Changes in fracture surface morphology and mechanical property of natural lemon eucalyptus composite due to hydrothermal treatment

• Lemon eucalyptus (lemon-scented gum ) specimens were hydrothermally treated. • Microstructures of the wood-derived natural composite material specimens were observed. • Torsion tests on specimens with and without hydrothermal treatment were conducted. • Compression tests on specimens before and after hydrothermal treatment were performed. • Fracture surface morphology and mechanical property changes were found due to the treatment. In this work, fracture surface morphology and mechanical property of the natural composite material derived from lemon eucalyptus (or lemon-scented gum) tree were investigated. Microstructure and fracture surface of the wood specimens were examined. Mechanical tests under torsion and compression were conducted. The modulus of elasticity (Young’s modulus) and shear modulus (modulus of rigidity) were determined. The effect of hydrothermal treatment (HTT) on the specimens was studied. It was found that both shear and compressive strengths of the natural composite material decreased after HTT at 200 °C. Increasing the treatment time led to more decrease in compressive strength. The fracture surface observation reveals intensive fiber formation from the hemicellulose degradation. Hydrothermal treatment is valuable for developing energy-saving and sustainable wood fiber production processes.