How to estimate cellulose condition in insulation transformers papers? Combined chromatographic and spectroscopic study

Preventive conservation of paper-based relics with visible light high-transmittance ultraviolet blocking film based on carbon dots

Paper-based relics is an important carrier for recording and preserving information, however, it faces irreversible UV-induced damage, including photocleavage, oxidation, acidification and discoloration, which seriously affects its value and lifespan. Carbon dots (CDs) possess excellent UV absorption and good chemical stability, making them suitable for UV protection. Herein, we propose a high-security and efficient method utilizing CDs films (CDFs) for preventive protection of paper against UV damage. The CDFs with high tunable UV absorbance and minimal absorbance in the visible light range, effectively shield paper from UV radiation while preserving its visual appeal. Moreover, the UV transmittance of the film can be fine-tuned to the content of CDs and can be easily removed from the paper without residue. Artificial accelerated UV aging experiments demonstrate the deceleration of acidification, oxidation, and photocleavage in the protected bamboo paper and Xuan paper. This research paces a new direction for the protection of paper and paper-based relics and artworks with emerging carbon materials, offering customizable protection effects tailored to specific preservation and exhibition requirements. This research pioneers a novel approach to preventive protection of paper and paper-based relics using emerging carbon dots materials, offering tailored protection for diverse preservation needs.

Carbon Quantum Dots for Long-Term Protection against UV Degradation and Acidification in Paper-Based Relics

Paper-based cultural relics constitute a significant and invaluable part of human civilization and cultural heritage. However, they are highly vulnerable to environmental factors such as ultraviolet (UV) photodegradation and acidification degradation, posing substantial threats to their long-term preservation. Carbon quantum dots (CQDs), known for their outstanding optical properties, high water solubility, and good safety, offer a promising solution for slowing down UV damage and acidification of paper-based relics during storage and transportation. Herein, we propose a feasible strategy for the simple preparation of CQDs with high dispersion stability, excellent UV absorption, room-temperature phosphorescence, and photostability for the safety protection of paper. Accelerated aging experiments were conducted using UV and dry-heat aging methods on both CQD-protected paper and unprotected paper, respectively, to evaluate the effectiveness of CQD protection. The results demonstrate a slowdown in both the oxidation and acid degradation processes of the protected paper under both UV-aging and dry-heat aging conditions. Notably, CQDs with complex luminescence patterns of both fluorescence and room-temperature phosphorescence also endue them as enhanced optical anticounterfeiting materials for multifunctional paper protection. This research provides a new direction for the protection of paper-based relics with emerging carbon nanomaterials.

Revealing the photochemical damage behavior of acidified Xuan paper based on the spectroscopic investigation and principal component analysis

In museums, there is a huge storage of Xuan paper cultural relics with profound historical and artistic significances. Exploring the photochemical damage behavior of Xuan paper that is generally in acidification, namely its damage mechanisms and laws, is crucial for the preventive lighting protection for paper cultural relics. In this study, the accelerated aging experiments in the range of visible light were conducted on Xuan paper samples with different degrees of acidification. The photochemical damage mechanisms of samples were traced, which is related with the synergistic effects of oxidation and hydrolysis reactions. It can be found that there is an effect of acidification, a long-standing material property of Xuan paper, on its damage, which further defines its preservation state in museums. On this basis, a spectral quantification method of infrared spectra combined with the principal component analysis was proposed to comprehensively analyze the photochemical damage law of Xuan paper in different preservation states. The analysis shows that the effect of acidification degree (pH values), spectra wavelength (λ), and their interaction on the damage to Xuan paper are statistically significant. Furthermore, the fitted mathematical function of pH values and λ is of great importance for evaluating photochemical damage, in order to further develop preventive lighting protection applications.

Lighting quantity indexes for lighting traditional Chinese paintings based on pigments protection and substrates protection in museums

In museum lighting, traditional Chinese paintings are the artworks with the highest light sensitivity. They are vulnerable to the color damage to pigments and the mechanical damage to substrates after the irradiation from light sources. As the basis of effective preventive protection, the research on the two lighting quantity indexes of illuminance and annual exposure (illuminance × time) is currently missing. In this study, the halogen lamp was used as the experimental light source to conduct a 1440 h irradiation experiment on the samples of paper and silk substrates under 4 illuminance levels, respectively, and the test of infrared spectrum was carried out on the samples every 240 h. The oxidation index of paper and crystallinity degree of silk were calculated then. Three-dimensional visual curved surface plots of mechanical damage to samples with the change of illuminance and time were established and then fitted into damage evaluation equations, which revealed and described mathematically the mechanical damage law of samples. Through the equations, the recommended values of illuminance and annual exposure for samples could be calculated. Combining the previous researches on pigments, the lighting quantity indexes of traditional Chinese paintings with different combinations of substrates and pigments were proposed.