In this study, to
improve the electrical properties and
impact
strength of phenolic formaldehyde (PF) resin, PF-based composites
were prepared by mixing graphene and the ionic liquid 3-decyl-bis(1-vinyl-1H-imidazole-3-ium-bromide) (C10[VImBr]2) via hot blending and compression–curing processes. The graphene
surface was modified using a silane coupling agent. The synergistic
effect of graphene and C10[VImBr]2 on the electrical
properties, electromagnetic shielding efficiency, thermal stability,
impact strength, and morphology of PF/graphene and PF/graphene/C10[VImBr]2 composites was then investigated. It
was found that the electrical conductivity of the composites significantly
increased from 2.3 × 10–10 to 4.14 × 10–3 S/m with an increase in the graphene content from
0 to 15 wt %, increasing further to 0.145 S/m with the addition of
5 wt % C10[VImBr]2. The electromagnetic shielding
efficiency of the composite increased from 4.70 to 28.64 dB with the
addition of 15 wt % graphene, while the impact strength of the composites
rose significantly from 0.59 to 1.13 kJ/m2 with an increase
in the graphene content from 0 to 15 wt %, reaching 1.53 kJ/m2 with the addition of 5 wt % C10[VImBr]2. Scanning electron microscopy images of the PF/GNP/C10[VImBr]2 composites revealed a rough morphology with numerous
microcracks.