Properties of laminated bamboo produced with the involvement of supercritical carbon dioxide treatment

Abstract

Supercritical carbon dioxide (SC-CO2) as a carrier solvent is becoming an alternative and environmentally sound method in the preservative treatment of wood and wood-based products. The potential of this new method has never been explored for its suitability in manufacturing laminated bamboo products which are widely used as construction materials for either indoor or outdoor purposes. The current study was aimed at examining the effect of SC-CO2 impregnation on the density and bonding strength of laminated bamboo Dendrocalamus asper. Samples of bamboo strip and their laminated products were prepared for impregnation treatments. Some of the bamboo samples were also proportionally divided into four outer-inner sections for the determination of anatomical structure presumed to have a relationship with the properties of laminated products. SC-CO2 impregnation was conducted in a vessel at the temperature of 35 °C and the pressure of approximately 8 MPa for 30 min. Results showed that SC-CO2 impregnation resulted in no adverse effects on the density and bonding strength of laminated bamboo. Various responses of laminated bamboo products to the SC-CO2 impregnation were noticed to associate with the decreased proportions of vascular bundles and the increased proportions of parenchyma cells from outer to inner parts of the bamboo. These results indicate the feasibility of the SC-CO2 treatment and the important of considering the anatomical structure of bamboo in producing laminates with high strength and durability properties.