Study on the flame retardant property and the pyrolysis process of a novel potassium-ferric carrageenan fiber

[Display omitted] •A new type of carrageenan fibers have been developed successfully.•CAF-K,Fe have good flame retardancy and special shape.•Pyrolysis process and flame retardant mechanism of CAF-K,Fe were deduced.•The way of Fe3+ combine with fibers was inferred. A novel carrageenan fiber-potassium ferric fiber (CAF-K,Fe) is prepared via wet spinning process and its flame retardant performance is analyzed. The pyrolysis process of CAF-K,Fe is studied through TGA, FT-IR, XRD and SEM testing. The results show that the CAF-K,Fe possesses fairly good flame retardancy whose limiting oxygen index (LOI) is 32 and residues is 28.6%. It is deduced that a large amount of Fe3+ react with the sulfate groups to form CAF-K,Fe. When temperature increased from 180 °C to 700 °C, CAF-K,Fe decomposes into Fe2O3, which adhere to the surface of the carrgeenan fiber evenly, acting as a protective film to insulate oxygen, absorb heat and thus show a flame retardant property itself. Thus, the fiber can be widely used in the textile industry due to its flame retardancy and environmental protection.