Relationship between phenolic adhesive chemistry and adhesive joint performance: Effect of filler type on fraction energy

Abstract The performance of adhesive bonded joints depends on many factors, one of which is the adhesive formulation. The effects of organic and inorganic fillers upon the fracture toughness of phenol–resorchinol–formaldehyde adhesive in hard maple joints were explored in this study. Analytical techniques (DSC, IR, SEM, and GPC), and solubility studies were employed to relate physical effects to chemical effects of teh fillers. The resin showed two distinct stages of cure: (1) a low temperature exotherm associated with resorcinol and paraformaldehyde and (2) a high temperature endotherm associated with the base resin. Filler was found not to affect the cure. Fillers did have a profound effect on the morphology of the wood‐adhesive interphase and upon the bulk adhesive properties. These effects, revealed in both SEM and fracture toughness studies, are discussed at lenghth.