What do you mean flame retardant fiber

The combustion performance of fiber refers to the degree of difficulty in burning fiber in air. International rules use the "Limiting Oxygen lndex", or LOI. The ultimate oxygen index (loi) is the lowest percentage of oxygen in a mixture of nitrogen and oxygen in the environment that causes the burning fiber to leave the source of the fire while the fiber is still burning. In the air, the percentage of oxygen is 21%, so if the LOI of fiber <21%, flammable or flammable, if l01>21%, flammable or flame retardant fiber. When LOI> is 26%, it is called a flame retardant fiber.