Signals of Isotopomers in 13C NMR Spectra of Polyisoprene Rubbers

Analysis of 13C-satellites was carried out in the 13C NMR spectra of isoprene rubbers with a natural content of 13C carbon isotope. 13C-satellites are the signals caused by the one-bond spin–spin coupling of 13C nuclei. The spin–spin coupling 1J(13C–13C) constants, as well as the magnitude of the effect of the isotopic substitution 1Δδ13C(13/12C), were measured under magnetic shielding of 13C nuclei. The results indicate that the configurational and local conformational structure of natural and synthetic isoprene rubbers is identical.