The main role of environmental flame retardant in fire

2022-07-11 09:26:32

Is it feasible to test the flame retardancy of flame retardants with lighters?

Generally, the common method of testing the flame retardancy of flame retardants is to use lighters. Is it feasible to test the performance of samples with lighters?

It is easy to judge the halogen system by directly testing the flame retardancy of products with lighters, because the mechanism of the system determines that the compactness of products has little effect on the flame retardancy effect. The same is true of hydroxide system.

However, for the carbon forming flame retardant of nitrogen phosphorus system, due to the carbon forming mechanism, the compactness of the product has a greater impact on the flame retardant. For example, the compactness of the newly extruded strip is limited, and there may be some pores inside, which has side effects on the carbon forming. However, the compactness of the products after injection molding is greatly enhanced, and the carbon forming effect is more rapid. Therefore, when testing flame retardants with lighters, we must distinguish the objects, so that the test results will be more accurate and it will be easier to identify the flame retardant grade of flame retardants.

Environmental friendly flame retardants play three main roles in fires:

1. Covering effect after adding environmental friendly flame retardant to combustible materials, it can form a glass like or stable foam covering layer at high temperature, isolate oxygen, and have the functions of heat insulation, oxygen isolation, and preventing combustible gases from escaping outward, so as to achieve the purpose of flame retardation. The reason is that on the one hand, it can prevent the polymer from further pyrolysis, on the other hand, it can prevent the internal thermal decomposition products from entering the gas phase to participate in the combustion process.

2. Inhibition of chain reaction according to the chain reaction theory of combustion, free radicals are needed to maintain combustion. Environmental friendly flame retardants can act on the gas-phase combustion zone, prevent the spread of flame, reduce the flame density in the combustion zone, and reduce the combustion reaction speed until termination. For example, halogen-containing flame retardants have the same or similar evaporation temperature and polymer decomposition temperature. When the polymer is heated and decomposed, the flame retardants also volatilize at the same time. It can capture the free radicals in the combustion reaction, so as to prevent the spread of flame, reduce the flame density in the combustion area, and finally reduce the combustion reaction speed until termination.

3. Smothering effect of non combustible gas when the environmental flame retardant is heated, it decomposes the gas that is not conducive to combustion, dilutes the concentration of combustible gas below the lower limit of combustion, dilutes the oxygen concentration in the combustion area, and prevents the continuation of combustion, so as to achieve the effect of flame retardation.