Graphene Special Structure
Graphene is a two-dimensional honeycomb carbon material, composed of carbon atoms in hexagonal arrangement. Carbon and carbon atoms by the combination of sp2 hybrid, its structure is very stable. The special structure of graphene leads to its many excellent properties.
Graphene is currently found in the hardness of the largest material, and has excellent mechanical properties, the theoretical surface area of up to 2600m2 / g, with outstanding thermal conductivity, up to 3000W / (m · K). In addition, graphene also has good conductivity. At room temperature, its electron mobility can be as high as 20000cm2 / (V · s).
Due to the excellent properties of graphene, the researchers consider adding it as a reinforcement to the matrix material to improve the performance of the matrix material.
However, the specific surface area of graphene tends to be agglomerated together, which not only reduces its adsorption capacity but also affects the excellent performance of graphene itself, thus affecting the performance of graphene reinforced composites. Moreover, this reunion is irreversible, unless the application of external forces, such as ultrasound and strong mixing, so that evenly dispersed. In order to obtain excellent graphene reinforced composites, researchers have done some research in overcoming the graphene agglomeration.
One of the commonly used methods is the preparation of off-oxide graphite by oxidized graphite and ultrasound, and then chemically reduced to graphene. There is a strong van der Waals force between the graphene prepared in this method and easy to accumulate in the solution.
Another common method is to uniformly disperse the graphene in an organic solvent or an aqueous solution of a surfactant to adsorb the molecular or surfactant molecules on the surface of the graphene, and to achieve the effect of the monoclinic graphene by the classical repulsive force and the intermolecular force dispersion.
The ability to inhibit the agglomeration of graphene by physical or chemical modification has been demonstrated, but whether the impurity introduced during the formation of the composite affects the properties of the composite remains to be studied. Some surface modifications and other methods may also be used to improve the dispersibility of graphene.
Jiang by surface modification of graphene, thereby improving the interface between graphene and copper matrix, polystyrene in the copper uniform dispersion of the composite material. The morphology of the composites was found to be uniformly dispersed in the copper matrix.
Jing used gallic acid with strong reducing ability as stabilizer and reducing agent to obtain high dispersibility of graphene. Their analysis is due to the formation of π-π conjugate interactions between the benzene ring structure and the graphene in the molecule, which is adsorbed on the surface of the graphene as a stabilizer.
This makes the graphene sheet has a strong negative charge, to prevent the further accumulation of graphene together to make it more difficult to reunite, to ensure that the prepared graphene has a high dispersion performance.
Through the above test can be seen, the material or process can be used to make gravel evenly dispersed in the matrix, thereby enhancing the performance of composite materials.