Introducing a uniform distribution of carbon nanotubes into a polymer matrix can yield property enhancements that go beyond that of a simple rule of mixtures. The challenge is to take full advantage of the exceptional properties of carbon nanotubes in the composite material. Carbon nanotubes are ideal reinforcing material for polymer matrices dur to their remarkable properties. However, property improvements are not significant due to poor interfacial bonding and severe agglomeration. The present study is focused primarily upon the mechanical properties of fiber-reinforced polymer composites containing graphene-carbon nanotube hybrid materials. The polymer composites utilize nanotechnology enhancements to provide advantageous durability and structural stability improvements over conventional fiber-reinforced polymer composites. The effect of hybrid material weight fraction on the modulus of elasticity and hardness is evaluated. Stress-strain responses of the composite tensile deformation are illustrated and the effect of strain on the bond order parameters is investigated. The present study aims to explore how to effectively improve the mechanical properties of polymers by utilizing graphene-carbon nanotube hybrid materials. Particular emphasis is placed upon the effect of weight fraction on the mechanical properties of polymer composites reinforced with graphene and carbon nanotubes. The results indicate that graphene-carbon nanotube multi-stack three-dimensional architectures can overcome the limitations and restricted performance typically encountered with carbon-based materials by using the combined strategies of three-dimensional architecture and low-dimensional nanomaterial characteristics. Poor dispersibility greatly affects the characteristics of the polymer composites. The modulus of elasticity of the polymer composite is enhanced as compared to the neat polymer. The hybrid material exhibits great improvements in hardness and yield strength and major deteriorations in strain at break. The carbon nanotubes exhibit no preferred orientation and are approximately random. The doping permanently increases the charge concentration in semiconducting carbon nanotubes present in the film, thereby decreasing the sheet resistance of the network. The ability to strengthen polymers is limited by the strength of interfacial bonding. The polymer composite differs from a conventional carbon-fiber composite where there is a much higher interface area between reinforcing carbon and polymer matrix phases.

Keywords: Graphene; Carbon; Composites; Polymers; Fibers; Hardness