Classification and basic principles of flame retardant methods for polymer materials

When polymer materials are heated in the air, they will decompose to form volatile combustibles, which can be burned when the concentration of combustibles and the temperature of the system are high enough. Therefore, the combustion of polymer materials can be divided into two processes: thermal and oxygen degradation and combustion, involving heat transfer, thermal and oxygen degradation of polymer materials in the condensed phase, diffusion of decomposition products in the solid phase and gas phase, mixing with air to form an oxidation reaction field and chain combustion reaction in the gas phase. When the heat source heat of the polymer material can decompose the polymer material, and the combustibles produced by the decomposition reach a certain concentration, and the system is heated to the ignition temperature, combustion can occur.

Whether the ignited polymer material can continue to burn after the ignition source is stabilized depends on the heat balance of the combustion process. The combustion of polymer materials can only continue when the heat generated by the supply combustion is equal to or greater than the total heat required for each stage of the combustion process, otherwise it will be stopped or extinguished. From the combustion mechanism of polymer materials, it can be seen that the essence of flame retardant effect is achieved by slowing down or stopping one or several elements.

These include six areas: improving the thermal stability of the material, capturing free radicals, forming a non-flammable protective film, absorbing heat, forming a heavy gas barrier, and diluting oxygen and flammable gases. At present, the behavior of flame retardants commonly used is mainly achieved through the physical pathway of cooling, dilution, formation of a separator film and the chemical pathway of terminating free radicals.

The general flame retardant mechanism is divided into gas phase flame retardant mechanism, condensed phase flame retardant mechanism and interrupted heat exchange flame retardant mechanism. Combustion and flame retardant are very complex processes, involving many influences and constraints, it is difficult to strictly divide the flame retardant mechanism of a flame retardant system into a certain one, and a flame retardant system often has several flame retardant mechanisms working at the same time.

It's too general, I learned carbon fiber ablation resistance, and other methods and flame retardants are fundamentally different things. Like melamine, it is used to paint flame retardant. It's just too much.

The basic principle is mainly the method of isolating oxygen, and there is also the method of carbonization. For a specific in-depth understanding, you need to go to the library to check the materials, which cannot be solved here.

Leave your mailbox, I have this information to send to you... or qq me: 122209028

1.Isolate the air (oxygen) gas for combustion conditions. For example, all kinds of fire extinguishers and other products, oil fire sand burial, Qiaohong activated carbon soil covering are made of this principle;

2.Reduce the temperature of combustion. For example, the water used in fire fighting is used to extinguish fires, in order to reduce the high temperature caused by combustion, and to eliminate the evil cycle of ignition and burning.

3.The material itself is not flammable.

Summary. One of the major disadvantages of polymer materials is their thermal stability and flame retardant properties. From the perspective of the structure of the polymer material itself, the flame retardant effect of the inert gas that can be cross-linked into carbon by heat or the heat can release inert gas is better, or it contains flame retardant elements (fluorine, bromine, chlorine, phosphorus, boron, etc.) such as PTFE itself has good flame retardancy.

In terms of external additives, it is to add flame retardants to make polymer materials obtain the corresponding flame retardant effect. Hope the above can help you.

One of the major disadvantages of polymer materials is their thermal stability and flame retardant properties. In terms of the structure of the polymer material itself, the flame retardant effect of the inert gas that can be cross-linked into carbon by heat or the heat can release inert gas is better, or it contains flame retardant elements (fluorine, bromine, chlorine, phosphorus, boron, etc.) such as PTFE itself has good flame retardancy. From the perspective of adding external call agent, it is to add flame retardant to make the polymer material obtain the corresponding demand for the pre-slip and anti-combustion effect.

Hope the above can help you.

Thank you. But what does this have to do with indicators? <>

Oh. According to its composition, it can be divided into two categories, one is the polymer itself with a flame-retardant crust structure, such as polyvinyl chloride, polyvinylidene chloride, fluorine-containing plastics, etc., or polymer materials that introduce flame-retardant le-imignition structures or flame-retardant elements into the molecule; The other type is a composite flame-retardant polymer material composed of flame retardant added to ordinary combustible polymer. There are three types of flame retardants added in the preparation of composite flame-resistant polymers, the first is inorganic salts, including antimony trioxide, hydrated alumina, zinc borate, magnesium hydroxide, etc., which absorb heat when encountering flames and hinder the propagation of fire-type flames; The second category is organic compounds containing halides and phosphorus, and its flame retardant mechanism is mainly to capture the free radicals required for combustion reactions; The third type is represented by polybendazoles, which carbonize when burned, forming a carbonized layer, thus preventing the flame from spreading.

Composite flame-resistant polymer materials are of great significance in preventing fires.

Flame retardant material is a kind of protective material, it is a material that can prevent combustion and is not easy to burn, such as solid materials such as cement, steel, glass and so on; There is a liquid state, also referred to as flame retardant, if the flame retardant is coated on the surface of various materials such as the firewall, it can ensure that it will not be burned at the time of **, and will not aggravate and expand the scope of combustion.

At present, flame retardant materials mainly include organic and inorganic, halogen and non-halogen. Highly flame retardant material.

Organic is bromine, nitrogen, red phosphorus and compounds as the representative of some flame retardants, inorganic is mainly antimony trioxide, magnesium hydroxide, aluminum hydroxide, silicon and other flame retardant systems.

The flame retardant is applied to flammable materials by adding blending, chemical reaction, coating or impregnation, etc., so that it has excellent flame retardant properties and application properties such as difficult to ignite, easy to self-extinguish, low flame propagation speed, low heat release and smoke release rate, non-toxic and other excellent flame retardant properties and application properties to become flame retardant materials.

Flame retardants are additives used to improve the flame resistance of materials, that is, to prevent materials from being ignited and inhibit the spread of flames. Flame retardants are mainly used for flame retardant synthetic and natural polymer materials (including plastics, rubber, fibers. Timber. Paper. coatings, etc., mainly plastics).

I hit the book hand. Wow Ka Ka I'm tired to death.

Flame retardants are divided into bromine, phosphorus, nitrogen, inorganic (magnesium hydroxide, boric acid New Year) flame retardants according to products: PP flame retardants, PE flame retardants, ABS flame retardants, PC flame retardants, nylon flame retardants, etc.

Flame retardants are divided according to the effect: non-dripping flame retardant, V0 flame retardant, V1 flame retardant, V2 flame retardant, flame retardant according to the characteristics: transparent flame retardant, halogen-free flame retardant, nano flame retardant, flame retardant according to the mechanism:

Additive flame retardants, reaction flame retardants, flame retardants, and flame retardants are divided into liquid flame retardants, solid flame retardants, etc.

Flame retardants exert their flame retardant effect through the mechanism of endothermy.

If a part of the heat emitted by the ignition source can be absorbed in a short time, then the flame temperature will be reduced, the heat radiating to the combustion surface and acting on the pyrolysis of combustible molecules that have been vaporized into free radicals will be reduced, and the combustion reaction will be inhibited to a certain extent.

Under high temperature conditions, the flame retardant undergoes a strong endothermic reaction, absorbing part of the heat released by combustion, reducing the temperature of the surface of the combustible, effectively inhibiting the generation of flammable gases, and preventing the spread of combustion.

The flame retardant mechanism of Al(OH)3 flame retardant is to improve the flame retardant performance by increasing the heat capacity of the polymer so that it can absorb more heat before reaching the thermal decomposition temperature. This type of flame retardant gives full play to its characteristics of absorbing a large amount of heat when combined with water vapor, and improves its own flame retardant ability.

Classification of flame retardants

1. Organophosphorus flame retardant.

Main products: tensor, phosphoric acid, phosphorous acid, organophosphorite branch salt, oxidation and phosphorus-nitrogen compounds, etc. The products of thermal decomposition of phosphorus compounds have a very strong dehydration effect, which can carbonize the surface of the covered polymer and form a carbon film to isolate the air, so as to achieve the effect of flame retardant.

Disadvantages: poor heat resistance, high volatility, deterioration of the heat deflection temperature of the plastic.

2. Inorganic phosphorus flame retardant.

Main products: red phosphorus, microcapsulated red phosphorus, phosphate, polyphosphoric acid (APP), etc. It is suitable for flame retardant systems with intumescent chain destruction, and is mainly used for flame retardant such as polyolefins, polyurethane cool foams, coatings, etc.

5. Triazine flame retardant.

Triazine flame retardants are mainly melamine and its derivatives, which have multiple reaction functions, excellent thermal stability, good flame retardant effect, and good compatibility with polymers. Main products: melamine, melamine cyanogenic vein (MCA), MPP, MP, etc.

Melamine and its derivatives are suitable for intumescent flame retardant systems, mainly used in intumescent flame retardant nylon.

The above content refers to Encyclopedia - Flame Retardants.