Preparation and Properties of Flame-retardant Viscose Fiber Modified with Poly[bis(methoxyethoxy)phosphazene]

Poly[bis(methoxyethoxy)phosphazene] (PMEP) was synthesized and applied to the preparation of flame-retardant viscose fiber using wet spinning method. The structure of PMEP was characterized by FTIR and NMR. The combustibility and thermal stability of the flame-retardant viscose fiber containing different percentage of PMEP (0-20 %) were evaluated by limit oxygen index (LOI), 45 degrees slope burning method, differential scanning calorimeter (DSC), and thermal gravity analysis (TGA). The results showed that the LOI of the flame-retardant viscose fiber containing 10 % or more PMEP could reach at least 28 % after normal family laundering, and the combustibility of the flame-retardant viscose fiber could reach the Japan industry standard JIS L1091-D (3 times of ignition). The analysis of the fiber thermal degradation suggested that PMEP as a macromolecular flame retardant had a multifunction of heat absorption, catalytic dehydration, carbonization, condensation-phase and gas-phase flame retardancy. The mechanical properties of the flame-retardant viscose fiber decreased insignificantly compared with that of virgin viscose fiber.