Publication

Abstract : The influence of poly(methyl methacrylate) (PMMA) incorporation in poly(vinylidene fluoride) (PVDF) on the dispersion of sonicated expanded graphite (s-ExGr), electrical conductivity, electromagnetic interference shielding effectiveness (EMI SE), and thermal properties of blend nanocomposites has been investigated. The electroactive beta phase of PVDF is induced along with gamma and alpha phases in the neat PVDF, PVDF-based blends, and blend nanocomposites prepared by temperature gradient introduced compression molding of solution-blended films as supported by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC) analyses. The dispersion of s-ExGr in blend nanocomposites is improved with increasing PMMA loading, as supported by frequency-dependent effective dielectric constant, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and dynamic mechanical analyses (DMA). Elemental mapping and DSC analyses of blend nanocomposites clearly prove the wrapping of PMMA onto graphite nanosheets. The morphological changes due to PMMA loading aids the selective localization of graphite nanosheets in the PMMA-rich phase in blend nanocomposites. The absorption-dominated EMI SE at 10 GHz for a 0.2 mm thick PVDF-30 wt.% PMMA-15 wt.% ExGr blend nanocomposite is 36.66 dB in comparison to 28.69 dB for PVDF-10 wt.% PMMA-15 wt.% ExGr. The improved dispersion of s-ExGr in PMMA-rich blend is also reflected in the enhanced triboelectric output voltage (19.84 V) under mechanical stimulus, attributed to filler dispersion-assisted surface roughness of the film as evidenced by atomic force microscopy (AFM) and water contact angle (WCA) analyses. Thus, the blend nanocomposites can be used for advanced electronics and self-powered sensors applications.