Structural, optical and some physical properties of PVDF films filled with LiBr/MnCl2 mixed fillers

Films of polyvinylidene fluoride (PVDF) filled with (X)LiBr(20−X)MnCl2 mixture, where X=0, 1, 2, 8, 16 and 20 wt%, were prepared by casting method and studied by ultraviolet/visible optical absorption (UV), differential scanning calorimetry (DSC), X-ray diffraction (XRD), infrared transmission (IR) and electron spin resonance (ESR). The optical absorption spectra suggested the presence of an optical gap (Eg) which depends on filler concentration (W) and arises due to the variation in crystallinity within the polymer matrix. Melting and degradation temperatures were identified using DSC. XRD implied a semicrystalline structure (containing α- and β-PVDF phases for all films). Conjugated double bonds and the role of dimethylformamide with a PVDF chain were detected by IR spectra. The ESR analysis revealed the existence of both isolated and aggregated Mn2+ ions within the PVDF matrix.

Research highlights
► Films of polyvinylidene fluoride (PVDF) filled with (X)LiBr(20−X)MnCl2 mixture were prepared by casting method.
► UV/Vis spectra suggested the presence of an optical gap (Eg), which depends on filler concentration.
► Eg arises due to the variation in crystallinity within the polymer matrix.
► Melting and degradation temperatures were identified using DSC.
► XRD implied a semicrystalline structure (containing α- and β-PVDF phases for all films).