Structure and Melting Behavior of Poly(vinylidene fluoride) Crystallized by Pressure Quenching

Abstract

Multiple melting behavior in Poly(vinylidene fluoride) crystallized by pressure quenching (0.1→600 MPa at 513 K) is analyzed by means of differential scanning calorimetry, X-ray diffraction and transmission electron microscopy (TEM). It is found that the endothermic peak at 477 K corresponds to the melting of the γ-form extended-chain crystal, and that at 479 K to the melting of an unknown phase ( γ'-form) similar to the γ-form crystal. The band structure is 80∼100 nm thick, which suggests the existence of extended-chain crystals, and is confirmed by TEM observation for both crystals of γ- and γ'-forms.