TY  - JOUR
A1  - He, Yushuang
A1  - Wang, Feipeng
A1  - He, Li
A1  - Wang, Qiang
A1  - Li, Jian
A1  - Qian, Yihua
A1  - Gerhard, Reimund
A1  - Plath, Ronald
T1  - An insight Into the role of Nano-Alumina on DC Flashover-Resistance and surface charge variation of Epoxy Nanocomposites
JF  - IEEE transactions on dielectrics and electrical insulation
N2  - The addition of nano-Al2O3 has been shown to enhance the breakdown voltage of epoxy resin, but its flashover results appeared with disputation. This work concentrates on the surface charge variation and dc flashover performance of epoxy resin with nano-Al2O3 doping. The dispersion of nano-Al2O3 in epoxy is characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The dc flashover voltages of samples under either positive or negative polarity are measured with a finger-electrode system, and the surface charge variations before and after flashovers were identified from the surface potential mapping. The results evidence that nano-Al2O3 would lead to a 16.9% voltage drop for the negative flashovers and a 6.8% drop for positive cases. It is found that one-time flashover clears most of the accumulated surface charges, regardless of positive or negative. As a result, the ground electrode is neighbored by an equipotential zone enclosed with low-density heterocharges. The equipotential zone tends to be broadened after 20 flashovers. The nano-Al2O3 is noticed as beneficial to downsize the equipotential zone due to its capability on charge migration, which is reasonable to maintain flashover voltage at a high level after multiple flashovers. Hence, nano-Al2O3 plays a significant role in improving epoxy with high resistance to multiple flashovers.
KW  - surface morphology
KW  - Epoxy resins
KW  - Electric potential
KW  - Surface treatment
KW  - Doping
KW  - Epoxy resin
KW  - multiple
KW  - flashover
KW  - nanocomposite
KW  - surface charge
Y1  - 2022
U6  - https://doi.org/10.1109/TDEI.2022.3173510
SN  - 1070-9878
SN  - 1558-4135
VL  - 29
IS  - 3
SP  - 1022
EP  - 1029
PB  - Inst. of Electr. and Electronics Engineers
CY  - Piscataway
ER  - 
TY  - JOUR
A1  - Ortmann, Thomas
A1  - Ahrens, Heiko
A1  - Milewski, Sven
A1  - Lawrenz, Frank
A1  - Groening, Andreas
A1  - Laschewsky, André
A1  - Garnier, Sebastien
A1  - Helm, Christiane A.
T1  - Lipid monolayers with adsorbed oppositely charged polyelectrolytes: Influence of reduced charge densities
JF  - Polymers
N2  - Polyelectrolytes in dilute solutions (0.01 mmol/L) adsorb in a two-dimensional lamellar phase to oppositely charged lipid monolayers at the air/water interface. The interchain separation is monitored by Grazing Incidence X-ray Diffraction. On monolayer compression, the interchain separation decreases to a factor of two. To investigate the influence of the electrostatic interaction, either the line charge density of the polymer is reduced (a statistic copolymer with 90% and 50% charged monomers) or mixtures between charged and uncharged lipids are used (dipalmitoylphosphatidylcholine (DPPC)/dioctadecyldimethylammonium bromide (DODAB)) On decrease of the surface charge density, the interchain separation increases, while on decrease of the linear charge density, the interchain separation decreases. The ratio between charged monomers and charged lipid molecules is fairly constant; it decreases up to 30% when the lipids are in the fluid phase. With decreasing surface charge or linear charge density, the correlation length of the lamellar order decreases.
KW  - lipid monolayer
KW  - polyelectrolyte adsorption
KW  - statistical copolymer
KW  - two-dimensional phases
KW  - surface charge
KW  - nematic phase
KW  - grazing incidence X-ray diffraction
Y1  - 2014
U6  - https://doi.org/10.3390/polym6071999
SN  - 2073-4360
VL  - 6
IS  - 7
SP  - 1999
EP  - 2017
PB  - MDPI
CY  - Basel
ER  -