analyse to reinforce epoxy systems. On comparing between nanodiamond–epoxy and CNT– epoxy composites at related nanofiller loadings in the low concentration range exhibit a significant increase in glass transition temperature, 37 °C and 17 °C for nanodiamonds and carbon nanotubes, respectively192. The fracture surfaces of both composites indicate a superior resistance to crack the propagation as compared to neat epoxy. Tensile characteristics of nanodiamonds – and carbon nanotubes–epoxy composites indicate the improvement of 6.4% and 2.9%, respectively. The nanocomposites also show 41% increase in microhardness for nanodiamonds and 12% for carbon nanotubes. The authors conclude that at identical nanofiller concentrations in the range 0.1–0.5 wt.% nanodiamonds show superior improvement as compared to the carbon nanotubes in epoxy matrix composites. For further enhancement the mechanical properties of the epoxy, nanodiamonds – epoxy composites with nanodiamonds content upto 35 vol.% were produced193. Hardness and Young’s modulus of these composites calculated by nanoindentation which was higher by 300% and 700% respectively, reaching modulus values upto 20 GPa and resulting the increased scratch resistance. The traditional view, where a polymer is considered as the matrix and nanoparticles are considered as the filler, need to be reversed in situations where the nanofiller is present in high concentrations.
At such high nanodiamonds loadings as indicated above, the composite material should be rather considered as a nanodiamonds network infiltrated by a polymer acting as a binder. Direct contacts between the nanodiamonds particles in such composites result the modified thermal conductivity194. It is essential to emphasize that due to their small sizes, shorter interparticle distances and direct contacts between nanodiamonds are attain at lower nanodiamonds contents compared to larger nanofillers, e.g., 10 nm diameter silica. Tribological studies indicate that an alumina counter body can harm by the nanodiamonds –epoxy agglomerates hold within these composites, suggesting very high hardness of the agglomerates, which can eventually replace micron-sized diamond particles in drilling and cutting tools. Average macroscale friction coefficients of epoxy composites carrying 7.5 vol.%