Synthesis and plasma surface functionalization of carbon nanotubes for using in advanced epoxy-based nanocomposites

In this study, thermal chemical vapor deposition (CVD) method was utilized to fabricate carbon nanotubes (CNTs) using an Fe/Al catalyst. Plasma enhanced CVD (PECVD) was applied to coat CNTs surfaces with a hydrophobic poly(hexafluorobutyl acrylate) (PHFBA) thin film. Then pure CNT and surface-modified CNT (f-CNT) were used as nanofillers at 0.5-3 wt% in bisphenol-A (DGEBA) and phenolic novolac types epoxy (EPN) resins to produce composite materials with superior properties. For characterization of both types of CNTs, FTIR, XRD, SEM, TEM and TGA analyses were performed. The morphologies of composites were examined via XRD and SEM. Thermal properties of composites were revealed by TGA. The influences of CNT surface functionalization and matrix type on the thermal, mechanical, electrical conductivity and surface wettability properties of composites were investigated. EPN based composites exhibited higher mechanical properties than that DGEBA based ones. At 1.5 wt% f-CNTs, the Young's modulus and tensile strength of the nanocomposites were found 6.9 +/- 0.50 GPa and 141.0 +/- 7.8 MPa, respectively using DGEBA matrix; 8.7 +/- 0.59 GPa and 153.4 +/- 7.9 MPa respectively, using EPN matrix. Composites electrical conductivity increased with increasing both type CNTs amount and reached a maximum value of 10(-4) S/m and 10(-6) S/m at 3 wt% of neat and f-CNTs contents.