Fabrication of self-bonding laminated bamboo via a dual-treatment method combining alkali treatment and hot pressing

Urea-formaldehyde and phenolic resins are often used in the preparation of bamboo- or wood-based materials. However, adhesives containing these resins can release harmful substances such as formaldehyde and phenols, posing risks to human health. Meanwhile, delignification is widely used for modifying bamboo- and wood-based materials, but it has some limitations such as high steaming temperatures and long processing time. In this study, a simple and effective self-bonding method for fabricating bamboo-based materials was developed. This method integrated partial delignification and bonding, and its main mechanism involved applying sodium hydroxide (NaOH) solution to the bonding surface of bamboo, followed by hot pressing. This process softened lignin under alkaline conditions, promoting interactions between cellulose chains and the softened lignin to form a strong network at the bonding interface. Laminated bamboo fabricated by treating bamboo with a 9 % NaOH solution followed by hot pressing at 140℃ for 60 min under 2 MPa pressure exhibited excellent bonding performance, demonstrating a 6.84 MPa bonding strength. This self-bonding method facilitates the development of adhesive-free bamboo- and wood-based products, reducing dependence on synthetic adhesives.