Polymer multilayer films for high temperature capacitor application

Abstract

Advanced film capacitors require polymers with high thermal stability, high breakdown strength, and low loss for high temperature dielectric applications. To fulfill such requirements, two polymer multilayer film systems were coextruded via the forced assembly technique. High glass transition temperature (T g ) polycarbonate (HTPC, T g = 165 C) and polysulfone (PSF, T g = 185 C) were multilayered with a high dielectric constant polymer, poly(vinylidene fluoride) (PVDF), respectively. The PSF/PVDF system was more thermally stable than the HTPC/PVDF system because of the higher T g for PSF. At temperatures lower than 170 C, the HTPC/PVDF system exhibited comparable breakdown strength and hysteresis loss as the PSF/PVDF system. While at temperatures above 170 C, the PSF/PVDF system exhibited a higher breakdown strength because of the higher T g of PSF. The electric displacement-electric field (D-E) loop behavior of the PSF/PVDF system was studied as a function of temperature. Moreover, a melt-recrystallization process could further decrease the hysteresis loss for the PSF/PVDF system due to better edge-on crystal orientation. These results demonstrate that PSF/PVDF and HTPC/PVDF systems are applicable for high temperature film capacitors.

Interface design for high energy density polymer nanocomposites

“…In terms of composite structures, sandwich or multi-layer structures have been shown to maintain a high dielectric strength. 279,280 Specifically, a layer with a higher breakdown strength, such as a pure polymer or a composite with a small amount of filler, is introduced into the multi-layer structured polymer composites which can improve the overall breakdown strength. The remaining nanocomposite layers contain a larger amount of fillers, which are beneficial in enhancing the electric displacement, as discussed in Section 2.4.…”

Enhanced dielectric properties of sandwich‐structured biaxially oriented polypropylene by grafting hyper‐branched aromatic polyamide as surface layers

“…Very recently, the emergence of sandwich structures provides a new insight to solve the paradox between high E and high ε r in dielectric polymer composites. This technology makes it possible to fabricate high performance dielectric composites by integrating the advantages of several dielectric materials with quit different properties . More importantly, the dielectric performance of multilayer composites could be tailored by turning their structure, such as number of layers, layer thickness, and stacking sequences .…”

Electromechanical deformation and failure of multilayered films

“…The forced assembly multilayer coextrusion process enables many polymeric systems having unique architectures to be produced including multilayer films, 10 cellular film/foam materials, 11–14 and fibrous membrane systems 9,15–18 . In addition, there has been numerous studies on the multilayered coextruded polymer systems directed toward applications including gas barrier films, 8,19 optical films, 20 shape memory films, 21–24 packaging film/foams, 25 fibrous membranes for filtration, 18,26 antibacterial membranes, 27,28 cellular membranes having through pores 12 and multilayer films with unique dielectric properties 29–36 . These investigations have emphasized the importance of scale within the multilayer films relative to enhanced performance characteristics.…”