JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構
JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構
JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構
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Irradiation Effect of Gamma-Rays on Cyanate<br />
Ester/Epoxy Resins<br />
A. Idesaki a) , H. Uechi b) , Y. Hakura b) , T. Nakagawa b) ,<br />
T. Ohshima a) , S. Matsuda b) and H. Kishi b)<br />
a) Environment and Industrial Materials Research Division, QuBS, <strong>JAEA</strong>,<br />
b) Graduate School of Engineering, University of Hyogo<br />
<strong>JAEA</strong> has developed a cyanate ester/epoxy resin as an<br />
1, 2)<br />
insulating material for ITER superconducting coil . Since<br />
the cyanate ester/epoxy resin shows higher radiation<br />
resistance than a pure epoxy resin, it is expected to be<br />
applied to insulating material of magnet systems used in<br />
accelerators such as J-PARC. In order to realize the<br />
application of the cyanate ester/epoxy resins, suitable resin<br />
composition has to be selected. However, there are several<br />
kinds of resins with different molecular structure for each<br />
cyanate ester and epoxy and the relationship between<br />
combination of them and their radiation resistance has not<br />
been clarified. In this work, the effect of molecular<br />
structure of epoxy on the properties of cyanate ester/epoxy<br />
resins such as gas evolution and glass transition temperature<br />
(Tg) after -ray irradiation was investigated.<br />
Table 1 shows the resin composition of cyanate ester and<br />
epoxy used in this work. A bis-A type cyanate ester<br />
(DCBA) and three kinds of epoxy (bis-A type (DGEBA),<br />
bis-E type (DGEBE) and bis-F type (DGEBF)) were used.<br />
The cyanate ester and epoxy were formulated by 50/50 in<br />
weight. The prepared resins were irradiated by -rays with<br />
dose of 5 MGy under vacuum at room temperature.<br />
Table 1 Resin composition of cyanate ester and<br />
epoxy.<br />
A<br />
1-17<br />
Cyanate ester (50 wt%) Epoxy (50 wt%)<br />
DGEBA<br />
B DCBA<br />
DGEBE<br />
C DGEBF<br />
Curing condition: 170 °C/1 h + 230 °C/4 h.<br />
When the cyanate ester/epoxy resins were irradiated,<br />
gases of hydrogen (H 2), carbon monoxide (CO), carbon<br />
dioxide (CO 2) and nitrogen (N 2) were evolved. Figure 1<br />
shows the G-value of gas evolution. The G-value means<br />
the number of evolved gas molecules in case of that the<br />
energy of 100 eV is absorbed by the material. The order of<br />
G-value of total gas was sample A (DCBA/DGEBA) ><br />
sample B (DCBA/DGEBE) > sample C (DCBA/DGEBF).<br />
Figure 2 shows change of Tg of cyanate ester/epoxy<br />
resins by -ray irradiation. While the Tg of all resins<br />
decreased after the irradiation, the order of decrease width<br />
was same as gas evolution (sample A > sample B > sample C).<br />
The results of gas evolution and decrease of Tg are<br />
considered to suggest that crosslinking part between cyanate<br />
<strong>JAEA</strong>-<strong>Review</strong> <strong>2010</strong>-065<br />
- 21 -<br />
ester and epoxy is decomposed by the irradiation and that<br />
the decomposition of crosslinking depends on the molecular<br />
structure of epoxy. In this work, it was found that the<br />
combination of bis-A type cyanate ester and bis-F type<br />
epoxy gives the highest radiation resistance. In future,<br />
formulating ratio of cyanate ester and epoxy on the radiation<br />
resistance of resins will be investigated.<br />
G-value (Gas)<br />
0.08<br />
0.06<br />
0.04<br />
0.02<br />
0<br />
H 2<br />
Sample A<br />
Sample B<br />
Sample C<br />
CO CO 2<br />
Acknowledgement<br />
We thank to Mitsubishi Gas Chemical Company, Inc. for<br />
providing cyanate ester resins.<br />
References<br />
1) A. Idesaki et al., Advances in Cryogenic Engineering, 54<br />
(2008) 169.<br />
2) Y. Shindo et al., Cryogenics, 50 (<strong>2010</strong>) 36.<br />
N 2<br />
Total<br />
Fig. 1 Evolved gases from cyanate ester/epoxy resins by<br />
-ray irradiation.<br />
Tg (℃)<br />
240<br />
220<br />
200<br />
180<br />
Unirradiated<br />
5MGy<br />
Sample A Sample B Sample C<br />
Fig. 2 Change of Tg of cyanate ester/epoxy resins by<br />
-ray irradiation.