Recent Studies on Dispersion of Graphene–Polymer Composites

Graphene is an excellent 2D material that has extraordinary properties such as high surface area, electron mobility, conductivity, and high light transmission. Polymer composites are used in many applications in place of polymers. In recent years, the development of stable graphene dispersions with high graphene concentrations has attracted great attention due to their applications in energy, bio-fields, and so forth. Thus, this review essentially discusses the preparation of stable graphene–polymer composites/dispersions. Discussion on existing methods of preparing graphene is included with their merits and demerits. Among existing methods, mechanical exfoliation is widely used for the preparation of stable graphene dispersion, the theoretical background of this method is discussed briefly. Solvents, surfactants, and polymers that are used for dispersing graphene and the factors to be considered while preparing stable graphene dispersions are discussed in detail. Further, the direct applications of stable graphene dispersions are discussed briefly. Finally, a summary and prospects for the development of stable graphene dispersions are proposed.

Extrusion and characterization of aluminum/graphene composites

Since its first synthesis in 2004 graphene was characterized intensively and exceptional properties in terms of e.g. mechanical strength, stiffness and electrical as well as thermal conductivity were revealed. These properties make graphene very attractive to be applied as additive in composite materials e.g. to increase strength and conductivity compared to the pure matrix material. In this study graphene nano platelets (GNP) in contents of 0. 5%, 1.0 % and 1.5 % were added to pure (99.7 %) aluminum powder and dispersed via EIRICH mixer method. This method is very appealing since homogenous mixtures can be achieved in significantly lower time when compared to e.g. the ball milling process. After subsequent cold compaction the composite materials were extruded with three different extrusion ratios. The influence of GNP content and extrusion ratio on the specific extrusion pressure is characterized as well the resulting rod surface quality, respectively. The effects of GNP content and extrusion ratio on homogeneity of graphene dispersion in the aluminum matrix, the relative density of the composite as well as hardness were also investigated.

Significant Improvement of Anticorrosion Properties of Zinc-Containing Coating Using Sodium Polystyrene Sulfonate Noncovalent Modified Graphene Dispersions

High-quality graphene zinc-containing anticorrosive coatings are highly and urgently desirable for effective, economical anticorrosion of metals and alloys in industrial products. The realization of such coatings is, however, hindered by the dispersibility and compatibility of the graphene in them. This work reports a novel direct modification of graphene using sodium polystyrene sulfonate (PSS) without reduction of graphene oxide, leading to homogeneous dispersion of graphene in water. The agglomeration of graphene is prevented thanks to the formation of π−π interaction between PSS and graphene sheets. Such graphene dispersion can effectively improve the anticorrosion performance of the zinc-containing epoxy coatings. With the addition of graphene modified by PSS into the 20% zinc-containing epoxy coating (graphene is 0.05% by weight of the coating), its anticorrosion properties revealed by both electrochemical characterization and the neutral salt spray tolerance analysis are rather close to those of 60% zinc-containing epoxy coating. These results demonstrate that direct PSS modification is an effective method for graphene dispersion and thus open a pathway to achieve graphene zinc-containing anticorrosive coatings with high performance.