Results and Discussion
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
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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.