J. Phys. II France
Volume 2, Numéro 3, March 1992
Page(s) 471 - 486
DOI: 10.1051/jp2:1992144
J. Phys. II France 2 (1992) 471-486

NMR spin-lattice relaxation from molecular defects in nematic polymer liquid crystals

M. Warner and D.R.M. Williams

Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE, G.B.

(Received 26 July 1991, revised 25 October 1991, accepted 21 November 1991)

We calculate the contributions $J_{1}(\omega_{0})$ and $J_{2}(2\omega_{0})$ to the NMR relaxation rate $T_{1}^{-1}(\omega_{0})$ caused by the motion of proposed molecular defects in polymer liquid crystals. The results are $J_{1}\propto \omega_{0}^{-1/2}$ and $J_{2}\propto \omega_{0}^{-1/2}$ for low Lamor frequencies $\omega_{0}$. The scaling of the J functions with chain length is also given. It is hoped that NMR may offer a way of determining the contribution of molecular defects to dynamical processes in well ordered polymer liquid crystal melts.

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