Zhang Wenjie, Wang Shan, Guo Hong
Key Laboratory of Archaeomaterials and Conservation, Ministry of Education, Institute of Cultural Heritage and History of Science & Technology, University of Science and Technology Beijing, Beijing 100083, China.
Chinese Academy of Cultural Heritage, Beijing 100029, China.
Polymers (Basel). 2024 Dec 31;17(1):83. doi: 10.3390/polym17010083.
Palm Leaf Manuscripts represent a significant component of the world's cultural heritage. Investigating their primary chemical components and understanding the transformations these materials undergo under environmental influences are crucial for elucidating their material characteristics and aging mechanisms and developing effective strategies for preventive conservation. This study utilized infrared absorption spectroscopy and X-ray diffraction analysis to examine changes in the primary chemical components of Palm Leaf Manuscripts under varying relative humidity conditions over extended periods. The findings reveal that dry environments lead to surface cracking, while humid environments promote mold growth, both of which contribute to the degradation of the primary chemical components. These degradative processes reduce cellulose crystallinity and thermal stability. The deterioration is particularly severe under high humidity, with hemicellulose degrading faster and more extensively than cellulose under the same conditions. After 200 days of aging at 10% RH and 90% RH, cellulose degradation reached 19.82% and 54.40%, respectively, while hemicellulose degradation was 34.78% and 64.28%. Correspondingly, the relative crystallinity of cellulose decreased by 8.01% and 13.11%. In contrast, samples maintained at 50% RH exhibited minimal deterioration, with cellulose and hemicellulose degrading by only 4.08% and 13.55%, respectively, and a 6.61% reduction in cellulose crystallinity. These results suggest that a relative humidity of 50% is optimal for the preservation of Palm Leaf Manuscripts. This study offers significant insights into the ageing mechanisms and preventive conservation of Palm Leaf Manuscripts, as well as other cellulose-based organic heritage materials.
贝叶经是世界文化遗产的重要组成部分。研究其主要化学成分，并了解这些材料在环境影响下所经历的变化，对于阐明其材料特性和老化机制以及制定有效的预防性保护策略至关重要。本研究利用红外吸收光谱和X射线衍射分析，研究了贝叶经主要化学成分在不同相对湿度条件下长期的变化情况。研究结果表明，干燥环境会导致表面开裂，而潮湿环境会促进霉菌生长，这两者都会导致主要化学成分的降解。这些降解过程会降低纤维素的结晶度和热稳定性。在高湿度条件下，降解尤为严重，在相同条件下，半纤维素比纤维素降解得更快、更广泛。在10%相对湿度和90%相对湿度下老化200天后，纤维素降解率分别达到19.82%和54.40%，而半纤维素降解率为34.78%和64.28%。相应地，纤维素的相对结晶度分别下降了8.01%和13.1%。相比之下，保持在50%相对湿度的样品降解最小，纤维素和半纤维素的降解率分别仅为4.08%和13.55%，纤维素结晶度降低了6.61%。这些结果表明，50%的相对湿度最适合保存贝叶经。本研究为贝叶经以及其他基于纤维素的有机遗产材料的老化机制和预防性保护提供了重要见解。
