An Investigation on the Effect of Barium Titanate Nanoparticles on the Properties of Electrospun PVDF Fibers

Polyvinylidene fluoride (PVDF) is a semi-crystalline polymer that has received a great deal of interest. PVDF crystallizes in five different phases. The β phase is the most important PVDF phase with the highest piezoelectric properties. Therefore, increasing the β phase fraction in this polymer is crucial. Various methods can be used for increasing β phase fraction in PVDF, amongst which electrospinning and introducing certain nanoparticles are worth mentioning.PVDF solution containing different amounts of barium titanate (BT) nanoparticles were prepared and electrospun. Finally, the obtained fibers were heat treated at 155°C for 2 h.Morphology observations showed the formation of uniform and beadless nanocomposite fibers. In addition, increasing the amount of BT nanoparticles decreased the average fiber diameter. The EDS results showed that BT nanoparticles were homogeneously distributed in the composite fibers. XRD patterns showed that the electrospinning method can induce β-phase formation in PVDF. Calculating the β-phase fraction showed an increasing trend up to 4 wt.% BT content due to the effective interaction between BT nanoparticles and PVDF chains. The β phase content reached 94.43% in PVDF-4%BT sample. Beyond that, nanoparticles agglomeration and the increased viscosity of the polymer colloid hinder β-phase formation. The contact angle of PVDF fibers decreased by increasing the BT content, and in the presence of 6 wt.% BT, the lowest contact angle, 126.8°, was obtained. The results of piezoelectric test showed that by adding 4 wt.% barium titanate to PVDF, the piezoelectric charge output of PVDF fibers increased from 6.34 pC/N to 8.85 pC/N.