To study the effect of household machine laundering on hydroentangled cotton nonwoven developmental fabrics, several sets of such fabrics, uniformly made with cottons of different fiber quality characteristics, were sequentially laundered repeatedly for their performance evaluation after one washing and drying cycle (1 W), 5 W, 10 W, and 20 W, using a standard AATCC method for washing. The control greige fabrics (i.e., before any wash) and their respective versions after the 1 W, 5 W, 10 W and 20 W were examined for their physical and mechanical properties. The laundering results showed that the fabrics, even after 20 wash cycles, had held up unexpectedly well. Nonwovens generally are not considered wash-durable, and more than a third of nonwovens today are used in durable applications that necessarily do not require laundering since most nonwovens inherently are considered “disposable” after one end-use application. At any rate, all the researched fabrics, irrespective of their fiber quality origin, showed a significant drop in tensile strength, mainly after the first wash. The drop was more severe in the machine direction (MD) than in the cross direction (CD). To primarily investigate the cause of the declined fabric tensile strength due to washing, SEM images of the fabrics before and after the washing(s) were studied for any structural deformation. The SEM images clearly showed that the fabrics before the wash had symmetrical, almost uniformly spaced clusters of well-defined fiber entanglements (corresponding to the geometric locations of the orifices in the water jet-strip). After the first wash, those entanglements somewhat appeared to have been considerably “loosened,” disintegrated, and even lost. It seemed that the washing affected the fabric structure mostly in the (hydroentangling) MD. A possible reason for this phenomenon could be the fact that the cotton card used in preparing the native batt for hydroentanglement had aligned and stressed the fibers mostly in the machine direction. The subsequent crosslapping operation to some extent had been altered (randomized), and the fiber orientation in its web output was subjected to the hydroentangling, water jet forces that also stressed the fibers mostly in the MD. Upon washing the hydroentangled fabric in water, the stressed fibers, as expected, somewhat relaxed by releasing some of the stored mechanical energy that originally had held the fibrous structure together by creating strong inter-fiber cohesion or frictional or mechanical bonds. In other words, the washing basically loosened or broke up some of the “mechanical entanglements” and, consequently, their (MD) frictional bonds that had been created by the forceful water jets of the fabric formation process. Research has been planned to stabilize these mechanical bonds by means of special finishing, such as blending cotton with fusible/bonding fibers, resin finishing, and/or even layered fabric-film reinforced composites.
Error Characteristic Analysis of Fluid Momentum Law Test Apparatus
