Enhanced Aramid/Al2O3 interfacial properties by PDDA modification for the preparation of composite insulating paper

To further improve the electrical insulation properties of meta-aramid paper, 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, Fourier transform infrared spectrometer 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. 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.