Thermal Conductivity of Nano-filled Epoxy Systems

Epoxy resin systems are used in high voltage transformers, cable terminations, bushings, power apparatus, or insulation for X-ray tubes. They could be used more widely, but low thermal conductivity limits their applications. Polymers used as insulating materials generally lack the ability to dissipate excess heat efficiently. The aim of this study is to investigate the influence of different types and filler loadings of electrically insulating - but thermally conductive - nanosized particles on the thermal conductivity of epoxy resin. The concentration of the filler is varied from 0.5 wt.% to 5 wt.%. A combination of ultrasonic processing and high shear force stirring is used to obtain an even dispersion of the corresponding filler in the base material. A silane coupling agent is used for surface functionalization of the nanoparticles. The application of the coupling agent improves the compatibility of the particles with the base polymer. Morphological characteristics of the samples are determined by using transmission electron microscope observation. The composites of epoxy resin containing nanoscale particles showed improved thermal conductivity values compared to epoxy resin without particles. The experimentally measured thermal conductivity results are compared with theoretical and empirical models for two component systems.