FTIR studies of Saran chars

FTIR spectroscopy has been applied to a study of oxidized Saran chars. A pregrind technique is applied during KBr pellet preparation which, along with inherent advantages of FTIR, produces much higher quality spectra than could previously be obtained. Bands occurring in the spectra of the oxidized carbons at 1720 and 1585 cm−1 are assigned to carbonyl vibrations in COOH groups and to aromatic ring stretching modes, enhanced in intensity by oxygen containing functional groups, respectively. The intensity of the 1720 cm−1 band is found to vary linearly with % burn-off in the carbon sample. It is suggested that the activity of the 1585 cm−1 band which is found to increase in intensity as a function of % burn-off, is caused mainly by an increase in oxygen containing functional groups at advancing levels of burn-off. A mechanism is postulated for the formation of surface anhydrides based on IR results. This involves early formation of anhydride structures followed by conversion of anhydrides to acidic groups via hydrolysis with atmospheric moisture.