Most polymeric materials are hydrocarbon organic structures, which are flammable and combustible materials with high heat release rates, high calorific values and fast flame propagation during combustion. In recent years, countries have been upgrading their regulations on flame retardant materials and have put forward higher requirements on the flame retardancy of polymer materials. The common methods used for flame retardancy of polymer materials are horizontal combustion method, vertical combustion method, oxygen index method and scorching wire combustion method.
Horizontal combustion method.
1. Basic concept: Horizontal burning can be carried out on plastic, rubber, foam, etc. (common horizontal burning levels: HB, HB40, HB75, HBF, HF-1, HF-2).
2. Common standards: UL94, ASTM D635, GB 2408 Method A, ASTM D4986, ISO9772
3. Test apparatus: Horizontal and vertical combustion tester
Vertical combustion method.
1. Basic concept: can be used for plastic board, rubber board, foam material, film material, etc. to burn in vertical direction (common vertical burning levels: V-0, V-1, V-2, VTM-0, VTM-1, VTM-2, FV0, FV1, FV2, VW-1).
2. Common standards: UL94, GB 2408 Method B, ASTM D3801, GB 4609, ASTM D4804, ISO 9773, UL 1581, UL 2556
3. Test apparatus: Horizontal and vertical combustion tester
Oxygen index method.
1. Basic concept: Under the specified conditions, the low oxygen concentration required for flaming combustion of materials in a mixture of oxygen and nitrogen, usually expressed as a value of the percentage of volume occupied by oxygen. High oxygen index means that the material is not easy to burn, low oxygen index means that the material is easy to burn.
2. Common standards: GB 2406.2, ASTM D2863, ISO 4589-2, JIS K7201-2
3. Test equipment: oxygen index tester
Scorching wire combustion method.
1. Concept: After heating a specified electric wire with high current to the test temperature (550°C-960°C) for 1min, the sample is scorched vertically with the specified pressure and the sample and the bedding are observed to determine the ignition risk of the sample by observing whether the sample ignites or holds the ignition time, and the ignitability, ignition temperature (GWIT), flammability and flammability index (GWFI) of the solid combustible material are obtained.
2. Common standards: IEC 60695-2, GB 5169, GB 4943
3. Test equipment: Scorching wire tester