Electrocaloric Effect in Electron Irradiated GNPs/P(VDF-HFP) Composites

Abstract

Nowadays, environmental issues lead the scientists to find and discover new materials and methods for advanced technology that eco-friendly, easy to process and low-cost. One of the sexiest issues that rapidly grows is eco-friendly cooling system with high energy efficiency. Not only for common cooling devices such as air conditioner and refrigerator, this cooling system is also proposed to be applied in thinny devices such as microchips with huge amounts of micro-components. The demand of this technology finally desire not only strong power and high storage energy density but also should be flexible, lightweight, durable and achievable. Among other ferroelectric materials, PVDF-based polymer shows the outstanding properties. Nevertheless, some approaches have been being investigated to improve the properties of the polymer. In this work, poly(vinylidene fluoride-hexafluoropropylene) was modified by incorporating graphene nanoplatelets conducting nanofillers to boost up dielectric properties and electrocaloric effect behavior. Further, combining this method with electron beam irradiation could bring the benefit for energy properties improvement. The neat polymer and composites thin films were kindly fabricated by solution casting technique. Crystalline phase modification affected by graphene nanoplatelets filler and electron irradiation towards its surface, microstructure, electrical, ferroelectric, electrocalorie effect and energy properties have been elaborated. As the result, reduction of pores size lead to improve film homogeneity and its hydrophobicity that als brought benefit for dielectric and energy properties. The percentage crystallinity and high polarity B-phase fraction improvement then drastically give an impact on electrical properties and electrocaloric effect by gaining polarization and permittivity. The elctrocaloric effect of the composites were bigger compared to pure P(VDF-HFP) indicated by the AT and Ic. Considering those two electrocaloric parameters, the | ATmax /T. | ratio for HFP/GN composites was improved to almost two times of the neat P(VDF-HFP). On the other hands, electron beam irradiation dramatically reduced the crystals size into two times smaller. Hence, bigger storage energy density can be generated along with dropping energy loss. As final result, energy efficiency of neat polymer was improved to 74.66% after irradiation, much higher that unirradiated samples of 68.11. this number was alsi bigger than previously reported by another study of 58%. For the composites, enery efficiency improvement was almost doubled for all condition filler concentration.