Effect of functional groups of multi-walled carbon nanotubes on the mechanical, thermal and electrical performance of epoxy resin based nanocomposites

This article concerns the effect of pristine, carboxylic and amino functionalized carbon nanotubes (CNTs) used as filler in epoxy based nanocomposites. The amount of CNTs was within the range 0.2-0.8 weight percentage. Their mechanical properties were investigated by means of flexural strength and resilience tests. The CNTs lead to an improvement of ductility and mechanical strength compared to the neat epoxy resin in the order: amino>carboxylic>pristine. The results of morphological, calorimetric, rheological and electrical conductivity tests suggest that this improvement is due to a good dispersion of the filler in the matrix and it occurs especially with low filler amounts (0.2-0.4wt%) of amino CNTs. In the nanocomposites realized with amino functionalized CNTs there is a interphase that creates a weak interfacial interaction between the filler and the epoxy resin. The thermal stability, as well as the electrical conductivity of resin, is not appreciably improved after the addition of either functionalized CNTs.