Applications for Red Phosphorus

As is evident, less than 10% of RP produced annually is used for military pyrotechnics. Its major use is in non-military applications where it is used mainly for the production of safety matches, aluminum phosphide (used for grain fumigation) and flame retardants. The use of RP as a flame retardant in the plastics industry, where it is added at the levels of a few percent to plastics such as poly- 

The acids formed are hygroscopic and absorb moisture from the atmosphere to produce submicron-sized droplets of an aqueous solution of phosphoric acid and a series of polyphosphoric acids. It is the mist of these acids which constitutes the white smoke cloud and scatters visible and near-IR electromagnetic radiation. The amount of smoke formed depends on the RH of the atmosphere. Under high humidity conditions, it is possible to achieve yield factors of four or even higher. 

Some pyrotechnic formulations based on epoxy-resin-plasticized RP in combination with Mg and other additives could screen IR radiation (0.82 pm, 3.0-5.0pm and 10.6 pm wavelengths) with high efficiency under field conditions and prove to be suitable for smoke grenades of modem construction [41]. 

Signaling smoke applications require formulations that produce large amounts of visible flame and smoke for relatively long duration. A formulation consisting 

The reactions involved during combustion of this formulation are complex. However, the combustion seems to indicate a concurrent oxidation of two fuels (Mg and P) by the oxides present. It is believed that a thermite-type reaction of the Mg provides heat to evaporate most of the phosphorus which then burns in air. The reactions involved may be shown by Equations 5.21  

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Applications for Red Phosphorus RP is commercially used in a wide variety of industrial applications safety matches, flame retardants, phosphides and pyrotechnics. (Figure 5.4). In most applications, the red allotrope is favored over the white because of its greater stability in air and also its easier handling characteristics. RP is also not considered problematic with regard to environmental and occupational health issues. It is not soluble in water and is considered nontoxic when pure. When the content of WP is less than 0.02%, the LD50-value is >15000mg/kg (rat). 

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