Electromechanical behaviour of biaxially stretched nematic liquid single crystal elastomers

A slab of nematic-side-chain-liquid-single-crystal elastomer (NSCLSCE), with the director initially oriented in the z direction, is subjected to a pair of equal mechanical stretches and electrical force fields in x and y directions. These electric fields tend to make the rotation of the director easier after the application of the mechanical force field. A non-linear expression for the free energy density is used to obtain the interval of stretching for which the system becomes unstable. Also the value of the electric field for which the rotation of the director starts without stretching is obtained. A comparison is made with uniaxial stretched samples and with previous biaxial experimental findings.