Pore Structure Of Crosslinked Cotton Fiber

People choose the cotton fabric for its excellent garment capabilities, however, the deficiency in elasticity made the cotton fabric to cockle easily during the wear and laundry. Therefore, the DP finishing becomes essentially important. The development of wrinkle resistance theory has gone through a long history and now the crosslinking theory has become predominant. In this paper, the cotton fabric samples were treated with different finishing formulations and filled into chromatography column under different nitrogen pressure, and then the changes in pore structure of cotton fiber were studied by using HPLC through Inverse Size Exclusion Chromatography (ISEC) method for the purpose to find the intrinsic relations between the pore structure and the fabric mechanical properties.When preparing the cotton column, the pore content of all dimensions in the fiber decreased with the increase of the nitrogen pressure. However, the change in pressure will not affect the distribution of pore dimension. Therefore, in order to ensure the uniformity and the compaction of the cotton column, a higher nitrogen gas pressure is preferred.The pore structure changed significantly after the crosslinking reaction. The content of medium and large pores (>30A|°) decreased and the small pores (<30A|°) increased largely. Moreover, with the increase of the concentration of the crosslinking agents, the content of large and medium pores further decreased, and the small pores got a further rise in content. It is surmised that the crosslink agents mainly entered the medium and large pores in the cotton fibers, establishing covalent bond between fibers, which will divide or even close the corresponding pores. What's more, in case that the medium and large pores were divided, the content of medium and large pores will decrease, coupling with a rise in the content of small pores; on the other hand, the content of small pores will keep unchanged if the medium and large pores were closed by the crosslinking reaction. The difference in crosslinking formulations (different catalysts, pre-treatment, crosslinking processes, etc.) will affect the changes in pore structure differently. Compared with the catalyst system of magnesium chloride-citric acid, the catalyst of LFC would reduce more medium and large pores content in the cotton fibers; however, the pad-process caused the similar change in pore structure as the impregnating-process. After the steaming process, the cotton fibers retained more medium and large pores and less small pores than the fibers with a curing process.Before the crosslinking reaction, the liquid ammonia treatment greatly changed the pore structure of cotton fibers by swelling effect, which caused a decrease in large and medium pores and an increase in small pores. Therefore, when compared with fabrics untreated with liquid ammonia, the difference in catalyst types and crosslinking processes diminished when concerning the change in pore structure. However, the fibers treated by the pad-process exhibited a less content in medium and large pores than the fibers after impregnating-process.The change in pore structure will also have something related to the mechanical properties of the fabrics. The interior of the fibers became evenly distributed and more ordered with the decrease of medium and large pores and the increase of small pores, as a result, the fabrics obtained better wrinkle resistance properties. On the other hand, with the rise in crosslinking degree, the fibers' ability of dispersing internal stress decreased, which resulted in the reduction of mechanical properties such as the tensile strength and the elongation.