Influence of alkaline treatment on physical, mechanical and thermal properties of bamboo fibre reinforced polyurethane composites

The extensive dependence on wood-based products has generated significant environmental concerns, including large-scale deforestation, disruption of forest ecosystems, elevated carbon emissions, and limited long-term sustainability. In response, recent research has explored bamboo fibre (BF) reinforced polyurethane foam (PUF) as a renewable and sustainable alternative material. The objective of this study was to investigate the influence of BF treatment with varying NaOH concentrations (3–12%) on the physical, mechanical, and thermal properties of BF/PUF composites. The treated samples were subjected to different alkali concentrations and subsequently characterised through water absorption, thickness swelling, mechanical testing, and thermogravimetric analysis (TGA). The results revealed that alkali treatment of BF markedly improved the physical performance of the composites, with BF/PUF treated with 6% NaOH demonstrating the lowest moisture content (17.65%), while 3% NaOH-treated BF/PUF showed the lowest water absorption (44.43%) and thickness swelling (1.45%), indicating superior dimensional stability. Furthermore, the 3% NaOH treatment also produced the highest flexural strength (0.19 MPa) and compressive strength (0.48 MPa). In terms of thermal behaviour, BF/PUF treated with 6% NaOH exhibited enhanced thermal stability compared to the other treatments. Overall, alkali treatment enhances BF/PUF composites, making them a sustainable alternative for eco-friendly products.