Temperature Induced Structural and Photoluminescence Properties of Poly Ethylene Glycol (PEG) Capped/Uncapped Cadmium Oxide Nanoparticles (CdO NPs)

International audienceUncapped and PEG capped CdO NPs were successfully synthesized by precipitation technique. XRD and TEM studies were used to investigate the particles structure, size and shape. As synthesized samples showed major hexagonal Cadmium Hydroxide [Cd (OH)2] phase and were completely transformed into cubic CdO crystalline phase above 400 °C annealing temperature. A good crystallinity was noticed in PEG capped CdO NPs. TEM images brought out the information about the synthesized nanoparticles (NPs) existed spherical in shape. The weight loss from thermogravimetric analysis (TGA) graphs depicted the formation of CdO NPs from Cd (OH)2. PEG on CdO NPs evidently increased the direct band gap emission intensity around 480 nm and while indirect band gap emission intensity of around 620 nm was increased in uncapped CdO NPs. Beside this, PL spectra revealed interesting changes with the effect of PEG, annealing temperature and excitation wavelengths. Hence PL spectra ascertained their possible use for optical and electronic applications

2D MXenes for combatting COVID-19 Pandemic: A perspective on latest developments and innovations

The COVID-19 pandemic has adversely affected the world, causing enormous loss of lives. A greater impact on the economy was also observed worldwide. During the pandemic, the antimicrobial aprons, face masks, sterilizers, sensor processed touch-free sanitizers, and highly effective diagnostic devices having greater sensitivity and selectivity helped to foster the healthcare facilities. Furthermore, the research and development sectors are tackling this emergency with the rapid invention of vaccines and medicines. In this regard, two-dimensional (2D) nanomaterials are greatly explored to combat the extreme severity of the pandemic. Among the nanomaterials, the 2D MXene is a prospective element due to its unique properties like greater surface functionalities, enhanced conductivity, superior hydrophilicity, and excellent photocatalytic and/or photothermal properties. These unique properties of MXene can be utilized to fabricate face masks, PPE kits, face shields, and biomedical instruments like efficient biosensors having greater antiviral activities. MXenes can also cure comorbidities in COVID-19 patients and have high drug loading as well as controlled drug release capacity. Moreover, the remarkable biocompatibility of MXene adds a feather in its cap for diverse biomedical applications. This review briefly explains the different synthesis processes of 2D MXenes, their biocompatibility, cytotoxicity and antiviral features. In addition, this review also discusses the viral cycle of SARS-CoV-2 and its inactivation mechanism using MXene. Finally, various applications of MXene for combatting the COVID-19 pandemic and their future perspectives are discussed

Electromagnetic Interference Shielding Characteristics of SrTiO3 Nanoparticles Induced Polyvinyl Chloride and Polyvinylidene Fluoride Blend Nanocomposites

The current work deals with the synthesis and characterization of strontium titanate (SrTiO3) nanoparticles reinforced polyvinyl chloride (PVC) and polyvinylidene fluoride (PVDF) blend nanocomposite films prepared via a solution casting approach. The structural, thermal, morphological characteristics of the PVC/PVDF/SrTiO3 nanocomposite films were explored through Fourier transform infrared spectroscopy- FTIR, X-ray diffraction–XRD, thermogravimetric analysis–TGA, scanning electron microscopy–SEM and atomic force microscopy–AFM. The electromagnetic interference (EMI) shielding efficiency (SE) of the PVC/PVDF/SrTiO3 nanocomposite films were investigated in Ku-band (12–18 GHz). The EMI shielding result demonstrated the enhancement in EMI SE values with an increase in the SrTiO3 loading. The PVC/PVDF/SrTiO3 nanocomposite exhibits the maximum EMI SE values ∼ − 12.51 dB at 10 wt% of SrTiO3 loading. These findings affirm the dominating absorption behaviour of the nanocomposite (73.9%) with an overall shielding ability of 99.6% and negligible transmittance

Dielectric properties of nano-MMT and graphene quantum dots embedded poly (vinylidene fluoride-cohexafluoropropylene) nanocomposite films

In this work, montmorillonite (MMT) nanoclay and graphene quantum dots (GQDs) embedded poly (vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) nanocomposite films were prepared using the solution-casting technique and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM). The thermal, mechanical and dielectric properties of PVDF-HFP/MMT/GQDs nanocomposite films were also investigated. The dielectric constant (e ' ), dielectric loss (e '' ) and conductivity (sigma) of synthesized nanocomposite films were evaluated in the frequency and temperature range f100 Hz-1 MHz and 30-150 C, respectively. The highest e ' with relatively high e '' was achieved at low frequency for increasing temperature for all the nanocomposite films. The conductivity results showed good increment from lower to higher frequency up to 100 kHz at increasing temperature. The Cole-Cole plots represent the complex impedance of PVDF-HFP/MMT/GQDs nanocomposites at 150 C. The attained results imply that the PVDF-HFP/MMT/GQDs nanocomposite films can be useful candidates for flexible electronic devices

Enhanced dielectric properties of green synthesized Nickel Sulphide (NiS) nanoparticles integrated polyvinylalcohol nanocomposites

A green synthesis approach has been adopted to prepare nickel sulphide nanoparticles (NiS NPs) using banana peel extract (BPE) as a reducing and capping agent. Polyvinyl alcohol (PVA)/NiS nanocomposite films were fabricated using a cost-effective solution casting technique by dispersing different contents of NiS NPs (0–3 wt%) in the PVA matrix. Various characterization techniques were employed to analyze the structural, thermal and morphological properties of the PVA / NiS nanocomposite films. Further, the dielectric behaviour of these nanocomposite films was investigated at frequency range 50 Hz–20 MHz and in the temperature range 40 °C–140 °C. Also, there exists a significant interaction between the polymer matrix and the nanofiller as evident from the notable improvement in the dielectric properties of the nanocomposites. The dielectric constant ( ε ) value of PVA/NiS nanocomposite film with 3 wt % NiS NPs loading was found to be 154.55 at 50 Hz and at 140 °C which is 22 times greater than the dielectric constant value of neat PVA (6.90). These results suggest that NiS NPs were dispersed homogeneously in the PVA matrix

Studies on the Electrical Properties of Graphene Oxide-Reinforced Poly (4-Styrene Sulfonic Acid) and Polyvinyl Alcohol Blend Composites

In the present study, graphene oxide (GO)-reinforced poly (4-styrenesulfonic acid) (PSSA)/polyvinyl alcohol (PVA) blend composite films were prepared using colloidal blending technique at various concentrations of GO (0-3wt.%). The morphological investigations of the prepared composites were carried out using polarized optical microscopy and scanning electron microscopy. The electrical properties of composites were evaluated using an impedance analyzer in the frequency range 50Hz to 20MHz and temperature in the range 40-150 �C. Morphological studies infer that GO was homogeneously dispersed in the PSSA/PVA blend matrix. Investigations of electrical property indicate that the incorporation of GO into PSSA/PVA blend matrix resulted in the enhancement of the impedance (Z) and the quality factor (Q-factor) values. A maximum impedance of about 4.32�106? was observed at 50Hz and 90�C for PSSA/PVA/GO composites with 3wt.% GO loading. The Q-factor also increased from 8.37 for PSSA/PVA blend to 59.8 for PSSA/PVA/GO composites with 3wt.% GO loading. These results indicate that PSSA/PVA/GO composites can be used for high-Q capacitor applications. 2018 World Scientific Publishing Company.Scopu

Studies on the Mechanical, Morphological and Electrical Properties of Highly Dispersible Graphene Oxide Reinforced Polypyrrole and Polyvinylalcohol Blend Composites

In the present study, water soluble polypyrrole (WPPy)/polyvinyl alcohol (PVA)/graphene oxide (GO) composite films were prepared via colloidal blending method at different GO loadings varying from 0 – 3 wt%. The dispersion of GO in the WPPy/PVA blend matrix was examined using polarized optical microscopy (POM) and scanning electron microscopy (SEM). It was observed that the tensile strength of the composite film was changed considerably due to the incorporation of GO in the WPPy/PVA blend. The electrical properties, viz. impedance (Z), phase angle (θ) and quality factor (Q), were evaluated using the precision impedance analyser in the wide frequency (50 Hz to 20 MHz) and temperature (40°C to 150°C) ranges. The impedance was notably increased from 7.8 x 105Ω (50 Hz, 70°C) for the WPPy/PVA blend to 1.37 x 107Ω (50 Hz, 40°C) for the WPPy/PVA/GO composites with 3 wt% GO loading. On the other hand, the phase angle was gradually increased from 99.7o (20 MHz, 140°C) for WPPy/PVA blend to 199.8o (20 MHz, 80°C) for WPPy/PVA/GO composites with 3 wt% GO loading. Furthermore, the Q factor also increased from 14. 9 (10 MHz, 120°C) for WPPy/PVA blend to 108.8 (10 MHz, 150°C) for WPPy/PVA/GO composites with 3 wt% GO loading. These composites can be a promising material for electronic applicationsScopu

Zlepšené dielektrické vlastnosti nanokompozitu PVA s integrovanými nanočásticemi sulfidu nikelnatého (NiS)

Pro přípravu nanočástic sulfidu nikelnatého (NiS NPs) byl použit extrakt z banánové slupky (BPE) jako redukční a uzavírací činidlo. Nanokompozitní filmy z polyvinylalkoholu (PVA) / NiS byly vyrobeny za použití efektivní techniky tj. odlití z roztoku s dispergovanými nanočásticemi NiS o hmotnostní koncentraci 0–3% v PVA matrici. K analýze strukturních, tepelných a morfologických vlastností nanokompozitních filmů PVA / NiS byly použity různé charakterizační techniky. Dále bylo zkoumáno dielektrické chování těchto nanokompozitních filmů při frekvenčním rozsahu 50 Hz - 20 MHz a při teplotním rozmezí 40 °C - 140 °C. Bylo zjištěno, že dielektrická konstanta (ε) nanokompozitního filmu PVA / NiS s využitím 3 hmot.% NiS byla 154,55 při 50 Hz a při 140 °C, což je 22krát větší než dielektrická konstanta čistého PVA (6,90). Tyto výsledky naznačují, že nanočástice NiS byly homogenně dispergovány v PVA matrici.A green synthesis approach has been adopted to prepare nickel sulphide nanoparticles (NiS NPs) using banana peel extract (BPE) as a reducing and capping agent. Polyvinyl alcohol (PVA)/NiS nanocomposite films were fabricated using a cost-effective solution casting technique by dispersing different contents of NiS NPs (0–3 wt%) in the PVA matrix. Various characterization techniques were employed to analyze the structural, thermal and morphological properties of the PVA/NiS nanocomposite films. Further, the dielectric behaviour of these nanocomposite films was investigated at frequency range 50 Hz–20 MHz and in the temperature range 40 °C–140 °C. Also, there exists a significant interaction between the polymer matrix and the nanofiller as evident from the notable improvement in the dielectric properties of the nanocomposites. The dielectric constant (ε) value of PVA/NiS nanocomposite film with 3 wt % NiS NPs loading was found to be 154.55 at 50 Hz and at 140 °C which is 22 times greater than the dielectric constant value of neat PVA (6.90). These results suggest that NiS NPs were dispersed homogeneously in the PVA matrix

Graphene oxide reinforced polyvinyl alcohol/polyethylene glycol blend composites as high-performance dielectric material

Novel flexible dielectric composites composed of polyvinyl alcohol (PVA), polyethylene glycol (PEG), and graphene oxide (GO) with high dielectric constant and low dielectric loss have been developed using facile and eco-friendly colloidal processing technique. The structure and morphology of the PVA/PEG/GO composites were evaluated using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The dielectric behavior of PVA/PEG/GO composites was investigated in the wide range of frequencies from 50 Hz to 20 MHz and temperature in the range 40 to 150 °C using impedance spectroscopy. The dielectric constant for PVA and PVA/PEG (50/50) blend film was found to be 10.71 (50 Hz, 150 °C) and 31.22 (50 Hz, 150 °C), respectively. The dielectric constant for PVA/PEG/GO composite with 3 wt% GO was found to be 644.39 (50 Hz, 150 °C) which is 60 times greater than the dielectric constant of PVA and 20 times greater than the dielectric constant of PVA/PEG (50/50) blend film. The PVA/PEG/GO composites not only show high dielectric constant but also show low dielectric loss which is highly attractive for practical applications. These findings underline the possibilities of using PVA/PEG/GO composites as a flexible dielectric material for high-performance energy storage applications such as embedded capacitors.Scopu

CHAPTER 12: Hybrid Nano-filler for Value Added Rubber Compounds for Recycling

The generation of waste and its treatment is a challenging problem nowadays. Rubber that is generally considered for recycling comes from the tyres of vehicles. After their use, the waste tyres can lead to hazardous effects to both public health and the environment due to inappropriate disposal or storage. The used rubber tyres take an extended period of time to decompose naturally, thereby increasing landfill pollution. Furthermore, the burning of rubber waste produces toxic and carcinogenic gases causing air pollution and risk to the health of living beings. Thus, fabrication of recycled product provides an alternative to avoid the above mentioned negative impacts. Nanofillers play an important role in altering the properties of recycled composite systems. The superior bonding between the nanofiller and rubber results in the improvement of functionality and enhancement of properties of the entire composite system. This chapter discusses the different recycling methods of rubber with hybrid nanofiller additions resulting in the fabrication of recycled nanocomposites which could be used as filler-extenders, ion exchangers or in road pavements.Scopu