Investigation of Viton O-Ring Performance for the SABRE Dark Matter Experiment

Viton O-rings will be used for critical seals of the liquid scintillator veto detector for the sodium iodide with active background rejection dark matter experiment in Australia. In this study, the combined effects of elevated temperature plus exposure to air and linear alkyl benzene (LAB) on the physical and chemical properties of Viton O-rings were investigated over time using compression set measurements and Young’s modulus tests, ATR-FTIR spectroscopy and the analysis of solvent-induced swelling. The measurements show the degradation of physical and mechanical properties of the Viton O-rings was found to be more pronounced under compression set conditions in air for the same temperature compared to LAB at the same temperatures. The ATR-FTIR results show that the effects of LAB on the surface composition of the Viton O-rings were not significant. According to solvent swelling analysis over time, the Viton O-rings are suitable for use with LAB as there were no obvious physical and chemical property degradations at three different ageing temperatures (22, 35 and 55 ºC). Furthermore, the overall conclusion is that the O-rings can be expected to function efficiently for much longer than the expected operating life of the SABRE experiment.