Ageing tests closer to real service conditions using hyper-sensitive microcalorimetry, a case study on EPDM rubberShow others and affiliations
2023 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 120, article id 107948Article in journal (Refereed) Published
Abstract [en]
Accelerated thermal ageing (ATA) coupled to mechanical testing is widely used to predict the lifetime of polymeric products. ATA implies that the mechanisms of ageing are the same at accelerated and service conditions, which may often not be the case. Hence, ageing closer to service conditions is of high importance, but require very sensitive tools. Therefore, a high sensitivity microcalorimetry (MC) method was applied here to assess if it can be a possible tool for lifetime/ageing prediction closer to service conditions. We chose to focus on a complex, yet commonly used, ethylene-propylene-diene terpolymer (EPDM) rubber. Arrhenius extrapolation of the heat flow data indicated two regimes at low and high temperature, with the former having the lower activation energy. The heat flow values measured by the MC revealed contributions from processes such as the melting of the antioxidant, its consumption at low temperature and the breakdown of residual peroxide. MC tests on the EPDM indicated a very low degree of oxidation appearing above 100 °C, too low to be observed with infra-red spectroscopy (FTIR), but noticeable with MC. The high sensitivity of the MC techniques enabled detection of early signs of polymer degradation/ageing and other thermally activated processes that take place at or close to service temperatures (such as those in nuclear power plants). The MC tests were combined with other techniques, such as scanning electron microscopy/energy dispersive X-ray spectroscopy, gas chromatography techniques, differential scanning calorimetry and FTIR to further understand the degradation mechanisms. © 2023 The Authors
Place, publisher, year, edition, pages
Elsevier Ltd , 2023. Vol. 120, article id 107948
Keywords [en]
Activation energy, Ageing, EPDM, Lifetime, Microcalorimetry, Rubber, Calorimeters, Degradation, Differential scanning calorimetry, Ethylene, Fourier transform infrared spectroscopy, Gas chromatography, Heat transfer, Mechanical testing, Nuclear fuels, Nuclear power plants, Scanning electron microscopy, Temperature, Accelerated thermal aging, Ageing tests, Case-studies, Ethylene propylene diene terpolymer, FTIR, High sensitivity, Lows-temperatures, Micro-calorimetry, Service conditions
National Category
Other Engineering and Technologies
Identifiers
URN: urn:nbn:se:ri:diva-64699DOI: 10.1016/j.polymertesting.2023.107948Scopus ID: 2-s2.0-85147854514OAI: oai:DiVA.org:ri-64699DiVA, id: diva2:1756968
Note
Funding text 1: The funding of this work by the Finnish Ministry of Economic Affairs and Employment within the framework of the SAFIR 2022 Finnish Research Program on Nuclear Power Plant Safety ( 2019–2022 ) is gratefully acknowledged. We also appreciate the support and funding from SSM Strålsäkerhetsmyndigheten Swedish Radiation Safety Authority and Energiforsk , which is a Swedish research and knowledge institute that advances and coordinates energy research. We acknowledge the support of James Walker and Co Ltd. (particularly Andrew Douglas, a material engineering group manager) for providing materials and technical discussions. We are grateful to the researchers employed at RISE, Per Borchardt for performing SEM-EDX and Richard Sott for GS-MS analysis.; Funding text 2: The funding of this work by the Finnish Ministry of Economic Affairs and Employment within the framework of the SAFIR 2022 Finnish Research Program on Nuclear Power Plant Safety (2019–2022) is gratefully acknowledged. We also appreciate the support and funding from SSM Strålsäkerhetsmyndigheten Swedish Radiation Safety Authority and Energiforsk, which is a Swedish research and knowledge institute that advances and coordinates energy research. We acknowledge the support of James Walker and Co Ltd. (particularly Andrew Douglas, a material engineering group manager) for providing materials and technical discussions. We are grateful to the researchers employed at RISE, Per Borchardt for performing SEM-EDX and Richard Sott for GS-MS analysis.
2023-05-152023-05-152023-05-26Bibliographically approved