Han Liuyang, Guo Juan, Wang Kun, Grönquist Philippe, Li Ren, Tian Xingling, Yin Yafang
Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China.
Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China.
Polymers (Basel). 2020 Apr 6;12(4):834. doi: 10.3390/polym12040834.
Waterlogged archaeological wood (WAW) artifacts, made of natural biodegradable polymers, are important parts of many precious cultural heritages. It is of great importance to understand the hygroscopic behavior of WAW in different deterioration states for the development of optimal drying processes and choices of safe storage in varying conditions. This was investigated in a case-study using two (Giam) and two (Teak) WAW samples collected from the Xiaobaijiao No.1 shipwreck. The deterioration state of WAW was evaluated by the maximum water content (MWC) method and by the cell morphological structure. Both and WAW could be classified into moderately and less decayed WAW. The hygroscopic behavior of moderately and less decayed WAW was then comparatively investigated using Dynamic Vapor Sorption (DVS) measurements alongside two sorption fitting models. Compositional analysis and hydroxyl accessibility measurements of WAW cell walls were shown to correlate with the hygroscopicity of WAW in different deterioration states. It was concluded that moderately decayed WAW possessed higher hygroscopicity and hysteresis than less decayed WAW because of the lower relative content of polysaccharides and the higher relative content of lignin, including the slow hydrolysis of O-acetyl groups of xylan and the partial breakage of β-O-4 interlinks, accompanied by an increased hydroxyl accessibility. This work helps in deciding on which consolidation measures are advised for shipwreck restauration, i.e., pretreatments with specific consolidates during wood drying, particularly for wooden artifacts displayed in museums.
饱水考古木材（WAW）文物由天然可生物降解聚合物制成，是许多珍贵文化遗产的重要组成部分。了解不同劣化状态下WAW的吸湿行为对于开发最佳干燥工艺以及在不同条件下选择安全储存方式至关重要。在一项案例研究中，对从小白礁一号沉船采集的两块（樟木）和两块（柚木）WAW样本进行了研究。通过最大含水量（MWC）法和细胞形态结构评估了WAW的劣化状态。樟木和柚木WAW均可分为中度和轻度腐朽的WAW。然后，使用动态蒸汽吸附（DVS）测量以及两种吸附拟合模型，对中度和轻度腐朽WAW的吸湿行为进行了比较研究。结果表明，WAW细胞壁的成分分析和羟基可及性测量与不同劣化状态下WAW的吸湿性相关。研究得出结论，中度腐朽的WAW比轻度腐朽的WAW具有更高的吸湿性和滞后性，这是由于多糖相对含量较低和木质素相对含量较高，包括木聚糖O - 乙酰基的缓慢水解和β - O - 4键的部分断裂，同时羟基可及性增加。这项工作有助于确定在沉船修复中建议采取哪些加固措施，即在木材干燥过程中用特定的加固剂进行预处理，特别是对于博物馆中展示的木制文物。
