Elastic properties of adhesive polymers. III. Adhesive polymer films under dry and wet conditions characterized by means of nanoindentation

The mechanical properties of cured wood‐adhesive films were tested in dry and wet states by means of nanoindentation. A fluid cell was used to monitor possible property changes as a function of changing moisture content. Under wet conditions, the elastic modulus and hardness of all tested adhesives (i.e., urea formaldehyde, melamine urea formaldehyde, phenol resorcinol formaldehyde, and one‐component polyurethane) were reduced to about half of their values in the dry state. After renewed drying, all adhesives largely recovered their initial mechanical properties.