The synergistic effects of a unique blend of carboxylic acid functionalized multi-walled carbon nanotubes and alkylamine functionalized graphene powder on the strength and stiffness properties of epoxy resins

Epoxy resins are indispensable materials in the manufacture of composite materials utilized in many industries, especially the automotive and aircraft. The novel hybrid nanocomposites modified with functionalized carbon nanomaterials are considered practical, economic and profitable solutions in the production of novel hybrid polymer composites with large mechanical performance utilized in such modern engineering applications. In regard to this, the evolution of the mechanical performance of a novel type of epoxy resin LR 285 utilizing unique hybrid mixtures compounded of carboxylic acid functionalized multi-walled carbon nanotubes (f-MWCNT) and alkylamine functionalized graphene powder (f-Gr) has been investigated in this study. The synergistic effects of these multifunctional carbon nanomaterials on the strength and stiffness properties of novel hybrid epoxy nanocomposites were demonstrated and compared. Three categories of nanocomposites have been prepared, namely: f-MWCNT/epoxy nanocomposites, f-Gr/epoxy nanocomposites, and novel hybrid f-MWCNT-f-Gr/epoxy nanocomposites. The samples were dispersed and fabricated utilizing a combination of mechanical stirring, ultrasonication, and shear mixing techniques at balanced geometric weight ratios (0.1wt.%). Transmission electron microscope (TEM) and scanning electron microscope (SEM) were utilized to verify the uniform dispersion and synergistic effects of multifunctional carbon nanomaterial in the epoxy matrix, and the mechanical fracture mechanisms of nanocomposites at failure regions for the tensile samples. The results showed the highest increase in the tensile strength and flexural strength at 32% and 34% for the novel hybrid f-MWCNT-f-Gr/epoxy nanocomposites, 26% and 28% for the f-MWCNT/epoxy nanocomposites, and 19% and 25% for f-Gr/epoxy nanocomposites, respectively compared with pure epoxy composites. The tensile modulus and flexural modulus also improved by 18% and 24% for the hybrid f-MWCNT-f-Gr/epoxy nanocomposites, 26% and 20% for the f-MWCNT/epoxy nanocomposites, and 17% and 14% for the f-Gr/epoxy nanocomposites, respectively. The strength and stiffness properties of f-MWCNT/epoxy nanocomposites were superior to f-Gr/epoxy nanocomposites. The mechanical fracture mechanisms in the hybrid f-MWCNT-f-Gr/epoxy nanocomposites increased due to the synergistic effects of hybrid multifunctional carbon nanomaterials into the epoxy resins. This led to further enhancements in the mechanical properties of the novel hybrid nanocomposites, precisely the strength.