1995 Volume 23 Issue 1 Pages 7-11
Large stress increase by application of electric fields (ER effect) was found for homogeneous fluids of liquid crystalline polymers based on polysiloxane (LC silicones). LC silicones diluted with dimethyl silicone, which mesogenic groups were introduced as biterminal group (biterminal type) and as side chain group (side chain type) showed much larger ER effect than those introduced as monoterminal group (monoterminal type). ER effect of the side chain type tended to increase with an increase in positive dielectric anisotropy of the mesogenic groups. The LC silicones showed shear thinning at high shear rate while they showed Newtonian flow at relatively low shear rates. Complex dynamic modulus and viscosity of the side chain type measured under an electric field did not depend on strain up to large strain amplitude while those under no electric field depended remarkably on the strain. These tendencies were discussed in relation to the existence of flexible chain spanning liquid crystalline domains.