| Graphene is one of the hottest materials in the field of nanoscience and nanotechnology. Due to its excellent properties such as electrical conductivity, thermal conductivity and mechanical properties, graphene based nanocomposites will be widely used in the future, while graphene/polymer nanocomposites are one of the most potential and most important applications in the field of nanocomposites. Graphene oxide (GO) and few-layer graphene (FLG) were prepared by oxidation reduction method using graphite as raw material in this paper. Then, graphene/PA6 nanocomposites were prepared by static casting anionic ring opening polymerization, liquid reactive extrusion and microspheres template methods, using FLG and ε-caprolactam (CL) as the main materials. Various characterization technologies were carried out to investigate the morphological structure, crystallization, thermal properties, mechanical properties and electrical properties. The main contents are as follows:(1) The development history, classification, basic properties, synthesis methods, characterization technologies and applications of graphene were briefly summarized. The research progress, preparation process and properties of graphene/polymer nanocomposites, especially graphene/PA6 nanocomposites were reviewed, the purpose and meaning of this paper were also clarified.(2) GO and graphene were prepared by the improved Hummers method, the prepared samples were characterized by Raman spectroscopy, atomic force microscopy (AFM), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results showed that the prepared graphene was the few-layer graphene (FLG).(3) GO/PA6 and FLG/PA6 nanocomposites were fabricated by static casting technology, using in situ polymerization of CL. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermal weight loss analysis (TGA), gel permeation chromatography (GPC) and mechanical properties testing were characterized to investigate the dispersion and the interfacial interactions between GO, FLG and PA6 matrix. The crystal behavior, thermal and mechanical properties of nanocomposites by addition of GO and FLG were also analyzed. Results showed:GO and FLG can be uniformly dispersed in the PA6 matrix; the interface binding degree of GO and PA6 was better than that of FLG; the addition of FLG and GO can promote the crystallization of PA6, and accelerate its crystallization rate; the strength of PA6 can also be increased obviously with incorporation of FLG and GO; when the content was the same, the effect of FLG and GO on the properties of PA6 matrix was similar. From the point of view of commercial production, it is proved that the graphene/polymer composites prepared by using unmodified graphene are more suitable than the use of modified graphene.(4) FLG/PA6 nanocomposites were prepared by the process of liquid reactive extrusion. The prepared samples were characterized by FE-SEM, TEM, XRD, DSC, TGA, GPC and mechanical properties testing. The performance of the prepared samples and the preparation process of the liquid reactive extrusion and the static casting technology were studied and compared. Results showed:when compared to static casting process, liquid reactive extrusion process is more suitable for industrial production because of it can be continuous production and the products are the masterbatches.(5) FLG/PA6/PBT-PTMG nanocomposites were prepared by the process of liquid reactive extrusion and melting extrusion, using FLG, CL and PBT-PTMG as the main raw materials. The morphology, thermal and mechanical properties of these ternary composites was studied, the synergistic effects on the strength and toughness of composites with different content of FLG and PBT-PTMG were discussed, the mechanism of strengthening and toughening was discussed too. Results showed:the strength and toughness of PA6 composites can reach the best balance with addition of appropriate amount of FLG and PBT-PTMG.(6) FLG/PA6 nanocomposites were prepared by microspheres template method, combined with high power ultrasonic. The morphology, crystallization, thermal, electrical and mechanical properties of the nanocomposites were characterized, the preparation methods of microspheres template and in situ polymerization were compared. The results showed that the advantages of the microsphere template method include:the content of graphene is not limited, the preparation technology is simple and environmentally-friendly, graphene and PA6 microspheres can achieve nanometer level blending which is easier to form graphene channel in PA6 matrix, thus provide a basis for further study on the electrical conductivity and thermal conductivity of graphene/PA6 nanocomposites.(7) The content of the full text is summarized, and the main innovation points of this paper are generalized. |
