Carbon nanotubes based composites with high dielectric constant and low loss

Recently, an extraordinary increase has been found in dielectric constant of the composites containing electrical conducting granules. Multiwalled carbon nanotubes (MWNTs) are selected as the conducting filler due to their large aspect ratio and unique physical properties, in particular electrical and mechanical. In this research, the dielectric properties of the functionalized multiwalled carbon nanotubes/BaTiO₃/Polymer composites are studied. Ball-milling equipment was used to fabricate mechanically treated composite fillers which were composed of BaTiO₃ nanoparticles and MWNTs. The hybrid films fabricated by incorporating these composite fillers in a Bismaleimide-triazine matrix had a high dielectric constant (Dk) above 50 and a significantly low loss, less than 0.02 at 10 Wt. % filler loading. However, the ratio of CNT to BaTiO₃ was very low, i.e. 1:10 MWNTs to BaTiO₃ content. We studied the effect of various loading ratios of MWNTs to BaTiO₃, which led to find out the percolation threshold in the hybrid film. Characteristics including material components, dielectric constant and loss, and topography at dielectric interfaces are compared. The effects of ball milling were investigated. The experimental results suggest that the dielectric properties of the hybrid films containing MWNT/BaTiO₃ as fillers can be improved significantly by tailoring the ratio of CNT to BaTiO₃ and refining the ball-milling process. This novel hybrid film composed of the composite filler and Bismaleimide-triazine (BT resin) matrix can be used as embedded capacitor material.