Effect of functionalized graphene on mechanical properties and dielectric constant of bismaleimide composites

Graphene oxide was obtained by improved Hummers method. Hydrated hydrazine, chitosan or potassium hydroxide was used to prepare different reduced graphene oxide (rGO) in order to choose the best reductant, respectively. The rGO was restored and modified by ionic liquid (NH₂IL) to obtain functionalized graphene (NH₂IL–rGO), the matrix (MBAE) was synthesized from 4,4′-diamino diphenyl methane bismaleimide modified by diallyl bisphenol A and Bisphenol A bisallyl ether. NH₂IL–rGO/MBAE composites were prepared from NH₂IL–rGO and MBAE via in situ polymerization, and also studied the effect of NH₂IL–rGO on the properties of composites. The results showed that the micro-morphology of composite existed two-phase structure between the matrix and NH₂IL–rGO, which gave the material excellent properties. The impact strength and bending strength of the composite reached the maximum and were 15.33 kJ/m² and 142 MPa, respectively, when the content of NH₂IL–rGO was 2 wt%. The thermal decomposition temperature of the composite was 435 °C, the dielectric constant of the composite abruptly reached 84 in the frequency range 10² ~ 10⁵ Hz.