The phase characteristics of vinylidene fluoride (VDF) segments in vinylidene fluoride (VDF) and hexafluoropropylene (HFP) copolymer (PVDF-HFP) under different quenching temperature were investigated by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) measurements. It was found that the alpha and beta crystalline phases of VDF segments formed in PVDF-HFP as those in pure PVDF. Compared with pure PVDF, HFP segments affected the beta phase formation obviously. Increasing of quenching temperature would decrease the fraction of beta phase in the quenched PVDF-HFP films, and the films thicker than 8 mu m were not in favor of the beta phase transformation. Blending PVDF-HFP with small amounts of PMMA (<= 10 wt%) yielded great effects on the crystal phase of VDF segments. But higher blending degree of PMMA couldn't increase the formation of beta phase further. (c) 2006 Springer Science + Business Media, Inc.