Comprehensive Characterization of Lignocellulose in Azelaic Acid-impregnated Wood

Abstract

Azelaic acid (AzA) impregnation is an effective method for improving the dimensional stability of wood; however, the related microstructural and mechanical changes in lignocellulose remain unclear. In this study, the microstructure and deformation behavior of AzA-esterified wood were investigated using an integrated approach combining thermal analysis, attenuated total reflection infrared (ATR-IR) spectroscopy, wide-angle X-ray diffraction (XRD), and compression testing. When heated below the melting point of AzA, unreacted AzA was observed on the wood surface and within the lumen. In contrast, heating above the melting point promoted diffusion of AzA into the cell wall and induced esterification, which progressed with increasing temperature. The maximum ester content was 1.08 mmol/g dry wood. Heat treatment at 120 °C or higher suggested the formation of cross-links between molecular chains. The relationship between nominal compressive stress (σ) and compression ratio (C) exhibited an inflection point at approximately 10 MPa, suggesting sliding behavior in the intercellular layer under low compressive loads. Furthermore, esterification-dependent differences in cellulose-derived molecular mobility and thermal decomposition behavior were observed.