Investigating the efficiency of textile fog-collectors on the basis of fiber parameters

The increasing demand of water in mankind necessitates the need to consider supplementary sources of water. Fortunately, under favorable topographical and atmospheric conditions, water can be collected from fog. Small water droplets appear on the surface of solid objects when fog precipitates on them. So, to some extent, fog can be utilized for relieving water shortage by employing water-collecting systems known as fog collectors that collect water from fog and the moisture present in air. Most of the fog collectors that have been used around the world are made up of polymers and textile materials. The main purpose of this study is, therefore, to investigate some physical fiber parameters influencing the efficiency of textile fog collectors. Consequently, several kinds of fibrous materials in the forms of yarn and/or fabric were investigated. Thus, it was statistically found that water collection efficiency is affected by parameters like fiber–water absorption, specific heat capacity of the material, and the existence of sites for holding moisture on the surface of the materials. In this respect, the effect of contact angle between threads within a fabric structure was investigated on the performance of textile fog collectors. This concept was performed using Eriksson’s model, which is a mathematical model.     

Textile colour matching using linear and exponential weighted principal component analysis

In this work, linear and exponential weighted principal component analysis techniques based on spectral similarity were employed for the prediction of dye concentration in coloured fabrics, which had been dyed with three component dye mixtures. The matching strategy was based on the equalisation of the first three principal component coordinates of the weighted reflectance curves of the predicted and target sample in a dynamic 3D eigenvector space. The performance of the proposed algorithm was evaluated by the root mean square differences of the reflectance curves and the relative error of the concentration prediction, as well as the metamerism index. The obtained results indicated that the developed exponential weighted principal component analysis method is more accurate than the spectrophotometric method and the simple principal component analysis matching strategy.     

Investigation of Structural,Electronics, Optical,Mechanical and Thermodynamic Properties of YRu2P2 Compound for Superconducting Application

Journal of Superconductivity and Novel Magnetism - The structural, electronic, optical, and thermodynamic properties of the YRu2P2 superconductor are investigated theoretically using the CASTEP...     

Silane grafting and moisture crosslinking of polyethylene: The effect of molecular structure

The silane grafting and moisture crosslinking of different grades of polyethylene have been investigated. Three types of polyethylene (HDPE, LLDPE, and LDPE) with different molecular structures and similar melt flow indices were selected. The initiator was dicumyl peroxide (DCP), and the silane was vinyltrimethoxysilane. The grafting reaction was carried out in an internal mixer. The extent of grafting and the degree of crosslinking were determined, and hot‐set tests were carried out to evaluate the crosslink structure of the different polyethylenes. The LLDPE had the highest degree of grafting, while the LDPE had the least. The rate of crosslinking for LDPE was higher than that of HDPE and LLDPE. The gel content of LDPE was higher than that of HDPE and LLDPE. Hot‐set elongation and the number‐average molecular weight between crosslinks (M_c) were lower for LLDPE and LDPE than for HDPE. Increasing the silane/DCP percentage led to peroxide crosslinking, thereby decreasing the M_c and hot‐set elongation. The number‐average molecular weight (M_n), molecular weight distribution, and number of chain branches were the most important parameters affecting the silane grafting and moisture crosslinking. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Covalent immobilization and characterization of Rhizopus oryzae lipase on core-shell cobalt ferrite nanoparticles for biodiesel production

Rhizopus oryzae lipase (ROL) was immobilized on the surface of silica coated amino modified CoFe2O4 nanoparticles and applied for biodiesel production.The results indicated more affinity of the ROL toward its substrate upon immobilization,as revealed by a lower Km value for the immobilized ROL compared to its free counterpart.Intrinsic fluorescence spectroscopy indicated a lower intensity for ROL immobilized on CoFe2O4 nanoparticles.Besides,immobilized ROL steady state anisotropy measurements presented lower values,which implied assembly of ROL molecules on magnetic nanoparticles upon immobilization as well as their restricted rotation upon covalent attachment.Thermal stability analysis revealed improved activity at higher temperatures for the immobilized enzyme compared to its free counterpart.Accordingly,Pace analysis to determine protein thermal stability revealed preservation of the protein conformation in the presence of increasing temperatures upon immobilization on nanoparticles.Finally,ROL immobilized on CoFe2O4 nanoparticles exhibited improved efficiency of biodiesel production in agreement with thermal activity profile.Therefore,the authors suggest application of the lipase mole-cules immobilized on CoFe2O4 nanoparticles for more efficient biodiesel production.     

Molecular dynamics simulation of diffusion and permeation of gases in polystyrene

Molecular dynamics simulations are performed to study the diffusion and permeation of gases, including argon, nitrogen, methane, carbon dioxide, and propane, in polystyrene over a wide range of temperatures. A jumping mechanism is observed for the diffusion of diffusants in polymer. The calculated diffusion coefficients agree well with the experimental data and with the results of former simulation studies. The relation between the diffusion coefficient and the molecular diameter is confirmed by the results. Our calculated results on the temperature-dependence of diffusion coefficients show that for some gases a break is seen, at the glass transition temperature, in the Arrhenius plot of ln (D) versus 1/T, while for some other light gases, argon and nitrogen, the plot is linear over the whole temperature range. We have also calculated the permeability coefficients, using the diffusion coefficients calculated in this work and our recently published solubility coefficients [Eslami and Müller-Plathe, Macromolecules 2007; 40:6413]. Our results show that the calculated permeability coefficients are higher than the experimental data by almost the same trend observed in the solubility calculations, but the ratios of calculated permeabilities are in a very good agreement with experiment.     

The impact of viscoelastic behavior and viscosity ratio on the phase behavior and morphology of polypropylene/polybutene‐1 blends

In this study, the influence of the viscosity ratio on the rheology, morphology, and interfacial interaction of polypropylene and polybutene‐1 (PB‐1) resins with various melt flow behaviors in the blend are investigated. A droplet‐matrix morphology is observed in the scanning electron microscope images for all formulations and the size of particles increased proportionally by increasing the viscosity ratio. Viscoelastic parameters of blends at various viscosity ratios and compositions are measured by small‐amplitude oscillation rheometry in the linear viscoelastic region. The Cole‐Cole plots showed a nearly semicircular arc for all compositions. This semicircular arc is observed while the viscosity ratio is lower than 1, and the Cole‐Cole plots deviated from the semicircular shape at PB‐1 content higher than 10 wt%. It is emphasized that, in addition to compatibility, the semi‐circularity of Cole‐Cole plots affects the size of the dispersed particles, which is under the influence of the viscosity ratio. It is found that the interfacial tensions of polypropylene and PB‐1 are not significantly different when changing the viscosity ratio and coarsening the morphology. The form relaxation times in the blends with lower viscosity ratios are shorter than the form relaxation times of the blends with higher viscosity ratios. J. VINYL ADDIT. TECHNOL. 21:94–101, 2015. © 2014 Society of Plastics Engineers     

Morphological studies of (polyamide‐6)/(silane‐grafted high‐density polyethylene)/nanoclay ternary nanocomposites

In this work, the influence of organoclay incorporation along with silane grafting of high‐density polyethylene (HDPE) on compatibilization and morphology of HDPE/(polyamide‐6) (PA6) blends was investigated. Analysis by Fourier‐transform infrared spectroscopy was done for the investigation of grafting efficiency of specimens. Scanning electron microscopy and thermal properties (diffraction scanning colorimetry) were examined to study the effect of silane grafting as well as adding organoclay in compatibilizing blends. Small‐angle X‐ray scattering, transmission electron microscopy, and dynamic rheology (Rheometric Mechanical Spectrometer) were also used to explain morphological changes. The results of scanning electron microscopy indicated that silane‐grafted HDPE had hydrophilic characteristics and therefore was more compatible with PA6 than neat polyethylene. Furthermore, in the same way, adding nanoclay to this blend resulted in more uniform and finer morphology. Results of diffraction scanning colorimetry confirmed the compatibilizing effect of both silane grafting of polyethylene and use of organoclay in blends by showing a strong deviation of separate melting peak of PA6 in the composites to reduced intensity and shift to lower temperatures. J. VINYL ADDIT. TECHNOL., 21:191–196, 2015. © 2014 Society of Plastics Engineers     

Improvement of Solar Cell Performance After Oxygen Removal by Electron Beam Melting

Two 450 kg multicrystalline silicon ingots were obtained by mixing and melting high purity silicon and silicon from the edges and the bottom of the casted ingots together in a casting furnace. For one of the ingot, the silicon from casted ingots was refined in an electron beam melting furnace to remove oxygen. The oxygen content was reduced from 10 to less than 0.0517 ppmw when silicon was refined at 500 kW with removal efficiency up to 99.429% in the most areas. The life time of the ingot after oxygen removal was measured to be far better than another one, whereas in the central parts the value was almost 6.7 µs. The efficiencies of both solar cells were initially 17.55% but after 4 h decreased to 17.05% and 15.55%, respectively. The solar cell after oxygen removal shows a better performance in degradation.