Improvement of optical, dielectric and mechanical properties of a new nanocomposite based on polyvinyl alcohol and layered double hydroxide

Abstract

In this work, films in the form of poly (vinyl alcohol)/Layered Double Hydroxide (PVA/LDH) nanocomposites were synthesized with different amount of LDH (0%; 4% and 6%), and characterized by X-ray diffraction (XRD), infrared spectroscopy scanning electron microscopy (SEM), impedance spectroscopy and UV-Vis-NIR spectroscopy. Different characterizations were used to investigate the electrical/dielectric, optical and mechanical properties of the nanocomposite films XRD and infrared spectroscopy results showed that clay particles exist in the polymer matrix. Electrical modeling was established using an equivalent electrical circuit consisting of two blocks, and confirmed by fitting the experimental conductivity data according to Jonscher’s double power law. Moreover, the reinforcement of the composite matrix by the addition of LDH particles, showed a shift of the relaxations towards the low frequencies, and led to an increase of dielectric constant, conductivity, and absorption of the light in the ultraviolet domain with a decrease of the gap energy. As for the mechanical properties, namely the Young’s modulus, is tripled when the clay content is about 6%.

Synthesis and modification of the structural, optical, and thermal properties of PVA–PEO by LDH nanoplates

“…The bands appear at energies lower than 1000 cm −1 owing to the vibration mode of M-O, and M-O-M [41]. Therefore, the bands at 475 and 588 cm −1 and the tiny band observed in the spectrum of 11 wt% LDH/blend film at 526 cm -1 are arising from the absorption of Fe-O, Zn-O, and/or Fe-O-Zn bonds, confirming the existence of Zn/Fe-LDH NP in the blend matrix [25,35]. It is observed that the relative intensities of the characteristic vibrational bands of the blend are decreased below 7.0 wt%, and then increased again.…”

“…The wideness and intensity of the band at these three positions change irregularly with increasing LDH NP content. A tiny band at 1640 cm -1 is attributed to the COOsymmetric stretching vibration [25]. The two bands observed at ∼1418 cm -1 and 837 cm -1 are assigned to the bending modes of the CH 2 and C-O groups, respectively [36].…”

“…According to Kim et al [24], loading LDH NP up to 2.0 wt% inside PVA/poly(acrylic acid) (PAA) improved the gas barrier, mechanical and ultraviolet (UV)-blocking properties of the nanocomposites and could be utilized as green packaging materials for the food and medicine fields. In addition, Assekouri et al [25] reported the improvement of the mechanical and dielectric properties of PVA by loading 4 and 6 wt% LDH NP. Pa et al [26] reported the improvement of the thermal and mechanical properties of PVA/starch loaded with GO/Ni-Al LDH up to 1.0 wt%.…”

Pb2+ recovery from real water samples by adsorption onto nano Fe3O4/chitosan‐acrylamide hydrogel ions in real water samples

“…Magnetic chitosan hydrogel adsorbent may be easily separated using a magnet instead of centrifuges or filtrations. Additionally, the use of pricey and dangerous organic solvents is decreased when using the magnetic chitosan hydrogel adsorbent with extraction in an aqueous sample (Table 5) [11,12,17,31].…”