3. Results and Discussion
3.1 SEM analysis
Figure 3 represents the SEM images of Al/MnO2 and Al/MnO2/ terpolymer nanothermite samples. Figure 3(a) is the Al/MnO2nanothermite without the addition of terpolymer. There are two main structures, nanoparticles and nanorods. The nanoparticles represent the fuel, Al NPs, while the nanorods are the oxidizer, MnO­2NRs. The diameter of Al NPs is in the range of 50 nm ~ 100 nm. The rods length is about several micrometers and the diameter of the rods is merely about 20 nm~ 50 nm. The Al NPs can directly contact the oxidizer. Besides, the agglomeration phenomenon is not very clear.
Figure 3(b), (c) and (d) are the Al/MnO2/terpolymer nanothermite with different contents of P(VDF-ter-HFP-ter-TFE) terpolymer, from 10wt% to 30wt% respectively. In Figure 3(b), with 10wt% terpolymer addition, some terpolymer binder can be found among the nanothermite components. In fact, the existence of terpolymer is not pretty obvious due to its content in nanothermite system is not high. So, a fair amount of fuel still can contact direct oxidizer. When the mass fraction of terpolymer reach 20wt% and 30wt%, the existence of terpolymer can be more easily found in Figure 3(c) and (d). As a kind of binder, terpolymer mainly exist among the components, which can bond the nanothermite components together to improve the integrity of the materials.