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Flat-On Secondary Crystals as Effective Blocks To Reduce Ionic Conduction Loss in Polysulfone/Poly(vinylidene fluoride) Multilayer Dielectric Films
Macromolecules ( IF 5.1 ) Pub Date : 2018-07-03 00:00:00 , DOI: 10.1021/acs.macromol.8b01037
Huadong Huang 1 , Xinyue Chen 1 , Ruipeng Li 2 , Masafumi Fukuto 2 , Donald E. Schuele 1 , Michael Ponting 3 , Deepak Langhe 3 , Eric Baer 1 , Lei Zhu 1
Affiliation  

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 study, 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.

中文翻译:

平板二次晶体是减少聚砜/聚偏二氟乙烯多层介电膜中离子传导损失的有效块

近来,基于聚偏二氟乙烯(PVDF)的多层膜已显示出良好的潜力,如高能量密度,高温和低损耗的聚合物电介质,可用于先进的电力和电力应用。但是,PVDF层中的杂质离子传导会导致高温下的明显介电损耗。在这项研究中,我们发现了一种简便的熔融重结晶方法来抑制聚砜(PSF)/ PVDF 50/50(v / v)33层薄膜中的离子传导损耗。通过结合使用差示扫描量热法,宽带电介质光谱法和同时进行的小角度X射线散射/广角X射线衍射技术,揭示了抑制离子传导的潜在机理。基本上,局限在400 nm层中的初级和次级PVDF晶体的生长和分层组织起着重要作用。当熔体再结晶过程中的冷却速率较高(例如,≥500°C / min)时,在有序堆叠的边缘初级晶体之间的小且取向差的次级晶体将允许杂质离子在PVDF层中自由传输。在低至中等的冷却速度(即<100°C / min)下,边缘的初级晶体薄层之间平坦的次级晶体的生长会阻止杂质离子的传输,从而抑制了离子传导引起的介电损耗。在这项研究的基础上,我们提出了一种改进的多层共挤出方法,该方法具有可控的冷却速度,以实现平坦的二次晶体,从而降低基于PVDF的多层介电薄膜中的高温介电损耗。
更新日期:2018-07-03
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