Nanoscale fracture analysis by atomic force microscopy of EPDM rubber due to high-pressure hydrogen decompression
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The relationship between internal fracture due to high-pressure hydrogen decompression and microstructure of ethylene–propylene–diene–methylene linkage (EPDM) rubber was investigated by atomic force microscopy (AFM). Nanoscale line-like structures were observed in an unexposed specimen, and their number and length increased with hydrogen exposure. This result implies that the structure of the unfilled EPDM rubber is inhomogeneous at a nanoscale level, and nanoscale fracture caused by the bubbles that are formed from dissolved hydrogen molecules after decompression occurs even though no cracks are observed by optical microscopy. Since this nanoscale fracture occurred at a threshold tearing energy lower than that obtained from static crack growth tests of macroscopic cracks (T s,th), it is supposed that nanoscale structures that fractured at a lower threshold tearing energy (T nano,th) than T s,th existed in the rubber matrix, and these low-strength structures were the origin of the nanoscale fracture. From these results, it is inferred that the fracture of the EPDM rubber by high-pressure hydrogen decompression consists of two fracture processes that differ in terms of size scale, i.e., bubble formation at a submicrometer level and crack initiation at a micrometer level. The hydrogen pressures at bubble formation and crack initiation were also estimated by assuming two threshold tearing energies, T nano,th for the bubble formation and T s,th for the crack initiation, in terms of fracture mechanics. As a result, the experimental hydrogen pressures were successfully estimated.
This research was supported by the NEDO Fundamental Research Project on Advanced Hydrogen Science (2006–2012).
- 1.Briscoe BJ, Savvas T, Kelly CT (1994) Rubber Chem Technol 67:384Google Scholar
- 3.Gent AN, Lindley PB (1958) Proc R Soc Lond A 249:195Google Scholar
- 5.Stevenson A, Glyn M (1995) Rubber Chem Technol 68:197Google Scholar
- 7.Zakaria S, Briscoe BJ (1990) Chemtech 20:492Google Scholar
- 8.Ender DH (1986) Chemtech 16:52Google Scholar
- 9.Briscoe BJ, Liatsis D (1992) Rubber Chem Technol 65:350Google Scholar
- 11.Yamabe J, Nishimura S (2009) Trans J Soc Mech Eng A 75:633Google Scholar
- 12.Yamabe J, Nishimura S (2009) Trans J Soc Mech Eng A 75:1726Google Scholar
- 13.Yamabe J, Nishimura S (2010) In: 18th European conference on fracture, CD-ROMGoogle Scholar
- 14.Yamabe J, Nishimura S (2009) In: Proceedings of the 14th symposium on fracture and fracture mechanics, pp 30–34Google Scholar
- 20.Dohi H, Sakai M, Nakamae H, Kimura H, Kotani M, Kishimoto H, Minagala Y (2007) Kautsch Gummi Kunstst 01–02:52Google Scholar