Viscoelastic Characterization At Low Temperature Of HNBR Rubber For Sealing Applications

Rubber compounds exhibit non linear viscoelastic mechanical behavior, stress-strain response strongly depends on time and temperature parameters. For numerous applications and mainly for sealing applications, rubber parts often work under a given displacement. This type of loading, named stress relaxation, leads to a load decrease versus time due to viscoelastic effects. In case of sealing applications, contact pressure developed by a seal decreases and in extreme situations leaks occur in case of unsatisfactory design and/or non applicable material. This presentation deals with stress relaxation phenomena for sealing applications at low temperatures, for temperatures nearly or inferior to glass transition temperature (Tg) of the polymer(s) retained for the rubber compound. In this domain, between the rubbery state and the glassy state, the final behavior of the seal will depend on the whole loading history applied to the material combined with dilation phenomena given small strain variations of the material.