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Saturday, June 2 • 11:00am - 11:30am
(Research and Technical Studies) Investigating Conservation Materials for Painted PMMA: Comparing Aging Environment Impact with Nano Thermal Analysis

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Nano Thermal Analysis (nano-TA) and Dynamic Load Thermal Mechanical Analysis (DL TMA) were used to investigate glass transition temperature (Tg) behaviour of aged butyl methacrylate resins proposed as conservation materials for painted PMMA. Samples of the resin mixture 1:1 Paraloid B-67 / Paraloid F-10 (poly isobutyl methacrylate / poly n butyl methacrylate, or piBMA / pnBMA) were aged in six environments involving cycles of UV filtered museum light, or elevated temperatures, and stored with the control samples in dark ambient conditions for 20 years.

Nano-TA is useful when characterizing multi-layered polymer films and varnish mediums. The technique allows local characterization of thermal properties at nanoscale resolution, which is beneficial when investigating photo-degradation of surfaces, and differences between surface Tg and sample-averaged Tg from bulk material. The nano thermal probe enables rapid multiple measurements, 40 in this study, to characterize the sample surface; and while the probe will alter the surface locally at the nanoscale, unlike bulk thermal analysis techniques, the samples are not destroyed.

Nano-TA revealed a trend in the surface Tg of the BMA medium related to the aging environments, even though there were no apparent changes to the appearance, color, or transparency of the samples; DL TMA identified a similar trend in the sample-averaged Tg of the bulk material. The Tg of two sets of samples presents a compelling warning when considering BMA mediums for use as conservation materials for painted PMMA. The samples exposed to ambient levels of artificial museum light for 16 weeks had a higher Tg than the dark-aged control samples. The samples exposed to UV filtered sunlight through a museum window for 14 weeks had a higher Tg than samples exposed to an equivalent dose of artificial museum light. The rise in Tg of these samples suggests photo-degradation, increased polymer cross-linking, decreased solubility, and altered long-term stability after a relatively short period of light exposure equivalent to the length of a temporary exhibition in a museum or historic property. The apparent increase in Tg of the aged BMA samples suggests long-term instability and sensitivity to museum lighting and elevated temperatures, which are properties that may influence conservation applications on painted PMMA. The apparent association between increased Tg and environmental conditions may prove useful also in the development of preservation strategies for art and design containing BMA mediums.

In this study, nano-TA contributed to the understanding of BMA aging when used as an artists’ or conservation material, and to the development of assessment methodologies and preservation strategies involving artificial and natural aging.

Speakers
avatar for Donald Sale

Donald Sale

Art Conservation & Research, Art Conservation & Research
Don is an accredited conservator of ICON (UK) involved in collaborative research and museum projects, advising and investigating aging, conservation, and repair materials for plastics in art and design, advising on collections care and display, and the conservation of contemporary... Read More →

Co-Authors
avatar for Dr. Angelica Bartoletti

Dr. Angelica Bartoletti

Research Conservation Scientist, Tate
Dr Angelica Bartoletti is a conservation scientist at TATE for the NANORESTART project. She has completed her PhD at University College London (UCL). Her research interests include the evaluation of the impact of traditional and innovative conservation treatments for cellulose and... Read More →
avatar for Dr Laurant Bozec

Dr Laurant Bozec

Associate Professor in Biophysics and Nanometrology, Eastman Dental Institute, University College London
Laurent Bozec is Associate Professor in Biophysics and Nanometrology at the Eastman Dental Institute, University College London. The major part of his research portfolio involves the characterisation at the nanoscale of connective and mineralised tissues in view to improve both... Read More →
avatar for Dr. Marianne Odlyha

Dr. Marianne Odlyha

Director of Physical Sciences Programme, Thermal Analysis Laboratory Manager Conservation and Art Preservation Laboratory Academic Lead, Department of Biological Sciences, Birkbeck, University of London

Saturday June 2, 2018 11:00am - 11:30am
Meyerland Meeting Room Marriott Marquis Houston

Attendees (48)