Depth profile analysis of the photochemical degradation of polycarbonate by infrared spectroscopy

Abstract The depth profile of the chemical changes in polycarbonate after photochemical degradation was investigated by infrared reflection spectroscopy with gradient shaving preparation. In addition, a spectral simulation technique to interpret the infrared ATR spectra with multiple angles of incidence was applied. The polycarbonate plates were photo-irradiated for 24 and 72 h by a weather meter. A band at around 1600 cm −1 caused by photo-Fries rearrangement was observed, and a carboxylic acid band caused by side-chain photo-oxidation was also observed. These drastic changes in the surface occurred to a depth of at least 0.5 μm. A technique employing IR simulation demonstrated that the drastic chemical changes occurred in the surface to a depth of 0.2 μm for 24 and 72 h treated samples. For a treatment time of at least 72 h, the rate of degradation is extreme in the region of a depth of 0–0.2 μm.