Exponentially reduced carrier mobility of natural ester via blocking effect of 2D hexagonal boron nitride nanosheets

Abstract

In this work, the boron nitride (BN) nanosheets were dispersed in natural esters to fabricate the dielectric nanofluid. Microstructures and chemical compositions of the nanosized BN are determined. The stability, viscosity, and thermal conductivity of the BN nanofluid, were obtained. And the dissipation factor, electrical conductivity, and relative permittivity of the BN nanofluid, were measured. The ion mobilities and migrating times of the nanofluid were measured under different volumetric fractions of BN nanosheets and temperatures. Results show that the electrical conductivity and dissipation factor of the nanofluid decreased by 54% and 48% with the addition of only 0.1% of BN nanosheets under 110°C. Both the half‐reduced carrier mobility of the nanofluid and the declined ion concentration by blocking of BN nanosheet contributed to the exponentially reduced electrical conductivity and enhanced dielectric performances of the BN nanofluid. The suppression coefficient k is proposed to quantitatively describe the hinder effect of ion migration in nanofluids by 2D BN nanosheet. Results provide a strategy to design and develop advanced nanofluids with low‐dielectric loss by aids of surface adsorption of ion and steric hindrance of 2D nanosheets.

Mineral and Ester Nanofluids as Dielectric Cooling Liquid for Power Transformers

“…Considering shape, it seems that nanoparticles with an elongated shape, such as nanotubes with high length/diameter (L/D) aspect ratios tend easily to aggregate [ 27 , 61 , 142 ]. A clear majority of the nanoparticles that were used in the reviewed research were described as spherical or quasi-spherical, especially the metallic oxides, but there are examples with other geometries, such as sheets [ 115 ].…”

“…Once the nanofluid is prepared, before its application, it is frequently dried under heat or/and vacuum, as with nanoparticles, for at least for 12 h [ 18 , 24 , 53 , 62 , 73 , 85 , 92 , 95 , 108 , 109 , 115 , 133 ]. This enhances the dielectric strength of the fluid, prevents the formation of new bubbles, gives the fluid time to dissipate existing bubbles [ 3 , 7 , 19 , 63 , 88 ], and can even eliminate traces of volatile solvents [ 61 ].…”

“…The Z potential reflects the difference in potential between the dispersion medium and the layer of fluid that is closest to the particles, typically a double layer of ordered molecules. The larger the Z potential, the more electrically stabilized the suspension [ 5 , 115 ], according to Table 11 [ 6 ]. Additionally, the electrostatic repulsion between the particles increases with the surface charge of the particles in the fluid [ 27 , 89 , 108 ].…”

“…It was mentioned earlier that in this case, the optimal coating of particles with surfactant is believed to be a monolayer, but this supposes that organic non-polar chains are on the surface. According to the definition of the Z potential, this situation corresponds to the zero potential; this is supported in the literature [ 170 ], but the opinion is not shared by other researchers who link the monolayer and the resulting stability to the higher absolute value of the Z potential [ 72 , 89 , 115 , 124 , 143 ]. In the same way, they disagree on what tendency the Z potential shows during the formation of a second layer of surfactant.…”

Improved thermal conductivity and breakdown strength of PVDF‐based composites by improving the dispersion of BN

“…Therefore, the introduction of BN nanosheets into the PVDF matrix can construct a network structure with high breakdown strength and high thermal conductivity in the polymer matrix, and improve the energy storage density of the composites. Obviously, BN/PVDF composites have a latent capacity for realising high-energy storage density [25][26][27][28].…”