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Vol.51, No.10, 713 ~ 719, 2013
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| Title |
| Mechanical Properties and Molecular Structure of Rubber Materials with Different Hardnesses for Vibration Isolation of Elevator Cabins |
| Byeong Kil Shin , Sang Hyeon Yoon , Hee Soo Lee , Young Seok Koo , Young Keun Jeong , In Goo Kang |
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| Abstract |
| The mechanical properties and molecular structure of rubber materials for reducing the vibration of elevator cabins were studied with respect to the hardnesses change to confirm the degradation behavior by temperature (85 ℃) and humidity (85% R.H.). To examine the effects of hardness on the mechanical properties after thermal and hydrothermal aging, the international rubber hardness degree (IRHD), tensile strength, and elongation % were compared with the elastic modulus as a function of degradation time. The microstructure showed that the crack growth of the rubber material with high hardness was fast after hydrothermal aging. It originated from a C = C bonding decrease, and the C = O and C-O-C bonding were increased by the penetration of humidity. In the results of solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to confirm the molecular structure, several peaks were assigned to respective vulcanized structures along with mechanical properties. Therefore, the degradation behavior after thermal/ hydrothermal aging was different according to low/high hardness: The mechanical properties of the rubber material with high hardness rapidly decreased due to the high density of cross-links and chain scission. (Received March 18, 2013) |
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| Key Words |
| rubber materials, international rubber hardness degree, mechanical properties, solid state 13C NMR, polymer structure |
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