Chitosan/halloysite clay mixture for preservation of waterlogged archaeological woods.

This work presents a sustainable protocol for the preservation of waterlogged archaeological wood (AW) by mixing chitosan (Chit) with halloysite clay nanotubes (HNTs). The conservation treatment is based on AW immersion within Chit/HNTs aqueous mixtures at variable composition. Surface characteristics of the treated wooden samples have been studied by colorimetric and microscopic techniques. Chemical elemental imaging shows the influence of the consolidation efficiency on the distribution of chitosan and clay inside the AW structure. The filling by chitosan/halloysite mixture generates improvements on the thermal and mechanical properties of archaeological woods. Besides, the treatment is efficient for wood preservation as demonstrated by aging tests under oxidative and acidic conditions. This paper demonstrates that the combination of chitosan polymer and halloysite clay nanotubes represents a promising alternative for conservation of waterlogged archaeological wood.