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What is flame retardant mechanism of unsaturated polyester resin ?

Jan 24, 2019

Flame retardancy of FRP pipes is usually achieved by adding a flame retardant to the resin matrix. The flame retardant can be classified into an additive type and a reactive type depending on the method of use. The additive type flame retardant mainly functions as a flame retardant by adding a flame retardant to the combustibles. The reactive flame retardant introduces a flame retardant group into the polymer material through a chemical reaction, thereby improving the flame resistance of the material, and preventing the material from being ignited and suppressing the propagation of the flame. Among the flame retardant types, the added flame retardant is dominant, and the range of use is relatively wide, accounting for about 85% of the flame retardant, and the reactive flame retardant only accounts for 15%.

Flame retardants exert their flame retardant effects through several mechanisms, such as endothermic action, covering action, inhibition of chain reaction, and suffocation of non-combustible gases. Most flame retardants work together to achieve flame retardant effects through several mechanisms.

The flame retardant can be classified into a halogen-based flame retardant, a phosphorus-based flame retardant, a nitrogen-based flame retardant, a phosphorus-halogen flame retardant, and a phosphorus-nitrogen flame retardant according to the flame retardant element contained therein. During the pyrolysis process, the halogenated flame retardant decomposes X and HX which capture and transport combustion radicals. HX can dilute the combustible gas generated during the cracking of combustible materials and block the contact of combustible gas with air. Phosphorus-based flame retardants produce phosphoric anhydride or phosphoric acid during combustion, which promotes dehydration and charring of combustibles and prevents or reduces the generation of combustible gases. Phosphoric anhydride also forms a glass-like melt on the surface of the combustible material during pyrolysis, which causes it to oxidize to form carbon dioxide, which acts as a flame retardant. In the nitrogen-based flame retardant, a nitrogen compound and a combustible substance act to promote cross-linking to form charcoal, reduce the decomposition temperature of the combustible material, and generate a non-combustible gas, thereby functioning to dilute the combustible gas. Phosphorus-halogen flame retardant and phosphorus-nitrogen flame retardant mainly achieve the flame retardant effect through the synergistic effect of phosphorus-halogen and phosphorus-nitrogen, and have the dual effects of phosphorus-halogen and phosphorus-nitrogen, and the flame retardant effect is better. 

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Neweco is one of the leading unsaturated polyester resin manufacturers and  suppliers,widely used in automobiles, ships, rail transit, wind power  generation, pipe cans, heat and corrosion protection, building  materials, stone repair, sanitary ware, artificial stone and other  industries. Suitable for hand lay-up, spray, pultrusion, winding,  molding, vacuum introduction / RTM, casting and other molding processes. Neweco Resin is committed to excellence and focuses on the application  of composite materials to provide customers with comprehensive  solutions.

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