DESC0024791

Radiation-resistant electrical insulators for superconducting magnet coils used in fusion energy reactor systems must survive high voltage operation, exhibit low gas generation under irradiation and have high strength and flexibility under shear. Epoxy resins are inherently good insulators and have high dielectric strength, high volume resistivity, low dielectric constant and low dissipation factor. However, neat epoxy polymers are unsuitable as such for use in reactors because of their poor high-temperature stability, poor abrasion resistance, and susceptibility to radiation. The thermo-mechanical and radiation-resistance properties of epoxy resins can be improved by incorporating soft modifiers into the networks. Polysiloxanes as soft modifiers would be better suited than nanoparticles in toughening epoxy resin at low, even cryogenic temperatures. Additionally, the introduction of aromatic systems into aliphatic polysiloxanes, along with the incorporation of anti-radiation molecules like styrene, can markedly enhance their resistance to radiation and reduce off-gassing when subjected to radiation. This modification effectively maintains the stability of the polymer even under exposure to high- energy radiation. With the above rationale, during Phase I, MMI will synthesize a range of epoxy-polysiloxane copolymer formulations and test them for relevant properties to down-select the best materials for further development. Additionally, polymer nanocomposites will be prepared by adding nanoparticles of montmorillonite, nano SiO2, and nano TiO2 before the stage of curing. The addition of these kinds of fillers to the base insulating polymer is expected to further improve its dielectric breakdown strength. High-performance electrical insulation materials besides being essential elements of the superconducting magnet, can also enable the miniaturization of power systems and help in creating novel power system architectures. Polymer-based insulators would be critical for grid-based power supply to remote areas. Currently, ceramic-based insulators are used, but there is a drive to replace them with polymeric insulators due to durability and weight advantages.