Project Researchers: Emma Richardson and Lucia Melita
Synthetic and semi-synthetic polymers comprise an increasing portion of cultural heritage and archival collections. The growth in polymer manufacturing and engineering that occurred throughout the twentieth century inevitably led to many artists and designers employing these new and relatively inexpensive materials in their works. However, the physical instability of some polymer formulations now pose particular problems for the heritage profession, where longevity and conservation is of primary importance. One such example is the case of cellulose acetate and cellulose nitrate film, which has been previously used as the substrate for photographic film and animation art works. It has long been known that cellulose derivatives degrade via deacetylation and chain scission, the former route favoured by high humidity. The effects of which cause a loss of mechanical integrity, which impacts on workability and handling. Often becoming brittle and exhibiting warping and buckling, gelatin photographic layers and paint layers become affected and can result in loss of the image.
Our research is directed at understanding the relationship between the moisture sorption and eventual degradation of cellulose derivative films, and their plasticizer and additive compositions. We are interested in the factors that affect plasticizer loss, and the impact this has on properties such as moisture sorption and mechanical integrity. Moisture plays an integral role in the deacatylation reaction of cellulose derivatives, therefore understanding which materials may be more vulnerable to penetration is key for collections management and treatment prioritization