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Influence of Polytetrafluorethylene on the Mechanical and Safety Properties of a Composite Modified Double Base Propellant

A novel Composite Modified Double Base (CMDB) propellant, formed by mechanically mixing aluminium/polytetrafluorethylene (Al/PTFE) powders, was prepared through a rolling process. A variety of tests, such as tensile properties, particle size analysis etc., were carried out to study the influence of PTFE on the CMDB propellant properties. The PTFE deformed from particles to fibres under a uniform shear force, forming a fibre network which greatly improved the propellant’s mechanical properties. Compared to that of the CMDB propellant without PTFE, the elongation of the propellant containing 6% PTFE was increased by 26 times, and moreover, the impact strength was enhanced by 326% at −40 °C. Significantly, the propellant friction and impact sensitivities were reduced by 75.8% and 35.6%, respectively. In addition, the presence of PTFE in the propellant resulted in fluorination of the Al. The gaseous combustion product AlF3 reduced the propellant combustion agglomeration. Consequently, PTFE significantly promoted the propellant’s mechanical performance, decreased the shock (friction, impact) sensitivity and reduced combustion agglomeration.