Electrically conductive nanocellulose/graphene composites exhibiting improved mechanical properties in high-moisture condition

Nanofibrillated cellulose (NFC) has received significant attention in materials science recently because of its unique properties such as high mechanical properties, high surface area, and applicable rheology. NFC-based papers possess high mechanical strength and excellent oxygen barriers. However, they exhibit poor mechanical properties in high-humidity environments because of their hydrophilicity, thus narrowing its applications. In this study, we demonstrated that an incorporation of chemically reduced graphene oxide (RGO) sheets into NFC paper resulted in significantly improved mechanical properties in high-humidity condition. Dynamic mechanical analysis showed that all NFC/RGO composite papers containing graphene ranging between 1 and 10 wt% were not broken in an extreme test condition at 80 °C and 80 % relative humidity. Meanwhile, neat NFC paper was broken when the temperature reached 50 °C. In addition, the tensile test demonstrated that Young’s modulus of the NFC/RGO composite paper was significantly higher than that of neat NFC paper. Furthermore, the NFC/RGO composite papers possessed high electrical conductivity, which was proportionally increased as the graphene loading content increased. The developed NFC/RGO composite materials can find potential uses as conductors, antistatic coatings, and electronic packaging, especially where high moisture is present.