Understanding the thermoplasticization mechanism of wood via esterification with fatty acids: A comparative study of the reactivity of cellulose, hemicelluloses and lignin

Abstract

Thermoplastic materials can be obtained through solvent free wood esterification with fatty acid using trifluoroacetic anhydride (TFAA) as promoter. This study aims to investigate the mechanism of wood thermoplasticization mechanism by understanding the role of each wood component in esterification. High accessibility for acylation was found in cellulose indicated by the highest weight percent gain (WPG), followed by lignin and hemicelluloses. However, significant chemical structural changes were recorded for each spruce wood components observed by Fourier-transform infrared spectroscopy (FTIR) and cross-polarization/magic angle spinning solid state nuclear magnetic resonance (CP/MAS 13C NMR), promoting thus the improvement of their thermal properties detected by (thermogravimetric analysis) TGA and (differential scanning calorimeter) DSC. Cellulose as a major component wood played an important role in wood plasticization, indicated by the low softening temperature before degradation recorded by (thermomechanical analysis) TMA. Hemicelluloses presenting lower WPG, showed the same effect as cellulose on thermoplasticization supported by the low softening temperature observed by TMA and (scanning electron microscope) SEM. Acylated lignin did not show thermoplastic properties, but resulted in important hydrophobic aspects of materials.