Effect of sonication on thermo-mechanical properties of epoxy nanocomposites with carboxylated-SWNT

In this work, a 2(k) factorial design was used to determine the interaction between sonication time, ultrasound amplitude, and carboxylic-functionalized single-walled carbon nanotubes (c-SWNT) content and their effect on the tensile, dilatometric, and dynamic-mechanical properties of casted epoxy nanocomposites reinforced with c-SWNTs. The nanocomposites were prepared with the help of a solvent (tetrahydrofuran) to reduce resin viscosity. Tensile strength increased with sonication for higher amplitudes and shorter times (20 min). The addition of 0.25 wt% c-SWNT enhanced the mechanical properties, increasing the Young's modulus up to 30% in comparison with neat epoxy prepared under the same conditions. Dilatometry tests showed that shrinkage takes place at the epoxy glass transition, while dynamic-mechanical analyses confirmed the tensile results and suggested that the presence of nanotubes yielded a more homogeneous epoxy resin network, probably due to the minimization of residual solvent. (C) 2009 Elsevier B.V. All rights reserved.