Vibrational spectrum of PVDF and its interpretation

IR spectra of poled and non-poled PVDF films were studied. Non-poled extruded samples were annealed and cooled at different cooling rates. Then, FTIR spectra of all samples were taken under scanning with different diaphragms. It was found that the spectra and their interpretation depend strongly on the scale of the scanning procedure for both poled and non-poled films. Scanning by a diaphragm with a diameter D close to the size of beta-phase domains d reveals the presence of the beta-phase in the annealed non-poled PVDF, whereas spectra obtained with a large diaphragm (D much greater than d) do not show discernable peaks inherent to the beta-phase. Cooling rate influence on the beta-phase contents is strong. When the diameter of the diaphragm D and size of crystalline gamma inclusions are of the same magnitude, peak splitting is observed in the poled PVDF. (C) 2004 Elsevier Ltd. All rights reserved.