FULLERENES C60/C70 AND C70 AS ANTIOXIDANTS FOR POLYSTYRENE

Two-step investigation was made to determine antioxidant properties of fullerenes C₆₀/C₇₀ and C₇₀ in polystyrene. The antioxidative activity of fullerenes C₆₀/C₇₀ has been studied by model reaction of the initiated oxidation of styrene and then in accelerated tests of C₆₀/C₇₀ and C₇₀ mixtures with polystyrene. It was established that the initiation and oxidation rates of the model reaction is substantially reduced in the presence of C₆₀/C₇₀. The rate constant for the addition of styryl radicals to C₆₀/C₇₀ was determined as K_{(333 K)} = (9.0 ± 1.5).107 M^-1 s^-1. By differential scanning calorimetry (DSC) and thermogravimetry (TGA) it was demonstrated that fullerenes show a stabilizing effect comparable with the influence of the sterically-hindered phenol Irganox 1010 and amine Agerite White. The suggestion was made that the retarding effect of fullerenes is connected with its interaction with macroradicals R. leading to formation of less active compounds.