CNT/epoxy composites

CNT can markedly reinforce polystyrene rod and epoxy thin film by forming CNT/polystyrene (PS) and CNT/epoxy composites (Wong et al., 2003). Molecular mechanics simulations and elasticity calculations clearly showed that, in the absence of chemical bonding between CNT and the matrix, the non-covalent bond interactions including electrostatic and van der Waals forces result in CNT-polymer interfacial shear stress (at OK) of about 138 and 186MPa, respectively, for CNT/ epoxy and CNT/PS, which are about an order of magnitude higher than microfiber-reinforced composites, the reason should attribute to intimate contact between the two solid phases at the molecular scale. Local non-uniformity of CNTs and mismatch of the coefficients of thermal expansions between CNT and polymer matrix may also promote the stress transfer between CNTs and polymer matrix. 

Fig. 8.4 Plots of relative change in electrical resistance against tensile deformation of a CNT/epoxy composite (a) shows the various characteristics of the piezoresistivity of nanocarbon networks linear resistance change in the elastic regime, nonlinear region after inelastic deformation and the permanent electrical resistance drop due to plastic deformation (image adapted from [30]) ...

Figure 14.11. Tensile strength of CNT/Epoxy composites with the 0.5 wt% SWNT loading (a) neat epoxy resin, (b) pristine SWNT/epoxy, (c) cut-SWNT/Epoxy (11).

Carbon nanomaterials themselves also have good electrocatalytic activities, thus their composites with insulating polymers could also be used as counter electrodes of DSSCs. For instance, the CNT/epoxy composite films with CNTs being aligned to be perpendicular and parallel to the film surface have been investigated. However, the performances were lower than bare CNTs. They can also be composited with elastic polymers to be used for stretchable electronic devices. 

As mentioned earlier, noncoyalent functionalisation of CNT can be achieved by wrapping the matrix polymer around the nanotube surface, which improves the composite properties through various specific interactions. In their turn, these interactions can improve the properties of nanotube composites. In this context, researchers have improved the electrical and thermal conductivity in CNT/epoxy composites. 

Gojny, F.H., J. Nastalczyk, Z. Roslaniec, and K. Schulte. 2003. Surface modified multi-walled carbon nanotubes in CNT/epoxy-composites. Chemical Physics Letters 370(5-6) 820-824. 

Kim J A, Song D G, Kang T J and Young J R (2006) Effects of surface modification on rheological and mechanical properties of CNT/epoxy composites, Carbon 44 1898-1905. 

Figure 5 Young s moduli of the CNT/epoxy composite for different combination of interphases, SWCNTs (blue) and DWCNTs (red). Designation of the combination of interphases with letters A-E one letter refers to SWCNTs, two letters to DWCNTs, the first letter stands for the epoxy/CNT interphase and the second letter for the interwall phase. Shear stiffness of the interphases A=5 MPa/nm, B=50 MPa/nm, C=500 MPa/nm, D=75 MPa/nm, E=150 MPa/nm.

Figure 10.4 (a) Schematic and SEM images of CNT preforms with [0] and [0/90] alignment of CNT sheets, (b) Schematic of the RTM process for fabricating CNT-epoxy composites. Reprinted from Ref [51] with permission from Elsevier, Copyright 2010. 

CNT/Epoxy Composites Dispersion, Matrix Bonding, and Functionalization... 

Figure 11. Transmission electron micrograph of a CNT/epoxy composite. Oxidation followed by sonication leads to an Improved dispersion. ...

Gintert MJ, Jana SC et al (2007) A novel strategy for nanoday exfoliation in thermoset polyimide nanocomposite systems. Polymer 48 4166 Gojny FH, Nastalczyk J et al (2003) Surfaa modified multi-walled carbon nanotubes in CNT/epoxy-composites. Chem Phys Lett 370 820 Gojny FH, Wichmann MHG et al (2004) Carbon nanotube-reinforced epoxy-composites enhanced stiffness and fracture toughness at low nanotube content. Composites Sci Tech 64 2363 Gojny FH, Wichmann MHG et al (2006) Evaluation and identification of electrical and thermal conduction mechanisms in carbon nanotube/epoxy composites. Polymer 47 2036... 

Long-term performance of unidirectional CNT/ epoxy composites... 

---