To determine the optimal preservation environment for Tibetan paper artifacts at high altitudes, it is essential to characterize the hygrothermal properties of the Tibetan paper material, which have not been previously reported. To fill this gap, the thermal conductivity test, static gravimetric test and cup test were carried out on Tibetan paper with and without scriptures (TPWS/TPWOS) under varying pressures (1.00, 0.80, and 0.60 atm). Results indicated that while air pressure did not affect thermal conductivity, it significantly influenced vapor permeability and equilibrium moisture content (EMC). A reduction of 0.1 atm air pressure resulted in an approximate 0.0045 kg/kg increase in equilibrium moisture content (EMC) and a 2.6 × 10−11kg/(m·s·Pa) increase in vapor permeability. Scriptures printed on the paper with ink affected the composition and pore structure of the paper, resulting in a higher thermal conductivity of 12.2% of the TPWS as compared to TPWOS. The TPWS had lower EMC performance and vapor permeability as compared to TPWOS. Furthermore, TPWS exhibited lower EMC and vapor permeability than TPWOS, with the difference in EMC decreasing and the difference in vapor permeability increasing as air pressure decreased. The fundamental hygrothermal data provided in this study are crucial for assessing the stability and durability of Tibetan paper artifacts under varied environmental conditions, thereby informing scientific preservation strategies to mitigate the potential environmental damage to the Tibetan paper artifacts.
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