Optimization of the sealing performance in transient conditions of rubber based hybrid nanocomposites by carbon nanotubes, as assessed by a tailored recovery test

A key property of rubbers for sealing applications is their ability to rapidly recover the deformation during a fast movement of the counterparts, occurring in a transient deformation phase. In this work, a simple experimental test method (recovery test) is put forward to mimic the transient phase and to get insight into the behavior of the material during such phase. The effect of the addition of small quantities of carbon nanotubes (CNT) to a carbon black filled nitrile butadiene rubber on the sealing ability of the material was studied. The recovery tests show that the overall recovery behavior is related mostly to the material stress relaxation behavior, while the recovery behavior at very short times, which is indicative of the performance during a transient deformation phase, is strongly influenced by the material elastic modulus and, therefore, it is improved by the presence of CNT in the elastomeric composite.