Preparation, Characterization, and Dielectric Properties of PP/CaTiO3 Composites for Microwave Substrate Applications

Calcium titanate (CaTiO3) filled polypropylene (PP) composites have been fabricated through compression molding method. The phase purity of the PP/CaTiO3 composites was studied using X-ray diffraction studies. Scanning electron microscopy technique has been employed to study the dispersion of the particulate filler in the PP matrix. The dielectric constant and loss tangent of the composites were measured at X-band frequency region using waveguide cavity perturbation technique. PP/CaTiO3 composite has an effective dielectric constant of 11.74 and loss tangent 0.007 at optimum filler loading. The experimental dielectric constant of filled composites was compared with theoretically predicted dielectric constant values obtained using different modeling approaches. The linear coefficient of thermal expansion of PP/CaTiO3 composites was studied using thermomechanical analyzer.