Moisture related elastic and viscoelastic behaviour of wood adhesives by means of in-situ nanoindentation

As a general trend, all adhesives respond with decreasing elastic modulus to increased humidity. EPI revealed the most stable elastic behaviour to moisture. In contrast PVAc, UF and ULEF show significant differences with changing relative humidity levels. Lowest creep and relaxation was observed for UF and ULEF, followed by EPI. The most sensitive behaviour to moisture was observed for PVAc adhesive polymer.