Optimization of air permeability of spunlaced filter fabrics using the Box–Behnken experimental design

One of the most important characteristics that a filter must possess is high air permeability. A good filter fabric must be able to capture the dust particles while maintaining a good airflow through it in order to reduce high pressure drop. Therefore, producing a filter fabric with the desired air permeability can be challenging as several process parameters such as fiber types, area weight and water jet pressure will interact with each other during spunlacing process and influence the fabric air permeability. To study the effects of these independent variables on the air permeability of three different types of spunlaced fabrics, the Box–Behnken design was used to model their effects. The fibers used were polyacrylonitrile, polyphenylene sulfide and blend of polyphenylene sulfide/polyimide. In addition, filtration properties of some of the filter samples were also evaluated. Based on the effects of the fiber types, area weight and water jet pressure on the fabric air permeability, the optimum conditions for achieving higher air permeability were fiber types (+1 level), area weight (0 level) and pressure (−1 level), respectively. The air permeability of the fabrics decreased with increasing water jet pressure for all fiber types and increasing area weight decreased the air permeability. It was observed that the independent variables had a significant effect on the air permeability. Filtration efficiency of the selected filters samples were ≥95%. Among the selected samples, polyphenylene sulfide/polyimide (440 g/m ² ) fabric has the lowest pressure drop whereas polyacrylonitrile (560 g/m ² ) has the highest pressure drop.