Thermomechanical Properties of Polymers for Use in Superconducting Magnets

The coefficient of thermal expansion (CTE) and the thermomechanical properties of the polymers used in superconducting magnets need to be known in order to predict their stress state under the different magnet assembly and operating conditions. We have measured Young's moduli of typically used polymers during in situ heat cycles with the dynamic resonance method. The dynamic test results are compared with Young's moduli determined from quasi-static stress-strain measurements at room temperature, 77 K and 4.2 K. A moderate elastic anisotropy is found for the fiber reinforced polymers. CTEs are compared based on dilation experiments. The CTEs of the fiber reinforced polymers studied are similar to those of copper or steel. In contrast, the pure resins exhibit relatively larger CTEs.