Combined phosphorus, Physical properties

Phosphorus is one of the most remarkable of the many remarkable substances known to the chemist. The curious method of its discovery, the universality of its distribution, its intimate connection with the phenomena of animal and vegetable life, its extraordinary physical properties and chemical activity, its abnormal molecular constitution, the protean ease of its allotropie transformation, all combine to make up a history which abundantly justifies its old appellation of the phosphorus miraibilia.—T. E. Thorpe. 

Arsenic Halides. Arsenic forms a complete series of trihalides, but arsenic pentafluoride is the only well-known simple pentahalide. All of the arsenic halides, the physical properties of which are given in Table 2, are covalent compounds that hydrolyze in the presence of water. The trihalides form pyramidal molecules similar to the trivalent phosphorus analogues and may be prepared by direct combination of the elements. 

Organic chemistry is the study of compounds containing carbon the ability of carbon to form as many as 4 strong bonds to many other atoms, e.g., carbon, hydrogen, oxygen, nitrogen, halogens, sulphur, phosphorus ensures a virtual infinite number of possible compounds the constituent atoms and their exact combination determines the chemical and physical properties of compounds and hence, their suitability for applications. 

Red phosphorus flame-retardants are effective in thermoset resin systems and also elastomers, often combined with ATH, or magnesium hydroxide in elastomers. A wide range of treated red phosphorus in dispersion or concentrate form, offered by Clariant, is easier to handle and safer to transport, compared with powder grades. Such phosphorus additives do not affect the electrical properties of the composite, and they have little impact on the physical properties of the laminates manufactured. 

ATH and MH are used primarily in wire and cables in poly( vinyl chloride) (PVC), polyethylene, and various elastomers. There is also some limited application of MH in polyamide-6. To pass flame retardancy tests, 35 to 65 wt% of metal hydroxide is required. Decreasing the loading of metal hydroxides will result in a significant gain in physical properties, especially low-temperature flexibility therefore, combinations with red phosphorus, sUicones, boron compounds, nanoclays (treated montmorillonites), and charring agents have been explored. Surface treatment of metal hydroxides also helps to improve physical properties and sometimes improves flame retardancy, due to better dispersion. 

Another interesting systemic phosphorus compound is fosetyl Al, a systemic fungicide. It has preventive and curative activity against many Oomycetes on many different crops. This combination of a phosphite and aluminium gives the necessary chemical and physical properties to the material to make it an effective fungicide. 

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