Fabrication And Properties Research Of Polymer Matrix Microwave Composites

In this paper, the effects of composition and process on dielectric and mechanical properties of polymer matrix microwave composites have been investigated and analyzed by DTA and SEM. With CaTiO₃, BaTiO₃, Pb(Mg_1/3Nb_2/3)O₃, Al, PTFE and epoxy resin, PTFE matrix and epoxy resin matrix composites were prepared by cold-press sintering and often press curing process. The effects of filling and matrix on dielectric properties of composites have been investigated. The result showed that CaTiO₃/PTFE microwave composites had excellent microwave dielectric properties. And then, the effects of coupling process, content of coupling agent and CaTiO₃, molding press and sintering temperature on dielectric and mechanical properties of CaTiO₃/PTFE microwave composites have been investigated. The result showed that the dielectric properties were remarkably improved with the pre-coupling process. When CaTiO₃ was 40wt%, dielectric constant was increased, and Qf was increased at first, and then reduced as the content of coupling agent increased. As the coupling agent was 2wt%, Qf obtained the highest value 8182GHz and the dielectric constant was 7.09. The modulus of pressing increased when the coupling agent added. The dielectric constant increased, Qf decreased remarkably, and bending strength increased at first, and then decreased as the content of CaTiO₃ increased. When CaTiO₃ was 30wt%, Qf was 16659GHz and bending strength obtained the highest value 22.05MPa. When CaTiO₃ was 60wt%, dielectric constant was 13 and bending strength was 10.20MPa. The dielectric constant, Qf and bending strength increased as the molding press increased. When the molding press was 4MPa, dielectric constant was 7.03, Qf was 9374GHz and bending strength was 19.92MPa. The dielectric constant and Qf increased at first, and then decreased, bending strength increased at first, then decreased, and at last increased as the sintering temperature increased. When the sintering temperature was 380℃, dielectric constant and Qf obtained the highest value, 7.24 and 10512GHz.