Nanofilled dielectrics for high voltage electrical insulation

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Further improvements to composite materials for use in high voltage applications using micron size fillers are not likely, as mixing of the viscous compositions has reached the limitation of current material processing technology. However, initial findings of nano-size particle (nanoparticle) filled dielectrics show similar improvements to materials at considerably reduced filler additions; thereby, the promise of further improvements to dielectric materials are likely with the existing processing technology. Most researchers agree that the problem with nanoparticles in organic materials (nanocomposites) is the dispersion of particles and uniform mixing is critical in the development of nanocomposites. One of the problems is that the nanoparticles agglomerate easily because of the high surface energy of the particles and conventional mixing techniques do not break apart the nanoparticle agglomerates. Another problem is the incompatibility of the hydrophobic polymer with hydrophilic nanoparticles, resulting in poor interfacial interactions. Thus, there is a great need to discover alternative ways to obtain a better dispersion of the nanoparticles. The reseach focuses on the surface modification of the nanoparticles by physical and chemical methods using surfactants. Although surfactants are commonly applied to liquids, their application to disperse nanoparticles in compositions forming solid dielectric materials has not yet been reported. The main advantage of using a surfactant is that it lowers the surface and interfacial tensions of the nanoparticles resulting in reduced agglomeration and makes it easier to disperse the particles. Preliminary findings have shown that triton, a common surfactant, aids in the dispersion of nanosilica and nanoalumina in silicone rubber. The research will concentrate on the understanding of how surfactants can improve the properties of nanodielectrics and which composite systems are appropriate to optimize the dielectric properties of these composites for high voltage electrical insulation.