FUNCTIONALIZATION OF CARBON-FIBERS

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