Change of mechanical and physical properties of an epoxy resin induced by carbon nanotube presence

Blends of carbon nanotubes (CNTs) and polymeric matrices became common due to their mechanical and physical properties. In particular, the epoxy resin matrix is an important thermoset polymer widely used for the manufacturing of advanced nanocomposites ranging from microelectronics to aerospace. The uniform dispersion of the CNTs in the epoxy matrix is a crucial point since they tend to cluster or agglomerate as bundles of micrometer sizes losing all the advantages resulting from the use of a nanoscale filler. Thus, the improvement of CNT dispersion in the polymer matrix is one of the major still unsolved issues. Besides, the capability to create a strong interfacial bond between the polymeric matrix and the CNT reinforcement is another important goal to improve the ultimate mechanical or physical properties in the nanocomposite. With this aim, in the present paper we studied the effect of improved dispersion of multi-walled CNTs in the epoxy based nanocomposites. So, pristine, carboxylic and amino functionalized multi-walled CNTs were used as nanofillers in the epoxy-based composites. Epoxy/CNTs composites were characterized by HRTEM, SEM, mechanical flexural and Izod resilience tests. These tests were performed both on the neat materials and on the nanocomposites in order to highlight the CNTs dispersion degree in the composite and/or the presence of interfacial bonds between the CNTs and the epoxy matrix. Experimental results have shown that the presence of chemical groups have improved the CNTs dispersion in the polymeric matrix, in particular for the amino ones. As a consequence, the mechanical and physical features are higher than the neat epoxy or the epoxy filled with pristine CNTs.