Abstract
Graphene oxide (GO) is a commonly used additive to enhance the mechanical properties of epoxy polymers. The efficiency of GO can be significantly influenced by various parameters, such as the quality of GO and the homogeneity of its dispersion. Efficient dispersion of graphene within the epoxy medium can notably improve the mechanical properties of multifunctional polymers. This work aims to maximize the effect of GO on the mechanical properties of bio-based polymers by synthesizing high-quality GO and achieving efficient dispersion in the epoxy. To this end, we investigated the effect of adding solvents (acetone, THF) on the mechanical behavior of multifunctional bio-based polymers subjected to several types of static loading. Five different types of materials were examined: neat epoxy resin as the reference material, enhanced epoxy resin without solvent, enhanced epoxy with acetone solvent, enhanced epoxy resin with THF solvent, and epoxy resin enhanced with pure graphite powder. The concentration of GO or graphite was maintained at 0.5 wt%. The findings were analyzed using Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), and Raman Spectroscopy. A significant increase in the tensile strength of polymers filled with GO without solvent was observed compared to the enhanced materials with solvents. Additionally, the fracture toughness properties were improved. SEM analysis of the fracture surfaces revealed resin penetration into the graphene sheets, indicating strong bonding of the amino groups to the graphene oxide in the case of the enhanced epoxy resin without solvent. In contrast, in the enhanced epoxies with the two types of solvents, the bonding between the GO and epoxy appeared to be either deteriorated or destroyed. TGA analysis revealed that both the neat and GO-reinforced resins without solvent were thermally stable up to 360°C, beyond which the material began to melt and decompose. Raman spectra showed the vibrations of the epoxy ring during the curing process, with the intensity of the observed peaks indicating the quantity of free epoxides in the samples. Finally, it was revealed that the enhanced material with GO exhibited reduced intensity (fewer free epoxides) due to the connection of epoxides with the functional groups on the surface of the graphene oxide.