Flame retardant modification of acrylic fiber with hydrazine hydrate and sodium ions

The sodium ions were introduced into the acrylic fibers by post-treating the fibers with hydrazine hydrate and aqueous sodium hydroxide to improve the flame resistance of the fibers. The molecular structure of the modified acrylic fibers was characterized by FTIR spectra. The flame resistance of the acrylic fibers was significantly increased after post-treatment and was relied mostly on the content of sodium ions. The flame-retardant mechanism of the modified fiber was studied in details. The micro calorimeter tests showed that the total heat release and the peak heat release rate were largely reduced after post-treatment. Photographs of the char residues and the results of TGA and TG-IR technique revealed that the flame retardance of the modified acrylic fiber was provided through the combination effect of the gas phase and condensed phase.