Factors Affecting the Intrinsic Anti-Oxidative Activity of Carbon-Nanofibers — Metallic Impurities

Abstract

Abstract It is reasonable to assume that the existence of inherent anti-oxidizing activity of nanotubes and nanofibers (CNT, CNF) would be a good tool for solving the problem of oxidative stability of polymer composites. CNT/CNFs have electron affinities similar to those of fullerenes and are therefore capable of acting as radical traps in free radical chain reactions, we found good evidence in our earlier works. Here, the anti-oxidizing activity of commercial carbon nanofibers of herringbone structure CNF-HB was examined with the aim to quantitatively assess the interference of Ni impurities. The model initiating the aerobic oxidation of cumene was used to determine the kinetic parameters of anti-oxidizing activity of commercial and purified CNF-HBs. CNF-HB inhibits the model reaction according to the mechanism of trapping of peroxy radicals: the oxidation proceeds with pronounced induction period and kinetic curves linearly at the semi-logarithmic coordinates (especially in the case of purified samples). For the first time effective concentration of inhibiting centres and inhibition rate constants for the CNF-HB have been determined. The inhibition rate constant is equal to k7 = (6 ± 1.0)×103 l mol−1 s-1 that is typical for the anti-oxidants of average force.