Abstract
Sulfonation of nylon 6 fibers by 2,5 dichlorobenzenesulfonyl chloride (dbsc) has a great effect on the heat and chemical stability of the fibers. Sulfur content, carbon residue, degree of crimp, and solubility in formic acid are all determined, the effects of dbsc concentration, reaction temperature, and reaction time are studied. Increasing dbsc concentration and temperature are more effective at increasing the sulfur content in modified fibers than increasing reaction time. The best results are obtained with a dbsc concentration of 25% and a reaction temperature of 115°C for 4 hours. At these conditions, the modified fibers have 4.9% sulfur content, 26.4% carbon residue, 97.5% degree of crimp, and lose solubility in formic acid, concentrated mineral acids, and aqua regia. They do not burn when put in direct flames, but glow and char without losing fiber form. No melting occurs at up to 1000°C, and the activation energy of decomposition is 194 kJ/mole compared to 46 kJ/mole for the unmodified fibers. Strength properties decrease.
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