Main methods for evaluating the combustion performance of flame retardant textiles

The evaluation of the flammability of fireproof fabrics is mainly considered from two aspects: flammability and flammability of fabrics (ie fire resistance).

There are two main methods for assessing the combustion performance of fireproof fabrics:

First, the burning rate of the fabric. That is to say, the fireproof fabric is removed from the flame after contacting with the flame for a certain period of time according to the specified method, and the time for which the fabric continues to burn with flame and the time for flameless burning, as well as the degree of damage to the fabric, is determined. The shorter the flame burning time and the flameless burning time, the lower the degree of damage to the fabric, which means that the fire resistance of the fabric is better; on the contrary, it means that the fire resistance of the fabric is poor.

Second, the oxygen index (also known as the extreme oxygen index) method. Oxygen is required for the combustion of fabrics. The oxygen index (LOI) is an expression of the oxygen required for fiber combustion. Therefore, the fire resistance of the fabric can be determined by measuring the oxygen index. The higher the oxygen index, the higher the oxygen concentration required to maintain combustion. The harder it is to burn. The index can be expressed by the smaller volume percentage of oxygen required for the sample to maintain candle-like combustion in a nitrogen and oxygen mixture: LOE = oxygen concentration / (oxygen concentration + nitrogen concentration) * 100% The oxygen index is less than 20%, it is easy to Combustible fibers; the oxygen index is between 20~26%, it is a combustible fiber; the oxygen index is between 26~34%, it is a flame retardant fiber; an oxygen index above 35% is a non-flammable fiber.

There are various combustion test methods, and the test results of various test methods are difficult to compare with each other. The combustion test method is mainly used to test the combustion breadth (carbonized area and damage length), afterburning time and smoldering time of the sample. According to the relative position of the sample and the flame, it can be divided into vertical method, inclined method and horizontal method. The oxygen index method is to place the clamped sample vertically into a transparent combustion cylinder, and there is an upward moving oxygen and nitrogen flow in the cylinder. The upper end of the sample is ignited, and the combustion phenomenon is observed immediately, and the continuous combustion time or combustion is compared with the specified limit. The distance, the oxygen index method is more suitable for use in process experiments.