The use of the Piezoelectric Composite Oscillator Technique for Measuring the Viscoelasticity of Liquid Crystals

Abstract

The development of liquid crystalline mixtures with short electro-optic switching times has made possible an array of new products, including hand-held televisions and lap-top computers with flat panel displays. Whereas the switching times for materials with long switching times has been correlated with their steady shear viscosities, this is not true for materials with short switching times. Since such materials exhibit viscoelasticity in dynamic tests conducted at ultrasonic frequencies, we expect the dynamic moduli to correlate with their switching times. The viscoelastic properties of pure MBBA were measured using a piezoelectric ultrasonic composite oscillator technique. The measurement technique and the relation between the linear viscoelastic behavior and the electro-optic switching behavior will be discussed.