Preparation and characterization of cyclotriphosphazenekeratin/viscose fibers

The aim of this study is to develop a flame-retardant viscose fiber using the phosphazene derivative of a natural polymer. Hexachlorocyclotriphosphazene (HCCTP) and keratin were used as the raw materials to synthesize cyclotriphosphazenekeratin (CCTPK). The Fourier transform infrared spectroscopic results indicate that CCTPK was successfully synthesized. The thermal analysis shows that the introduction of phosphazene into keratin lowered the primary decomposition temperature, increased the decomposition rate, and caused less weight loss. CCTPK blended viscose fibers were prepared by the wet spinning method, and the properties of the fiber were investigated. Limiting oxygen index of the flame-retardant fiber containing 10 % flame retardant was 28.6 %, which decreased to 27.5 % after 30 washing cycles. After burning, the scanning electron microscopy image showed an inflated carbonized coat on the fiber surface. The effect of CCTPK on the mechanical properties of the fibers was insignificant. CCTPK was compatible with keratin, and the flame retardancy of the viscose fiber was significantly improved.