Young's Modulus and Thermal Expansion of Filled Cyanate Ester and Epoxy Resins

During the winding of high field superconducting magnet coils, small gaps inevitably form between the wire and the supports. These gaps must be filled with a material that will fully support the superconductor and prevent cracking of the epoxy or cyanate ester resin. Many times the simplest solution is to manually chop some glass fiber and pack it into the space hoping it will be uniformly infiltrated with epoxy. But what are the properties of this makeshift filler? Two epoxy resin systems and one cyanate ester resin were highly filled with ceramic and glass particles. Measurements of the thermal expansion show that they can approach the expansion values of typical superconducting magnet supports and cable, but are still 20% too high. Young's modulus was also measured at room temperature and in liquid nitrogen.