The flame retardant effect of magnesium hydroxide flame retardant is to prevent or inhibit the speed of physical or chemical changes during the combustion process of polymer materials. Specifically, these effects are reflected in the following six aspects.
1. The heat absorption effect
Its role is to slow down the heating rate of polymer materials.For example, borax has a crystalline water of 10 molecules. Due to the release of crystalline water to absorb 141.8kJ/mol heat, the temperature of the material has been suppressed due to its heat absorption, which produces flame retardant effects.The flame retardant effect of aluminum alumina is also due to its heating and dehydration.In addition, the melting droplets often generated by some thermoplastic polymers often produced. Because they can leave the combustion area and take away the react heat, they can also exert a certain flame retardant effect.
2. The coverage effect
Its function is to form a stable coverage layer at higher temperatures, or decompose to generate foam -like substances, covering the surface of the high polymer material, making the combustible gas generated by the high polymer material due to thermal decomposition, and it is difficult to escape, and right and right The function of the material takes up the heat and isolates the air, thereby inhibiting the cracking of the material and achieving the effect of flame retardant. Such as phosphate compounds and fire foaming coatings can be played according to this mechanism.
3. Dilute effect
Magic hydroxide flame retardants with this function can produce a large amount of non -combustible gases when heating and decomposition, and the combustible gases and oxygen in the air in the decomposition of polymer materials are diluted and the concentration range is not achieved. , Thereby preventing the fire and burning of high polymer materials. Can be used as diluted gases include Co₂, NH₃, HCI and H₂O. This non -combustible gas can be generated when heating ammonium phosphate, ammonium chloride, ammonium carbonate, etc.
4. Transfer effect
Its role is to change the thermal decomposition mode of high polymer materials, thereby inhibiting the generation of flammable gases. For example, the use of acid or alkali to make cellulose dehydration and decompose into charcoal and water, because without producing combustible gases, it cannot be burned with fire. Ammonium chloride, ammonium phosphate, and phosphate can decompose to produce such substances, catalytic material thick rings of carbonization to achieve flame retardant.
5. Inhibitory effect (capture free radicals)
The combustion of polymer is essentially the free radical chain reaction of thermal decomposition products. Some substances can capture the activity intermediate of the combustion reaction HO*, H*, O*, HOO*, etc. , Reduce the burning speed until the flame is extinguished. Commonly used organic halogen such as bromine and chlorine has this inhibitory effect.
6. Enhance effect (synergy effect)
Some additives do not have flame retardant or flame retardant effects when used alone, but when it is used with other flame retardants, it can significantly improve its flame retardant effect. This effect is called enhanced or synergistic effect. Trinity dioxide is used with magnesium hydroxide, which is the most typical example. As a result, it can not only improve flame retardant efficiency, but also reduce the amount of flame retardant.