Du Pont differential scanning calorimeter. Linseed oil, castor oil, olive oil and cod-liver oil were investigated.
The relationships enthalpy of mixing and excess Gibbs energyvs. composition were studied. We report hereHE andGE for 2-CH3-c-C5H4N (α-picoline)+ (1−x) CH3CH(OH)CH3, (1−x) CH3CHCH3CH2OH, (1 −x) CH3CH2(OH)CHCH3 or (1 −x) CH3C(CH3) (OH)CH3
Oxidation of saturated fatty acids ethyl esters: laurate, myristate, palmitate and stearate was investigated by means of DSC
techniques under isothermal and non-isothermal conditions. The activation energies of isothermal oxidation were similar to
each other (112–123 kJ mol−1) and no influence of carbon length on the rate of oxidative decomposition was observed. Results obtained from non-isothermal
experiments were similar only for the first stage of oxidation.
Authors:T. Kasprzycka-Guttman, B. Kowalski, and A. Országh
The relationship enthalpy of mixing and excess molar volume of mixing versus composition were studied at 313.15 K for binary systems of 2,4,6-collidine with normal aliphatic alcohols. It was found that at this temperature the values ofHE andVE are negative and change with the length of the alkyl group of the alcohol.