Secondly, NR has a narrower distribution of dipolar couplings than SBR due to the chemical structure of this homopolymer. This fact provokes that slight variations in the network structure for NR are clearly reflected in the distribution of dipolar couplings, so this technique is much more sensitive to small changes in NR than in SBR. According to this issue, the sensi- tivity for detecting variations in the spatial distribution of cross-links in the NR phase decreases in blends where the fraction of SBR is higher.