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Abstract: In this work, ceramic–polymer composites were fabricated from barium strontium titanate powder (BST) and polypropylene-graft-poly(styrene-stat-divinylbenzene) (ER) using a twin-screw extruder. The compounding process was characterized by rheological measurements. The effects of volume loading of BST on dielectric and mechanical properties were investigated. The dielectric properties were measured as a function of frequency and BST loading. For example, the relative permittivity and loss tangent (tan δ) of the BST–ER composites at 1GHz were gradually increased from 2.4 and 0.0001 to 28.5 and 0.0085, respectively, as the loading was increased from 0 to 50.5vol.%. Stearic acid (StA) was used as a surface-modifier of the BST. With an approximate surface coverage of 83%, an improvement in processability and a slight increase of the permittivity was observed, while tan δ remained low. The excellent dielectric characteristics of these composites, with high permittivity and low tan δ, make them attractive novel electronic materials for high frequency applications. [Copyright &y& Elsevier]

Abstract: Ferroelectric ceramic–polymer composites provide flexible self-sustaining thin layers with unique electrical and mechanical properties, and thus a novel way to fabricate RF devices. In this work, a composite made of ferroelectric ceramic (barium strontium titanate, BST) and thermoplastic polymer (polyphenylene sulfide, PPS) was studied with various BST loadings up to 70wt.%. The microstructures exhibited uniform distribution of ceramic particles in the polymer matrix. RF measurements showed that the relative permittivity and loss tangent of the composites gradually increase with increasing BST loading. At 1GHz a composite with 70wt.% BST loading had relative permittivity and a loss tangent of 13.5 and 0.0025, respectively. [Copyright &y& Elsevier]