Improved mechanical properties and thermal stability of phenol formaldehyde resin by incorporating poly(vinyl alcohol)-grafted reduced graphene oxide nanohybrid

Poly(vinyl alcohol) grafted reduced graphene oxide (PVA-rGO) nanohybrid has been synthesized by a facile hydrothermal method. Transmission electron microscopy, ultraviolet-visible spectroscopy, fourier transform infrared spectroscopy and (HNMR)-H-1 spectroscopy confirmed that the PVA chains were successfully grafted onto the surface of graphene oxide sheets by esterification reaction, and meanwhile graphene oxide was reduced to rGO during hydrothermal process. Thermogravimetric analysis indicated that the PVA content in PVA-rGO was evaluated to be around 26.9 wt%. Subsequently, PVA-rGO nanohybrid was incorporated into a water-soluble phenol formaldehyde resin (PF) matrix to fabricate PVA-rGO/PF composites via a solution blending and casting approach. The mechanical properties and thermal stability of PVA-rGO/ PF composites were investigated by universal mechanical tester, impact tester and thermogravimetric analysis. And the results showed that their mechanical properties and thermal stability were improved significantly by the addition of 3 wt% of PVA-rGO, which was mainly attributed to a good dispersion of PVA-rGO in PF matrix as well as a strong interfacial interaction between the PVA-rGO nanohybrid and PF matrix, as revealed by the results of scanning electron microscopy. Our study provides a new insight into the study of water-dispersible graphene functionalized with polymer molecules and its applications in water-soluble polymers.