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R. Prokopec, K. Humer, H. Fillunger, R. Maix, H. W. Weber:
"Property Changes Of Cyanate Ester / Epoxy Insulation Systems Caused By An Iter-Like Double Impregnation And By Reactor Irradiation";
Advances in Cryogenic Engineering: Transactions of the Int. Cryogenic Materials Conf. - ICMC, 56 (2010), 119 - 126.

Because of the double pancake design of the ITER TF coils the insulation will be
applied in several steps. As a consequence, the conductor insulation as well as the pancake
insulation will undergo multiple heat cycles in addition to the initial curing cycle. In
particular the properties of the organic resin may be influenced, since its heat resistance is
limited. Two identical types of sample consisting of wrapped R-glass / Kapton layers and
vacuum impregnated with a cyanate ester / epoxy blend were prepared. The build-up of the
reinforcement was identical for both insulation systems; however, one system was
fabricated in two steps. In the first step only one half of the reinforcing layers was
impregnated and cured. Afterwards the remaining layers were wrapped onto the already
cured system, before the resulting system was impregnated and cured again. The
mechanical properties were characterized prior to and after irradiation to fast neutron
fluences of 1 and 2x10²² m^-2 (E>0.1 MeV) in tension and interlaminar shear at 77 K. In
order to simulate the pulsed operation of ITER, tension-tension fatigue measurements were
performed in the load controlled mode. The results do not show any evidence for reduced
mechanical strength caused by the additional heat cycle.

Fiber reinforced composites, Cyanate ester, Mechanical behavior, Neutron irradiation, Double impregnation

http://publik.tuwien.ac.at/files/PubDat_186374.pdf