Electrical properties of epoxy/POSS composites with homogeneous nanostructure

The knowledge of the structure-property relationship at nanoscale level is important to develop advanced dielectric polymer composites. Herein dielectric epoxy/polyhedral oligomeirc silsesquioxanes (POSS) composites with homogeneous nanostructure were prepared. Unlike the conventional inorganic nanoparticles (e.g., silica) used for polymer nanocomposite preparation, the POSS molecules used in this work have three advantages: a comparable size with the segments of polymer chains, being capable of reacting with the base polymer, good solubility in many solvents. These three advantages make the POSS be dispersed in polymers at a molecular level and thus their nano-effect could be fully utilized. Microstructure analysis by transmission electron microscopy, atomic force microscopy and X-ray diffraction confirmed the molecular-level dispersion of POSS in the epoxy composites. On this base, the partial discharge erosion resistance, frequency/temperature dependence of dielectric response, space charge distribution and breakdown strength of the epoxy/POSS composites were investigated. Moreover, the correlation between the nanostructure and properties of epoxy/POSS composites was documented.