Results and Discussion

Mullins Effect

As mentioned, the characterization tests involved two load-unload-recovery cycles so as to examine the Mullins effect. Typical results for the stress-strain curves generated with a fresh sample are shown in Fig. 4. Like other rubberlike

Copyright by ASTM Int’l (all rights reserved); Tue May 6 12:07:08 EDT 2014 Downloaded/printed by

Rochester Institute Of Technology pursuant to License Agreement. No further reproductions authorized.

FIG. 4—Loading-unloading tests on a fresh specimen at a crosshead speed of 2.64 mm/min to a max strain of 25 %. Circles and triangles represent the first and second loading cycles, respectively. Arrows indicate the loading-unloading directions.

materials, these sealants exhibit a strong Mullins effect in that there is a signifi­cant reduction in the stress at a given strain level during the second loading, as compared to the stress level on the first loading. The unloading curves, however, are identical.