Various natural (cotton and hemp), regenerated (viscose) and synthetic (acrylic) polymer fibers were chosen to produce fibrous systems on the same circular knitting machine under controlled conditions so as to obtain as similar as possible construction of the plain knitted fabrics. The method employed in compression test involved lateral compression of the sample (normal to its plane), recording the corresponding changes in thickness and load, and also removing the load while recording the recovered thickness of the sample [4,7]. The method applied gives reproducible results. In this experiment five successive compression cycles (loading– unloading) were performed for each knitted fabric without moving the sample and the thickness measurement over a pressure range of 0.45–2560cN/cm2 with the progressively increased (or decreased) compression stages. Each knit was investigated by making five separate tests on different portions of the knit, so the thickness measurement was the average of these five tests.
The energy-absorption properties of the knitted fabrics were evaluated from the compression-release curves by calculating the area below the compression curve as the indication of work done or energy absorbed by the fabric (WCtot), the area below the release curve indicating the energy released upon the removal of compression load (WCel) and the area occupied by a hysteresis loop as a measure of nonelastic compression work or the energy lost (WC).