高圧水素ガス環境下におけるEPDMのブリスタ発生限界の推定

概要

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Transparent EPDM composite crosslinked by peroxide with no fillers was exposed to hydrogen gas at a maximum pressure of 10MPa, and then the behavior of blister initiation and growth in the composite after decompression was observed by an optical microscope. The critical pressure where no blisters initiated P_<H,cr> was 1-2MPa, while micrometer-sized blisters initiated in the composite at P_H>1-2MPa. It is considered that these blisters initiated due to stress concentration of micrometer-sized bubbles under an inner pressure II formed by supersaturated hydrogen molecules after decompression; then the energy release rate-tearing energy, T-of these bubbles was calculated theoretically or by FEM. Parallel to the calculation, static crack growth tests were conducted, and the threshold tearing energy for the static crack T_<S,th> was experimentally obtained. From the criterion expressed by T>T_<S,th>, the inner pressure at blister initiation II_F was estimated and then was compared with P_<H,cr>. Consequently, II_F≈P_<H,cr>, i.e., the critical pressure where no blisters initiated was successfully estimated in terms of fracture mechanics.
2009-05-25