Dielectric performance of composites of BaTiO3 and polymers for capacitor applications under microwave frequency

Composites of nano-sized barium titanate (BaTiO3) with volume fractions up to 0.5 and poly(butylene terephthalate) (PBT) or linear low-density polyethylene (LLDPE) were made via extrusion. Scanning electron microscopy demonstrated that BaTiO3 is well dispersed in the polymer matrices. The crystalline content (DSC) and thermal stability (TGA) of both polymers decreased with increasing BaTiO3 loading. Dielectric properties of the composites were measured using a vector network analyzer. Both dielectric permittivity and tangent loss increased with increasing BaTiO3 content. At 2.45 GHz, the dielectric permittivity for 48 vol% BaTiO3-filled LLDPE and 43 vol% BaTiO3-filled PBT was 25 and 21.2, respectively. There was a good fit between the Lichtenecker model and experimental data obtained up to a certain value, with the permittivity variations being dependent on volume fraction. The improved dielectric performance achieved on inclusion of BaTiO3 confirms both composite systems as potential candidates for microwave frequency capacitor applications.

Automated summary

Nano-sized barium titanate composites with PBT or LLDPE were successfully prepared through extrusion, showing well-dispersed BaTiO3 in the polymer matrices. As the BaTiO3 loading increased, the crystalline content and thermal stability of the polymers decreased, while both dielectric permittivity and tangent loss increased. The inclusion of BaTiO3 improved the dielectric performance, making both composite systems potential candidates for microwave frequency capacitor applications.