Research on micro-damage behavior of wool fabrics drying in domestic dryer.

To evaluate the performance degradation of fabric drying in domestic air-vented dryer, the appearance, mechanical, and microscopic properties of the wool fabric after different drying cycles were studied. Pilling and dimensional stability tests were performed according to established international standards. Microscopic studies were carried out by Scanning Electron Microscopy (SEM) and X-ray (XRD). The results show that pilling is the dominant damage mechanism and gradually increased during lower number of drying cycles (0-10 cycles). The results of dimensional stability showed that the highest dimensional shrinkage of knit wool fabric was first five drying cycles, and then increased at a relatively slow rate with the increase in drying cycles. And fabric shrinkage takes place mainly in the warp direction. The SEM images of wool fiber showed that the scales on the fiber surface were intact in the first 15 drying cycles but start to flake after 20 drying cycles. In the drying process, fabrics can suffer several fractures such as cut fracture, split fracture, partial fracture and distortion and even scale flaking and interior structural distortion of fiber. The damages occur quite randomly, but complexity and severity of damages increased with increase in drying cycles. XRD analysis showed that drying had little effect on fiber crystallinity, indicating that drying only leads to changes in the physical properties of wool fabrics instead of changes in the chemical composition of the fiber. And found SEM analysis is not only an effective method to characterize the change in the surface morphology of the fibers resulting from the drying treatments, but also explain the cause of fabric performance degradation such as pilling and strength reduction during drying.