Improved dielectric properties of poly(vinylidene fluoride)-BaTiO3 composites by solvent-free processing

Composites of poly(vinylidene fluoride) (PVDF) and BaTiO3 nanoparticles (average diameter ca. 125 nm) are fabricated by a solvent-free and industrially scalable technique, that is, melt blending, followed by compression molding. The effect of processing parameters on the spectroscopic, microstructural, thermal, mechanical and dielectric properties are evaluated as a function of composition (loading up to 30 vol%). The presence of nanoparticle inclusions as well as specific compression molding parameters demonstrate both to affect the molecular relaxations of the PVDF matrix, studied by correlating the results of different techniques, and to induce the PVDF crystallization as beta phase. Processing parameters also play a key role for optimizing the dielectric properties. An improved dielectric behavior of the composites is obtained in terms of both permittivity, whose value increases up to four times that of neat PVDF, and dielectric losses, lower than 5% between 10 and 3 center dot 10(4) Hz. The obtained performances resulted enhanced compared to analogous composites prepared with the use of solvents.