Microwave dielectric properties of polybutylene terephtalate (PBT) with carbon black particles

Abstract

Abstract The synthesis of composites based on polymers containing carbon as additives is rather relevant because it has been found that applications in several industries are increasing, particularly due to their unusual mechanical and electrical properties. By choosing the adequate doping concentrations, we can precisely control the electrical properties in the microwave frequencies, in order to tailor the desired behavior. In this study, we present the results of the complex‐permittivity measurements, ϵ* = ϵ′ − í ϵ″, at 2.7, 5, and 12.8 GHz, on polybutylene terephtalate (PBT), with different concentration of black carbon particles, using the resonant‐cavity method. Measuring the shift in the resonant frequency of the cavity, Δf, caused by the insertion of the sample, we can calculate to the real part of the complex permittivity, ϵ′, while the measure of the change in the inverse of the quality factor of the cavity, Δ(1/Q), allow us to calculate the imaginary part, ϵ″. Maxwell–Wagner–Sillars (MWS) and Looyenga mixture laws are applied to the obtained results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 61–63, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20901