Synthesis, characterization, thermal, dynamic mechanical, and dielectric studies of Ba0.7Sr0.3TiO₃/polystyrene composites

Ba 0.7 Sr 0.3 TiO 3 /polystyrene composite films were successfully prepared through solution casting route and characterized by SEM and XRD. The particle size distribution of sol‐gel synthesized Ba 0.7 Sr 0.3 TiO 3 filler was analyzed by dynamic light scattering. The Z‐average size of Ba 0.7 Sr 0.3 TiO 3 particles is 314.78 nm (∼0.3 µm). At low concentrations of the filler there is no significant agglomeration between the particles whereas at higher concentrations of the filler (∼40 vol%) agglomerates were observed in the composite film as evidenced by scanning electron microscopy. The thermal and dynamic mechanical properties of the synthesized composites were studied in detail that show the 30 vol% Ba 0.7 Sr 0.3 TiO 3 /PS to be the most effective composite. The dielectric properties of Ba 0.7 Sr 0.3 TiO 3 /PS composites as a function of the filler content in the polymer matrix in the range 10 Hz to 1 MHz and at 5 GHz along with temperature dependent dielectric studies for 30 vol% and 50 vol% Ba 0.7 Sr 0.3 TiO 3 /PS composites at 10 kHz and 1 MHz have been reported. The dielectric constant for 50 vol% Ba 0.7 Sr 0.3 TiO 3 /PS composite at 5 GHz is 10.34 which is higher than reported literature values for similar polystyrene composites with other fillers. Different theoretical models were employed to predict the effective permittivity of the composites and compared with the experimental results. POLYM. COMPOS., 39:E1714–E1724, 2018.