Uniformly dispersed submicrometre BaTiO3 particles in PS based composites. Morphology, structure and dielectric properties

Composites based on polystyrene (PS) filled with submicrometre particles of BaTiO3 were prepared making use of high energy ball milling (HEBM) and hot pressing. The effect of processing and the amount of BaTiO3 particles on the morphology and structure of the composites was studied to finally correlate them with their dielectric behaviour. The method of processing used was proven to be efficient to uniformly disperse the particles within the polymer matrix. Neither the milling process nor the presence of BaTiO3 nanoparticles (below 40% wt) seemed to alter the structure of the PS polymer. The glass transition temperature, as well as the thermal degradation of the polymer, remains almost without any alteration, suggesting that: i) the presence of the particles does not modify the dynamics of the PS matrix and ii) there are no strong physico-chemical interactions between the PS and the BaTiO3 particles. Changes in the relative permittivity of the systems due to milling and the incorporation of the particles were studied. HEBM by itself does not significantly affect the dielectric constant whereas the presence of BaTiO3 increases it, following reported theories.