Electrochemical exfoliation of water-dispersible graphene from graphite towards reinforcing the mechanical and flame-retardant properties of poly (vinyl alcohol) composites

Functional graphene is a very efficient support material to improve the performance of polymer composites, but the commercial application of functional graphene is hindered by its complex preparation procedure and high pollution. Herein, the water-dispersible graphene nanosheets (DGNS) were prepared by a simple and eco-friendly electrochemical method assisted with an anionic surfactant DNS86, and then DGNS were mixed into poly (vinyl alcohol) (PVA) matrix to fabricate PVA composite films. DGNS could be well dispersed in PVA matrix and form strong interfacial interaction with PVA molecular chains. The tensile strength, tensile modulus and storage modulus of PVA composite film containing 0.3 wt% DGNS were increased by 50.1%, 50.4% and 154.5%, respectively, compared to those of pure PVA. Moreover, the addition of DGNS also improved the flame retardancy of PVA composite films, achieving an obvious reduction (60.9%) in the peak heat release rate with the load of 2.0 wt% DGNS. The analysis revealed that the addition of DGNS could facilitate the formation of the compact and highly graphitic char residues, retarding the heat and mass transfer to protect underlying matrix during combustion process. This paper will supply a promising strategy to industrially produce functionalized graphene nanosheets for graphene-based reinforced composites.