Preparation And Properties Of Microwave Dielectric Polymer Matrix Composites

With the rapid development of modern microwave communication and radartechnology, the microwave dielectric substrate material with high dielectric constantand low dielectric loss has become one of the hot spots in materials research workersconcerned. In order to obtain the high dielectric ceramic/polymer composite with thedielectric constant more than7, the dielectric loss than0.003, the composite wereprepared by mechanical blending method. The effect of particle size and type of filler,filler pre-process selection matrix, fiber reinforced composite and process parameterson the microstructure, dielectric properties, mechanical properties of the compositewere investigated. The main contents are as follows:The TiO2/PTFE(powder) composites were investigated. The effect of fillerpretreatment, particle size, content of filler was analyzed on the microstructure,density, dielectric properties of the composites. Using2wt%dosage silane couplingagent KH550, the composite material had a high dielectric constant and low dielectricloss. Using three different particle size TiO2powders as fillers, content changed from40wt%to60wt%(43.3vol%)，combined with the process parameters(6MPa moldingpressure, the sintering temperature at370℃), the dielectric constant of the compositeusing powder B changed from6.8to9.2, while the dielectric loss changed from0.0014to0.0021. The dielectric constant of the composites using powder Cincreased from6.9to14.3, the dielectric loss increased from0.0011to0.0025.The TiO2(B)/PTFE(emulsion) composites was investigated. When filler contentchanged from40wt%to60wt%(43.3vol%), combined with the processparameters(8MPa molding pressure, the sintering temperature at390℃), thedielectric constant of the composite material increased from7.05to11.92, while thedielectric loss increased from7.5to11.92. For Sr5Ce2Ti8O24/PTFE(emulsion)composite, when the filler content changed from40wt%to60wt%(37.2vol%), thedielectric constant of the composites increased from5.9to11.3, while the dielectricloss increased from0.0018to0.0025. When using the PTFE emulsion as matrix, thedielectric properties of the composite material was improved.Chopped quartz fibers were used to reinforce composite material. Researching the structure, dielectric properties and mechanical properties microstructure of thecomposite. The dielectric properties of the composites decreased slightly, while themechanical properties were improved. When using PTFE emulsion matrix,composite’s density and compressive strength were improved. TiO2(B)/PTFE(emulsion) plus2wt%(2.4vol%) fiber composites with filler content of60wt%(43.3vol%), it’s compressive strength increased to32.58MPa.