The cross-link densities in NR, SBR, and their blend subjected to prolonged weathering are first investigated by a 1 H low-field MQ NMR spectroscopy based on the robust pulse sequence introduced earlier. The evolution of cross-link densities of NR and SBR within the blends at different intervals of weathering is quantified through phase-specific studies by 1 H DQ MAS NMR spectroscopy using the BaBa-xy16 pulse sequence. The formation of highly constrained fractions due to weathering is evaluated by free induction decay (FID) combined with magicsandwich echo (MSE)-FID and Hahn-echo T2 relaxometry, which is suitable to quantify solidlike components with dipolar couplings too strong for the above-mentioned technique. Further, the changes in the materials are chemically investigated by Fourier-transform infrared (FTIR) spectroscopy. Lastly, to get a physical perspective, dynamic mechanical thermal analysis (DMTA) and atomic force microscopy (AFM) are employed for probing the macroscopic and microscopic moduli, respectively.