Magnesium/Teflon/Viton (MTV) and Magnesium/Teflon/ Hytemp (MTH) aircraft decoy flares continue to be important countermeasures used to protect military helicopters and fixed-wing aircraft against heat-seeking missiles. Environmental and safety concerns are major drawbacks to the current processing technology for manufacturing these compositions. This is due primarily to use of large quantities of acetone and hexane, a hazardous air pollutant (HAP), in the manufacturing process. Significant amounts of these flammable solvents vaporize into the atmosphere, where they pose environmental, personnel health, and safety hazards. The production of MTV/MTH flares has resulted in numerous events involving personnel injury and death. Current manufacturing processes, although improved over historical methods, are batch processes that require transfers of large quantities of highly flammable solvents from one container to another. Risks of accidental ignitions are high, but eliminating these risks has been shown to be both difficult and expensive.
The objective of this project was to develop an environmentally acceptable aircraft decoy flare formulation produced by a twin-screw extrusion process that does not require the use of HAPs or volatile organic compounds (VOC) during its manufacture. The new material must meet or exceed current MTV or MTH countermeasure product performance specifications.
A formulation and process was developed to demonstrate the feasibility of producing an aircraft decoy flare composition via a solvent-free twin-screw extrusion process. The formulation employs magnesium, Teflon, and a thermoplastic binder, hence the designation MTTP. After screening a number of candidate thermoplastics, the thermoplastic selected was PVC-co-PVAc. A combustion residue analysis was conducted on the MTTP formulation via EPA Method 8280 and Method 8080 to determine if dioxins or furans were produced. The composition was then produced during multiple runs on a 19-mm twin-screw extruder. Burn time and radiant energy were measured on a number of extruder runs. An interim hazard classification was obtained. For subscale characterization and evaluation in their respective flare configurations, eight pounds of material were packaged and shipped to the U.S. Army Armament Research, Development, and Engineering Center (ARDEC) and slightly more than eleven pounds of material were packaged and shipped to Naval Surface Warfare Center (NSWC) Crane. NSWC Crane completed sensitivity and differential thermal analysis testing. ARDEC completed static and wind tunnel testing of 32 full-size MTTP flares.
A continuous twin-screw extruder was used to mix/extrude MTTP into a decoy flare composition that meets current MTV or MTH countermeasure product specifications. The twin-screw extrusion process will significantly reduce the air pollution, personnel health hazards, potential loss of life through solvent fires, and hazardous wastes associated with the standard batch process for MTV or MTH countermeasure production. A preliminary cost analysis shows that $3.4 million could be saved in countermeasure production over the next five years by eliminating hexane and acetone from the manufacturing process. An additional cost savings would result from the improved process yield using the new technology. (Project Completed – 2005)