SWNT/epoxy composite

Figure 14.2. The mechanical properties of 0.5 wt% SWNT/Epoxy composites (a) tensile test of neat epoxy resin (b) tensile test of pristine-SWNT/epoxy ...

Figure 14.4. SEM images of pristine and epoxy grafted SWNT reinforced nanocomposites (a) pristine SWNT/epoxy composite and (b) epoxy grafted SWNT/epoxy composite (11).

The cross-section of the nanocomposites was examined by SEM (JSM-7401F) and shown in the Figure 14.12. For the p-SWNT/ epoxy composite, the CNTs tend to aggregate together and form large-diameter ropes. The phenomena of pullout can be observed. However, cut-SWNTs were well dispersed in the epoxy resin and... 

In another work, SWNT-epoxy composites gave dT/dFf of 107.3 GPa. However, PAMAM-O-functionalised SWNT-epoxy composites had a higher dr/dFf of 153.6 GPa. In this paper, the authors used the Halpin-Tsai equation to predict the modulus of fibre reinforced composites.The experimental values were only half of their model prediction. The reason for this was that most of the SWNTs in epoxy showed significant curvature. If the experimental values of their work were scaled up, their theoretical maximum values would be dI7dFf 300 GPa, which is in excellent agreement with previous theoretical predictions. 

Finally, Li et al studied SWNT-epoxy composites by nano-hardness testing. They observed an increase in modulus from 4 to 7 GPa with 5 wt% SWNT (d T/dFf 94 GPa). Increases in hardness from 0.35 to 0.45 GPa were also observed. 

Moniruzzaman M, Du F, Romero N and Winey K I (2006) Increased flexural modulus and strength in SWNT/epoxy composites by a new fabrication method, Polymer 47 293-298. 

Another parameter influencing the mechanical properties of nanotube composites is the CNT alignment. The effects of CNT alignment on electrical conductivity and mechanical properties of CNT-polymer nanocomposites have been discussed in a number of researches [118-120]. For example, it has been reported that with increasing CNT alignment, the electrical and mechanical properties of the SWNT-epoxy composites increased due to an increased interface bonding of CNTs in the polymer matrix [119],... 

The S-N data of die SWNT/epoxy composite is shown in Fig. 13.11. Also included in the figure is the tensile strength data of SWNT, obtained previously. Since the SWNT volume fraction varied from sample to sample, stress on SWNT cannot be inferred directly if die composite stress were used in the S-N plot. Therefore, the maximum cyclic stress of SWNT, calculated using rule-of-mixture, is plotted against the number of cycles to failure of the composite. The Young s modulus of SWNT was estimated as 800 GPa, and the maximum cyclic stress of SWNT was calculated to be between 5.37 and 24 GPa. 

Using a surfactant to improve the dispersion of CNTs may be problematic, since the surfactant exists in the resultant nanocomposite and might deteriorate the properties of the product. For example, Bryning and co-workers reported that the thermal conductivities of the surfactant-SWNT/epoxy composites were much lower, while the interfadal thermal... 

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