Fourier Transform IR Spectroscopic Characterization of the Functional Groups on Carbon Black

The chemical and physical properties of carbon black are strongly influenced by the presence of surface oxides which are formed during the manufacturing process. This paper demonstrates that the nature and relative concentrations of these species can be determined using the high signal to noise and energy throughput capabilities of Fourier transform infrared spectroscopy. Spectra associated with the functional groups have been derived from transmission measurements of dilute dispersions of carbon black in KBr using computer assisted techniques. The resultant spectra consist of characteristic bands at 1725, 1595 and 1245 cm-1 whose intensities are strong functions of the manufacturing conditions. The concentration and thickness dependence of the absorbance follows Beer's Law indicating that this method can be used to quantitatively characterize the concentrations of each species. The technique is used to compare the characteristics of commercially available carbon blacks and to determine the changes that occur as the result of selective heating and titration experiments.