Dielectric Relaxation Mechanism of single-walled carbon nanotubes epoxy composites

The modification of carbon nanotubes (CNTs) with organic compounds especially with amines gained in the last years special attention due to particular applications as electromagnetic shielding of electronic devices [1-2]. Nevertheless intrinsic difficulties and unresolved issues related to the incorporation of carbon nanotubes as conductive fillers in polymer matrices and the interpretation of the processing behaviour have not yet been resolved. For example in the case of epoxy systems it was proposed that the source of conductivity is the presence of ‘‘ionic impurities’’ and hence it was assumed that a correlation should exist between the decreasing conductivity and the increasing extent of cross-linking and/or viscosity [3-5]. As previously reported [3-5] the hypotheses that conductivity always decreases and that ionic impurities are the only charge carriers in reactive systems whose mobility affords a direct measure of the advancement of reactions are restrictive. Of interest in the present work is to present a study on the effect of the nanotubes molecular architecture on specific dipole dynamics during the cure kinetic. The interaction of amine groups with CNTs would have a direct effect on the network for the following reasons: (1) the amine groups are electron donating and responsible for charge transfer to nanotubes; (2) they should affect the mean-square dipole moment. The principal objective of this study is to elucidate how a change in the aspect ratio of nanotubes affects the cure dynamics of epoxy/amine networks.