Characterization of Archaeological European White Elm (Ulmus laevis P.) and Black Poplar (Populus nigra L.)

Abstract

The present study aims at characterization of freshly-cut and archaeological European white elm and poplar. The archaeological elm sample was buried at a depth of 8–10 m inside of soil with age approximation of ~1800–2000 years old, and the archaeological poplar sample was a part of a boat in a freshwater lake or river with age estimation of ~1000–1200 years. Alteration in the chemical structure of the elm and poplar samples due to the ageing process were confirmed by X-ray photoelectron spectroscopy (XPS). Both archaeological wood (AW) samples illustrated considerably lower cellulose crystallinity than the fresh samples as determined by X-ray diffraction. The sorption behavior of AW and fresh wood (FW) samples were evaluated by means of dynamic vapor sorption (DVS) analysis. Results exhibited a higher equilibrium moisture content (EMC) and sorption hysteresis values in archaeological elm and poplar as compared with the fresh samples. Higher hydrophilicity of the AW samples than the FW ones is attributed to their higher amorphous structure. The extensive degradation of AW samples were also confirmed by scanning electron microscopy (SEM) micrographs.