Technological properties homogenization on sapwood and heartwood of short rotation teak wood by non-biocide method based on chemical and thermal treatments

Short rotation teak has been widely planted and developed in Indonesia. Its heartwood presents sufficient natural durability and poor impregnability; meanwhile, its sapwood requires special treatment to increase its dimensional stability and durability. The objective of this work was to investigate the effect of chemical and thermal treatment on technological properties homogenization on sapwood, heartwood of short rotation teak, and their transition. Furfurylation, thermal treatment, and combination of chemical and thermal treatment using glycerol-maleic anhydride (GMA-thermal) were performed on sapwood, heartwood, and their transition (50:50 sapwood-heartwood). The wood samples were analysed using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) to determine the chemical changes after chemical and thermal treatments. The properties of short rotation teak woods were evaluated by measuring their mass change, retention, bulking effect, leaching, volumetric swelling, anti-swelling efficiency, color changes, and decay resistance. ATR-FTIR analysis shows that the polymerization of furfuryl alcohol and GMA in wood occurred within all parts (sapwood, heartwood, and transition) of the short rotation teak wood. Weight losses due to leaching, volumetric swelling, and weight loss due to fungal decay were similar between transition sapwood and transition heartwood after furfurylation and GMA-thermal at 220 °C treatments. The results indicate that short rotation teak board consisting of sapwood and heartwood was homogenized after furfurylation and GMA-thermal at 220 °C treatments. The non-biocidal chemical and thermal treatment could be a valuable eco-friendly modification method for the sawn timber industry to bring high quality and more uniform boards on the markets and be a good selection for improving the quality of the short rotation teak wood.