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Test method for flammability of flame retardant materials
1. Determination of decomposition temperature
The decomposition temperature of plastics is generally determined according to the method specified in ISO 871-2006 (GB/T 4610-2008).
According to the definition of this standard, the decomposition temperature refers to the temperature at which the material begins to decompose and release combustible gas under specified test conditions, expressed in degrees Celsius.
2. Determination of flash point temperature and autoignition temperature
The flash temperature (flash point) and autoignition temperature (autoignition point) of polymer materials are usually measured by the test method of American national standard ANSI/ASTM D1929. The device used is a hot air electric stove.
3. Determination method of oxygen index
"Oxygen index refers to the minimum oxygen concentration required for the specimen to maintain stable combustion in the mixed flow of oxygen and nitrogen under specified conditions." ASTM D2863.
Because this method is very effective to judge the combustion difficulty of materials in contact with flame in air, and can be used to grade the combustion performance of materials, it has been paid attention to by countries all over the world.
Many major industrial countries have formulated relevant standards: JIS K7201, Britain, BS 2782, Part1/144, China, GB/T 2406, Japan. In order to unify various national standards, ISO has proposed the international standard ISO 4589 for the determination method of oxygen index. IEC has also added the oxygen index method in IEC332-3 as an appendix to this standard.
4. Test method for flame retardancy
It is a widely used method to evaluate the flame retardancy of polymer materials by flame retardancy test. It mainly includes horizontal combustion and vertical combustion.
There are many standards in this field, such as Chinese GB/T 2408, American ANSL/UL-94, ASTM D568, ASTM D635, British BS4735, Japanese JIS C 6481, International Electrotechnical Commission, IEC 707, IEC 92-101, International Standard, ISO 1210, ISO 3582, ISO 3795
5. Test method for heat of combustion
The heat released by materials during combustion is also the most important factor causing casualties in fire.
Main test methods refer to: ISO5660-1 cone calorimetric test ISO 9705 GB/T 25207
6. Test method for smoke emission
There are two kinds of smoke emission tests of flame retardant materials: mass method and photometry.
Mass determination method: determine the loss value of the mass of the material before and after smoking, so as to infer the amount of starting smoke. The relevant test standards are: ASTM D 757 ASTM E 162 ASTM D 4100
Photometric method: Determine the attenuation effect of generated smoke on light intensity to judge the amount of smoke. Relevant test standards: ISO 5659 ASTM E 84 ASTM E 662 ASTM D 2843 GB/T8323
7. Analytical method for gas (toxicity) released from combustion
"Gases released by combustion of flame retardant materials are generally divided into two categories: combustible gases, such as methane, ethane, aromatic hydrocarbons, etc.; incombustible gases, such as carbon dioxide, nitrogen, ammonia, water vapor, hydrogen halide, SO2, NOX, formaldehyde, HCN, etc."
The toxicity of these gases can be obtained through chemical analysis. The most intuitive method to determine the toxicity of gases released from combustion is animal exposure. The test standard related to toxicity is: British naval engineering standard NES713 Japan JIS A 1321 Germany DIN 53436
Among many combustion test methods for flame retardant materials, the oxygen index method and UL94 plastic flammability test method are the most representative and widely used. The former can measure the flame retardancy of the material through the oxygen index value, while the UL94 test results give the flame retardancy classification of the material.