Evaluation of structural parameters to predict particle filtration and air permeability performance of woven textiles

The COVID-19 pandemic has highlighted environmental and supply issues related to single-use protective masks for both the general public and some healthcare workers. Reusable fabrics are an interesting alternative to disposable nonwovens and offer a prospect of protection in other fields such as against fine particles in urban areas. In this paper, the behavior of 22 woven fabrics regarding air permeability, simulating breathability through the material, and filtration against 3 µm diameter particles is investigated. First, basic laws are verified between the performance of a single layer of fabrics and that of a stack. A relationship is established between air permeability and filtration efficiency, allowing one to be calculated when the other is known. Second, the influence of parameters defined at various scales of the structure (fibers, yarns and fabrics) is analyzed. The most sensitive structural parameters that can be considered as predictors are then identified and used in a model allowing the calculation of air permeability. In this model two levels of porosity are taken into account: a macroscopic porosity at the scale of the woven structure and a microscopic porosity at the scale of the thread. The model proposed in this study offers a convenient method to design an effective filter from data easily measurable during manufacturing.