Dielectric and magnetic properties of polyvinylidene fluoride polymer composites highly loaded with nickel

摘要

In this work, electroactive polyvinylidene fluoride (PVDF) was a matrix for dispersing 10 wt% ferromagnetic nickel (Ni) particles. The composites were formed into its shape by using a spin coater with varying spinning speeds from 750 to 3750 rpm to obtain the thicknesses between 68 μm and 40 μm on printed circuit board substrates. Magnetic hysteresis loops of the composites were dependent on the spinning speed because the spin regulated the dispersion and size distribution of Ni particles in the PVDF matrix. Owing to the Ni agglomeration, the composites prepared by 750, 1500 and 2250 rpm spinning clearly displayed soft ferromagnetic properties but the capacitance was decreased with the decrease in spinning speed. In every sample, the capacitance was reduced with the increase in frequency from 1 kHz to 100 kHz and remained minimal up to 1 MHz. These changes in capacitance can be explained by the polarization of surface charges of Ni clusters of varying sizes from different spinning speeds. The dissipation factor was, by contrast, sensitive to the frequency and the dispersion of Ni only at frequencies higher than 60 kHz.