Ba0.7Sr0.3TiO3/polystyrene composite films were successfully prepared through solution casting route and characterized by SEM and XRD. The particle size distribution of sol‐gel synthesized Ba0.7Sr0.3TiO3 filler was analyzed by dynamic light scattering. The Z‐average size of Ba0.7Sr0.3TiO3 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% Ba0.7Sr0.3TiO3/PS to be the most effective composite. The dielectric properties of Ba0.7Sr0.3TiO3/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% Ba0.7Sr0.3TiO3/PS composites at 10 kHz and 1 MHz have been reported. The dielectric constant for 50 vol% Ba0.7Sr0.3TiO3/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. © 2018 Society of Plastics Engineers

A series of materials of the composition Ba 0.7 Sr 0.3 Zr x Ti (1 − x) O 3 (BSZT), where x = 0.00, 0.01, 0.02 and 0.03, were synthesised through the sol-gel method whereupon the manifestations of partial substitution of Ti 4+ by Zr 4+ on the structural and dielectric behaviour of Ba 0.7 Sr 0.3 TiO 3 (BST) were studied. X-ray diffraction patterns of all samples showed the development of a single-phase crystalline perovskite structure. The dielectric behaviour of the ceramic samples has been studied in detail in the frequency range 10 Hz to 1 MHz at room temperature, and as a function of increase in temperature. The sample with 2% Zr recorded the highest dielectric constant. The dielectric loss values for all the BSZT compositions are remarkably low, tan δ = 0.021∼0.026 at 1 MHz, in contrast to the literature reports. It is observed that small amount of Zr doping on BST, where 0 < x ≤ 0.03 results in the enhancement of dielectric constant while decreasing the bulk density and dielectric loss.

The incorporation of high dielectric constant filler particles into thermoplastics is an attractive approach to develop materials with high dielectric strength, low dielectric loss, and mechanical stiffness, for electronic packaging purposes. Herein, we report the preparation and properties of polystyrene (PS) based low loss 0-3 composites with inorganic PbZr 0.3 Ti 0.7 O 3 (PZT) filler particles in concentrations ranging from 0%-20% (w/w). The PZT particles were synthesized using the sol-gel process and the composites were prepared by a two-step, solvent-free approach: (1) melt mixing, followed by (2) hot press. The thermal and mechanical properties of the composite samples were investigated. The dielectric behavior of the as-synthesized composites showed pronounced improvement over pure PS, as is seen from the increased dielectric constant and extremely low loss tangent. For 20 wt.% PZT loading, the dielectric constant of the composite is as high as 12 at 1 MHz frequency, which is about five times greater than that of pure PS (ε = 2.5). All the PZT/PS composites exhibit remarkably low dielectric losses, even at lower frequencies (tan δ ≤ 0.04), which is better than reported literature values of PS based composites. The variation in dielectric constants of the samples with increasing temperatures was also recorded.

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