A series of composites blending thermoplastic polyurethane (TPU) with poly(vinylidene fluoride) (PVDF) were prepared in this work to realize a high energy storage density. Low loading of TPU (<3 vol. %) shows a uniform dispersion state in the PVDF matrix. We demonstrate that the incorporation of TPU induces high breakdown strength which results in promoted energy storage performance. In addition, the influence of the different TPU hardnesses (65, 75, and 85) on the breakdown strength of TPU/PVDF composites was also investigated. Finally, a maximum value up to 537.8 MV/m at 3 vol. % TPU with a hardness of 65 was obtained, which led to a high energy density of 10.36 J/cm³.

Herein we report the highly improved electromechanical actuation of thermoplastic polyurethane (TPU) by blending with polydimethylsiloxane (PDMS) to construct a bicontinuous structure. TPU/PDMS blend films with various PDMS loadings were fabricated through a simple solution-assisted casting method. Infrared spectroscopy measurements confirmed that TPU and PDMS are thermodynamically incompatible with each other. For TPU₈₀ with 80 parts of PDMS, a bicontinuous phase structure was achieved. The TPU₈₀ film showed greatly decreased elastic modulus and improved elongation at break compared to pristine TPU. It also showed the highest dielectric constant among the TPU/PDMS blend films with various contents of PDMS due to strong interfacial polarization. Most importantly, the TPU₈₀ film exhibited a maximum areal strain of 2.3% under an electric field of 40 V μm⁻¹, which is about 60 times higher than that of pristine TPU. The results described in this work demonstrate that the construction of a bicontinuous interface structure at the micrometer scale is very effective to develop elastomers with superior electromechanical actuation performance.

In this work, composites with different flake-like WS₂ filler contents were prepared, using ethylene propylene diene monomer as matrix. The nonlinear electric conductivity of composites at 25, 50, and 80 °C was measured, and the mechanisms were analyzed. It is found that exfoliation of WS₂ and testing temperature both have a direct influence on composites' electric conductivity. The inflection point and nonlinear coefficient of composites' nonlinear conductivity are also analyzed. The low WS₂ content (4.31 vol. %) composite started to show nonlinear conductivity. Direct current dielectric breakdown strength was also measured. The thermal conductivity of composites was measured to verify the improvement of thermal conductivity. The obtained data show that the thermal conductivity of the composite can be increased to about 45% and 40% at 25 and 75 °C, respectively.

With the rapid construction of new power systems characterized by high renewable energy penetration, high power electronics integration, and high voltage levels, the insulation reliability of critical power equipment—including cable accessories, gas-insulated switchgear (GIS), and power electronic modules—faces unprecedented challenges. Field grading materials (FGM), as core functional media for adaptive electric field homogenization and insulation failure prevention, have emerged as a research hotspot spanning materials science, electrical engineering, and polymer engineering. Starting from the current research status of FGM, this review systematically summarizes filler optimization strategies, covering single fillers, hybrid fillers, trace co-fillers, and structural modification approaches. The applications of FGM in transmission cables, GIS, high-voltage electrical machines, and wide-bandgap power electronic modules are then elaborated in detail. Emphasis is placed on performance enhancement routes of FGM, particularly thermal conductivity improvement via constructing three-dimensional thermally conductive networks and intelligent early warning based on thermochromic materials. Finally, the existing bottlenecks of FGM are analyzed in terms of material stability, multi-physical field coupling adaptation, and engineering industrialization. Future development trends are prospected toward high-performance, multifunctional, intelligent, and engineering-oriented FGM. This review aims to provide theoretical references and technical support for the design and application of advanced FGM in new power systems.

In this work, a small amount of ionic liquids (ILs, 1-vinyl-3-ethylimidazolium tetrafluoroborate) was used to modify tungsten disulfide (WS₂), and then, the modified WS₂ was mixed with ethylene propylene diene monomer (EPDM) to obtain IL-WS₂/EPDM composites with different IL contents. The content of WS₂ in composites was determined from the result of our previous work. The nonlinear electrical conductivity of composites at 25 °C, 50 °C, and 80 °C was measured and analyzed subsequently. A small amount of ILs has an influence on the nonlinear property of composites, and the inflection point of the ternary composite can be controlled by changing IL contents. The direct current (DC) breakdown strength and thermal conductivity of composites were also measured and researched. Addition of ILs would decrease the breakdown strength of IL-WS₂/EPDM composites.

Nano size semiconducting particles are the most commonly used fillers in field grading material to homogenize the inner electric field distribution. In this work, commercially purchased WS ₂ and the exfoliated ones were used as filler into EPDM to fabricate WS ₂ /EPDM composites with different WS ₂ loading. Nonlinear electric conductivities were measured at 25 50 and 80 respectively. The influence of temperature on the conductivity was introduced to analysis the conductivity changes of the WS ₂ /EPDM composite at higher temperature. Direct current breakdown strength was also studied. Tests result shown that the properties of exfoliated WS ₂ filled composite had more regular change and the best performance. It turned out that uniform size and morphology of filler will be helpful for the properties of composite. The nonlinear conductivity performance created the possibility of using WS ₂ as nonlinear conductivity filler in field grading material.