Transforming inferior short-rotation teak: unleashing superior durability and stability with lactic acid-based bio-treatments

This study focused on enhancing the properties of inferior short-rotation teak (SRT) wood through impregnation with lactic acid (LA)-based treatments, aiming to improve its dimensional stability, biological durability, and thermal stability. Applying a vacuum-pressure of 12.2 bar for two hours, followed by curing at 150 °C and 180 °C, the research found that wood treated at 180 °C with a 10% LA and 10% citric acid (CA) composition demonstrated superior performance. Specifically, the treated woods exhibited higher anti-swelling efficiency (ASE), lower water uptake (WU), lower swelling value (Sv), and lower leaching (Wlc), as well as better resistance to white-rot fungi, subterranean termites, and thermal stability. The best results retained by the treated wood were 69% ASE, 27% WU, 3% Sv, and 1% Wlc, with durability classified as class I. Microscopic analysis reveals that the impregnants effectively filled the wood pores. Chemical analysis on the modified wood demonstrated a decrease in hemicellulose content and an increase in α-cellulose and lignin. FTIR analysis further confirmed strong chemical bonds formed between the LA + CA impregnants and wood cellulose and lignin. These findings highlighted the potential of LA + CA treatment combined with 180 °C curing on the SRT wood for high-quality interior and exterior wood applications.