Determination of carbonyl-containing functional groups in oxidized polyethylene

A combined (chemical and infrared (IR) spectrophotometric) method is discussed for the simultaneous determination of concentrations of carboxyl (A), ketone (K), and ester (E) groups formed in the oxidation of polyethylene (PE). The IR absorptivities of these functional groups were determined by using model compounds [stearic acid, stearone, poly‐(1,4‐butylene sebacate)]. The integral absorption of the CO band of polymer samples which contained several oxo groups of different types was found to be additive. This method was applied to the determination of the carboxyl, ester, and ketone content of samples oxidized at different oxygen pressures.