Lignocellulosic Micro and Nanofibrillated Cellulose Produced by Steam Explosion for Wood Adhesive Formulations

The reinforcing impact of Lignocellulosic micro and nanofibrillated cellulose (L-MNFCs) obtained from Eucalyptus Globulus bark in Urea-Formaldehyde UF adhesive was tested. L-MNFCs were prepared by an environmentally friendly, low-cost process using a combination process involving steam explosion followed by refining and ultra-fine grinding. Obtained L-MNFCs showed a web-like morphology with some aggregates and lignin nanodroplets. They present a mixture of residual fibers and fine elements with a width varying between 5 nm to 20 μm, respectively. The effects of the addition of low amounts of L-MNFCs (1% wt.) on the properties of three different adhesives (Urea-Formaldehyde UF, Phenol-Formaldehyde PF, and Tannin-Hexamine TH) were studied by the evolution of the pH, the viscosity, and the mechanical properties. Results showed that the viscosity of PF and UF adhesives increased with the addition of L-MNFCs, unlike TH. Meanwhile, the addition led to better mechanical behavior for the three adhesives. Particleboards were then prepared using modified UF with L-MNFCs and tested. Results showed that an amount of 1% wt. of L-MNFCs was sufficient to increase the internal bonding by ≈67%, the modulus of elasticity by ≈43%, and the modulus of rupture by ≈29%.