The first ignifugantes substances that were used in plastics were halogenated compounds (based on organic compound containing mainly Bromine and chlorine) and organophosphorus compounds. The mechanism of action of this compound se basa en act as "catchers" radicals high energy produced by burning substances.
A separate group is made up of other inorganic compounds that contain a significant percentage of water hydration such as trioxide Aluminum (Al (OH) 3) and magnesium hydroxide (Mg (OH) 2). From these compounds can be formulated halogen-free materials. However, it requires high concentrations (greater than the 30-40%) to reach an adequate cooling able to inhibit the ignition, and once the water is released, the plastic again be flammable.
In this regard, it is important to consider both types of flame retardant incorporated in very high percentages also affect the process and the physical and thermal properties of the material, such as fluency, temperature bending under load (HDT), resistance traction and resistance to impact.
In addition to the previous ignifugantes, also used Antimony oxide for its synergistic effect with halogenated compounds and other agents as flame retardants boric acid or zinc borate.
The choice of ignifugante to use, depends largely on the plastic matrix to change, and must reach a balance between the required properties to the material and its reaction to fire. In general, you should use more than one type of ignifugante to influence all those factors acting on the mechanism of a fire. Following is a table summarizing the main mechanisms involved, depending on the type of ignifugante employee, as well as the parent plastic in which are more effective.
No hay comentarios:
Publicar un comentario