Development and characterization of a formaldehyde-free adhesive from lupine flour, glycerol, and a novel curing agent for particleboard (PB) production

A formaldehyde-free adhesive has been developed from defatted lupine flour (defLF), glycerol, and a novel curing agent (CA). The CA was prepared from reactions of epichlorohydrin (ECH) and 3-(dimethylamino)-1-propylamine (DMAPA) and characterized by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (H-1 NMR) spectroscopies. The adhesive has a low viscosity of 472 cP at a total solids content (SC) of 60% and could be easily applied onto wood particles for the production of particleboards (PBs). The internal bond (IB) strength, modulus of rupture (MOR), and modulus of elasticity (MOE) of the resulting PBs exceeded the industrial requirements. The adhesive with defLF/glycerol/CA mass ratio of 2:4:3 led to the best overall properties of the resulting PBs. The curing mechanisms of the adhesive were mainly attributed to the reactions between lupine protein and the CA.