Wetting of soy protein adhesives modified by urea on wood surfaces

Wetting of soy protein adhesives modified by urea on wood surfaces was investigated with sessile liquid droplet method. Dynamic contact angles were used to illustrate the wetting process. The effects of wood surface roughness and urea concentration on contact angles were investigated. Moreover, two wetting models were used to describe the dynamic contact angle process, in which the contact angle change rate constant (K) can be used to quantify the adhesive spreading and penetration during the wetting process. The results showed that the wetting models could accurately describe the dynamic wetting process of soy protein adhesives on wood surfaces.