Vulcanized natural rubber was characterized by high-resolution latex-state 13C-NMR spectroscopy. Signals characteristic of natural rubber were shown in the spectrum without background, suggesting little effect of chemical shift anisotropy and/or dipole-dipole interaction. Half widths of signals were independent of vulcanization time, whereas spin-lattice relaxation time was dependent slightly on the time. Small signals at 44ppm and 58ppm in the aliphatic carbon region were assigned by Distortionless Enhancement by Polarization Transfer (DEPT) and Attached Proton Test (APT) to secondary, tertiary and quaternary carbons of cross-linking points.
