Different pre-ignition reaction mechanisms for improving the combustion of fluoropolymers, containing different fluorine contents with aluminum particles

The use of fluoropolymers to modify aluminum (Al) powder has been demonstrated to improve the combustion efficiency. Different fluoropolymers have been observed to exert varying effects, but the reason remains unknown, so this work employs the ReaxFF-MD method combined with ignition experiments to examine the interaction process between PTFE, PVDF, THV and nano-sized Al particles (ns-Al). The pre-ignition reaction (PIR) mechanism of different fluoropolymers with ns-Al is distinct. For PTFE without H, its F atoms directly react with the oxide layer to form Al_xF_y or Al_xO_yF_z. This is referred to as PIR1. In H-containing PVDF and THV, the reaction between F atoms and H atoms with the oxide layer generates Al_xF_yH_z or Al_xO_yF_zH_n, which is classified as PIR2. The two PIR mechanisms exhibit notable differences. These results reveal the difference in the promotion of ns-Al ignition and combustion by fluoropolymers with different fluorine contents at the atomic level.