Martin-Gallego et al. Nanoscale Research Letters 2011, 6:610 http://www.nanoscalereslett.com/content/6/1/610 Page 3 of 7 Figure 1 Experimental setup. depends on their chirality [1]. However, to simplify the discussion, we assumed that the thermal conductance mainly occurs via a phonon conduction mechanism since the aim of this article is to provide a general description of the experimentally determined K. Table 1 presents the K measurements of the nanofluids only at 30°C as no significant changes with the tempera- ture were observed. The results indicate that MWNTs are the most effective carbon nanofillers to improve the K of liquid resins. Indeed, the K of the nanofluids gradu- ally increased as a function of MWNT content, reaching a 70% improvement at 1 wt.% loading. The better perfor- mance of MWNTs can be due to their lower specific sur- face area [SSA], as compared with SWNTs, and to the presence of the internal layers which enable phonon con- duction and hence minimize coupling losses. K of nano- composites is sensitive to the quality of the interfacial bonding between the filler and the matrix, intimately related to a phonon coupling mechanism. This mechan- ism is influenced by numerous factors such as the length of free path for phonons, the boundary surface scattering, the number of vibration modes, and the resistance to heat flow at the interface, known as Kapitza resistance [26]. In general, the Kapitza resistance increases with the SSA, decreasing the efficiency of phonon transport. A lower improvement was obtained with the acid-trea- ted carbon nanotubes (f-MWNTs), even though the functionalization decreases the SSA of the nanotubes. Figure 2 TEM images of nanofluids. (a) Resin loaded with 1 wt.% MWNTs and (b) with 1 wt.% FGS.