The fire resistance of rubber foam is affected by chemical composition and flame retardant. Its molecular structure determines flammability, and flame retardants can be flame retardant by decomposing to produce non combustible gases or forming protective films. It has applications in building insulation and wire and cable fields, providing a certain guarantee for safety.
1〠Basic principles
consult are collectively referred to as the rubber and plastic industries, and their fire resistance mainly depends on their chemical composition and the added flame retardants.
In terms of chemical composition, the molecular structure of rubber foam itself can affect their flammability. For example, the main component of natural rubber is polyisoprene, which contains a large number of carbon hydrogen (C-H) bonds in its molecular chain. Under high temperature and oxygen conditions, the C-H bonds are easily broken, leading to combustion reactions. However, polyvinyl chloride (PVC) in plastics has reduced combustion performance compared to some pure hydrocarbon plastics due to the presence of chlorine atoms. Because chlorine atoms interfere with the free radical chain reaction during combustion, they play a certain flame retardant role.
The function of flame retardants: In order to improve the fire resistance of rubber, flame retardants are usually added. There are multiple mechanisms of action for flame retardants. For example, some flame retardants decompose when heated to produce non combustible gases such as carbon dioxide, ammonia, etc. These gases can dilute the oxygen concentration and prevent the combustion reaction from continuing. Some flame retardants also form a protective film on the surface of the material to isolate oxygen from contact with the material, thereby achieving the purpose of flame retardancy.
2〠Fire performance indicators
Combustion performance level
The combustion performance level of rubber foam materials varies depending on the formula. Some rubber materials that have undergone flame retardant treatment can reach B1 level flame retardant level. In the GB 8624-2012 "Classification of Burning Behavior of Building Materials and Products" standard, B1 grade materials burn slowly when exposed to a fire source and can self extinguish in a short period of time after leaving the fire source. However, there are also some rubber materials that have not been added with flame retardants or have poor flame retardant effects, which may only reach the B2 level of flammability or even lower.
Oxygen Index (OI)
The oxygen index refers to the minimum oxygen concentration required for a material to maintain stable combustion (i.e., flame combustion) in a mixture of oxygen and nitrogen under specified conditions, expressed as a volume percentage. For rubber and plastic materials, the higher the oxygen index, the better their flame retardant performance. Generally, the oxygen index of non flame retardant rubber materials may be around 17-20, while after flame retardant treatment, the oxygen index of rubber materials can be increased to above 26-30, meeting the standards of flame retardant materials.
3〠Fire resistance performance in application scenarios
Building insulation field
The use of rubber insulation materials in building insulation systems requires strict control over their fire resistance performance. If it is a building in densely populated areas, it is required to use rubber insulation materials with good flame retardant properties. For example, in buildings such as hospitals and schools, using rubber insulation materials that meet B1 level flame retardant standards can to some extent prevent the spread of fires. But in the event of a large fire or prolonged high temperature environment, lower flame retardant rubber materials may still burn, releasing toxic gases and posing a threat to personnel safety.
Wire and cable industry
Rubber foam materials are commonly used for insulation and sheath of wires and cables. Rubber materials with good fire resistance can slow down the spread of fire along wires and cables when faults such as short circuits occur. By adding appropriate flame retardants, the oxygen index of rubber materials can be increased. In the event of a fire, the outer layer of rubber materials on wires and cables can effectively prevent flames from burning and spreading on their surface, buying time for firefighting and personnel evacuation.