抄録
This article analyzes the mechanism of crease. It classifies the role of the rheological properties of fiber and the role of frictional force between textile elements in crease. Crease angle θ can be related to the above-mentioned two factors by the following equation: θ=θ1; -θ2; . θ1; is the inherent crease angle of fiber and θ2; is the fraction originating from the frictional force in the recovery process.
Therefore, it should be possible to evaluate θ1; from an elastic recovery test in which fibers undergo the same rheological history as in crease. In a fixed group of poplins constituted of various textile fibers, there is a good correlation between the crease angles of these fabrics heat-treated properly and an angle θe; =180(1-P.S./100), Where P.S. is the residual strain ratio at 2% strain in tensile stress relaxation recovery test. The time dependence of the crease angle is strongly influenced by the stress relaxation character of fibers. θ2; can be depressed by suitable heattreatment or oiling. The depression of the θ2; in the heat-treated fibers is presumably due to the reason that the pressure of contact, mainly between warp and weft, decreases by the thermal stress relaxation of fibers.
