Enhancement of DC breakdown performance of LDPE films based on silver nanoparticle surface modification of biomimetic dopamine technology

Low density polyethylene (LDPE) film samples with the surface treatment by silver nanoparticles based on the biomimetic dopamine technology are obtained and the influence of the treatment on the space charge behavior as well as DC breakdown performance of the selected insulating system is studied. The results obtained by the energy dispersive spectrometer and the scanning electron microscope indicate that Ag particles with nanoscale or larger size form and distribute uniformly on the surface of LDPE modified in the dopamine solution, silver nitrate solution (AgNO₃) and dopamine solution in sequence. Space charge profile measured by the pulsed electro-acoustic method shows that homo-charge injection is suppressed with proper surface treatment. DC breakdown strength increases initially and then decreases with the increase of the size of Ag particles. The electrical breakdown strength of the specimen D6-Ag1-D24 is the highest, which increases by 9.5% compared with that of untreated LDPE. Finally, it is considered that the treatment of LDPE based on the biomimetic dopamine technology changes the chemical and physical properties of the surface through forming a three-layer structure, which plays a similar role as the nano-dielectrics. Such treatment can impact the space charge injection and accumulation, and further the corresponding DC breakdown strength, which provides a novel method to optimize the dielectric strength of the polymeric insulating materials.