Improved dimensional stability and mechanical properties of rubberwood via modification with maleated lignin and densification

Abstract

Abstract Rubberwood was modified using a two-step process involving impregnation with maleated lignin (ML) followed by densification. The effects of ML modification and densification on the physical and mechanical properties of modified wood were studied. The successful preparation of ML was confirmed using Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. In addition, scanning electron microscopy was used to characterize the densified rubberwood structure, which featured fully compressed cell walls and cell lumina filled with ML. The rubberwood modification resulted in a more uniform structure and increased density compared to untreated wood. Further, water immersion and moisture absorption experiments revealed thickness swelling of only 27.7% and 20.9%, a reduction of nearly 76% and 55%, respectively, compared to the densified wood that was only impregnated with water. The ML modification can alleviate the embrittlement of wood caused by densification. The modulus of rupture and modulus of elasticity of ML-treated and densified wood improved by nearly 54% and 200%, respectively, compared to untreated wood. Therefore, the synergistic treatment strategy can contribute to the high-value utilization of low-quality rubberwood.