Non‐destructive thermal ageing evaluation of P (VDF‐HFP) film based on broadband dielectric response

Abstract

Capacitors and sensors based on polymer dielectric materials are key components in electrical systems and electronic devices. Considering the temperature rise during operation, an effective evaluation method for the thermal ageing of polymer matrix is urgently needed. P(VDF-HFP) film with a thickness of 20 μm is manufactured by solution casting and a thermal ageing experiment up to 1000 h is conducted. Dielectric responses of wide ranges of temperatures and frequencies are measured for samples with different ageing durations. The universal relaxation law and Dissado-Hill dielectric response model are applied to further investigate the results. The characteristics of individual processes are obtained, which demonstrate that the main chain relaxation following the Vogel−Fulcher −Tammann equation and side chain relaxation following the Arrhenius equation both remain unchanged after thermal ageing. However, the activation energies of those two processes change significantly during the process and show different variation trends. The activation energy of the side chain relaxation gets larger monotonically due to the influence of annealing and the breaking of crystalline region. As a result, a non-destructive evaluation method for the thermal ageing of P(VDF-HFP) is proposed accordingly.

Microscopic mechanisms analysis of various dielectric response processes in oil‐paper insulation with different insulating states

“…Then, the microscopic mechanisms of the two relaxation processes in the oil‐paper insulation samples were analysed [18], which were impregnated with different insulating oils. Meanwhile, microscopic mechanisms of various dielectric response processes under different testing temperatures were analysed [19].…”

Thickness-Dependent Dielectric Screening in Few-Layer Phosphorus

“…In order to fabricate field-effect transistors with higher mobility and lower power consumption, modifications to dielectric properties are necessary . The dielectric constant ε, which defines the polarization, plays a crucial role in understanding electromagnetic interactions through dielectric screening. , Moreover, dielectric screening is crucial to the determination of electron dynamics, exciton binding energies, and electron–electron and electron–phonon interactions in superconducting states. − To optimize the performance of phosphorus-based transistors, it is necessary to gain a deeper understanding of the role of layered structures in the dielectric screening of 2D phosphorus. However, it is still unclear how the dielectric constant varies with thickness in VPs and BPs.…”