At the extended weathering durations, the coupling strengths of the blend are intermediate to those of NR and SBR. Interestingly, no significant variation of Dmed,1 can be observed for the three materials between 504 h and 988 h. Also, the invariance of the corresponding coupling widths suggests no significant chemical modifications in the samples beyond 500 h. In comparison to the previous work, these trends highlight that sulfur-cross-linked NR is chemically unstable at higher temperatures (thermo-oxidative aging at 80 °C), whereas sulfurcross-linked SBR is more susceptible to artificial weathering.