1. Introduction
Nanothermite has received extensive attention as energetic materials for
its excellent thermal, combustion and reaction characteristics with
applications in propellants, explosives and pyrotechnics [1-2].
Conventionally, nanothermite consists of two components, a fuel and an
oxidizer [1-2]. Comprehensively considering the cost, calorific
value and safety, aluminum (Al) nanoparticles is the most popular choice
for the fuel[3]. As for oxidizer, there are so many potential
candidates, such as copper oxide (CuO), iron oxide
(Fe2O3), silicon dioxide
(SiO2), manganese dioxide (MnO2), nickel
oxide (NiO) [4-10]. Among them, the formula of Al and
MnO2 is one of the most promising energetic materials
with a high burning rate, an adiabatic temperature and a relatively low
ignition point [11]. In nature, fluorine is the most electronegative
element in periodic table of elements with the electronegativeity of
3.98 on Pauling scale [12-13]. Thus, recently, the combination of
nanothermites and fluorine polymers has aroused wide concern from
researchers [14-16].
Fluorine polymers have been already widely used in many applications,
such as membrane, tubing, fibers, filler and coating materials, which
contain fluorine atoms in the molecular chains [17-19]. The most
famous fluorine polymer is polytetrafluroethylene (PTFE) because of the
highest fluorine content, about 76% [20]. Tang and his co-author
had paid much attention on the mechanical properties and impact-induced
characteristics of PTFE/Al/CuO reactive materials [21-22]. The flame
and energy release rate greatly improved due to the addition of Al/CuO
thermite. Recently, a comparative research reported about three kinds of
PTFE-based thermite materials,
PTFE/Al/Fe2O3,
PTFE/Al/MnO2and PTFE/Al/MoO3 [23]. The results showed that the
formula of PTFE/Al/MnO2 released the most energy during
compression, and the detailed thermal reaction processes of
PTFE/Al/MnO2 was also reported [24]. But the
components were mainly at the micron-scale with slow energy release. In
fact, because of the poor solubility and agglomeration of PTFE, it is
hard to obtain the uniform well-mixed samples, especially for
nanothermites, which is also the main drawback for further application
in energetic materials field [25]. Thus, poly(vinylidene
fluoride-ter-hexafluoropropylene-ter-tetrafluoroethylene) (poly(VDF-
ter- HFP-ter - TFE)) terpolymer with both high fluorine content and good
solubility can be used as a substitute for PTFE in nanoenergetic
materials application [25]. However, few researches focus on the
application of poly(VDF- ter- HFP-ter - TFE) on nanothermites.
Therefore, in this paper,
poly(VDF- ter- HFP-ter - TFE) terpolymer is selected as energetic
additive and binder, and the Al/MnO2/ poly(VDF- ter-
HFP-ter - TFE) nanothermite samples are prepared by using electrospray
method. The morphologies, thermal properties and combustion performance
are investigated. Furthermore, the mechanism of terpolymer on
nanothermite system is also discussed and analyzed which will provide a
practical guidance for fluorine- containing nanothermite research and
application.