Fire‐retardant properties of the viscose rayon containing alkoxycyclotriphosphazene

The viscose rayon containing cyclotriphosphazene were prepared by the method of blending spinning. The combustibility and thermal stability of the fire‐retardant viscose rayon were evaluated by 45 ° slope burning method, limit oxygen index (LOI), differential scanning calorimetry, thermogravimetry analysis. The results indicated that the LOI of the modified fiber could reach LOI ≥ 28, and the combustibility of the modified fiber could reach the fire‐retardant standard of Japan industry standard JIS 10 91–77 (times of ignition ≥ 3 times). The analysis of the fiber's thermal degradation suggested that the flame retardant plays a multirole of heat absorption, catalytic dehydration and carbonization, condensation‐phase and gas‐phase flame retardation.