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

正如之前的研究所确定的那样，对遗产收藏品中的塑料物品的分析表明，开花和出汗等物理迹象表明塑料降解，而纤维素塑料材料的收缩、破裂和断裂是这种破坏的长期表现。艺术品表面的增塑剂的存在和表征已经通过一系列分析技术来确定，包括FT-IR和Py-GC/MS，而它们的挥发性使得SPME-GC可以在气体排放产品中检测到它们。然而，目前只有当这些物理外观发生变化时，通过塑化剂丢失而导致的降解对保育者来说才变得明显。退化的早期检测方法或预测模型，考虑到材料的性质和储存环境，并可使预防性保存方法在较早阶段开始，从而在可观察到的变化之前减缓退化机制。为了探索塑化剂损失在塑料降解中的作用，该项目将寻求制备多个相同的醋酸纤维素和聚氯乙烯样品，这些样品可以进行人工老化研究并监测由此产生的降解情况。与史密森博物馆保护研究所的合作将使制作的样品与遗产收藏品中保存的材料的成分非常相似。将尝试使用成像的(半)定量方法，例如近红外高光谱成像，对增塑剂运输进行建模和验证，这是一种需要专门为该项目开发的方法。该项目支持艺术、遗产和考古领域的CDT科学和工程，与其两个方面保持一致：数据创建和数据到知识。它还与EPSRC的优先事项“测量和传感”、“材料表征”和“数据到知识”保持一致。

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'.