Preparation And Properties Of 3D Graphene Prepared / Epoxy Composites

In recent years, graphene/epoxy composites, which have extremely high mechanical properties, excellent thermal conductivity, good electrical conductivity and other advantages, have attracted tremendous research interest. However, some bottlenecks, such as the dispersion and disordered arrangement of graphene in preparation process of the direct-mixing graphene/epoxy composites, have become the adverse factors to improve the performance of composites and seriously limited its extensive applications in many fields. Aiming at these above problems, preforming process for graphene sheet was put forward and three-dimensional graphene preforming architecture (3DGA) was constructed with the covalent bonds. Then the 3DGA/epoxy composites were prepared in resin transfer molding (RTM) method, in which the perfprmance of 3DGA/epoxy composites was in contrast with that of thermal exfoliation graphene (EG)/epoxy composites with direct-mixing method. Furthermore, by studying the microscopic pore structure of 3DGA, the relationship between it and the mechanical, thermal, electrical properties of 3DGA/epoxy composites was explored. The main contents of this study mainly include the following aspects:(1) The 3DGA/epoxy composites were prepared by RTM method, and compared with the EG/epoxy composites with direct-mixing method in performance. The results shown that EG/epoxy composites performed best at the EG content of 0.10 wt%. Once the content of EG increased, the properties of E G/epoxy composites decreased. while the tensile, flexural, compressive properties and thermal stability of 3DGA/epoxy composites with high 3DGA content of 0.20 wt% have significant advantages over EG/epoxy composites, and even more than doubled. These fully demonstrated the feasibility of this research.(2) The pore diameter of 3DGA reduced when the particle sizes of graphene sheets decreased. And the effect of the pore size of 3DGA on the properties of the composites has been studied. When the pore size of 3DGA was reduced to several micron, the content of 3DGA increased from 0.19 wt% to 0.58 wt%, and the performances of 3DGA/epoxy composites continues to improve, for example, the tensile strength increased by 41.7%, the flexural strength and modulus increased by 78.4% and 50.5% respectively, and the glass transition temperature increased by 10 ℃.(3) The element labeling, FESEM and EDX have proved the complete network structure of 3DGA in composites. In a simple thermal treatment process, the 3DGA still maintained a good state of three dimensional conductive network, and the conductivity of the epoxy composites reinforced by thermal treated 3DGA was improveed by nearly 6 orders of magnitude. At the same time, there was only a slight decrease in compression performance of the composites. This connected network structure in 3DGA built by graphene sheets has enough advantages in terms of improving the conductivity of graphene/epoxy composites.