Polyurethane resin-based adhesives: curing reaction and properties of cured systems

A polyether, moisture curable, polyurethane resin was used as an adhesive on plastic and aluminium substrates, in order to investigate the influence of the surface properties on adhesion. The curing kinetics of the adhesive, in controlled temperature and humidity conditions, was evaluated and an elastomeric product was obtained after curing. The surface properties of the cured resin and of the different substrates (PPO/PA6 blend, polypropylene and aluminium) were evaluated and compared by using a contact angle technique. Adhesion measurements were performed using single-lap joints; the strength values obtained were correlated to the structure of the adhesive and to the surface treatments performed on the substrates.