Preparation and functional properties of PVDF-based composites

The demand for high dielectric constant materials and high energy density capacitors has rapidly increased in recent years due to the continuous and rapid development of the electronic industry and the need to store electrostatic energy more efficiently. The combination of dissimilar materials in a composite represents an effective approach for the optimization of the dielectric properties. The addition of ferroelectric (barium titanate, BaTiO3) nanoparticles with high dielectric constant (k 1000) enables the relative dielectric constant of the polymer (k 3-10) to be significantly increased without compromising some of the most useful properties of the material. Polymer composites were prepared using polyvinylidene fluoride (PVDF) as a matrix and BaTiO3 nanoparticles (d~100 nm) as inclusions. The composites were fabricated by mixing PVDF and BaTiO3 particles at 200°C using the melt-blend method. The microstructure was observed on fracture surfaces by SEM. The amount of ferroelectric beta phase in the PVDF matrix was determined by FT-IR spectroscopy and the dielectric propeties were determinated at different frequencies and temperature by impedance spectroscopy. Simulation of the field distribution in model composites was performed by 3D finite element modelling.