نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری،دانشگاه صنعتی مالک اشتر، تهران، ایران
2 کارشناسی ارشد،دانشگاه صنعتی مالک اشتر، تهران، ایران
3 استادیار،دانشگاه صنعتی مالک اشتر، تهران، ایران
4 دانشجوی کارشناسی ارشد،دانشگاه صنعتی مالک اشتر، تهران، ایران
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Polymers exhibit the least dielectric constants among all materials due to the lack of magnetic dipole moment, non-polar electric structure, amorphous microstructure, and low density (low molecular packing). These properties have caused them to be highly regarded by the electricity, telecommunication, and communication industries. Moreover, preparing polymer foams is cost effective way to reduce their dielectric constant. The fabricating methods of materials with desired dielectric constants is applied in the design and production of telecommunications equipment, including reflectors, Fresnel lenses, Luneburg lenses, and so on. The subject of this article is to investigate the effect of the morphology of expanded polystyrene foams on their dielectric constant, which is the ratio of the displacement current density of electromagnetic waves to the conduction current density of waves in the lossy medium. Expanded polystyrene foam samples with different porosity, cell wall thickness, average cell sizes, and homogeneity or heterogeneity were prepared using an oven. The cell structure, and dielectric characteristics of the foams respectively with scanning electron microscope, vector network analyzer, and Lensed horn antenna was checked using the dielectric measurement method in the free space method. The effect of cell size in expanded polystyrene foam in equal and different densities on the dielectric constant is investigated in this article. The average cells size increases at higher density in PS foams with different densities and the dielectric constant shows an increase. As, the samples at the equal density, the dielectric constant decrease slightly with the cell size increment. Moreover, the dielectric constant of PS foam with the equal density and homogenous structure is less than heterogeneous one.
کلیدواژه‌ها [English]
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