Electrostriction Constant of Polymer Films

In Table 2, the electrostriction constant is given for various polymer films (Nakamura and Wada, 1971 Kawai (2), 1970). The values by Nakamura and Wada were obtained at the strain frequency f0 —130 Hz and electric field frequency / = 1 MHz. Values by Kawai were measured at /=/0 = 150 Hz. The values are negative because the density decreases during elongation. 

Polymer Kawai (2) (1970) Observed Nakamura and Wada (1971) Observed Calculated from Eq. (103)  

The last column of Table 2 lists the values of k calculated from Eq. (103). In the calculation, s at 1 MHz was used and Poisson s ratio m was assumed to be 0.35. Agreement between observed values and calculated ones is fairly good except for poly (vinylidene fluoride) (PVDF) and poly (methyl methacrylate) (PMMA), which exhibit a remarkable dielectric relaxation at room temperature. 

Greaves and Lamb (1971) observed sound emission from polyethylene film due to the electrostriction effect. 

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III. Methods for Measuring the Piezoelectricity and Electrostriction Constant of Polymer Films 3.1. Measurement of the Piezoelectric Constant... 

Fig. 8. Block diagram of the apparatus for measuring the complex electrostriction constant of polymer films (Hayakawa and Wada (2), 1971)...

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