Reactivity and reaction mechanism of Al-PTFE mechanically activated energetic composites

Abstract

In order to study reactivity and reaction mechanism of Al-polytetrafluoroethylene (PTFE) mechanically activated energetic composites, reaction molecular dynamics simulation was carried out to predict the pyrolysis process of PTFE. Then the reaction mechanism of PTFE pyrolysis products with Al was calculated by using density functional theory (DFT). Furthermore, the concentrated ignition characteristics were characterized. Finally, the pressure and temperature during the reaction process of Al-PTFE were tested, and the chemical structure before and after heating reaction were researched. Calculation and experimental results show that the main pyrolysis products of PTFE are C2, F, CF2, CF and CF3, and the degree of polymerization has little effect on the pyrolysis products. Among CF2, CF and CF3, it can be found that the energy barrier of reaction between CF3 and Al is the smallest (only 2.39 kJ•mol−1). The mechanical activation process can give higher reactivity to Al-PTFE mixture during concentrated ignition process.The reaction process of the decomposition of PTFE starts at 718K, and then the thermit reaction between the free radicals of decomposition products and Al begins at 898K.