The application of pyrolysis gas chromatography mass spectrometry for the identification of degraded early plastics in a sculpture by Naum Gabo

A study was carried out to characterise the materials of a highly degraded plastic sculpture by Naum Gabo in the collection of the Philadelphia Museum of Art. Samples from the sculpture were analysed using pyrolysis gas chromatography mass spectrometry (Py-GCMS) in conjunction with Fourier transform infrared microspectroscopy (MFTIR) and other techniques. Py-GCMS confirmed that Gabo had used cellulose acetate and cellulose nitrate plastics; the identification of the former was based on the detection of trace levels of 5-acetoxymethylfurfural and other characteristic carbohydrate-derived pyrolysis products bearing an acetyl group. Because of the unusually severe state of degradation of certain parts of the sculpture, the pyrolysis data were critical for identification of the cellulose acetate polymer, which could not be achieved using MFTIR. The original polymer has undergone almost complete reversion to a cellulose-like structure through hydrolysis and deacetylation.