Multimodal spectroscopic assessment of mechanical and chemical properties of ABS objects in cultural heritage preservation

Abstract

The 1960s saw the emergence of plastic as an indispensable component in various fields, including art and design. Acrylonitrile-butadiene-styrene (ABS) is widely used by artists and designers for a range of applications including sculptures and decorative pieces. Consequently, the necessity to conserve ABS from deterioration is a crucial issue in the field of cultural heritage preservation. Many studies have highlighted the criticality of the stability of the polybutadiene component when exposed to light. We propose a new multimodal spectroscopic approach to assess the conservation status of plastic design objects. This non-destructive approach combines correlative Brillouin and Raman micro-spectroscopy (BRaMS), external reflection IR spectroscopy and portable NMR relaxometry. BRaMS is a novel non-destructive technique in the field of heritage conservation, allowing simultaneous monitoring of chemical and mechanical changes occurring at the sample surface. The present study focused on photochemically aged LEGO® bricks made of ABS and aimed to i) correlate chemical and mechanical changes induced by light exposure and ii) introduce a surface degradation index (SDI), measurable in situ by external reflection IR spectroscopy, to assess the state of conservation of plastic artefacts. Finally, non-invasive investigations were carried out on real design objects using the MObile LABoratory (MOLAB) platform.