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

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

The Impact of Blue Inorganic Pigments on the Microwave Electrical Properties of Polymer Composites

“…The conjugation of both conditions permits us to conclude that the cavity can be used up to variations of Δ f / f 0 of 0.56% and Δ(1/Q) of about 4.2 × 10 −3 . If the measurements overcome this limit, the sample volume should be reduced until the results falls into the linear regime [20].…”

Microwave dielectric properties of (Bi1−xFex)NbO4 ceramics prepared by the sol–gel method

“…We measured the shift in the resonant frequency of the cavity, Δf, caused by the insertion of the sample, which can be related to the real part of the complex permittivity, ε 0 , and the change in the inverse of the quality factor of the cavity, (1/ Q), which gives the imaginary part, ε″. The relations are simple when we consider only the first order perturbation in the electric field caused by the sample [10][11][12][13],…”

Sol-Gel Synthesis, Structural Characterization and Microwave Dielectric Properties of Bismuth Niobate Modified by Iron Inclusion

“…Considering only the first-order perturbation in the electric field caused by the sample [30][31][32][33],…”

“…The permittivity values of a sample can be obtained through the changes in the resonant frequency, Δf, and in the inverse of the quality factor Δ(1/Q) of the resonant cavity, when introducing a sample in the cavity, where the electric field is maximal [30][31][32][33].…”