Improvement of Air Filtration Efficiency Using Meltblown Electrets, 1995 Nonwovens Conference Proceedings

Peter P. Tsai & Larry C. Wadsworth

The University of Tennessee

Air particle filtration efficiency is governed by mechanical mechanisms, i.e. interception, impaction, brownian diffusion and gravitational settling, as well as by electrostatic mechanisms, i.e. coulombic force and induction forces. The mechanical mechanism is determined by fibrous surface area of the web. Therefore, the reduction of fiber diameter improves the filtration efficiency. But the web air resistance is relatively increased by reducing the fiber size. However, the filtration efficiency can be greatly improved by electrostatically charging the filter media without affecting the air permeability. This paper compares the difference in filtration efficiencies among nonwoven webs and the difference between the control and electrostatically charged meltblown nonwoven webs. The paper also discusses the importance of using a proper technique to charge the filter media so that a high filtration efficiency can be obtained.