Field gradient-fast-magic angle spinning (FG-FMAS) NMR spectroscopy has been developed to analyze crosslinking junctions of vulcanized natural rubber. The dipole-dipole interaction of the rubber was eliminated by fast magic angle spinning. The FG-FMAS NMR spectroscopy enabled to apply various pulse sequences such as DEPT, APT, HETCOR, HMQC, HSQC and HMBC to the vulcanized natural rubber. In the present study, the crosslinking junctions of the vulcanized natural rubbers, prepared by conventional vulcanization (CV), efficient vulcanization (EV) and semi-efficient vulcanization (SemiEV), were analyzed by FG-FMAS NMR spectroscopy. The amount of tertiary carbons linking to sulfur of the CV rubber was the same as those of the EV and SemiEV rubbers, when the rubbers were analyzed by 1H-NMR spectroscopy. 13C-NMR spectroscopy revealed that the amount of quaternary carbons linking to sulfur of the CV rubber was largest among the rubbers. The mechanical properties of the CV rubber were the most excellent; hence, the quaternary carbons linking to sulfur as crosslinking junction was assigned to the molecular singularity.

Characterization of vulcanized natural rubber through field gradient-fast magic angle spinning NMR spectroscopy

245th National Meeting (2013)

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