Determination of residual dipolar interaction from transverse 1H NMR relaxation in elastomers

The formula expressing the proton transverse magnetization decay for elastomers is reconsidered. It is improved by incorporating the relaxation contribution. The spin-spin relaxation times T2 are estimated from spin-lattice relaxation times in the laboratory frame T1 and spin-lattice relaxation times in the rotating frame T1ρ measured at the low static magnetic field. The improved formula together with distributed residual dipolar couplings is applied to several samples of elastomers, and residual dipolar couplings are estimated. A good correlation between a swelling ratio and the residual dipolar coupling is obtained.