Characterization of flame-retardant performance of polyester/flame-retardant viscose blended yarn

In this paper, a flame-retardant blend yarn was designed with flame-retardant viscose fiber and polyester. Flame-retardant viscose fiber was blended with polyester by core-spun method. Polyester was set as a core and the flame-retardant viscose fiber was set as a sheath to change the flame retardancy and disadvantage of moisture permeability. After the flame-retardant viscose fiber was spun into roving, polyester was added in spun yarn. The core yarn samples with different ratios were prepared by adjusting the amount of flame-retardant viscose fiber. The flame retardancy of core-spun yarn was evaluated by limiting oxygen index, scanning electron microscope, thermogravimetric analysis, and thermogravimetric/Fourier transform infrared techniques. Limiting oxygen index of the yarn with 50% flame-retardant viscose fiber and 50% polyester was 27.6% and just decreased slightly to 27.1% after 30 washing cycles. Polyester begins to melt from inside core-spun yarn after heating and the molten polyester flows to outer layer of yarns by the diversion effect of higher temperature. Then it was carbonized by the polymetaphosphate which was generated by the flame-retardant viscose fiber. In thermal processes, the major product of thermal decomposition was CO ₂ .