SWCNT-based nanocomposites

SEM image of the fracture surface of 5.7 vol% SWCNT-Fe-Al203 composite densified by spark plasma sintering (SPS) of a mixture of nanometric alumina and ropes of SWCNTs. Reprint from Nature Materials, No. 2, 2002, pp. 38-42, Zhan G.-D., Kuntz J.D., Wan J. and Mukherjee A.K., Single-wall carbon nanotubes as attractive toughening agents in alumina-based nanocomposites, with the permission of Nature Materials and of the authors (http // www.nature.com/nmat/index.html). 

As shown in Table 5.1, the percolation thresholds in both SWCNT-and MWCNT-based nanocomposites of iPP-g-MA and PS roughly... 

Although the influence of the aspect ratio of the CNTs on the electrical percolation threshold indisputably is felt, we only see relatively small differences in the percolation thresholds for SWCNT-and MWCNT-based nanocomposites. The earlier mentioned viscosity effect and the favorable combination of surface tensions in the case of iPP and the CNTs play a role as well. But the overruling reason for the low percolation threshold of the PP-based composites is without doubt the intrinsic conductivity of the iPP that was used in this study, allowing a relatively large distance between neighboring CNTs and still enabling the electrons to travel through the matrix from one tube to another effortlessly. 

Based on TGA and elemental analysis, up to one in 20 nanotube carbons (5 %) has been found to possess an aryl addend [174], For the preparation of PS-CNT nanocomposites, the same authors functionalized SWCNTs by in-situ generation of a diazonium compound from 4-(10-hydroxydecyl)aminobenzoate [175], From rheology data it was suggested that the reinforcement and dispersibility of the thus functionalized SWCNT-composites were improved over PS composites with pristine SWCNTs. 

Sanchez studied the functionalization of oxidized SWCNTs and MWCNTs dispersed in thermoplastic elastomers based on poly(butylene terephthalate) (PBT)/ poly(tetramethylene oxide) (PTMO). These nanocomposites showed good dispersion and enhancement in thermo-oxidative stability [27]. 1 % of pristine multi-walled carbon nanotube (MWCNTs) were dispersed in silicon rubber. The SR nanocomposites showed 28 % better thermal stability and 100 % improvement in the ultimate tensile strength is achieved as compared with the pristine polymer matrix counterpart [28]. Also ionic liquids have been tested to improve the dispersion and thermal stability of MWCNTs in polychloroprene rubber (CR) showing improvement in these properties [29]. On the other hand the effect of carbon nanofiber on nitrile rubber was studied. It has been found that the nanofiber increase the thermal stability and decrease the flammability [4]. 

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