Effect of Amount of Functionalised Carbon Nanofibres in Polyurethane Dispersions

Waterborne polyurethane (WBPU) adhesives reinforced with carbon nanofibres (CNFs) were prepared, and their properties were evaluated as a function of content (0.1–1 wt%). The incorporation of carbon nanofibres into waterborne polyurethane adhesives presents great difficulty because of their tendency to form aggregates, which prevents an efficient dispersion. It is therefore necessary to introduce functional groups on the surface of the nanofibres to improve their interaction with any polymer. In this research, carbon nanofibres were preoxidised by chemical functionalisation to enhance their stability in waterborne polyurethane adhesives. The results showed that the chemical treatment used to functionalise the carbon nanofillers and the experimental procedure employed to incorporate them into the polyurethane were adequate, as stable dispersions were obtained. Moreover, the addition of nanofibres to the waterborne polyurethanes improved their rheological and viscoelastic properties, resulting in an increase in viscosity and causing changes in the crystallisation kinetics.