Dielectric materials can store and release electrical energy quickly and efficiently and have potential applications in the fields of rail transportation, air and space detection, and electromagnetic weapons. However, the most promising dielectric polymer composites under research suffer either from unsatisfactory energy density (U e ) or from increasing the U e at the cost of energy efficiency (η). Herein, by the solution casting method, a nanocomposite film is fabricated by introducing trace selfassembly phase-transitioned lysozyme (PTL) modified boron nitride nanosheets (mBNNS) into a blend matrix consisting of poly(vinylidene fluoride−hexafluoropropylene) P(VDF−HFP) and poly(methyl methacrylate) (PMMA). The results suggest that PTL helps improve the interfacial compatibility of the corresponding nanocomposites via hydrogen-bonding interaction effectively. The nanocomposite film with 5 wt % mBNNS shows remarkably enhanced breakdown strength (E b ) of ∼500 MV/m and U e of 14.9 J/cm 3 , which are 166% and 244% of the blend matrix, respectively. Meanwhile, η of the nanocomposite film reaches ∼71% because of the clipping effect of linear PMMA on the large ferroelectric crystal phase of P(VDF−HFP) and the barrier effect of the highly insulating two-dimensional (2D) mBNNS, which effectively reduces the relaxation and leakage losses. Our research results show that by using a low-loss matrix and trace high-insulation 2D nanosheets, it is possible to achieve dielectric materials with high η and high U e at the same time.
Thermal decomposition
kinetic behavior of energetic materials is
of substantial importance for safety enhancement in manufacturing,
usage, and storage. The thermal decomposition kinetic behavior of
2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was studied by simultaneous
differential scanning calorimetry and thermogravimetric analysis (DSC–TG).
The thermal decomposition of LLM-105 is a two-step process in which
the overall reaction was deconvoluted into two reaction steps for
better analysis through different physical meanings consideration
of the kinetic data derived from DSC
and TG. Kinetic parameters of the two individual reaction steps were
characterized through isoconversional and combined kinetic analysis
methods. It was found that the activation energy of the first reaction
step was 222.2 ± 0.5 kJ mol–1, whereas that
of the second reaction step was 244.5 ± 0.5 kJ mol–1. Both steps mostly obeyed the nucleation and growth models (Avrami–Erofeev
(A3)). The validity of the obtained kinetic parameters was tested
through the successful reconstruction of the original experimental
curves. The nucleation and growth were also confirmed through scanning
electronic microscopy observations of the morphology evolution during
the LLM-105 decomposition. The obtained kinetic parameters and kinetic
models contributed to a comprehensive and in-depth understanding of
the thermal decomposition of LLM-105.
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