Development of transparent wood from tropical species: effects of lignin removal and epoxy resin infusion on meranti merah, mempisang and kedondong

In Malaysia, buildings contribute approximately 66% of national energy consumption. In response, the government enacted the Energy Efficiency and Conservation Act (EECA) to enhance energy efficiency and promote sustainable practices by 2050. Transparent wood (TW), an emerging material with low light scattering and thermal insulation properties, offers potential for sustainable construction in line with EECA goals. This study investigates the fabrication of TW from three tropical species—meranti merah, mempisang, and kedondong—through chemical delignification and subsequent epoxy resin impregnation. Four delignification durations (3, 6, 9 and 12 hours) were tested to determine optimal lignin removal. Meranti merah and mempisang showed optimal lignin content at 6 hours (18.76 and 21.95%), while kedondong peaked at 12 hours (21.44%). Meranti merah exhibited the highest tensile strength (113.4 MPa at 3h), while mempisang showed stable performance. Optical transmittance improved in all TW samples compared to delignified wood, with the highest values recorded for mempisang (57%) and meranti merah (56%). Post-treatment density increases confirmed successful polymer infiltration. Among the three species, meranti merah demonstrated the best combination of mechanical strength and optical clarity, making it a strong candidate for TW applications in sustainable construction.