Assessing the physical stability of archival cellulose acetate films by monitoring plasticizer loss

Cellulose acetate film plasticized with diethyl phthalate was subjected to artificial aging regimes and the loss of plasticizer determined by means of Thermogravimetric Analysis and Fourier-transform Infrared Spectroscopy. Alterations in the strain hardening capability of the films was monitored by Dynamic Mechanical Analysis, and the connection between flexibility, strain hardening and the degree of plasticization investigated as a means of monitoring the physical condition of archival cellulose acetate film. It was found that the higher the plasticizer content the greater the ability to strain harden, and therefore the least vulnerable to mechanical damage from archival handling. The correlation between the critical plasticizer content and the working properties of cellulose acetate film provides a means of assessing stability, and highlights artifacts at risk from physical damage

Assessment of the composition and condition of animation cels made from cellulose acetate

Cellulose diacetate and cellulose triacetate cels from animated feature films in the collection of the Walt Disney Animation Research Library were tested by several analytical techniques in order to assess their composition and look for evidence of degradation. Triphenyl phosphate and a range of phthalate plasticizers were identified using pyrolysis-gas chromatography/mass spectrometry, which also showed evidence that evaporation of more volatile plasticizers may have occurred. Plasticizer content measurements by solvent extraction, found to be more accurate than volatile content data from thermogravimetric analysis, revealed there was less residual plasticizer in triacetate cels compared to diacetate cels. Gas chromatography/mass spectrometry, performed to quantify the acetyl content of cels after removal of plasticizers by solvent extraction, revealed some evidence for hydrolysis of the oldest cels, although the reduction could be related to original variations in acetate content from the polymer manufacturers. Use of Fourier-transform infrared spectroscopy to measure deacetylation of the cellulose acetate polymer based on the hydroxyl to carbonyl peak area ratio proved less satisfactory. Moreover, because the cels cannot be measured directly due to interference from plasticizers, non-invasive assessment of deacetylation using a portable instrument would be impossible. The results from this analytical survey provide an important point of reference against which long-term changes in cel composition can be monitored. © 2014 The J. Paul Getty Trust. Published by Elsevier Ltd. All rights reserved