Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
We have examined the poling time dependence of the field-induced phase transition (from phase II to polar phase II) of biaxially oriented poly(vinylidene fluoride) films by x-ray methods. These results were compared with the poling-time dependence of the piezoelectric response (d31 and e31) determined using a piezotron Model U (Toyo Seiki, Tokyo). The piezoelectric response shows an initial rapid increase with poling time followed by a slow increase as the poling time increases. The x-ray results show that the field-induced phase transition is time dependent, and occurs first for those crystallites with their a axes perpendicular to the film surface. Crystallites with a in the plane of the film transform at a much slower rate. The data indicate that the poling time dependence of d31 and e31 (and, presumably, film polarization) are dependent on the transition rates.
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