Degradation of plasticized PVC for biomedical disposable device under soft x-ray irradiation

Plasticized poly(vinyl chloride) (PVC) used for biomedical disposable devices was studied in the non-sterilized state after different exposure times to soft x-ray irradiation in a commercial photoelectron spectrometer (Al Kalpha, 15 kV/300 W; Mg Ka, 12 kV/240 W) by XPS surface analysis. The detailed spectra of C1s, Cl 2p and O1s have been recorded and processed. Irradiation with soft x-rays induces a clear decrease of the total Cl 2p intensity, an increase of total C is intensity and a doubling of the O1s intensity after 45 min of irradiation with Al Ka (300 W). Irradiation with Mg Kalpha (240 W) is slightly less damaging. These results can be interpreted with the classical PVC degradation model, e.g. bond cleavage with the formation of HCl gas, although the Cl 2p high-resolution spectra reveal the formation of an additional side-product, probably CaCl2. For further studies of plasticized PVC using XPS surface analysis it can be concluded that a complete analysis of a polymer sample should not take >10 min of x-ray exposure in order to avoid notable polymer degradation. Copyright