Elastic recovery after compression in HNBR at low and moderate temperatures: Experiment and modelling

Abstract

Elastic recovery after compression or compression set is one of the key indicators of elastomer performance in sealing applications, such as O-rings in flange joints. In this work, findings of a study of the compression set property of a hydrogenated nitrile butadiene rubber (HNBR) at temperatures above and below the glass transition temperature Tg are presented. The compression set in the elastomer is found to increase with cooling up to 100% at the glass transition temperature and decrease with time after unloading even at temperatures below Tg. The effects of reinforcing filler (carbon black) and the initial compression time are also considered. Equivalence of time and temperature effects on the compression set of the elastomers is then demonstrated. A viscoelastic model describing the time-temperature variation of the compression set is proposed and verified by finite element analysis (FEA) and experimental results. It is shown that modelling captures well the experimental behaviour of the elastic recovery of the studied HNBR at ambient and low temperatures.