Fullerenes C60/C70 and C70 as antioxidants for polystyrene

Two-step investigation was made to determine the antioxidant properties of fullerenes C-60/C-70 and C-70 in polystyrene. The antioxidative activity of fullerene C-60/C-70 has been studied by model reaction of the initiated oxidation of styrene and then in accelerated tests of C-60/C-70 and C-70 mixtures with polystyrene. It was established that the initiation and oxidation rates of the model reaction is substantially reduced in the presence of C-60/C-70. The rate constant for the addition of styryl radicals to C-60/C-70 was determined as k((333 K)) = (9.0 +/- 1.5) x 10(7) 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.