Study of cyclic bursting loading on needle-punched nonwovens: Part Ⅱ - Change in air permeability and compression behavior

摘要

Efforts have been made to investigate the physical properties of needle-punched nonwovens, such as compression and air permeability, before and after the application of cyclic bursting pressure. It is observed that the structural parameters, such as areal density, needling density and fibre fineness, have significant effect on the aforementioned fabric characteristics. More compression is observed in a sample with low mass density. Sample made of coarser fibre shows lower compression as compared to finer fibre samples. The air permeability decreases with increase in mass density. On conducting cyclic bursting test on a sample, the values of air permeability and compression change significantly. The cyclic parameters, such as pressure magnitude and rest time at cyclic peak pressure, cause significant structural changes and reorientation of the fibre during deformation. Increase in pressure and rest time causes increase in compression parameter (alpha) and air permeability. Nevertheless, at low cyclic pressure level (10% of bursting pressure), the network becomes compact due to fibrous reorientation, and therefore both the values of compression parameter (alpha) and air permeability show initial drop. On examining the samples made of coarser and finer fibres, the variation is observed in the extent of change in the air permeability.