The Study of Effect of a Polyurethane Filament on Mechanical Properties of Plain Stitch Fabrics

Abstract

In an attempt to investigate good fit of underwear, two kinds of plain stitch fabric were used as test specimens to study their different mechanical properties. The two fabrics were knitted with the same cotton yarn. For one fabric, a polyurethane filament was mixed as a double yarn together with a cotton yarn. In spite of the very small amount of polyurethane filaments, the elongation ratio of the plain stitch fabric containing polyurethane filaments at the same applied load was more than three times higher than that of the other plain stitch fabric with no polyurethane filaments. Such a large deformation mechanism was investigated in terms of the different structures of the two kinds of yarn pulled out from the knitted fabrics. Results showed that crimps of a cotton yarn, by doubling a polyurethane filament in a free state, are sharper than intrinsic crimps of a cotton yarn. The sharper crimps result from the shrinking force of an extended polyurethane filament within a double yarn.