Preparation and characterizations of a chitosan-based medium-density fiberboard adhesive with high bonding strength and water resistance

An efficient method was developed for preparing medium-density fiberboard (MDF) adhesives with high performance, using chitosan as the main component and glutaraldehyde as a crosslinking agent. The effects of glutaraldehyde content on the bonding strength and water resistance were investigated. The results indicated that the optimum internal bonding strength (IB, 1.22 MPa), modulus of elasticity (MOE, 3162.69 MPa), modulus of rupture (MOR, 29.10 MPa), water absorption (WA, 22.23%) and thickness swell (TS, 26.17%) of the MDF complied with the requirement of the Chinese national standard for MDF. The chitosan-based adhesive was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray diffractometry (XRD). The thermal stability and water holding capacity of the chitosan-based adhesives were influenced by the extent of crosslinking. The excellent properties were attributed to the network structure of the chitosan-based adhesives, formed by crosslinking of chitosan with self-polymerized glutaraldehyde or glutaraldehyde monomers through CN bonds.