Electrical Properties of Insulator-Conductor Composites

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The main objective of this project is to investigate the electrical properties of insulator-conductor composites using dielectric and impedance spectroscopy as the primary experimental tool and finite element modeling as the primary computer simulation tool. A series of carbon black-polymer composites with varying volume fractions will be fabricated and tested. Once the percolation thresholds have been identified, a large number of samples with the critical volume fraction of carbon black will be prepared and tested. Multiplane analysis of the dielectric functions (permittivitty, impedance, electric modulus and admittance) will also be done and modeled for all samples tested. The microstructure of all measured samples will be evaluated and quantitative correlations between the electrical data and the microstructural parameters will be made (e.g. size, distribution, connectivity). The microstructural results will be used as input for the finite element modeling to further refine the interpretation. It is expected that this project will help determine the significance of the percolation parameters as they relate to the actual microstructure of materials. This project will train up to 3 graduate students in this subject matter.%%%Percolation in conductor-insulator mixtures is the subject of this project. Distribution of telephone lines in a network helps explain percolation. The basic concept is that if all the necessary connections are made, a phone call placed in Vancouver will reach Atlanta instantaneously. If any connections are broken or are inoperative, the phone call does not complete and the desired communication is broken. This concept can be applied to many other problems in a variety of fields. In this project, percolation will be studied by evaluating the electrical conductivity of mixtures of insulating and conducting particles. Even though percolation has been studied for many years, most previous work has only considered direct current behavior. The main objective of this project is to evaluate the effect of frequency (alternating current) on the percolation behavior. Both experimental measurements and computer simulations of idealized insulator-conductor mixtures will be used. This project will train up to 3 graduate students in this subject matter.***