The role of plasticiser loss in the degradation of plastic objects in heritage collections

As determined by previous studies, analysis of plastic objects in heritage collections has revealed that physical signs such as bloom and 'sweating' are indicative of plastic degradation with shrinkage, cracking and breakage of cellulosic plastic materials being the longer term manifestations of such damage. The presence and characterisation of plasticisers on artefact surfaces has been determined by a range of analytical techniques, including FT-IR and Py-GC/MS, whilst their volatile nature has allowed their detection in gaseous emission products by SPME-GC. However, degradation via plasticiser loss currently becomes apparent to conservators only when these changes in physical appearance occur. Early detection methods or predictive models of degradation which take into account a material's properties and storage environment, and could enable preventative conservation methods to begin at an earlier stage, thus slowing degradation mechanisms before observable changes result.
In order to explore the role of plasticiser loss in plastic degradation, the project will seek to prepare multiple identical samples of cellulose acetate and PVC which can be subjected to artificial ageing studies and monitored for resulting degradation. Collaboration with the Smithsonian Museum Conservation Institute will enable the preparation of samples which closely resemble the composition of materials held within heritage collections. Modelling of plasticizer transport will be attempted and validated using (semi-)quantitative methods of imaging, such as near infrared hyperspectral imaging, a method that will need to be developed specifically for the purpose of the project.
The project supports the CDT Science and Engineering in Arts, Heritage and Archaeology through alignment with two of its strands: Data Creation and Data to Knowledge. It also aligns with the EPSRC priorities 'Measurement and Sensing' and 'Materials Characterisation' and 'Data to Knowledge'.

1. Academic beneficiaries: The CDT will develop scientific and engineering excellence in the domain of cultural heritage scientific and engineering research and more fundamentally in the enabling domains of imaging and sensing, visualisation, modelling, computational analysis and digital technology. While the CDT focusses on the complex materials and environments of the arts, heritage and archaeology, it will be broadly influential due to the range of novel methods and approaches to be developed in collaboration with the Diamond Light Source and the National Physical Laboratory. The establishment of a student and alumni-managed 'Heritage Science Research Network', will enable CDT's cross-disciplinarity to bridge EPSRC subject boundaries impacting scholarly research in the arts and humanities and social sciences.
2. Heritage beneficiaries: The CDT will have a transformational effect on public heritage institutions by dovetailing 'Data creation', 'Data to knowledge' and 'Knowledge to enterprise' research strands. The resulting advances in understanding, interpretation, conservation, presentation, management, communication, visualisation of heritage, and improved visitor participation and engagement will lead to significantly improved public service and value creation in this sector. This will sustainably boost the cultural heritage tourism sector which requires significant heritage science capacity to maintain the UK's cultural assets, i.e. museum, library, archive and gallery collections and historic buildings. 15 globally leading heritage Partner institutions (both national and international) will contribute to dissemination through established and new heritage networks e.g. the EU Heritage Portal (http://www.heritageportal.eu/).
3. Industry, particularly three crucial sectors: (i) sensors and instrumentation, which underpin a wide range of industrial activity despite the small size (UK Sales £3Bn), and are a key enabling technology for successful economic growth: 70% of the revenues of FTSE 100 companies (sales of £120Bn) are in sectors that are highly dependent on instrumentation; (ii) creative industries, increasingly vital to the UK with 2M employees in creative jobs and the sector contributing £60Bn a year (7.3%) to the UK economy. Over the past decade, the creative sector has grown at twice the rate of the economy as a whole; (iii) heritage tourism sector contributing £7.4Bn p.a. to the UK economy and supporting 466,000 equivalent jobs. Without the CDT, this crucially important economy sector will experience an unsustainable loss of capacity. The impact will be achieved in collaboration with our Partners: Electronics, Sensors, Photonics KTN, TIGA and Qi3, a technology commercialisation, business development and knowledge transfer company.
4. Public: The intensive public engagement activities are built into CDT including dissemination and engagement events at heritage institutions, popular science conferences and fora, e.g. Cheltenham Science Festival, European Science Open Forum and British Science Festival, as well as events organised by the HEIs' Beacon projects (e.g. UCL Bright Club). Cross-cohort encouragement to engage in these events will realise the substantial potential for the CDT to popularise science and engineering. More widely, visitors and users of heritage will benefit from the development of new and more engaging presentation tools, and pervasive and mobile computing.
5. Policy: SEAHA will engage with policy makers, by contributing evidence to policies and research agendas (the PI is actively involved in the EU JPI Cultural Heritage and Global Change, in which she advised on the development of the EU Cultural Heritage Research Agenda endorsed on 22/03/2013) and develop policy briefings for governmental and parliamentary bodies. The CDT is also a strategically important development of the AHRC/EPSRC Science and Heritage Programme ensuring continued global UK leadership in the SEAHA domain.