Effect of a third component on the electrical properties of conducting polymer composites
01 Dec 1985-Journal of Materials Science Letters (Kluwer Academic Publishers)-Vol. 4, Iss: 12, pp 1445-1448
TL;DR: Resistance electrique de polymeres renforces par 2 types de charges (noir de carbone, silice ou argile) as mentioned in this paper, i.e.
Abstract: Resistance electrique de polymeres renforces par 2 types de charges (noir de carbone, silice ou argile)
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TL;DR: In this paper, the authors studied the ac electrical conduction of poly(methyl methacrylate)/carbon black composite of different carbon black (CB) filler concentrations (2, 6, 12 wt%).
Abstract: The study deals with the ac electrical conduction of poly(methyl methacrylate)/carbon black composite of different carbon black (CB) filler concentrations (2, 6, 12 wt%). The ac electrical conductivity was studied as a function of filler concentration, frequency in the range from 100 kHz to 2 MHz, and temperature in the range from 300 to 450 K. It was found that ac electrical conductivity increases by increasing both temperature and CB concentration. The observed overall mechanism of electrical conduction has been related to the transfer of electrons through the CB aggregations distributed in the polymer matrix. The observed increase in conductivity with CB concentration was interpreted through the percolation theory.
49 citations
TL;DR: In this paper, a fine-grained powder of BaTiO3 was placed in the polymerization reaction mixture of PANI/Barium titanate composites to obtain piezoresistivity properties.
Abstract: Conducting polyaniline/barium titanate (PANI/BaTiO3) composites exhibiting piezoresistivity properties have been synthesized by the in situ deposition technique by placing a fine grade powder of BaTiO3 in the polymerization reaction mixture. The polyaniline was formed preferentially on the ceramic particles giving a much higher yield for PANI than in absence of the BaTiO3 These composites exhibited piezoresistivity with the piezosensitivity being maximum at a certain composition. The current–voltage characteristics clearly revealed a nonlinear space charge controlled charge transport process. A large hysteresis in these characteristics was also observed which was dependent on the BaTiO3 content in a composite. The various results have been explained on the basis of the charge transport mechanism in the heterogeneous conducting material having insulating domains dispersed in it.
43 citations
TL;DR: In this article, the electrical properties of polyester elastomer filled with various metallic and ferrite fillers have been investigated as a function of temperature, frequency and filler concentration.
Abstract: The electrical properties, namely d.c. and a.c. conductivity, of polyester elastomer filled with various metallic and ferrite fillers have been investigated as a function of temperature, frequency and filler concentration. The temperature dependence of resistivity exhibited two regions of low and high activation energy (ΔE). The value of ΔE the lower temperature region (I) decreased while in the higher temperature region (II) it increased with the increase of work function of the metal used. Only in the case of ferrite-filled composites could a positive temperature coefficient of resistance be observed. The frequency dependence of conductivity revealed that there is a very large intergranular capacitance which was even more in the case of ferrite-filled samples than in metal-filled ones. The various results have been explained on the basis of Schottky barrier formation and the depletion regions formed near the polymer-metal interface.
37 citations
TL;DR: The AC-impedance and dielectric properties of hybrid polymer composites made up of epoxy (diglycidyl ether of bisphenol-A) matrix filled with various zinc oxide concentrations (0, 4.9, 9, 14.9 an...
Abstract: The AC-impedance and dielectric properties of hybrid polymer composites made up of epoxy (diglycidyl ether of bisphenol-A) matrix filled with various zinc oxide concentrations (0, 4.9, 9.9, 14.9 an...
36 citations
Cites background from "Effect of a third component on the ..."
...Therefore, more charge carriers may be able to ‘hop’ by tunneling, resulting in the decrease in the bulk resistance.(21,25,42,58,59) The conductivity of the prepared composites is apparently enhanced with increasing temperature as shown in Figure 8....
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TL;DR: In this paper, the authors deal with the measurements of the equivalent impedance, insertion loss (IL), and return loss (RL) of a conductive composite material called "Magnex DC" performed at microwave frequencies.
Abstract: This paper deals with the measurements of the equivalent impedance, insertion loss (IL), and return loss (RL) of a conductive composite material called “Magnex DC”, performed at microwave frequencies. It is found that the equivalent impedance of this composite material decreases as the frequency increases in the X-band (8–12.4 GHZ) and the IL of a 1.4 mm thick specimen is greater than 9 dB over the whole band. The utilization of this material in electromagnetic shielding is considered. Furthermore, results of the measurements performed on a tapered specimen are also reported.
33 citations
References
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TL;DR: In this article, it was shown that the electrical conductivity of carbon polyvinylchloride composites can be attributed to a novel mechanism of tunneling with potential-barrier modulation by thermal fluctuations.
Abstract: We present evidence that in carbon-polyvinylchloride composites, consisting of aggregates of carbon spheres (100-400 \AA{}) dispersed in the insulating matrix, the electrical conductivity can be ascribed to a novel mechanism of tunneling with potential-barrier modulation by thermal fluctuations. Theoretical consideration of the tunneling-probability modification by thermal fluctuating electric field across tunnel junctions yields expressions for the temperature and the field dependences of the conductivity in excellent accord with experimental results.
548 citations
479 citations
TL;DR: In this paper, high-density polyethylene and nickel powders of particle sizes Rp and Rm were mixed and compacted at room temperature under a pressure of 1000 kg/cm2 and the electrical resistivity of the compacts had a value of 1016 Ω cm unless the composition of metal reached a critical value, beyond which the resistivity decreased markedly by as much as twenty orders of magnitude.
Abstract: Powder samples of high‐density polyethylene and nickel of particle sizes Rp and Rm , respectively, were mixed and compacted at room temperature under a pressure of 1000 kg/cm2. Microscopic examination of polished sections of the compact, by reflected light, showed that the metallic particles did not penetrate the polymeric particles and that this resulted in a segregated distribution of metallic particles at high ratios of Rp/Rm . The electrical resistivity of the compacts had a value of 1016 Ω cm unless the composition of metal reached a critical value, beyond which the resistivity decreased markedly by as much as twenty orders‐of‐magnitude. This critical composition was found to decrease with an increase in the ratio Rp/Rm throughout the range studied of from 1 to 16. The general features of the dependence of electrical resistivity on composition of metal could be rationalized by reference to a model according to which small particles of nickel form a monolayer on the large particles of polymer in the mixture of powders. This arrangement was supposed to be but little changed during compaction and to result in a segregated distribution of metal which can be visualized as approximating to the accommodation of metallic particles on three mutually perpendicular sets of lattice planes. The critical composition for a sudden decrease in electrical resistivity was assumed to correspond to the first nonzero probability for infinitely long chains of contiguously occupied lattice sites.
445 citations
TL;DR: In this article, the electrical conductivity of carbon particle-filled polymers was measured as a function of carbon content to find a break point of the relationship between the carbon content and the conductivity.
Abstract: The electrical conductivity of carbon particle-filled polymers was measured as a function of carbon content to find a break point of the relationships between the carbon content and the conductivity. The conductivity jumps by as much as ten orders of magnitude at the break point. The critical carbon content corresponding to the break point varies depending on the polymer species and tends to increase with the increase in the surface tension of polymer. In order to explain the dependency of the critical carbon content on the polymer species, a simple equation was derived under some assumptions, the most important of which was that when the interfacial excess energy introduced by carbon particles into the polymer matrix reaches a “universal value”, Δg
*, the carbon particles begin to coagulate so as to avoid any further increase of the energy and to form networks which facilitate electrical conduction. The equation well explains the dependency through surface tension, as long as the difference of the surface tensions between the carbon particles and the polymer is not very small.
435 citations
TL;DR: In this paper, three distinct physical processes control electron transport in conductor-filled polymer systems: percolation, thermal expansion and quantum mechanical tunneling (possibly quantum fluctuation augmented) are discussed.
Abstract: This article contends that three distinct physical processes control electron transport in conductor-filled polymer systems. Percolation is required to explain the macroscopic conduction in the disordered medium. Quantum mechanical tunneling (possibly quantum fluctuation augmented) is needed to describe conduction between adjacent conductive particles at the microscopic level. And, thermal expansion is invoked to deduce constituent volume densities and microscopic tunnel lengths. Each of these mechanisms is given a mathematical form. The ansatz is used to predict resistivity vs. temperature and resistivity vs. conductor-filling fraction functions. Successes and deficiencies of the theory are discussed with respect to experimental data and theoretical considerations.
269 citations