Chemists present bio-based water-borne polyurethanes which were reinforced with cellulose nanocrystals as coating films.
The results showed the feasibility of using nanocomposite WBPUs as coatings.
In the study, two different bio-based water-borne polyurethanes (WBPUs) that use castor oil and tartaric acid in their formulations were modified by the incorporation of a renewable reinforcement, cellulose nanocrystals (CNC), to be further applied as metal coatings of tailored properties.
Feasibility of using nanocomposite WBPUs
Different mixed suspensions were prepared by blending aqueous suspensions of CNC with the WBPU dispersions to achieve CNC concentrations of 5 wt. % and 10 wt. % (dry basis). The viscosities of the mixed suspensions were adjusted, so that they could be used in dip-coating of aluminum plates, used as substrates. The coatings were tested using macroscopic methods such as knife and tape tests and contact angle. Microscopic techniques such as nanoindentation, nanoscratch and nanowear were carried out.