Recent Advances in Carbon Nanotube-Reinforced Epoxy Composites: Enhancing Tensile Strength through Nanoscale Reinforcement

Introduction:
Carbon nanotube (CNT)-reinforced epoxy composites have emerged as high-performance materials due to their ability to significantly enhance mechanical, thermal, and electrical properties. Their nanoscale dimensions, high aspect ratio, and exceptional tensile strength make CNTs ideal candidates for improving load-bearing capacity and structural integrity in epoxy matrices, with applications spanning the aerospace, automotive, and structural engineering industries.

Methods:
This review synthesizes findings from over a dozen recent studies that examined the effects of varying CNT concentrations, functionalization, dispersion techniques, and hybridization with other nanomaterials such as graphene nanoplatelets (GNPs). Data were analyzed in terms of the following key mechanical indicators: tensile strength, flexural strength, compressive strength, fracture toughness, impact resistance, and elastic modulus.

Results:
Significant mechanical enhancements were observed with optimal CNT loadings. A 0.5 wt% CNT addition improved transverse tensile strength by 32.7% and modulus by 9% . At 2.0 vol%, tensile strength and modulus increased by 26.7% and 21.5%, respectively. Functionalization with amino groups led to a 42% improvement in tensile strength and 95% in fracture toughness. Flexural strength rose by 44% and flexural modulus by 16% with 1.5 wt% COOH-MWCN. Synergistic reinforcement using CNT/GNP hybrids improved impact strength by 69%, while thermal stability increased by 130%. Optimal mechanical performance was typically achieved at CNT concentrations between 0.15 wt% and 0.8 vol%.

Conclusion:
CNT incorporation markedly enhances the mechanical properties of epoxy composites through improved stress transfer, crack deflection, and interfacial bonding. Functionalization and hybridization further amplify these effects. However, uniform dispersion and optimal loading remain critical for maximizing benefits. Future research should focus on scalable processing methods and hybrid architectures to overcome current challenges and expand industrial adoption.