Thermal stability of wood-wood and Wood-FRP bonding with polyurethane and epoxy adhesives

The temperature-dependent creep of different polyurethane (PUR) and epoxy (EP) adhesives was investigated in relation to glue line thickness. A water-based hydroxymethylated resorcinol coupling agent was developed which improves the delaminating resistance of PUR and EP adhesives. The results show that crosslinked polymers of PUR and EP adhesives display significant viscoelastic responses over temperature ranges that are relevant for practical applications. Thus, temperature-dependent creep is a risk factor that needs to be considered for structural applications.