Robust Wood Sawdust/Microfibrous Cellulose Composite Board Cross-Linked by Phosphoric Acid-Activated Glutaraldehyde

The recycling use of wood sawdust to process composite boards has received much attention in recent years. To avoid the use of chemical adhesives, natural cellulose-based materials were often used as adhesives to combine wood sawdust. Rather than utilizing nanocellulose, the report herein describes a method to prepare a robust composite board that is based on microfibrous cellulose, which is a low-cost commercial product. To effectively cross-link wood sawdust and microfibrous cellulose, phosphoric acid-activated glutaraldehyde was used as catalyst. Compared to its uncross-linked counterpart, the modulus of elasticity and modulus of rupture of the composite board that had been cross-linked by glutaraldehyde and phosphoric acid were significantly strengthened to 3.45±0.06 GPa and 36.5±3.5 MPa, respectively. Moreover, the moisture resistance of the cross-linked composite board was also enhanced. After soaking in water for 24 h, the mass swelling ratio and thickness swelling ratio of cross-linked composite board had only changed 49% and 21%, respectively. These performances even exceeded that of composite board prepared from nanocellulose. The method described in this work may have applications in commercial processing and the recycling of wood sawdust.