Mechanical Shear of Layers in Smectic-Aand Smectic-BLiquid Crystal

Abstract

The force transmitted through the layers of smectic-$A$ and smectic-$B$ phases of butyloxy-benzylidene-octylanine (4O.8) have been measured at frequencies between 1 and 10 000 Hz, in the presence of an ac shear parallel to the layers. It is found that the smectic-$A$ behaves as a viscous fluid. The smectic-$B$ shows an elastic response, with a shear modulus $C_{44}\sim {10}^6$ cgs units. The low-frequency plastic behavior and the high-frequency dispersion which is related to internal friction are discussed.