Preparation of Si@PVDF composite microspheres by electrostatic spraying for enhanced energetic characteristics

In this study, Si@PVDF composite microspheres are prepared by the electrostatic spraying method. The spheres are with average diameter of around 2 mu m (when at ideal stoichiometry), within which Si nanopowder is uniformly distributed. The exothermic properties of samples are studied through simultaneous thermogravimetry and differential scanning calorimetry. Benefiting from the improved interfacial contact quality, Si@PVDF shows increased chemical reactivity in terms of reduced reaction onset temperature, peak temperature and apparent activation energy than those of physically mixed Si/PVDF counterpart. Si/PVDF cannot be ignited through Joule heating, either in the powder of pellet form, while selfsustained combustion propagation is observed for Si@PVDF pellets. The combustion behaviors of Si@PVDF pellets are systematically studied in open-air (where light signal is analyzed) and constant-volume (where pressure signal is analyzed) conditions. The results show that the combustion process is influenced by the equivalence ratio, porosity of the pellet and the accessibility of O 2 gas in the environment. Overall, the encapsulation of Si nanopowder into PVDF microspheres using electrostatic spraying shortens the mass and heat transfer distance and thus realizes enhanced energetic characteristics.(c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

Si@PVDF composite microspheres with Si nanopowder uniformly distributed were prepared by electrostatic spraying method. The improved interfacial contact quality in Si@PVDF led to enhanced chemical reactivity, as evidenced by reduced reaction onset temperature, peak temperature, and apparent activation energy compared to physically mixed Si/PVDF counterpart. Si/PVDF could not be ignited by Joule heating, while self-sustained combustion propagation was observed for Si@PVDF pellets. The combustion process of Si@PVDF pellets was influenced by equivalence ratio, pellet porosity, and O2 accessibility in the environment.