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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
