Flat-On Secondary Crystals as Effective Blocks To Reduce Ionic Conduction Loss in Polysulfone/Poly(vinylidene fluoride) Multilayer Dielectric Films
- Case Western Reserve Univ., Cleveland, OH (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- PolymerPlus, LLC, Valley View, OH (United States)
Recently, poly(vinylidene fluoride) (PVDF)-based multilayer films have demonstrated good potential as high energy density, high temperature, and low loss polymer dielectrics for advanced electrical and power applications. However, impurity ion conduction in the PVDF layers can cause significant dielectric loss at high temperatures. In this study, we discovered a facile melt-recrystallization method to suppress ionic conduction loss in polysulfone (PSF)/PVDF 50/50 (v/v) 33-layer films. By use of combined differential scanning calorimetry, broadband dielectric spectroscopy, and simultaneous small-angle X-ray scattering/wide-angle X-ray diffraction techniques, the underlying mechanism for the suppression of ionic conduction was unraveled. Basically, the growth and hierarchical organization of primary and secondary PVDF crystals confined in 400 nm layers played an important role. When the cooling rate during melt-recrystallization was high (e.g., ≥ 500 °C/min), small and poorly oriented secondary crystals between orderly stacked edge-on primary crystals allowed free transport of impurity ions in PVDF layers. At low to moderate cooling rates (i.e., <100 °C/min), growth of flat-on secondary crystals between the edge-on primary crystalline lamellae blocked the transport of impurity ions, suppressing the dielectric loss from ionic conduction. On the basis of this paper, we propose a modified multilayer coextrusion method with controlled cooling rates to achieve flat-on secondary crystals for the reduction of high temperature dielectric loss in PVDF-based multilayer dielectric films.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1462415
- Report Number(s):
- BNL-207898-2018-JAAM
- Journal Information:
- Macromolecules, Vol. 51, Issue 14; ISSN 0024-9297
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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