X-RAY PHOTOELECTRON-SPECTROSCOPY AND INFRARED STUDIES OF X-RAY-INDUCED BEAM DAMAGE OF CELLULOSE, ETHYL CELLULOSE AND ETHYL-HYDROXYETHYL CELLULOSE

The cellulose derivatives ethyl cellulose and ethyl-hydroxyethyl cellulose (EHEC) have been studied by XPS in the form of solvent-cast films. All the films, as well as a sample of cellulose used as a standard material, show significant surface degradation on irradiation in the time period consistent with XPS data acquisition. Under the experimental conditions employed here the four materials studied behave similarly, in that a reaction occurs in the cellulose skeleton, resulting in dehydroxylation of some of the pyranose units in the surface layers, with concomitant elimination of molecules of water. An infrared (IR) analysis of the ethyl cellulose and high-molecular-weight EHEC films indicates the presence of a strong carbonyl band, no evidence for which is found in the XPS spectra. However, other features of the IR spectra support the proposed dehydroxylation mechanism. The origin of this inconsistency is unclear but may be attributable to either differences in the surface and bulk degradation products formed or to the detection differences of the XPS and IR techniques.