Reduction of energy consumption of green plywood production by implementing high-efficiency thermal conductive bio-adhesive: Assessment from pilot-scaled application

Abstract

The development of high-performance protein based non-formaldehyde adhesives is hindered by poor adhesive properties and undesirable curing rate. This study aims at preparing energy-saving plywood composites using an eco-friendly soy protein adhesive (SPA) at a pilot scale, while significantly improving the hot-pressing energy efficiency and plywood properties. Hence, a novel type of hybrid soy protein-inorganic adhesive (SPA-LBN@KF) formulation based on the mineral functionalized kenaf fibers (LBN@KF) was developed, in which, kenaf fibers (KF) were in-situ anchored by highly thermal conductive hexagonal boron nitride (h-BN) particles. The characteristics of the tailored LBN@KF fibers were examined to explore the synergistic reinforcement effects between the protein cross-linking network and the wood substrate during the resin curing. The thermal analysis revealed that the LBN@KF induced thermal conductive networks were formed during the plywood pressing, which increased the thermo-curing rate of the SPA-LBN@KF resin.The proposed adhesive formulation could be used to make full-size plywood at a pilot-scale. In the pilot-scale test, it was quantitatively demonstrated that the energy consumption of the plywood pressing step decreased by 23–27% compared to the conventional pressing method. The produced plywood specimens exhibited relatively high bonding strength (1.57 ± 0.11 MPa for wet shear strength), which met the minimum requirements specified by the GB/T 9846.3–2004 standards. These findings demonstrated that the applied multifunctional reinforcements in the thermosetting resin not only improved the adhesion properties of the adhesives, but also promoted the practical application of bio-adhesive to the wood-based products.