Production of piezoelectric PVDF films

摘要

A method of producing piezoelectric and pyroelectric polyvinylidene fluoride (PVDF) films is shown. A stretched PVDF film having a predominantly &bgr;-type crystal structure is rolled for thickness reduction. The rolling orients a substantial percentage of b axes of . beta. crystals normal to the film surface, as determined by X- ray diffraction patterns. An optional annealing step is shown, wherein the rolled film is heated, optionally while under pressure. Improvement in the piezoelectric constant of 25 percent or more is typical.