Impact of temperature on mechanical properties and dimensional stability in a novel gradient pressure bamboo flattening technique

Bamboo is an ideal engineering material for construction and furniture applications due to its rapid growth and exceptional mechanical properties. In recent years, bamboo flattening techniques have been extensively studied and applied. In this work, a straightforward and efficient method for flattening arc-shaped bamboo splits is proposed. Gradient pressure was used in the flattening process, increasing bamboo density by 12% – 15%. Also, the mechanical properties of the flattened bamboo splits exhibited significant enhancement. The maximum flexural strength and modulus of elasticity (MOE) values were achieved when flattened at 180°C. The modulus of rupture (MOR) and MOE of flattened bamboo were determined to be 212.04 MPa and 14.14 GPa, which are 57.19% and 35.53% higher than those of natural bamboo. Further, the outer surface of flattened bamboo exhibited hydrophobic characteristics, as evidenced by the contact angle exceeding 90°. The dimensional stability and water absorption of flattened bamboo splits were influenced by flattening temperature variations. Temperatures ≥180 °C resulted in excellent dimensional stability, with warpage levels below 2%. This process can improve the dimensional stability and mechanical properties of bamboo, and the flattened bamboo splits do not require further drying treatment, which positively affects bamboo processing and utilization.