【摘要】 贝叶经是珍贵的文化遗产，了解不同环境因素对其各方面性能的影响，对于研究贝叶经的本体材料特性、老化机制和预防性保护有着重要的意义。本工作通过模拟老化试验结合动态水蒸气吸附、静态热机械分析等先进方法，研究了不同相对湿度(RH)对贝叶经各方面性能的长期老化作用。结果表明，长期处于干燥或潮湿环境都会使贝叶经的各方面性能受到较大影响，不利于贝叶经的保存：干燥环境会导致贝叶经表面出现开裂现象，进而影响贝叶经的力学性能；潮湿环境则令贝叶经受到霉菌侵蚀，导致贝叶经的颜色、光泽度和吸湿性显著变化，令贝叶经的主要化学成分发生降解，并显著影响贝叶经的力学性能。于50%RH中老化的样品未出现明显病害，各方面性能均未发生明显变化，这表明50%RH是贝叶经保存相对适宜的湿度条件。研究有助于了解贝叶经的各方面性能和在不同环境中的劣化过程，并能为珍贵贝叶经的长期保存和预防性保护提供数据支持。更多还原

【Abstract】 Palm leaf manuscripts, as a critical component of cultural heritage, hold immense historical and cultural significance, particularly in South Asia and Southeast Asia. Despite their historical importance, these manuscripts are highly susceptible to environmental factors such as relative humidity(RH), which can significantly influence their physical, mechanical, and chemical properties over time. This study aims to investigate the effects of varying RH levels on the aging behavior of palm leaf manuscripts to identify optimal conditions for their long-term preservation.In this study, palm leaf samples were prepared using traditional methods involving leaves of Corypha umbraculifera L., which were boiled, dried, flattened, and refined. Accelerated aging experiments were conducted at five controlled RH levels(10%, 30%, 50%, 70% and 90%) over 100 days at 25℃. A combination of advanced analytical techniques, including dynamic vapor sorption(DVS), thermomechanical analysis(TMA), Fourier transform infrared spectrometry(FTIR), scanning electron microscopy(SEM), and gloss measurement, was employed to assess the morphological, chemical, and mechanical changes of the manuscripts under these conditions.The findings demonstrate that both excessively dry and highly humid conditions adversely affect the preservation of palm leaf manuscripts. Under low RH conditions(10% and 30%), the samples exhibited significant surface cracking and shrinkage, which severely compromised their mechanical properties, such as hardness and flexural strength. The cracking was particularly severe at 10% RH, leading to irreversible structural damage. Conversely, high RH conditions(70% and 90%) promoted mold growth on the samples, causing substantial changes in appearance, including discoloration and loss of gloss. Mold growth also resulted in increased hygroscopicity and accelerated chemical degradation of cellulose and hemicellulose, as evidenced by diminished characteristic peaks in the FTIR spectra. These chemical alterations correlated with a marked decline in mechanical properties of the manuscripts, including a substantial reduction in flexural strength and modulus.In contrast, samples aged at 50% RH exhibited minimal changes across all parameters. The manuscripts retained their original morphological, chemical, and mechanical characteristics, with no significant alteration in surface appearance, color, gloss, or structural integrity. The mechanical properties, including flexural strength and modulus, showed negligible deterioration, highlighting the stability of the material under these conditions. These results suggest that 50% RH is an optimal condition for the preservation of palm leaf manuscripts, as it effectively balances the risks of desiccation and mold-induced degradation.The study also elucidates the underlying mechanisms of manuscript degradation under varying RH conditions. Low RH environments induce moisture loss, which leads to internal stresses and subsequent surface cracking. These physical damages are accompanied by a loss of flexibility and mechanical strength, rendering the manuscripts brittle and vulnerable to further deterioration. In high RH environments, microbial activity is intensified, with mold producing organic acids and enzymes that accelerate the hydrolytic degradation of cellulose and hemicellulose. This dual process of physical and biochemical degradation severely compromises the manuscripts’ preservation.Furthermore, the research highlights the significance of maintaining stable environmental conditions for preventive conservation. The integration of advanced analytical techniques, such as DVS for hygroscopic behavior analysis and TMA for mechanical performance evaluation, provides a robust methodological framework for assessing the impact of environmental factors on organic cultural heritage. Unlike previous studies primarily focusing on visual and morphological changes, this research delves into the chemical mechanisms of degradation, offering a comprehensive understanding of how relative humidity influences the aging of palm leaf manuscripts.The findings of this study have broader implications for the conservation of organic cultural heritage materials. The identification of 50% RH as the optimal preservation condition offers practical guidance for the storage and display of palm leaf manuscripts in museums, libraries, and archives. By emphasizing the interplay between environmental factors and material properties, this research provides critical data for the formulation of evidence-based conservation strategies.In conclusion, the study underscores the necessity of precise environmental control for the preservation of palm leaf manuscripts. Both excessively low and high RH levels pose significant risks to their longevity, highlighting the importance of maintaining a stable and moderate RH environment. While 50% RH has been identified as the optimal condition, future research should explore the combined effects of temperature, pollutants, and other environmental factors to develop a more comprehensive understanding of the long-term preservation requirements for palm leaf manuscripts.更多还原