A research team led by Prof. CHEN Biao, Prof. DING Yanwei et al. from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS), have conducted in-depth and systematic research on the intrinsic influence of production techniques on the ageing of bamboo paper, the mechanisms of ageing behaviour, and the assessment of the degree of micro-damage of ageing. This work was published in Journal of Cultural Heritage.
At present, numerous bamboo paper heritage have developed a serious problem of ageing and decay and are in urgent need of conservation. As paper fibres are rich in hydrophilic groups, they have a strong affinity for polar solvents such as moisture. During long-term natural storage, the paper interacts constantly with moisture in the air, which has a serious impact on the life of the artefact.
SEM Images of Various Bamboo Papers. (Iamge by CHEN Biao and DING Yanwei et al.)
Researchers conducted an in-depth study of the moisture absorption behaviour of traditional handmade bamboo paper under different ageing patterns. This is the first work to investigate the moisture adsorption behaviour of naturally and artificially aged bamboo paper using the dynamic vapour sorption analysis (DVS). The microstructural state of the aged bamboo paper was analysed through relevant testing methods to elucidate the intrinsic mechanism of the change in its moisture adsorption properties.
The results show that ageing does not alter the water adsorption mechanism of bamboo paper, but the relative content of hydrophilic groups such as hydroxyl groups within the paper decreases during ageing, resulting in fewer effective adsorption sites on the surface of the paper, which affects its monolayer and multilayer adsorption capacity.
In addition, the physical structure of the ageing bamboo paper suffers damage, which affects the paper's capillary adsorption capacity to some extent. Due to the greater fibre breakage in naturally aged bamboo paper, the creation of a new pore structure is an important reason why its capillary sorption capacity is higher than that of unaged and artificially aged samples. Based on the result, storage humidity conditions for bamboo paper artefacts should be controlled around 50% RH to help maintain the stability of the paper.
The research provides a theoretical basis for exploring the optimal humidity conditions for the preservation of bamboo paper artefacts and formulates a scientific and reasonable conservation and restoration plan.
(Written by JIANG Zhimo, edited by QIU Rong, USTC News Center)