Kömmling Anja, Jaunich Matthias, Pourmand Payam, Wolff Dietmar, Hedenqvist Mikael
Bundesanstalt für Materialforschung und -prüfung, 12200 Berlin, Germany.
KTH Royal Institute of Technology, Department of Fibre and Polymer Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, SE-100 44 Stockholm, Sweden.
Polymers (Basel). 2019 Jul 29;11(8):1251. doi: 10.3390/polym11081251.
Determining a suitable and reliable end-of-lifetime criterion for O-ring seals is an important issue for long-term seal applications. Therefore, seal failure of ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) O-rings aged in the compressed state at 125 °C and at 150 °C for up to 1.5 years was analyzed and investigated under static conditions, using both non-lubricated and lubricated seals. Changes of the material properties were analyzed with dynamic-mechanical analysis and permeability experiments. Indenter modulus measurements were used to investigate DLO effects. It became clear that O-rings can remain leak-tight under static conditions even when material properties have already degraded considerably, especially when adhesion effects are encountered. As a feasible and reliable end-of-lifetime criterion for O-ring seals under static conditions should include a safety margin for slight dimensional changes, a modified leakage test involving a small and rapid partial decompression of the seal was introduced that enabled determining a more realistic but still conservative end-of-lifetime criterion for an EPDM seal.
为长期密封应用确定合适且可靠的O形环密封件寿命终止标准是一个重要问题。因此，在静态条件下，对在125℃和150℃压缩状态下老化长达1.5年的乙丙三元橡胶（EPDM）和氢化丁腈橡胶（HNBR）O形环的密封失效进行了分析和研究，使用了非润滑和润滑密封。通过动态力学分析和渗透率实验分析了材料性能的变化。用压痕模量测量来研究尺寸局部变化（DLO）效应。结果表明，即使材料性能已经大幅下降，O形环在静态条件下仍可保持不漏，特别是当遇到粘附效应时。由于静态条件下O形环密封件可行且可靠的寿命终止标准应包括轻微尺寸变化的安全裕度，因此引入了一种改进的泄漏测试，该测试涉及对密封件进行小幅度快速局部减压，从而能够为EPDM密封件确定更实际但仍保守的寿命终止标准。
