Effects of Water-Pretreatment on Tensile Strength of Crosslinked Cotton Fibers

The effects of convolutions on mechanical properties of cotton fibers treated with vapor-phase (VP) -formaldehyde (HCHO) were studied . Cotton was pretreated to remove the convolutions in three different fiber assembly states, namely, fiber, yarn, and fabric. The samples were further treated with the liquid ammonia (L. NH3), NaOHaq., and NaOHaq. /L. NH3. It was found that (1) the microscopic and structural changes are closely related with the tenacity retention of cotton, and (2) the tenacity retention increases with an increase in the X-ray orientation degree. The tenacity retention of fibers and yarns is larger than that of fabrics at the same X-ray orientation degree and bound HCHO level. The effects of extension and orientation of amorphous regions in cotton fibers on the tenacity retention before and after VP-HCHO-finishing were examined from the S-Scurves of ramie fibers untreated and treated with water, and the relaxation times (T1c) of cotton fibers untreated and treated with water using CP/MAS 13C-NMR, respectively. The results indicate that the tenacity retention of cotton fibers before and after VP-HCHO-finishing is closely related with the extension and orientation of amorphous regions of cotton fibers. The relation between X-ray orientation degree under load and stress of cotton and ramie fibers before and after VP-HCHO-finishing was also discussed.