Introduction of structural properties and flame retardant properties of red phosphorus flame retardant

In the work of flame retardant modification of polymer materials, we often hear people say white phosphorus, yellow phosphorus, red phosphorus, from their names we can see Out, is the phosphorus of different colors. However, white phosphorus and yellow phosphorus refer to a substance. Yellow phosphorus is a yellow waxy solid formed by partial oxidation of white phosphorus. Chemically speaking, white phosphorus and red phosphorus are allotropes, just like diamond and graphite. Different elements belonging to the same element. Next, let’s talk about the structural properties and flame retardant properties of red phosphorus.

Structural properties of red phosphorus flame retardant

Chemically speaking, the structure determines the properties. Since red phosphorus and white phosphorus have very different structures, their properties are also different. Red phosphorus is stable in the air, while white phosphorus spontaneously ignites in the air; red phosphorus is basically non-toxic, while white phosphorus is highly toxic; red phosphorus can be used as a flame retardant, and white phosphorus can be used as an incendiary bomb. In terms of structural composition, white phosphorus is composed of P4 molecules, and the phosphorus atoms in the molecule have a regular tetrahedral structure. Red phosphorus is also composed of P4 molecules, but one of the bonds that make up the molecules is broken and polymerized to form a polymer structure. Therefore, it can It is said that red phosphorus is an inorganic polymer substance. Its molecular formula can be written as (P4)n (n represents the degree of polymerization). Note: White phosphorus can generate red phosphorus when heated in isolation from air.

Red phosphorus (RP), or red phosphorus, is red to deep purple powder in appearance, insoluble in water, dilute acids and many organic solvents, but slightly soluble In absolute ethanol, phosphorus tribromide and sodium hydroxide aqueous solution. When red phosphorus is heated to 200°C in air, it will ignite and generate P2O5. In addition, red phosphorus can also burn when heated in chlorine gas. Since the phosphorus element in red phosphorus is in a low valence state (zero valence), when it is blended with KClO3, KMnO4, peroxide and other strong oxidants, it may explode if the conditions are right.

Flame retardant properties of red phosphorus flame retardant

Red phosphorus flame retardant is the flame retardant with the highest phosphorus content among phosphorus flame retardants. According to the functional components contained, it can be divided into halogen flame retardants, phosphorus flame retardants and other flame retardants. Phosphorus flame retardants are widely used, and their status is second only to halogen flame retardants. With the accusation and questioning of halogenated flame retardants by people who don’t know the truth and the price increase of halogenated monopoly companies, phosphorus-based flame retardants are becoming more and more popular. As a member of phosphorus-based flame retardants, red phosphorus has a higher flame-retardant efficiency than other phosphorus-based flame retardants because it only contains the flame-retardant element phosphorus, and it is the same even when the amount of flame retardants is very low. In some cases, the flame retardant efficiency of red phosphorus is even slightly better than that of halogen flame retardants.

Furthermore, it has been reported that no phosphorus-based flame retardant can compete with red phosphorus for flame retardancy of PET (polyethylene terephthalate) . For the base material, the added flame retardant is foreign matter after all. If the compatibility between the two parties is poor, it is easy to damage the excellent performance of the base material itself. For red phosphorus, the required flame retardant performance can be achieved by adding a small amount, so the original excellence of the flame retardant substrate is easier to maintain. In addition, red phosphorus has a high melting point and poor solubility, which is beneficial to the maintenance of certain physical properties of polymers compared with other flame retardants. Finally, red phosphorus has a small amount of smoke, low toxicity, and a wide range of applications. It can be used alone or in combination with other flame retardants. It can be widely used in flame-retardant polyolefins, polystyrene, polyester, and polyurethane. , nylon, polycarbonate, polyoxymethylene, epoxy resin, rubber, textiles, etc.