Abstract:In this work, we report the transfer of graphene onto eight commercial microfiltration substrates having different pore sizes and surface characteristics. Monolayer graphene grown on copper by the chemical vapor deposition (CVD) process was transferred by the pressing method over the target substrates, followed by wet etching of copper to obtain monolayer graphene/polymer membranes. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) measurements were carried out to explore the graphene layer transferability. Three factors, namely, the substrate roughness, its pore size, and its surface wetting (degree of hydrophobicity) are found to affect the conformality and coverage of the transferred graphene monolayer on the substrate surface. A good quality graphene transfer is achieved on the substrate with the following characteristics; being hydrophobic (CA > 90 • ), having small pore size, and low surface roughness, with a CA to RMS (root mean square) ratio higher than 2.7 • /nm.
Comparison of early-and late-growth crystal morphologies of several water-soluble ionic materials suggests that early rapid growth is accompanied by a speci®c type of morphological distortion. This distortion, involving a change in the relative growth rate of just one growth direction, is consistent with our previously proposed mechanism for the transition from normal, polyhedral crystal growth to dendritic growth. Interpretation of this morphological distortion was aided by morphology prediction methods based on computed attachment energies.
Ammonium Dihydrogen Phosphate crystals doped with Glycine (GADP) has been grown by slow evaporation method, Rotation method and Sankaranarayanan - Ramasamy (SR) methods with different molar concentration. The Fourier Transform Infra-Red (FTIR) studies have been investigated on the as grown GADP crystals. The FTIR spectrum shows the interaction between ADP and the dopant by the additional peaks which corresponds to the functional groups of Glycine. The standard spectrum statistics of FTIR confirms the presence of all the functional groups. The spectrum for ADP crystals doped with Glycine grown by Rotation and SR methods have similar peaks with slight variation as that of conventional slow evaporation method grown Glycine doped ADP crystals.
Zeolite A crystals were synthesized at 100°C from sodium metasilicate and aluminium foil by microwave assisted hydrothermal technique. It was confirmed by using X-ray diffraction technique that zeolite A was produced. The influence of heating rate on the zeolite crystal size was investigated using 2.5°C/min, 7.5°C/min, and 50°C/min. It was shown that the low heating rate resulted in larger crystal size with high crystallinity. To evaluate the effect of crystal growth inhibitors (GCIs) on the zeolite synthesis and crystal size, three types of CGIs, namely Poly Ethylene Glycol (PEG); Poly Ethylene Glycol-Methyl Ether (PEG-ME); and Brij-96, were utilized. It was found that PEG gave the best result in terms of zeolite size compared to the other two CGIs by resulting in reduction of the size of zeolite A crystals into about half compared to that without CGI.
In this work, we have developed a new protocol to prepare conductive polyaniline (PANi) nanofibrous mats via an electrospinning process. The newly developed method started with doping pure polyaniline with concentrated sulphuric acid. The doped PANi is then blended with other spinnable polymers such as Polyacrylonitrile (PAN). The prepared blend is then converted into a solid nanofibrous mat using an electrospinning process. Different parameters, such as solution weight fractions, electrospinning voltage, and feed rate, were optimized and their effect on fibre morphology and conductivity were studied. Several measurement techniques were used to assess the properties of the developed mats. The measurements include Field Emission Scanning Electron Microscopy (FESEM), the intrinsic conductivity of PANi fibres and the conductivity of fibrous mats. Results revealed a direct relationship between the average fibre diameter and the morphology and the conductivities of both the fibres and the mats. Doped polyaniline showed higher conductivity compared with the pure one with an increase in average fibre diameters. Blending polyaniline with PAN improved the mat's morphology and affects their conductivities. In addition, electrospinning process parameters such as feed rate and applied voltage showed a major effect on the fibre’s morphology and conductivity.
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