Characterization of the trans-structure in the molecular chain structure of natural rubber

Natural rubber (NR) has excellent mechanical properties due to its unique molecular chain structure. In previous studies, the signal of the cis- and trans -isoprene units was deduced by 13 C-NMR spectrum of the low molecular weight fraction of NR. In this study, through investigating the 1 H-NMR spectra of ribbed smoked sheet 1 (RSS-1) and standard Chinese rubber whole fraction (SCR-WF), and Eucommia ulmoides gum (EUG), trans -1,4-polyisoprene (TPI), found that the methyl-proton in the cis- and trans -isoprene units in 1 H-NMR spectra of NR showed signals at 1.61 and 1.53 ppm, respectively. Further, the content of trans -structure in the molecular chain of NR of different producing areas was calculated. The results show that the content of trans -structure in the molecular chain structure of RSS-1 and SCR-WF were 1.500 and 1.054%, respectively.