The development of lightweight vehicles has promoted the widespread application of polymer materials in the automotive industry. Polymer materials can be seen in various components of automobiles, such as interior materials, load-bearing parts, and new energy power batteries. Due to the special requirements of automotive use, flame retardancy is a very important factor in performance.
However, the flame retardancy performance of most polymer materials is not ideal. Therefore, when polymeric materials are applied to automotive components, they need to be modified for flame retardancy, and the polymer materials with flame retardancy properties can be prepared to increase their limiting oxygen index (LOI) to 25.0% ~35.0%, effectively improving the safety performance of automobiles.
The development of flame retardant polymer materials in China started relatively late, but has developed rapidly. In recent years, the fast-growing new energy vehicle industry has directly boosted the demand for flame retardant polypropylene.
Temperature, combustibles and oxygen are the three elements of combustion. Flame retardancy can be achieved by slowing down or preventing one or more of these elements. The flame retardancy mechanism of polymer materials is generally divided into three types: gas-phase flame retardancy, condensed-phase flame retardancy, and interruption of heat exchange flame retardancy.
Gas-phase flame retardancy system refers to the flame retardant effect that interrupts or delays the chain reaction of combustion in the gas phase.
When heated or burned, flame retardant materials can produce free radical inhibitors, thereby interrupting the combustion chain reaction.
When heated or burned, flame retardant materials can generate fine particles that promote the combination of free radicals to terminate the chain reaction of combustion.
When heated or burned, flame retardant materials can release a large amount of inert gas or high-density steam, which suffocates the combustion and terminates the combustion process.
Condensed-phase flame retardancy refers to the retardation or interruption of the flame retardant effect generated by the thermal decomposition of the flame retardant material in the condensed phase.
Flame retardants in the condensed phase can delay or prevent the thermal decomposition that produces combustible gases and free radicals.
Inorganic fillers with larger specific heat capacity in flame retardant materials can make the materials difficult to reach the thermal decomposition temperature by storing and conducting heat.
When burning, flame retardant materials can generate a porous carbon layer on their surface, which is difficult to ignite, insulated, and isolated, blocking the diffusion of combustible gases and heat, slowing or terminating the combustion of polymer materials.
The flame retardant polymer materials transfer part of the heat generated by the combustion to reduce the temperature of combustibles to below the thermal decomposition temperature of materials, making them unable to maintain the production of volatile substances, thereby achieving flame retardation.