FUNCTIONALIZATION OF CARBON-FIBERS

This work reports on a study conducted to achieve carbon fibre functionalization by means of a diazide derivative (p-(azidosulfonyl)benzoyl azide) in two stages. The first stage comprises surface oxidation of the fibres, which causes an increase of the number of superficial COOH groups. During the second stage the oxidated fibres are brought to react with the diazide derivative via the isocyanate group, obtained by means of the Curtius transposition of the carbonyl azide group. Fibre oxidation depends on reaction time, following a similar pattern as the one described for carbon black particles. Oxidized fibre functionalization is evidenced both in the progressive decrease in SO2N3 groups in the reagent solution and through differential scanning calorimetry analysis (DSC), which shows an exothermal peak around 190-degrees-C due to the decomposition of the azide grafted onto the carbon fibre. The degree of attainable functionalization is a function of COOH group concentration, generated during fibre oxidation, and the ratio of the functionalizing agent with regard to the carboxy groups formed.