4. Conclusions
The present study is focused primarily upon the mechanical properties of
fiber-reinforced polymer composites containing graphene-carbon nanotube
hybrid materials. The graphene-carbon nanotube fiber-reinforced polymer
composites utilize nanotechnology enhancements to provide advantageous
durability and structural stability improvements over conventional
fiber-reinforced polymer composites not containing graphene or carbon
nanotubes. The effect of the 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 for the
fiber-reinforced polymer composite. The major conclusions are summarized
as follows:
- 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
carbon nanomaterial characteristics.
- The poor dispersibility of graphene-carbon nanotubes greatly affects
the characteristics of the composites which they form with the polymer
matrices into which they are introduced.
- The modulus of elasticity of the 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.
- Though graphene and carbon nanotubes have extraordinary mechanical
properties, their ability to strengthen polymers and epoxies is
limited by the strength of interfacial bonding.
- The graphene-carbon nanotube fiber-reinforced polymer composite
differs from a conventional carbon-fiber composite in that there is a
much higher interface area between reinforcing carbon and polymer
matrix phases.