Vichi Alessandra, Eliazyan Gayane, Kazarian Sergei G
Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.
Mesrop Mashtots Institute of Ancient Manuscripts, Matenadaran, 53 Mashtots Avenue, Yerevan 0009, Armenia.
ACS Omega. 2018 Jul 2;3(7):7150-7157. doi: 10.1021/acsomega.8b00773. eCollection 2018 Jul 31.
The analytical study of historical collagen-based materials such as leather book covers is a complex task for conservation scientists. Historical leather presents a heterogeneous composition of both organic and inorganic materials that show an evident reactivity, particularly when exposed to specific environments. Its correct preservation in archival documents remains challenging as some aspects of its chemical composition, degradation, and effectiveness of conservation treatments are still not fully understood. Here, we describe a novel application of attenuated total reflection (ATR)-Fourier transform infrared spectroscopic imaging coupled with a macro ATR accessory to study historical leather book covers. This nondestructive and high spatial resolution approach has allowed the visualization of degradation phenomena affecting this fragile material, particularly the gelatinization of collagen and, for the first time, the detection of the formation of calcium stearate (metal carboxylates or soaps). In addition, the distribution of modified soybean oil used as a treatment to maintain properties such as elasticity and hydrophobicity of the leather was studied. The effect of anomalous dispersion on the strong IR bands obtained in the ATR mode and the resulting changes to the band positions are also discussed. This research addresses issues that are relevant to the conservation of archival materials of cultural heritage for future generations.
对诸如皮革书皮等基于胶原蛋白的历史材料进行分析研究，对文物保护科学家来说是一项复杂的任务。历史皮革呈现出有机和无机材料的异质组成，这些材料表现出明显的反应活性，尤其是在暴露于特定环境时。由于其化学成分、降解以及保护处理效果的某些方面仍未被完全理解，因此在档案文件中对其进行正确保存仍然具有挑战性。在此，我们描述了一种将衰减全反射（ATR）-傅里叶变换红外光谱成像与宏观ATR附件相结合的新应用，用于研究历史皮革书皮。这种无损且具有高空间分辨率的方法能够可视化影响这种脆弱材料的降解现象，特别是胶原蛋白的凝胶化，并且首次检测到硬脂酸钙（金属羧酸盐或肥皂）的形成。此外，还研究了用作处理以保持皮革弹性和疏水性等特性的改性大豆油的分布情况。还讨论了异常色散对在ATR模式下获得的强红外波段的影响以及由此导致的波段位置变化。这项研究解决了与为子孙后代保护文化遗产档案材料相关的问题。
