Fuente: Polymers Polymers, Vol. 18, Pages 1079: Towards Qualification of Epoxy Resins for Superconducting Magnets Exposed to Radiation Doses Exceeding 100 MGy: Effect of the Radiation Source and Environment
Polymers doi: 10.3390/polym18091079
Authors:
Christian Scheuerlein
Federico Ravotti
Giuseppe Pezzulo
Torsten Koettig
Oliver Aberle
Ana-Paula Bernardes
Roland Piccin
Michael Eisterer

To qualify epoxy resin systems for use in superconducting magnets of future particle accelerators up to peak doses beyond 100 MGy, the effects of the irradiation source, the irradiation environment and the irradiation temperature have been assessed. Identical epoxy resin samples have been irradiated with 60Co gamma rays, 24 GeV/c protons and by mixed neutron/gamma radiation in a reactor and at a spallation source up to a dose of 170 MGy. Irradiation-induced cross-linking and chain scission have been monitored by Dynamical Mechanical Analysis (DMA). When irradiations are performed with the same dose rate and in the same environment, the different radiation sources have a similar efficiency to produce radiation damage, and the total absorbed dose is a good scaling factor to compare irradiation effects in polymers. To distinguish between the influence of the irradiation temperature and of environmental oxygen, proton irradiations have been carried out in ambient air, inert gas at ambient temperature and in liquid helium. Compared to ambient air irradiation, in inert atmosphere more cross-linking is observed. Cross-linking rates are strongly reduced at 4.2 K. For some polymers the irradiation temperature has a strong influence on the chain scission rate. The most-radiation-hard epoxy resin systems maintain substantial mechanical strength up to doses beyond 100 MGy.