Modelling and dielectric behavior of ternary composites of epoxy (BaTiO

The aim of this article is to explore materials made of polymer-titanate composites for application towards the size reduction of high frequency electronic components. A study has therefore been done on the dielectric effect of composites made of an epoxy matrix loaded with a mixture of barium titanate and calcium titanate. The effects have been quantified according to volume fraction of load. Results obtained from time domain reflectometry have been compared to modelling predictions from the generalized Lichtenecker law. Low frequency analysis (in the range DC — 500 MHz) has also been performed throughout this work, and it has primarily concentrated on conductivity behaviour which may be attributed to the effects of a percolation process. The study has confirmed the validity of the ternary mixture law being applied in order to predict the electromagnetic behaviour of the composite material. This material family may therefore find use in microelectronic applications and in the miniaturization of circuit components (substrates, components, cavities, antennas, etc.)

Dielectric behavior of ternary composites of epoxy/BaTiO

The work we present in this article is an investigation of the optimal dielectric behaviour of a ternary composite based on a mixture of epoxy resin, titanates and oxides. Titanates are known by their capacity to provide high dielectric constant values that make their use very important in system of telecommunication, transmission microwaves, and in integrated circuit technology. A comparative study is established on two types of oxides added to titanates of either calcium, barium, or magnesium following different proportions. The protocol used to characterise different mixtures is the Time Domain Reflectometry (TDR). The acquired results show a good concordance between the experimental values of the ternary mixture dielectric constant and the theoretical models deduced from the Lichtenecker modified law. The copper oxide (CuO) is revealed to be more influential than the magnesium oxide (MgO) on the added titanate because of an insignificant dielectric behaviour that the latter presents. On the other hand, the linear behaviour of $\varepsilon_{s}$ appeared with a CuO concentration round about 15% in a RE.BT.CuO mixture. For a fixed barium titanate fraction (27%) this linear evolution is located between the upper and the lower limits derivative from direct and inverse Wiener laws

Dielectric study of primary amines from room temperature down to −180 °C and from 10 kHz up to 35 GHz

The aim of this paper is to present the NH2 dielectric behaviour in the primary amines for the importance it bears in the interaction of aminoacids and proteins and their influence in the electric conduction processes. For that, the dielectric properties of 1-propylamine, 1-butylamine and 1-pentylamine have been studied. Measurements were performed between room temperature and −180 °C in the low frequency range and micro-waves measurements were done between −40 °C and 25 °C. The isofrequency recordings of dispersion ε′ and absorption ε′′, for these three primary amines, show clearly the relaxations and the effect of the aliphatic chain length

Relaxation diélectrique de solutions aqueuses d'éthylène glycol aux micro-ondes

Les auteurs présentent des séries de résultats de mesures en hyperfréquences concernant les permittivités diélectriques de l'éthylène-glycol et de ses solutions aqueuses à 20 ○C, pour diverses concentrations, entre 100 MHz et 20 GHz. Ils ont utilisé trois techniques différentes : des mesures précises à trois fréquences fixes parfaitement stabilisées en guides d'ondes 1,20 ; 3,26 et 9,45 GHz par une méthode réflectométrique ; des mesures utilisant l'analyseur de réseau vectoriel HP 8510 B fonctionnant entre 45 MHz et 20 GHz ; et des mesures par réflectométrie en domaine de temps (R.D.T.). Ils montrent que l'analyse de la relaxation peut être représentée par la superposition de deux domaines de dispersion de type “Debye" pour l'éthylène glycol et ses solutions aqueuses. Par décomposition spectrales, ils déduisent la permittivité statique, les temps de relaxation et la permittivité à fréquence infinie à 20 ○C? Ils proposent que ces mélanges soient de type associé-associé suivant le concept de Schallamach, qui montre que pour des mélanges de ce type, il existe des relaxations d'agrégats contenant les deux types de molécules plutôt que des relaxations de molécules individuelles.