For further improve the electrical insulation properties of meta-aramid paper(PMIA), polydimethyldiallyl ammonium chloride (PDDA) was used for the modi cation of nano-Al 2 O 3 in this work. The modi ed products were characterized by means of transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR) and liquid Zeta potential. The original and PDDA modi ed nano-Al 2 O 3 was doped into the aramid ber composite, and the effects of PDDA and ller mass fraction on several properties such as electrical conductivity, breakdown strength and surface charge dissipation rate of insulating paper were studied. Finally, the interfacial properties of the composites were investigated using molecular dynamics (MD). The results showed that PDDA was successfully coated on the surface of nano-Al 2 O 3 , and its surface potential was changed from negative to positive, which could improve the interface characteristics between ller and matrix and enhance the dielectric strength of aramid paper. Besides, saturation effect of PDDA modi cation was observed, and when the amount of PDDA was 10% and the content of modi ed nano-Al 2 O 3 was 3%, the breakdown strength of aramid paper was increased by 20%, and the volume conductivity was decreased by 68%. The simulation result revealed that PDDA could improve the insulation performance of aramid paper by reducing the interfacial binding energy between aramid and ller.

Poly-m-phenyleneisophthalamide (PMIA) with excellent chemical stability and breakdown strenth is regarded as the next generation of insulating paper in power system. However, the basic intensity of PMIA is not enough to match its operating cost, and it is promising to enhance the performance by nano composition. In this paper, the influence of nano-TiO 2 ith a mass fraction of 1 to 5 wt% on insulating properties is studied, including breakdown voltage and bulk conductivity. The silane coupling agent aminopropyltriethoxysilane (APTES) together with the polydopamine (PDA) are used for modifying the fillers interface. The results show that, APTES covalent grafting and PDA physically coating can improve the dispersion and compatibility of nano-TiO 2 in aramid fiber matrix, thus regulating the interface trap characteristics and reducing the probability of electric field distortion in insulating paper. When the modified TiO 2 content is 2 wt%, the breakdown voltage is the highest, which is 23.9 kV/mm, 54% higher than that of pure aramid paper. In addition, this article discusses the modification mechanism from molecular dynamic simulation and trap characteristics. Based on molecular dynamics calculation, three interface models of PMIA-TiO 2 , PMIA-TiO 2 /APTES, PMIA-TiO 2 / APTES/PDA are constructed, and the synergistic effect of PDA is confirmed from the microscopic level.

For further improve the electrical insulation properties of meta-aramid paper(PMIA), polydimethyldiallyl ammonium chloride (PDDA) was used for the modification of nano-Al2O3 in this work. The modified products were characterized by means of transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR) and liquid Zeta potential. The original and PDDA modified nano-Al2O3 was doped into the aramid fiber composite, and the effects of PDDA and filler mass fraction on several properties such as electrical conductivity, breakdown strength and surface charge dissipation rate of insulating paper were studied. Finally, the interfacial properties of the composites were investigated using molecular dynamics (MD). The results showed that PDDA was successfully coated on the surface of nano-Al2O3, and its surface potential was changed from negative to positive, which could improve the interface characteristics between filler and matrix and enhance the dielectric strength of aramid paper. Besides, saturation effect of PDDA modification was observed, and when the amount of PDDA was 10% and the content of modified nano-Al2O3 was 3%, the breakdown strength of aramid paper was increased by 20%, and the volume conductivity was decreased by 68%. The simulation result revealed that PDDA could improve the insulation performance of aramid paper by reducing the interfacial binding energy between aramid and filler.

For further improve the electrical insulation properties of meta-aramid paper(PMIA), polydimethyldiallyl ammonium chloride (PDDA) was used for the modification of nano-Al2O3 in this work. The modified products were characterized by means of transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR) and liquid Zeta potential. The original and PDDA modified nano-Al2O3 was doped into the aramid fiber composite, and the effects of PDDA and filler mass fraction on several properties such as electrical conductivity, breakdown strength and surface charge dissipation rate of insulating paper were studied. Finally, the interfacial properties of the composites were investigated using molecular dynamics (MD). The results showed that PDDA was successfully coated on the surface of nano-Al2O3, and its surface potential was changed from negative to positive, which could improve the interface characteristics between filler and matrix and enhance the dielectric strength of aramid paper. Besides, saturation effect of PDDA modification was observed, and when the amount of PDDA was 10% and the content of modified nano-Al2O3 was 3%, the breakdown strength of aramid paper was increased by 20%, and the volume conductivity was decreased by 68%. The simulation result revealed that PDDA could improve the insulation performance of aramid paper by reducing the interfacial binding energy between aramid and filler.