Development of low environmental impact protective coatings based on a furan resin and cellulose nanocrystals

Abstract

A furan resin, synthesized from furfural and phenol, was previously proposed as a less environmental impact alternative to traditional phenolics’ coatings to protect aluminum. In this work, the furan resin was modified with 10 and 20%wt of prepared cellulose nanocrystals (CNC), a biobased nanoreinforcement. Several techniques such as AFM, FTIR, DMA, TGA, XRD, nanoindentation experiments and contact angle measurements were applied to characterize CNC, coatings mechanical performance, materials thermal degradation behavior and chemical structure. It was found that all materials show an excellent interfacial adhesion with the aluminum substrate. CNC incorporation enhances coatings’ mechanical resistance to permanent damage and unexpectedly reduces the elastic modulus. This is because CNC affects the polymerization hindering furan matrix crosslinking. CNC addition slightly accelerates the thermal degradation rate in the overall degradation zone of furan resin keeping the same degradation mechanism and the formation of the protective char.