Amplitude analysis modulus-phase relations

Electromechanical measurements were first performed by Vallerian et al. in 1990 [15]. An ordered and surface stabilized prepolymer was cross-linked in a conventional TD-covered glass cell and the mechanical deformation achieved by an oscillating piezotransducer. A linear increase in the piezoelectric signal is observed, with an increasing amplitude of the deformation as shown in Figure 13.6. As expected, the piezoelectric response decreases with the temperature, which can be related to the order parameter and the tilt angle. However, with these measurements, no mechanical stress was analyzed. In 1994, Brehmer et al. [31] additionally analyzed the stress/strain relation that enables quantitative analysis of the electromechanical response as a function of temperature as shown in Figure 13.7. The piezoelectric coefficient exhibits a maximum at low temperatures of about 6.5 pC/N. Due to the experimental setup, the modulus could only be determined half-quantitatively. It has to be noted that the phase (T > 53 °C) also clearly... 

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