Curing and Adhesive Bond Strength Development in Naturally‐Based Adhesives

The processes of curing and adhesive bond strength development occupy much of the methodology described in scientific publications reporting the development of new naturally-based adhesive formulations with optimized performance. This fact shows that information on the transition of naturally-based adhesives from the liquid state through gelation to the formation of the cured and crosslinked wood-adhesive bond is of great importance. The four techniques most commonly used to analyze curing of naturally-based adhesives are briefly described, i.e., the gel time test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Further the principles of four techniques used to monitor the development of bond strength of wood joints bonded with naturally-based adhesives are explained, i.e., dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), automated bonding evaluation system (ABES), and tensile-shear strength testing. The second part of this chapter summarizes recent scientific studies reporting about curing and bond strength development of the most commonly used naturally-based adhesives.