FTIR and DSC studies of mechanically deformed beta-PVDF films

Films of semicrystalline poly(vinylidene fluoride) (PVDF) in the beta -phas e were studied by Fourier transform infrared (FTIR) spectroscopy and differ ential scanning calorimetry (DSC). The main goal of this study was to impro ve the understanding of the structural changes that occur in beta -PVDF dur ing a mechanical deformation process. FTIR spectroscopy was used to examine the structural variations as a function of strain. DSC data allowed measur ement of the melting temperatures and enthalpies of the material before and after deformation, providing information about the changes in the crystall ine fraction. After the molecular vibrations were assigned to the correspon ding vibrational modes, we investigated the energy and intensity variations of these vibrations at different deformations. A reorientation of the chai ns from perpendicular to parallel to the stress direction was observed to o ccur in the plastic region. During the deformation, a decrease in the degre e of crystallinity of the material was observed, but the thickness of the l amellae did not change significantly.