CHAIN CONFORMATION IN NEMATIC ELASTOMERS

The anisotropy of the main chain conformation of a side-on fixed liqui d crystal elastomer on application of a mechanical stress has been mea sured in the isotropic and nematic phases by small angle neutron scatt ering. The radii of gyration parallel and perpendicular to the stress field have been determined on elongation and as a function of temperat ure. A weak anisotropy of the main chain conformation is found only in the nematic phase at sufficiently high values of elongation. A compar ison to a theory based on a Landau de Gennes expansion of the free ene rgy for oriented monodomain samples which includes coupling between el astic deformation and nematic strain is made.