There are usually two ways to judge the flame-retardant properties of flame-retardant fabrics, one is to judge the burning rate, and the other is to judge by the polar oxygen index method of the fabric.
Judging by the burning rate of the flame-retardant fabric: After the fabric is in contact with the flame for a certain period of time according to the prescribed method, the flame is removed, and the time for the fabric to continue burning and smoldering and the length of damage to the fabric are measured. The shorter the continuous burning and smoldering time and the lower the damage length, the better the flame retardant performance of the fabric.
The oxygen index method is more suitable for process experiments. It is judged by measuring the extreme oxygen index (LOI) of the sample: the oxygen index refers to the amount of oxygen required for the combustion of the fabric. The higher the oxygen index, the oxygen required to maintain the combustion The higher the concentration, the harder it is to burn.
The volume concentration of oxygen in the air is about 21%. The oxygen index is less than 20%, it is a flammable fiber, the oxygen index is between 20% and 26%, it is a combustible fiber; the oxygen index is between 26% and 34%, it is a flame-retardant fiber; the oxygen index is above 35%, it is non-combustible fiber.