Polymer-based composites with improved energy density and dielectric constants by monoaxial hot-stretching for organic film capacitor applications

Abstract

Randomly oriented multiwalled carbon nanotubes (MWCNT)/polyarylene ether nitriles (PEN) composite films were prepared by solution casting method. The as-prepared films were then under monoaxial hot-stretching in the oven to enhance their orientations and crystallinities. Results showed that hot-stretching process enhanced the mechanical and thermal properties significantly. The development of electrical conducting pathways during the monoaxial hot-stretching of MWCNT/PEN composite films was studied. Since the content of MWCNTs filler is close to the percolation threshold, ca. 6 wt%, the dielectric properties, electrical conductivity, breakdown strength and energy density were found to be very sensitive to the stretch ratio. The electrical conductivity of composites with 50% stretch ratio increased from 5.2*10 -5 S ·cm -1 to 1.6*10 -4 S·cm -1 (1 kHz). Besides, dielectric constant of composites with 50% stretch ratio increases amazingly from 378.0 to 1298.1 (100 Hz). Mostly importantly, the composites with 50% stretch ratio compensates some dielectric constant with breakdown strength, and finally, the energy density of the composites with 50% stretch ratio increases by about 40%, from 2.51 to 3.50 J/cm 3 , which has huge potential to be used as organic film capacitors.

“Toolbox” for the Processing of Functional Polymer Composites

“…Different from the random filler dispersion, aligned, oriented or ordered fillers network as another important filler network structure could be constructed via T + S combination, wherein magnetic/electric field (S6) [ 163 , 164 ], hot drawing/melt spinning (S4) [ 165 , 166 ], injection molding (S5) [ 167 ], electrospinning (S11) [ 6 ] or freeze drying (S13) [ 118 ] combined with corresponding melt blending (T1) or solution blending (T3), namely combination of T1 or T3 with S4, S6, S5, S11 or S13, that have been proved to form aligned fillers network within polymer matrix. Specifically, aligned Co nanowires network within PVDF matrix was prepared via combination of solution blending (T3), drop casting (S7) and magnetic field (S6).…”

Synergistic enhancement of mechanical, crystalline and dielectric properties of polyarylene ether nitrile‐based nanocomposites by unidirectional hot stretching–quenching

“…To further improve their properties, additives including carbon nanotubes, graphene, titanium dioxide, polyaniline, barium titanate and others are usually introduced to form polymer‐based composite materials . Polyarylene ether nitriles (PENs), as high‐performance thermoplastic engineering resins, are well known for their outstanding properties such as high thermal stability and radiation resistance, excellent mechanical properties and chemical inertia, and have been used at elevated temperatures and in aggressive chemical environments encountered in automotive and electric applications . However, the further application of PEN in specialist areas including aerospace, military and under extreme conditions is still a challenge.…”

Flexible Ultrahigh-Temperature Polymer-Based Dielectrics with High Permittivity for Film Capacitor Applications

“…As we all know, it is effective to enhance the dielectric properties by incorporating PEN with a variety of inorganic conductive fillers, including polyaniline [ 6 ], carbon nanotubes [ 7 ], graphene [ 8 ], etc. Although this kind of PEN composites may possess higher permittivity, their intrinsic percolation characteristics resulted in higher dielectric loss and significantly lower breakdown strength [ 9 ]. Therefore, more attention to achieve synchronous improvement of permittivity and breakdown strength has been focused on fabrication of PEN composite dielectrics.…”