Enhanced Tensile and Flexural Properties in Carbon Nanotubes and Modified Carbon Nanotubes Added Carbon Fiber-Reinforced Epoxy Resin Thermoset Composites

In this study, carbon fiber (CF)/epoxy/multi-walled carbon nanotubes (MWCNTs) and CF/epoxy/modified MWCNTs-COOH (weight percentages were 0 and 0.5) were used to fabricate the thermoset composite materials with higher mechanical properties compared to the pristine. The thermoset composites were fabricated using vacuum infusion methods. The addition of MWCNTs on the microstructure of the laminates was studied by using a scanning electron microscope (SEM) and optical microscopy (OM). The samples with MWCNTs-COOH demonstrated an improvement of 26% tensile strength and 43% tensile modulus compared to the samples without MWCNTs. These enhancements were 16% tensile strength and 22% tensile modulus in samples with MWCNTs. The samples with MWCNTs-COOH demonstrated an improvement of 21% flexural strength and 36% flexural modulus compared to the samples without MWCNTs. These enhancements were 9.5% flexural strength and 22% flexural modulus in samples with MWCNTs. Scanning electron and optical microscopic examinations of fractured surfaces showed that the enhancement in the flexural characteristics of MWCNT/epoxy composites was attributed to the better interfacial properties caused by existence of the MWCNTs and MWCNTs-COOH in the epoxy matrix. The results of this research can be applied in advanced manufacturing of composite materials in Industry 4.0 in aerospace (such as parts of fuselage panels, skins and spars).