Electrical Properties and Scaling Behavior of MWCNT-Soda Lime Silica Glass

Multiwall carbon nanotube (MWCNT)-soda lime silica glass composites were prepared by the direct mixing method. The dielectric properties of the composites were studied to explore the effect of MWCNT content on the conduction and relaxation mechanisms in such composites. A gradual increase in the direct-current (dc) conductivity sigma (dc) was observed up to 7 wt.% MWCNT, with a sharp increase in sigma (dc) for the 10 wt.% sample. Such behavior was related to the increase of internanotube connections. The correlation between sigma (dc) and the nanotube loading p followed the fluctuation-induced tunneling (FIT) model, which can be described by the equation, ln sigma (dc) ae p (-1/3). The alternating-current (ac) conductivity exhibited two distinct regimes: (i) a low-frequency plateau and (ii) a high-frequency dispersion regime. The switchover frequency between the two regimes indicated the conductivity relaxation. The onset frequency shifted to higher frequencies with increasing MWCNT content, which was related to connectivity improvement. Investigating the universality of the ac conductivity of these composites, it was found that the data obtained followed a Rolling scaling model. The obtained master curve revealed that the conductivity relaxation can be considered a temperature-independent process. The frequency dependence of the ac conductivity dielectric constant followed the intercluster polarization model.