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Influence of room-temperature-stretching technology on the crystalline morphology and microstructure of PVDF hard elastic film



The crystalline morphology and microstructure during stretching of polyvinylidene fluoride hard elastic film under room temperature was followed using wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). It was found that an endotherm plateau from the contribution of some new crystals formed during annealing appeared and some thinner lamellae existed in the annealed film. During stretching, the endotherm plateau disappeared and those thinner lamellae transformed into β-phase. At the same time, some initial pores were observed. With increasing stretching ratio from 20 to 100%, the β-phase content increased, whereas within the strain rate range of 0.003–0.034 s−1, its content was least under 0.017 s−1. During stretching, lamellae separation, crystalline morphology transformation and disappearance of grown crystals formed by annealing coexisted. From the viewpoint of pore initiation, less crystalline morphology transformation was beneficial for the lamellae separation. Higher stretching ratio resulted in the breakage of separated lamellae. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40077.

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