Affect of polydispersity on the properties of waterborne polyurethane dispersions based on polycarbonate polyol

Waterborne polyurethane dispersions (PUDs), with possible use as adhesives, derived from polycarbonate diols (PCDs) were evaluated. The influence of the NCO/OH ratio and particle size distribution on the properties of both the aqueous dispersions and dry films were evaluated.The polydispersity of the PUD was increased by increasing its hard segments content. On the other hand, the properties of the PUDs depended on both the NCO/OH ratio and the polydispersity. As the NCO/OH ratio increased, the Brookfield viscosity of the PUDs decreased due to broader particle size distribution. On the other hand, an increase in the NCO/OH ratio decreased the crystallinity of the polyurethane films. Furthermore, the greater the polydispersity the higher the urea hard segment content, the higher the glass transition temperature value and the higher the elastic modulus of the polyurethanes.