Lamellar magnesium hydroxide crystals were prepared successfully on the surface of polysulfonamide fibers with carboxylic acid groups. The polysulfonamide fabrics with Mg(OH)2 crystals were characterized by Scanning electron microscopy, Inductively coupled plasma atomic absorption spectrometer X-ray diffraction, Vertical flammability test and Thermalgravimetric analysis. The vertical flammability test showed that the damaged length of original polysulfonamide fabrics was 34mm, while that of the polysulfonamide fabrics with Mg(OH)2 crystals (treated by 7.5% NaOH solutions) was 14mm. In addition, the Mg (OH)2 crystals played a critical role in the improvement of thermal stability and heat insulation of polysulfonamide fabrics.
