Development of needle-punched nonwoven fabrics from flax fibers for air filtration applications

This paper reports an exploratory study on the production and measurement of the air permeability, mechanical properties, pore size distribution and filtration efficiency of different nonwoven fabrics produced by systematically changing the machine variables to influence the physical parameters of the fabrics. Only flax fiber waste was utilized for this trial, so that the possibility of value addition to a cheap source of raw material could be explored. The changes in air permeability were interpreted in terms of fabric density profile and pore size distribution. The tensile strength, fiber orientation distribution and bond strength between the layers of multi-layered fabrics were investigated. The filtration parameters, such as filtration efficiency, dust holding capacity and pressure drop, were evaluated. Furthermore, the effect of calendering on pore size and filtration properties was evaluated to explore the possibility of fine-tuning the performance of filters. The results in this study showed an overall improvement in all filtration characteristics due to the calendering operation.