This paper describes the results of some physical tests conducted on polymeric materials used in the construction of superconducting magnets. A brief description of the various testing techniques is also given.
Results of physical tests on polymers at cryogenic temperatures
M. Van de Voorde
Polymeric materials play an important role in the construction of superconducting magnets for high energy accelerators and storage rings. The materials used for such applications must possess good mechanical properties which will withstand the stresses introduced during magnet construction and operatien. In addition, they should also have suitable thermal and electrical properties at low temperatures even in a radiation field.
Properties of polymers at low temperatures
Polymeric materials are used in superconducting magnet technology for conductor insulation, for the impregnation of windings, for structural components such as spacers, clamps, supports, etc.
A description of the chemical, mechanical, thermal, and electrical properties of these materials as a function of temperature and radiation is given in the following sections.
There are many variables in the polymer processing that may significantly affect their structure and thus their properties. Therefore, these results are intended for quick reference and comparison of polymers available in Europe.
Various types of thermoplastics, with promising properties at low temperatures, have been investigated. The study of the thermosetting compounds has been limited to epoxy resins of the Bisphenol A type. All materials considered showed a satisfactory resistance to thermal shock (298-77 K). In addition, all samples were examined in polarized light after the thermal shock test, and only those free from fissures and internal stresses were further examined. Before physical testing, the specimen were stored for several days in a dessicator to prevent water absorption.