Enhanced mechanical and thermal properties while maintaining transparency of epoxy resin film by introducing shear-oriented cellulose nanocrystals

Alignment of cellulose nanocrystals (CNCs) in the aqueous phase have been studied in depth. However, there are few reports on the orientation control of CNCs as rod-like nano fillers in epoxy resins. In this research, the rheological behavior of CNCs/epoxy resin system before curing indicating that CNCs in which can be oriented through shear-induced orientation. Based on this point, shear-oriented CNCs reinforced resin composite films were successfully prepared, mechanical properties, optical properties and thermal stability of which were sys-tematically investigated. Firstly, mechanical properties of composite films can be significantly improved by introducing oriented CNCs at all CNC content. And the aspect ratio of oriented CNCs also has an obvious impact on their enhancement effect. Secondly, although their transmittance decreases with the increase of CNC content, it is possible to obtain composite films with a transmittance close to that of pure epoxy resin film by adjusting the preparation process of CNCs. Finally, the thermal stability of oriented CNCs reinforced epoxy resin composite films at low CNC content is improved, but then decreases with the increase of CNC content. The successful preparation of oriented CNCs reinforced epoxy resin composite films with better mechanical and thermal properties while maintaining transparency will be conducive to expanding the applications of epoxy resins reinforced with rod like micro/nano fillers.