Poly(vinylidene fluoride) films, in the ferroelectric β phase, were prepared with different techniques: crystallization by solution, mechanical stretching and electrospinning. Using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), we observed that films obtained from crystallization in dimethylformamide (DMF) solution at 60 ºC contain only non-oriented β phase. Films obtained by uniaxial stretching at 80 ºC and draw ratio 4, of samples originally in the α phase, result predominantly in the oriented β phase, though with still a small amount of the α phase. Membranes prepared by electrospinning method are constituted by nanofibers exclusively in the β phase and with the chain axis preferably aligned along the fibers, parallel to the membrane surface. The crystallinity percentage and the melting temperature, both inferred from calorimetric measurements (DSC), were little influenced by the techniques employed.
PVDF; electrospinning; morphology; crystalline phase; nanofibers
