Influence of fiber diameter, fiber combinations and solid volume fraction on air filtration properties in nonwovens

In air filtration, nonwoven materials are known to be pertinent structures for fine filtration and moderate pressure drop. In order to develop a filter that combines good permeability and high efficiency, it is important to identify the relevant structural parameters of the nonwoven. The main criteria studied in this paper are fiber fineness, solid volume fraction and basis length (total length of fiber in unit area of nonwoven). The effect of combining different fiber diameters in order to reach the best compromise is also investigated. Our results show that the use of binary blends of different fiber diameters improves overall filtration behavior, in comparison to nonwoven filters with equivalent unimodal diameter distribution. A theoretical filtration model is used to predict filtration behavior for different structural characteristics and these predictions are compared to experimental results. However, this comparison demonstrates the limits of existing models in the case of fiber blends.