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How does plastic modification achieve flame retardancy?

Time : 2023-07-13 Hits : 3

Materials must be flame retardant in numerous situations, with electrical equipment being one of the most frequent uses. Although often less stringent, the vehicle sector also has flame retardancy regulations. By adding flame retardants, flame retardancy can be obtained. Most polymers may catch fire. The need to increase plastics' flame retardancy is essential due to the widespread use of plastics in building, furniture, transportation, aviation, aerospace, electrical appliances, etc.

Flame retardants, often referred to as flame retardants, fire retardants, or fire retardants, are functional additives that provide flammable polymers flame retardancy; the majority of them are found in the periodic table of elements in groups VA (phosphorus), VIIA (bromine, chlorine), and IIIA. (Antimony and Aluminum) compounded elements.

The flame retardant category also includes molybdenum compounds, tin compounds, and iron compounds with smoke suppression effects. These compounds are primarily suitable for plastics with flame retardant requirements and delay or prevent the burning of plastics, especially polymer plastics, while also lengthening the ignition time, making them difficult to ignite and self-extinguishing when ignited.

Principle of flame retardant

1) endothermic effect

Any combustion has a limited capacity for rapid heat release. The temperature of the flame will drop, radiate to the combustion surface, and act on the gasified gas if some of the heat supplied by the fire source can be quickly absorbed. Free radicals that have been broken down into combustible molecules will produce less heat, and the combustion reaction will be somewhat impeded.

The flame retardant has a potent endothermic reaction at high temperatures, which decreases the surface temperature of combustibles, absorbs some of the heat produced by burning, and effectively limits the production of flammable gases as well as the spread of fire.

In order to better operate as a flame retardant, Coace's W5A flame retardant works by increasing the polymer's heat capacity, which allows it to absorb more heat before reaching the thermal breakdown temperature. When mixed with water vapor, this type of flame retardant fully utilizes its capacity to absorb a lot of heat and enhances its own flame retardant capability.

Flame Retardant Compatibilizer Toughener

2) Effect of covering

In order to achieve the goal of flame retardancy, flame retardants are added to combustible materials. At high temperatures, the flame retardants can form a glassy or stable foam covering layer, which can isolate oxygen and perform the functions of heat insulation, oxygen isolation, and preventing combustible gas from escaping.

For instance, when heated, flame retardants made of organic phosphorus can form carbonized layers or cross-linked solids with more stable structures.

The development of the carbonized layer has the potential to both stop further pyrolysis of the polymer and stop the internal thermal breakdown products from entering the gas phase and contributing to combustion.

3) Chain reaction with inhibition

Free radicals are necessary for combustion to continue, claims the chain reaction hypothesis of combustion. In order to stop the flame from spreading, reduce the flame density in the combustion zone, and ultimately slow down the combustion reaction speed until it stops, flame retardants can operate on the gas phase combustion zone to trap free radicals in the combustion reaction.

The evaporation temperature of a flame retardant containing halogens, for example, is the same as or very similar to the temperature at which the polymer decomposes. The flame retardant volatilizes simultaneously with the polymer when it is heated to break it down. The thermal decomposition product and the halogen-containing flame retardant are both present in the gas phase combustion zone at this time, and the halogen can capture free radicals in the combustion reaction to stop it from spreading, reduce the flame density in the combustion zone, and finally slow down the rate of combustion until it stops.

4) Non-combustible gas asphyxiation

The lower limit of combustion is lowered when the flame retardant is heated because it decomposes into non-combustible gas and dilutes the concentration of combustible gas created when combustibles are broken down. Additionally, it has the effect of lowering the oxygen content in the combustion zone, stopping further burning, and producing the flame retardant effect.


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