Abstract
We study the stretching driven director-switching in a thin film of liquid crystal elastomers having the initial director in the thickness direction (x-direction). The thin film specimen is uniaxially stretched in the z-direction normal to the initial director. The stress-strain curve has the three characteristic regions: the small strain region (I) obeying linear elasticity, the moderate strain region (II) exhibiting a quasi-plateau stress, and the large strain region (III) where the stress increases again. The Poisson's ratio μ_<yz> in the strain region (II) is considerably small (〜0.17) while those in the region (I) and (III) are nearly 0.5. These features in the strain region (II) result from the cooperative uniform rotation of director towards the stretching direction. The strain dependence of the IR dichroic ratio of the mesogen also supports this picture.
