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ABSTRACT: Introduction. When developing a composite material, it is important to understand how the components included in its composition affect its properties. Fillers, by interacting with the matrix, can alter its initial structure, resulting in the composite acquiring characteristics different from the matrix. The high modifying ability of nanofillers is determined by their significant specific surface area. This allows for the total interfacial area between the matrix and the dispersed phase to be covered even with a relatively low concentration of particles, thereby enabling the use of a small amount of filler. Methods and materials. Composite materials with nano carbon fillers were investigated, including fullerenes, nanotubes, and graphene. Fractographic analysis of the tensile fracture surfaces of the samples was chosen to evaluate the structure of the composites, which allows determining the nature of the failure and the ability of the composite to restrain crack propagation. The microstructure of the composite materials, as well as the morphology of the reinforcing nano carbon fillers, were examined with a Tescan MIRA3 scanning electron microscope. Results and discussion. In a graphene composite, crack energy is dissipated through branching and elongation of the crack path. Carbon nanotubes, being embedded in the crack walls, hinder the opening of the crack edges. Crack energy is also consumed in overcoming friction forces during the extraction of nanotubes from the epoxy matrix. Agglomerates of fullerenes act as effective crack front arresters, forcing the crack to circumvent them, thereby creating new areas of fracture surfaces. This leads to an increase in the crack front length and the energy required for material failure. Conclusion. Adding nano-carbon fillers (graphene, CNT and fullerenes) as reinforcing components in the epoxy binder alters the structure. The study defines possible mechanisms for hardening of the composite materials due to adding the nano-carbon fillers. |
