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Castable, Solvent-Free, Red Phosphorus Smokes for Target Markers

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Final rept.

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Red phosphorous RP is a material that has been used historically for the production of certain types of target and location markers. Binders are necessary in the production of RP smoke grains because they provide structural integrity to the grain, whether in explosively disseminated markers such as the MK67 or in long duration markers such as the MK25MK58. Without a binder, RP will disseminate in a fine granular form, burn rapidly, and fail to sustain a white cloud for a sufficient amount of time to adequately mark a target. In addition, a major benefit of a binder is that it coats the RP particles and desensitizes them to electrostatic energy relative to uncoated or dry RP. Two methods can be used to produce pyrotechnic smoke compositions containing red phosphorous. One method is to pre-blend RP with a binder linseed oil, polyester, others in a standard mixer, and press the resulting composition. This is the process for the MK25MK58 and the M264. While the current MK25MK58 process does not use solvents, the M264 process can require up to 100 by weight of solvent. These applications both require multiple pressing steps, and post-press reaming in the case of MK25MK58. The second method is to dissolve a butyl-rubber binder in a solvent, disperse RP in the solvent binder, then extrude the desired RP smoke grain geometry, such as in the MK67. This method provides potential for recycling solvents, but does still require their use. Volatile organic compounds VOCs such as acetone, and Hazardous Air Pollutants HAPs such as hexane are commonly used. The Miscellaneous Organic National Emission Standard for Hazardous Air Pollutant NESHAP law requires controls on VOC and HAP emissions with the clear intent to minimize these emissions and protect the environment. These solvents are typically quite flammable, ESD sensitive, and are generally harmful andor toxic if inhaled or ingested. Pressed compositions can utilize less binder because they are consolidated un

Subject Categories:

  • Inorganic Chemistry
  • Combustion and Ignition
  • Air Pollution and Control

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