**4. Conclusions**

Polymer PVDF was electrospun to form fiber mats and continuous twisted yarns. Samples of the mats and yarns were polarized by stretching, heating and poling. The as-spun and polarized mats and fibers were measured for their charge via a Faraday bucket. The results showed the mats had significantly higher charge per mass than the yarns at the same mass. The measured charge per unit mass of the mats increased as the mass of the mat increased. The measured charge per mass of the yarns slightly decreased as mass increased. The polarization treatments used in this work did not significantly increase the charge of the mats and yarns. Charge measurements of stacked layers of mats suggest that the charge measured by the Faraday bucket is a complicated combination of surface area and bulk mass. Changing the basis weights of fiber mats (instead of stacking layers) gave similar trends suggesting the same mechanisms may apply to both stacked and directly spun mats. The nearly constant measured charges of the yarns suggest that the charge per mass may be related to the surface area per mass of the yarns.

### **Acknowledgements**

This work was funded by Coalescence Filtration Fibers Consortium (CFNC): Parker Hannifin, Hollingsworth and Vose, and Donaldson. We acknowledge the assistance of technicians Steve Roberts and William Imes for fabrication and operation of the Faraday bucket.

*Nanofibers - Synthesis, Properties and Applications*
