Silanes for conservation of archaeological woods using modeled birch wood: antifungal, physical-chemical and TGA studies.

From the paper

Abstract

Conservation of ancient wooden artifacts, in addition to consolidation advantage, prevent its deterioration over time. In this research, silane consolidants, including methyltrimethoxysilane (MTMS) and 3-mercaptopropyltrimethoxysilane (MPTMS) with 25 wt% in ethanol were applied under controlled conditions on modeled birch wood (Betula pendula) as a conservation strategy for archeological woods in terrestrial environments. While the wood samples were gradually saturated and dried, aesthetics and cell-walls integrity were also considered. The leaching characteristics, visual and physical changes of wood specimens were evaluated during 4 aging periods to assess their performance and stability. Morphological and chemical reactions were analyzed by FE-SEM microscopy and ATR-FTIR spectroscopy, respectively. For comparison, antifungal properties and thermogravimetric analysis (TGA, DTG) were also examined on the samples. As results, silanization reduced the wood-water interactions while maintaining the aesthetic properties, especially with MPTMS. Maximum water-repellency of silane-treated woods were achieved after a water post-treatment, which probably indicates the secondary hydrolysis of silanes in the presence of water and their re-polymerization. Biological-durability testing (according to EN 113-2) of birch wood (not-durable), against Basidiomycete fungi (i.e., Trametes versicolor and Gloeophyllum trabeum) showed ~ 90% (very-durable) and ~ 65% (moderately-durable) efficiency for MPTMS- and MTMS-treated wood respectively. Based on FTIR and TGA analysis, more interactions of MPTMS with lignin was found, which is more consistent with the chemical nature of most archaeological woods. Thermal-stability and low hygroscopicity of silane-reinforced woods were also confirmed by TGA/DTG, indicating high conservation potential of silanes for historical woods. Meanwhile, a complementary study on real ancient samples is recommended.