Study On Multifunctional BMI Composites Based On 3D Graphene

As a new type of carbon material,graphene aerogel has the characteristics of light weight and good electrical conductivity.The preparation of polymer matrix nanocomposites with graphene aerogels has solved the problem of agglomeration that occurs where graphene sheets are used as fillers.In this paper,graphene oxide(GO)prepared by Hummers method was used as precursor to prepare graphene aerogel(GA)by chemical reduction and self-assembly.The effect of microwave reduction on the conductivity of aerogels was investigated.Then,the graphene aerogels before and after microwave reduction were used to prepare the bismaleimide(BMI)composites.The electrical conductivity and electromagnetic shielding properties of aerogel/BMI composites were studied.The experimental results show that the oxygen-containing groups on the graphene aerogel lamellae was effectively removed in the microwave reduction process.The sp~2 hybrid structure of carbon atom was also restored and the conductivity of aerogel was enhanced.Compared with those of graphene aerogels before reduction,the carbon oxygen ratio of aerogels increased from 6.6 to 7.2 after reduction,and the content of C=C functional groups increased from 28.9%to 39.6%.The conductivity of aerogels prepared using 9mg/ml GO solution as precursor increased from 34.7S/m to 42.1S/m.The BMI composites prepared with microwave reduction of graphene aerogel(MRGA)have better conductive and electromagnetic shielding properties than the GA/BMI composites.When the aerogel content is 1.63wt%,the conductivity of MRGA/BMI is 15.64S/m,and the electromagnetic shielding effectiveness is 25d B,which is 42.3%and 31.6%higher than those of GA/BMI,respectively.In addition,the results show that the electromagnetic shielding of the composite is mainly absorption loss,the maximum absorption efficiency is 99.5%.The thickness of the composites has also a significant impact on the electromagnetic shielding performance.