Effects of alignment of graphene flakes on water permeability of graphene-epoxy composite film

In this study, the electric field-assisted alignment of graphene flakes in B-stage graphene-epoxy composite film was demonstrated. Compared with conventional electric field-induced alignment method which involves curing liquid phase polymer matrix, the electric field application on B-stage composite film with controlled viscosity can achieve graphene flake alignment without any curing reactions, thereby enabling further processes such as film application, assembly and curing. B-stage graphene-epoxy composite was prepared by solution-mixing method, and electric field was applied parallel to the film with various temperature and electric field strengths. Cross-sectional SEM images revealed that graphene flakes were horizontally aligned better as film viscosity decreased and electric field strength increased. However, curing reaction at high temperature should be considered because high temperature was needed to achieve low viscosity. The aligned graphene-epoxy composite film showed lower water vapor transmission rate (WVTR).