The use of graphene materials, i.e. graphene oxide, reduced graphene oxide, graphene nanoplatelets and their functionalized forms as fillers of epoxy composites, is reviewed. The purpose of the time- and reagent consuming functionalization methods of graphene materials is justified by the noticeable improvement of dispersity and adhesion of the graphene sheets to the epoxy matrix, which affects the final properties of graphene-epoxy composites. The state-of-the-art of multifunctional graphene-epoxy composites developed over the last years is critically reviewed. The influence of the graphene filler structure and dispersion preparing procedure on the morphology of epoxy-graphene composites and, consequently, their electrical and thermal conductivities, mechanical strength and flame retardant characteristics is considered. An evolution from epoxy-graphite microcomposites to epoxy-graphene nanocomposites is presented, showing the benefits of graphene materials for composites. Some recent works on the epoxy composites reinforced with hybrid graphene fillers and combinations of graphene materials with other fillers are described.

In this paper, we investigated theimpact of glassy carbon (GC) reinforcement oncrystal structure and the mechanical performance of high-density polyethylene (HDPE). We made composite samples by mixing HDPE granules with powder in ethanol followed bymelt mixing in a laboratory extruder. Along with the investigated composite, we also prepared samples with carbon nanotubes (CNT), graphene (GNP) and graphite (Gr) to compare GC impact with already used carbon fillers. To evaluate crystal structure and crystallinity, we used X-ray diffraction (XRD) and differential scanning calorimetry (DSC). We supported the XRD results with a residual stress analysis (RSA) according to the EN15305 standard. Analysis showed that reinforcing with GC leads to significant crystallite size reduction and low residual stress values. We evaluated the mechanical properties of composites with hardness and tensile testing. The addition of glassy carbon results inincreased mechanical strength incomposites with CNT and GNP.