Disclinations Observed During the Shear of MBBA

Abstract

We describe observations made with an optical microscope of the formation of two distinct types of disclinations during the shear of a small molecule nematic, MBBA. Once formed, these disclinations grow and deform in the shear field. We also report observations of the relaxation of these defects after the cessation of shear. The optical contrasts and associated distortions are shown to be more localised during shear than in the absence of flow. The two types of disclinations are believed to be singular structures of strengths ± 1/2 and non-singular structures of strengths ± 1.