Main methods to evaluate the combustion performance of flame-retardant textiles
Tag:
Flame retardant fabrics, flame retardant textiles, flame retardant fabrics burning properties
The evaluation of the flammability of flame-retardant fabrics is mainly considered from two aspects: the flammability of the fabric and the flammability of the fabric. Combustibility (i.e. flame retardancy).
There are two main methods to evaluate the burning performance of flame retardant fabrics:
1. The burning rate of fabric. That is, the flame-retardant fabric is in contact with the flame for a certain period of time according to the prescribed method and then the flame is removed, and the time for the fabric to continue burning with flame and the time for flameless burning is measured, as well as the degree of damage to the fabric. The shorter the flaming burning time and the flameless burning time, and the lower the degree of fabric damage, the better the flame retardant performance of the fabric; conversely, it means the fabric has poor flame retardant performance.
2. Oxygen index (also called extreme oxygen index) method. Fabrics require oxygen to burn. The oxygen index (LOI) is an expression of the oxygen required for fiber burning. Therefore, the flame retardant performance 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, that is, It means it is more difficult to burn. This index can be expressed by the smaller volume percentage of oxygen required for the sample to maintain candle-like combustion in a mixed gas of nitrogen and oxygen: LOE = oxygen concentration / (oxygen concentration + nitrogen concentration) * 100% The oxygen index is lower than 20%, which is easy Combustible fiber; an oxygen index between 20 and 26% is a flammable fiber; an oxygen index between 26 and 34% is a flame-retardant fiber; an oxygen index above 35% is a non-flammable fiber.
There are various combustion test methods, and it is difficult to compare the test results of various test methods with each other. The experimental results can only explain the combustion of the sample to a certain extent. Performance pros and cons. The combustion experiment method is mainly used to test the combustion extent (charring 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, tilt method and horizontal method. The oxygen index method is to put the clamped sample vertically into a transparent combustion tube. There is an upward moving oxygen and nitrogen flow in the tube. The upper end of the sample is ignited. The combustion phenomenon is then observed, and the continuous burning time or combustion is compared with the specified limit. distance, the oxygen index method is more suitable for process experiments.
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