| Silicone softener has been used to improve the hand of cotton fabric as an additive in the wrinkle-resistant finish of cotton fabric. Epoxy-terminated polysiloxanes, which belong to silicone softener, can impart softness to cotton fabric. The reactive group at each end of the polymer chain can undergo crosslinking reaction with the hydroxyl group on cellulose, which can improve the wrinkle recovery of fabric. In this project, Epoxy-terminated polysiloxanes of different DP were used to treat cotton fabric. The influence of DP and process conditions on the finishing performances was examined. RGPC was used to study the pore structures of cotton fibre intact and treated by softeners in order to see whether the softeners entered into the pores of cotton fibre.The influence of DP on the softening performance of the softeners, which was evaluated by stiffness, bending rigidity and bending hysteresis, was studied. It was found that better softeness was obtained when softeners with higher DP were used.The influence of curing temperature on the performance of cotton fabric treated by the softeners was studied. The performance was evaluated by WRA, BS and RBS. It was found that as the temperature increased, the WRA of treated fabrics increased while the RBS decreased. For each softener, the highest increase of WRA was obtained when the temperature raised from160℃to170℃. Thus the proper curing temperature was170℃.The influence of the sort of catalyst and the dosage on the performance was studied. Several catalysts in some reports were chosen to catalyze the reaction between epoxy-terminated polysiloxanes and cellulose. In those reports, they were used to catalyze the reaction between epoxy group and cellulosic hydroxyl group in cotton. When the whiteness and wrinkle recovery of treated fabric were considered, aluminium sulphate was suitable to catalyze the reaction. The most suitable concentration was0.8g/L～1g/L for each softener. The pH value on the surface of cotton fabric had significant influence on the perfonnance of aluminium sulphate. The pH of weak acid faciliated the performance of aluminium sulphate while the pH of weak alkaline had negative effect.The influence of condition and process on the performance was studied. Cotton fabric was crosslinked by emulsions of softeners through one-bath method. The effect of each step in the process was determined. It was found that both high curing temperature and catalyst were requred to crosslinking reaction. The demand of wrinkle resistant finish could not be met by epoxy-terminated polysiloxanes alone. For each softener, one-bath method and two-bath method had almost the same finishing perfonnance when the other finishing conditions were the same.The influence of solvent on the perfonnance was studied. Water and isopropanol were used. It was found that for the same softener, the WRA of cotton fabric treated in different solvents was almost the same while the RBS had significant difference. The RBS of cotton fabric treated in isopropanol was lower than that of cotton fabric treated in water.When cotton fabric was treated by softeners at the same mass concentration or molar concentration, the higher DP was more favorable to the increase of wrinkle recovery of cotton fabric.The SEM analysis showed that the surface of untreated cotton fibre was clean while the surface of treated cotton fibre had much sendimentation. The sendimentation of softener with higher DP was more significant than that of softener with lower DP.RGPC was used to study the pore structures of cotton fibre intact and treated by softeners of DP28and DP200. It was found that the pore structure was greatly changed after the finish. It could be concluded that the softener had entered into the pores in the cotton fibre. The softener imparted softeness to cotton fabric through both the sendimentation on the surface of the fibre and the entry into the pores in the fibre. |
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