Preparation And Characterization Of Graphene And Its Nylon 6 Composites And Fe₃O₄ Hybrid Nano Materials

As a typical 2D carbon nanomaterial, graphene has attracted great attention. In this thesis, we prepared high quality graphene using the intercalation-exfoliation method. The effects of exfoliation agents on graphene products were studied. By utilizing the prepared graphene as a fundamental material, we prepared graphene/MC nylon composites and graphene/Fe3O4 hybrid nano materials separately, besides we did several researches about the electricity properties, crystallization properties and microwave absorption properties of the composites, the main works are as follows:(1) First, stage-one graphite intercalation composites(GICs) were obtained by using FeCl3 to intercalate natural flake graphite at high temperature and high pressure. The XRD patterns showed that the distance of the graphite enlarged to 0.93 nm from the original data of 0.33 nm. Then we exfoliated the GICs with three different regents as NaBH4, H2O2 and DA, XRD data illustrated that the characteristic peaks of GICs were disappeared after treating with NaBH4, while they were still remarkable after treating with H2O2 and DA, these all proved the effect of the NaBH4 is better than the others. Finally we dispersed the NaBH4 exfoliated graphite into ethanol, with the help of sonication, the graphene–ethanol dispersion was prepared. The D peak of the graphene was low in the Raman patterns, with ID/IG=0.09, which was lower than 0.16 of graphite, meaning that graphene had a quite integral structure, and the photos confirmed that graphene generated wrinkles to be stable in the atmosphere due to its special 2D structure.(2) The graphene was used as an additive to modify MC nylon. The effect of graphene to the polymerization of the composites was studied. And also the electricity and crystallization properties of the composites. The results showed that the addition of the graphene has improved the electrical properties effectively. With the addition of two phr of graphene, the volume resistivity of the composites reached to 7.9×107Ω·cm from 5.6×1012Ω·cm of the pure MC nylon, which has decreased by five orders of magnitude, making the composites meet the requirements of antistatic property.(3) Microwave absorption materials that meet the requirements as “thin, light, wide, strong” were prepared by loading the Fe3O4 nanoparticles on to the surface of the graphene. The results showed that, the pure graphene had a high complex permittivity due to its excellent electricity properties, it was hard to meet the impedance matching with the electromagnetic waves, the reflection loss of the pure graphene was quite low, only reaching-2d B, which was useless in the reality. When the Fe3O4 nanoparticles are loaded on the graphene, with the thickness of the hybrid agents was 1.5 mm, the maxim reflection loss of the nano hybrid materials reached-8 dB with Fe3O4 content of 11.2%, and the reflection loss reached-10.5 dB with the content of 23.3%, which illustrated the materials’ practical application.