The present work was undertaken to enhance the productivity of manufacturing operations that involve heating materials by increasing the possibilities for electromagnetic heat processing of materials. The approach taken was to design a composite material with suitable mixture formulae to have prescribed electromagnetic loss characteristics.
Investigation began by surveying industrial uses of electro-magnetic energy in heat processing of materials. From applications, the survey shifted to electromagnetic properties of materials with focus upon dielectric properties of materials. Several techniques were considered for altering the dielectric properties of a lossless plastic and the approach chosen was to dilute the base plastic with a lossy particulate. Investigation continued in the area of dielectric properties of mixtures and theoretical calculations of dielectric constant and loss factor were compared for various mixture theories.
Dielectric samples were prepared and tested to compare theoretical mixture formulae calculations with experimental results of the dielectric constant and loss factor. Polystyrene was chosen for the base plastic because of its low loss VI characteristics and because it is relatively inexpensive and widely used. Aluminum was chosen for the loading material because of its loss characteristic and because a readily available supply of controlled shape and size existed. Three shapes ("sphere", disc, needle) of aluminum were compounded with the styrene at three (4, 11, 18) percent volume loadings. The mixtures were injection molded into dielectric specimen discs and silver electrodes were applied to the specimen faces.
Samples measurements were made with Hewlett-Packard impedance analyzers and a modified General Radio micrometer electrode at discrete frequencies up to 100 MHz. A lumped element circuit model was developed for the fixtures and the fringe capacitance was empirically derived. A control-C program was written to extract dielectric constant and loss factor of the sample from the measured values of impedance.
The results were compared with theory and discussed with respect to practical implications and continued work. Temperature rise of the loaded materials was predicted for localized irradiation with long wavelength electromagnetic energy for three filler types.
Library of Congress Subject Headings
Plastics in electrical engineering; Dielectrics; Electromagnetic waves; Electrical engineering--Materials
Electrical Engineering (MS)
Department, Program, or Center
Electrical Engineering (KGCOE)
P. S. Neelakantaswamy
F. I. Tseng
Egan, Lawrence R., "Development of a composite material with enhanced electromagnetic power dissipation characteristics" (1987). Thesis. Rochester Institute of Technology. Accessed from
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