The Impact of Iron‐Containing Particulate Matter on the Chemical Degradation of Cellulose Acetate in Collections

Particulate matter (PM) can interact with environmental factors, contributing to the chemical and physical degradation of cultural heritage materials. Although the influence of PM on polymeric materials has been widely reported-often linked to degradation in both functional and aesthetic properties-its specific impact on chemical stability remains insufficiently explored, necessitating further study to elucidate potential implications. In particular, the impact of PM on degrading cellulose acetate (CA) remains unclear, especially in storage environments employing open containment and controlled ventilation which may inadvertently promote PM accumulation. Previous studies on cellulose fibers identified a correlation between higher iron concentrations in PM and aggravated chemical degradation. Focussing on CA, this paper investigates the impact of PM on CA degradation, with particular emphasis on the role of iron in mediating chemical instability. Degradation was assessed through changes in surface appearance, degree of substitution, plasticizer content, VOC emissions, weight loss, and spectral changes in artificially aged and unaged plastic samples. Analytical techniques included scanning electron microscopy, Fourier-transform infrared spectroscopy, thin-film solid-phase microextraction gas chromatography/mass spectrometry, and visible spectrophotometry. Findings indicate that iron in PM can accelerate deacetylation of CA. These results have implications for refining conservation strategies and mitigating risks associated with historical CA objects in both displayed and storage conditions.