Controlled growth of magnesium hydroxide crystals and its effect on the high-temperature properties of cotton/magnesium hydroxide composites

摘要

Controlled magnesium hydroxide particles were assembled successfully on the surface of cotton fibers for the improvement of flammability and thermal stability of cotton/magnesium hydroxide composites. Unlike previous researches where magnesium hydroxide particles have been blended into polymer matrix, self-assembly of particles onto the fiber surface demonstrated in this research provided substantially excellent properties. The morphology, structure and properties of cotton/magnesium hydroxide composites were characterized. Here, the fibers exhibited a swelling surface after the urea-modification, resulting in the more amounts of magnesium hydroxide crystals growing. Without the presence of sodium chloride, the particles self-assembled into lamellar-like structure on the surface of cotton fibers and into rod-like structures with the presence of sodium chloride thereby enabling us to control the growth of the particles. The vertical flammability test showed that the introduction of sodium chloride resulted in the change of morphology of magnesium hydroxide crystals, which had the important effect on the fire-proofing properties of cotton/magnesium hydroxide composites. The weight loss of origin fabrics, citric acid-modified cotton fabrics with Mg(OH)_2 crystals grew with salts and urea/citric acid-modified cotton fabrics with Mg(OH)2 crystals grew with salts were 81.5%, 57.4% and 48.9% respectively when heated to a temperature of 500 °C.