| 초록 |
Poly(vinylidene difluoride) (PVDF) and its copolymers have several crystal structures, especially β-structured crystal has all-trans conformation with aligned dipoles that is directly related to the pyro-, piezoelectric properties of PVDF. Owing to the superior electric properties of β-formed PVDF, so many researches have been proceeded to enhance the portion of β-crystal in a matrix. There are two ways basically for letting β-phase be major in a matrix. One is mechanical stretching. Among the crystal structures, β-phase has most elongated unit length because of its all-trans conformation. With sufficient thermal energy enough to change the conformational structure, external tension makes the phase be transformed into β-phase. The other one is electric poling. Strong electric field permitted on PVDF sample induces the dipole alignment, leads to all-trans conformation. |
