Investigation of stretch on air permeability of knitted fabrics part II: effect of fabric structure

The structure of a fabric plays vital role in determining its air permeability. So, the study and comparison of air permeability of various fabric structures have their own significance. A detailed study is carried out here on various fabric structures to understand the effect of fabric structure on air permeability at their dry, wet and fully relaxed states. An automatic fabric stretching device has been designed and fabricated as an attachment with air permeability tester to test the air permeability of fabric samples under dynamic condition for this investigation. It is a fully automatic stretching equipment to stretch the fabric samples as per the preset value. The stretching device can be set with a predetermined degree of fabric stretch either in percentage or in mm and rate of extension also can be preset in mm per minute. From the results, it is clear that fabric structure has explicit impact on air permeability both in the unstretched and stretched states of the samples. Loose fabric structure and porous fabric structure show maximum air permeability under both sedate state and incrementally stretched states and vice versa.