Synergistic effect between flame retardant viscose and nitrogen-containing intrinsic flame-retardant fibers

A simple but effective method was proposed to promote the flame retardancy of blended fibers based on the synergistic effect between flame retardant fibers. The flame retardant viscose (FRV) is blended with three kinds of nitrogen-containing intrinsic flame-retardant fibers (NIFRFs), respectively. The limiting oxygen index, cone calorimeter test, thermogravimetric analysis coupled with Fourier transform infrared, scanning electron microscopy, X-ray photoelectron spectroscopy, and the laser Raman spectroscopy are used to have a comprehensive investigation on the flame retardant properties and mechanism of blended fibers. Results show that there is an obvious synergistic effect between FRV and NIFRFs. However, it is found that the improvements in flame retardancy of fiber blends have no direct relationship with the nitrogen content of NIFRFs. The difference of thermal degradation temperature (T-dmax) has more influence on the synergistic flame retardancy of the two fibers. The closer the T-dmax of FRV and NIFRF is, the more obvious the synergistic effect between blended fibers is. The residual char of blended fibers are all more compact and integrated than those of pure fibers. The FRV/poly(m-phenylene isophthalamide) (PMIA) 20/80 has the highest LOI of 47.5%, showing the best flame retardancy. [GRAPHICS] .