Investigation of the degradation of cellulose acetate museum artefacts

Cellulose acetate artefacts from various museums have been analysed by micro-FTIR spectrometry and ion chromatography in an attempt to identify whether there are any common factors associated with their degradation. There was good correlation between the IR spectra, the concentration of ions extracted from an artefact and the visual degree of degradation. Deacetylation, which produced acetate, was found to be the primary process with chain scission (indicated by the appearance of oxalate ion) occurring after degradation is well advanced. Oxidative degradation (indicated by formate) was not a major factor for most artefacts studied, however the loss of formate by volatilization cannot be excluded. Changes to the polymer matrix as a consequence of degradation were indicated in some artefacts by the presence of plasticiser on the surface and increased levels of extractable chloride and/or sulphate.

A simple test of the onset of degradation was developed that involved analysis of an aqueous swab of the surface of an artefact by ion chromatography. Analysis by X-ray fluorescence spectrometry allowed identification of selenium as a potential stabilizing element in certain areas of a doll which were less degraded than other parts that had no selenium.