Abstract

Petrochemical-based phenol-formaldehyde (PF) adhesives are widely used in plywood production. To substitute phenol in the synthesis of PF adhesives, lignin can be added due to its structural similarity to phenol. Moreover, micro-fibrillated cellulose (MFC) can further enhance the bond performance, mechanical properties, and toughness of adhesive systems. Thus, the aim of this study was to evaluate the adhesion performance of lignin-PF (LPF) adhesives reinforced with MFC. In LPF formulations, three levels of MFC (0, 15, and 30 wt% based on the total solid content of adhesives) were added to the homogenous adhesive mixture. Three-layer plywood panels from birch (Betula pendula Roth.) veneers were assembled after hot pressing at 130 degrees C under two pressing durations, e.g., 60 and 75 s/mm. Tensile shear strength was measured at dry (20 degrees C and 65% RH) and wet conditions (water soaked at room temperature for 24 h). The results indicated that the addition of lignin reduced the strength of LPF adhesives in both dry and wet conditions compared to the control PF adhesive. However, MFC reinforcement enhanced the shear strength properties of the plywood. Furthermore, a longer pressing time of 75 s/mm slightly increased the shear strength.

Keywords

bio-based adhesives; tensile shear strength; viscosity; adhesive penetration; birch veneer

Published in

Forests
2023, Volume: 14, number: 11, article number: 2249

SLU Authors

• Adamopoulos, Stergios

  • Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Wood Science


Publication identifier

DOI: https://doi.org/10.3390/f14112249

Permanent link to this page (URI)

https://res.slu.se/id/publ/126799