Showing papers in "Materials Sciences and Applications in 2012"
TL;DR: In this article, the structure of polyurethane polyol was determined using FTIR and 13C NMR, showing that hydrogen bonding was formed between the soft segmented chain of the polyol and the hard segmented MDI.
Abstract: Polyurethane (PU) was prepared from palm kernel oil-based monoester polyol (PKO-p) via prepolymerization method at NCO/OH ratio of 200/100, 150/100, 100/100, and 75/100 at ambient temperature under nitrogen gas atmosphere. The structure of the synthesized prepolymerized PKO-p PU was determined using FTIR and 13C NMR. The disapperance of NCO peak in the FTIR spectrum at 2270 cm–1 - 2250 cm–1 cm showed that MDI has completely reacted to form PU. The appearance of C=O peak at 1700 cm–1 indicated that hydrogen bonding was formed between the soft segmented chain of the PKO-p and the hard segmented MDI. Hence, urethane bond was the main polymeric chain in the PU.
90 citations
TL;DR: In this article, microstructure and variations in porosity in Ti-6Al-4V samples built with electron beam melting (EBM) over a range of melt scan speeds, ranging from 100 mm·s-1 to 1000 mm· s-1, were examined.
Abstract: Microstructure and variations in porosity in Ti-6Al-4V samples built with electron beam melting (EBM) over a range of melt scan speeds, ranging from 100 mm·s-1 to 1000 mm·s-1 were examined Microstructure was characterized by refinement of α-phase and transformation to α′-martensite Light optical microscopy, scanning electron microscopy, and transmission electron microscopy were used to observe these phenomena, while corresponding tensile testing and associated macro and microindentation hardness measurements were used to define the microstructural variations Relative stiffness was observed to be linearly log-log related to relative density, corresponding to ideal porosity associated with open-cellular structures
68 citations
TL;DR: In this article, the authors demonstrated the feasibility of using poly(ethylene glycol) dimethacrylate (PEG-DMA) gels with a photoinitiator for encapsulation and stabilization of painted biomimetic membrane arrays for novel separation technologies or biosensor applications.
Abstract: Hydrogels are highly water-absorbent hydrophilic polymer networks, which show potential in many biocompatible applications. In previous work, we demonstrated the feasibility of using poly(ethylene glycol) dimethacrylate (PEG-DMA) gels polymerized with a photoinitiator for encapsulation and stabilization of painted biomimetic membrane arrays for novel separation technologies or biosensor applications. These gels were formed from PEG-DMA monomers suspended in phosphate buffered saline (PBS) solution and gelated by radical polymerization in the presence of the photoinitiator Darocur 1173. In this work, we show that the properties of a PEG-DMA hydrogel formed by photoinitiated polymerizetion can be tailored by varying the photocrosslinking time. Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy (RS) showed that the optimal crosslinking time for the gel was 6 - 10 minutes and that the water content of the gels could be tuned in the range of 50 - 90 wt%. The resistivity was between 0.8 - 3.5 Ωm, which is comparable to that of PBS. The low resistivity of the gel makes it compatible for encapsulating membranes for (ion channel based) biosensor applications. With FTIR and RS we identified spectral features of the hydrogel, which may serve as a diagnostic tool to monitor changes in the gels due to variation in parameters such as time, pH, temperature, aging or exposure to chemicals or biological material.
48 citations
TL;DR: In this paper, natural dyes from flame tree flower, pawpaw leaf and their mixtures were used as sensitizers to fabricate dye-sensitized solar cells (DSSC).
Abstract: Natural dyes from flame tree flower, Pawpaw leaf and their mixtures were used as sensitizers to fabricate dye-sensitized solar cells (DSSC). The photoelectrochemical performance of the Flame tree flower dye extract showed an open-circuit voltage (VOC) of 0.50 V, short-circuit current density (JSC) of 0.668 mA/cm2, a fill factor (FF) of 0.588 and a conversion efficiency of 0.20%. The conversion efficiency of the DSSCs prepared by pawpaw leaf extract was 0.20%, with VOC of 0.50 V; short-circuit current density, JSC of 0.649 mA/cm2 and FF of 0.605. The conversion efficiency for the flame tree flower and pawpaw leaf dye mixture was 0.27%, with VOC of 0.518 V, JSC of 0.744 mA/cm2 and FF of 0.69. Although the conversion efficiencies, Jsc and the Voc of the prepared dye cells were lower than the respective 1.185%, 7.49 mA/cm2 and 0.64V reported for ruthenium, their fill factors (FF) were higher than that of ruthenium (0.497). It was also observed that both the short-circuit current density and the fill factors of the cells were enhanced using mixed dye.
43 citations
TL;DR: In this article, a comparative study was carried out using Keratin fiber, a fibrous protein, found in the chicken feathers, and five different samples of the feather were analyzed by Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD).
Abstract: Because of the constant challenge to preserve the environment and the search for new materials, a comparative study was carried out using keratin fiber, a fibrous protein, found in the chicken feathers. Five different samples of the feather were analyzed by Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD). First in their natural form Keratin Fiber (KF); the second treated with sodium hydroxide (KFNaOH); the third and fourth samples were semi carbonized at 220℃ in an oven without atmospheric control for 24 hours (samples obtained: Clear brown (SCFC) and Dark brown (SCFD)); and the fifth sample was carbonized by pyrolysis Carbonized Feathers (CF). The SEM result shows that the KF has a hollow structure, with knots and hooks. The KFNaOH structure presented rougher than that of the KF, but lost their hooks. The SCFC and SCFD presented brittle structures, but preserved the hollow structure of KF; however, it was only noticeable to a magnification of 3000 times. On the other hand, the CF, was shiny, black, and showed a higher amount of porosity with open micro-pores and micro-tubes, preserved the hollow structure of KF than any other samples studied, and also presented well-defined closed micro-tubes. From the XRD analysis of the KF, CF, KFNaOH, SCFC and SCFD, presented semi-crystalline structures, with the following indices of crystallinity, 20.09%, 18.93%, 17.97%, 15.02% and 14.31%, respectively. The CF presented smaller size crystallites, in between the micro- particulates, around 27 nm and the KFNaOH with larger size around 74 nm. From this study it was concluded that micro-porous carbon material from chicken feathers (KF) could be efficiently obtained through pyrolysis.
41 citations
TL;DR: In this paper, the effect of copper doping on the structural and magnetic properties of nickel ferrites sintered at 1000°C has been examined and the X-ray diffraction measurements clearly showed the formation of single phase spinel ferrite structure in all the prepared ferrite compositions.
Abstract: The Ni1–xCuxFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) ferrites have been prepared by sol-gel method in order to obtain homogeneous crystal structure and they are sintered at high temperature. The effect of copper doping on the structural and magnetic properties of nickel ferrites sintered at 1000°C has been examined. The X-ray diffraction measurements clearly showed the formation of single phase spinel ferrite structure in all the prepared ferrite compositions. Because of the high sintering temperature the particle size is observed beyond the nano-scale range in all the compositions. The lattice parameters are found to increase with increasing doping concentration of the copper content. Magnetization results exhibit a non-collinear ferrimagnetic structure for x = 0.0 to 0.5 and Neel’s collinear ferrimagnetic structure for x = 0.5 to 0.9 suggesting a change in magnetic ordering.
38 citations
TL;DR: In this article, the potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to produce high value products that have technical and environmental demand.
Abstract: The potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2%, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to produce high value products that have technical and environmental demand. The two treatment methods used for rice straw are alkali and acidic treatments of rice straw. The removal of impurities and waxy substances from fiber surface avoid creation of rougher topography after treatment and improves the quality of fiber, also content of hemi cellulose and lignin decrease so increase effectiveness of fiber due to dispersing of fiber in matrix. The reinforcing material is embedded in the matrix material to enhance tensile and flexural behaviors of the synthesized composite. The result of investigating these two mechanical properties, using statistical analysis & design of experiments, showed an enhancement in the mechaniccal properties of the virgin polymer composite compared to the virgin polymer. The flexural stress of the composite increased three times the virgin flexural stress, while the tensile stress increased eight times the original tensile stress.
38 citations
TL;DR: In this article, the results confirmed that nanocrystalline Cu-doped ZnO particles have a hexagonal wurtzite structure with a high degree of crystallization and a crystallite size of 10 - 16 nm.
Abstract: Nanocrystalline Cu-doped ZnO particles were synthesized by the co-precipitation method. The composition, structural, optical and magnetic characterizations were performed by energy dispersive X-Ray spectroscopy, X-Ray diffraction, UV-Visible spectrometer, and vibrating sample magnetometer. The results confirmed that nanocrystalline Cu-doped ZnO particles have a hexagonal wurtzite structure with a high degree of crystallization and a crystallite size of 10 - 16 nm. For Cu above 11 at%, the X-Ray diffraction pattern possessed CuO secondary phase which shows the solubility limit of Cu in the ZnO lattice. Up to 11% at Cu, the presence of Cu in the ZnO lattice as Zn substitution indicated by an in- crease in lattice parameter values. Nanoparticles showed weak ferromagnetic characteristics at room temperature. The absence of secondary phase related to magnetic precipitate shown intrinsic ferromagnetic behaviour.
37 citations
TL;DR: In this article, the extraction of chitosan from chitin that is present in the exoskeletons of shrimps Litopenaeus vannamei and crabs Ucides cordatus was exploited to find an alternative use, which can help solving the environmental problem as well to provide extra income to the fishermen.
Abstract: Chitin is widely distributed in nature, being the main structural component of the exoskeleton of crustaceans and is non-toxic, biodegradable and biocompatible. These exoskeletons once discarded become an industrial waste creating environmental pollutant. In order to find an alternative use, the present work exploits the extraction of the chitosan from chitin that is present in the exoskeletons of shrimps Litopenaeus vannamei and crabs Ucides cordatus and transforms it into high valued products, which can help solving the environmental problem as well to provide extra income to the fishermen. One example is the manufacture of nanomembranes from chitosan for the application in medical textiles. Nanomembranes using electrospinning of chitosan solutions (7% and 5wt%) with 100:0 v/v (TFA/DCM) and 70:30 v/v (TFA/DCM) were produced. Morphological properties of chitin and chitosan were studied using SEM, DRX, and thermal properties through TG/DTG and molecular structure by FTIR analysis. TG/DTG showed thermal decomposition of chitosan samples. X-ray diffraction analysis indicated the semi-crystalline structure of chitosan, and highly crystalline structure for chitin. Morphologies of the nanomembranes were also observed from scanning electron micrographs. Results showed that the nanomembranes with 5% chitosan solutions with 70:30 v/v (TFA/DCM) showed facilitation in the formation of the nanomembranes. The nanomembranes of shrimp and crab with 5% 70:30 v/v (TFA/DCM) had higher breaking tension and breaking extension. With positive results obtained, the present work will help the authorities to organize the fishermen to have consciousness in the collection of exoskeleton waste as well as helping to have a better environment.
28 citations
TL;DR: In this article, amine terminated hollow glass microspheres were prepared by adopting three different routes and the results were investigated using FT-IR and SEM to establish the formation of amine groups and observe the morphological structure of the modified HGMs.
Abstract: Hollow Glass Microspheres are high-strength, low-density additives made from water resistant and chemically-stable soda-lime-borosilicate glass. These hollow glass microspheres offer a variety of advantages over conventional irregularly-shaped mineral fillers or glass fiber. Their spherical shape helps reduce resin content in a variety of applications. They also create a ball bearing effect that can result in higher filler loading and improved flow. In this research, amine terminated hollow glass microspheres were prepared by adopting three different routes. The results were investigated using FT-IR and SEM to establish the formation of amine groups and observe the morphological structure of the modified HGMs. The results obtained were used to select a suitable less toxic and environmental friendly modification method based on the chemicals used.
28 citations
TL;DR: In this article, the pit morphology and growth kinetics of commercially pure aluminium in naturally aerated NaCl solutions were studied using an image processing method based on reflected light microscopy.
Abstract: The pit morphology and growth kinetics of commercially pure aluminium in naturally aerated NaCl solutions were studied using an image processing method based on reflected light microscopy. In order to distinguish between pits and pre-existing cavities, metallographic examination and statistical analysis were carried out before and after corrosion testing. The results show that the pit shapes and sizes are more dependent on the immersion time than the chloride concentration. Pits are predominantly hemispherical, but they undergo reasonable geometric transitions associated with increased immersion time and occur without significant depth variation. The role of chloride ions is more closely associated with the pit nucleation phenomenon.
TL;DR: In this paper, the authors synthesize hydroxyapatite (HA) in situ by the precipitation method, with and without the presence of collagen (COLL), to study its influence on HA's structural and morphological characteristics.
Abstract: Hydroxyapatite (HA) was synthesized in situ by the precipitation method, with and without the presence of collagen (COLL), to study its influence on HA’s structural and morphological characteristics. The material was characterized by energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TG) and scanning electron microscopy (SEM). The Ca/P molar ratio was influenced by collagen addition—1.89 and 2.38 for samples without and with collagen, respectively. The WAXD pattern revealed better resolution and intensity besides higher crystallinity degree of the HA in the presence of collagen. The photomicrographs showed a strong influence of collagen on the HA morphology.
TL;DR: In this paper, superconducting samples of type (Bi1.8Pb0.4)Sr1.9Ca2.1Cu3O10+δ were prepared, with Pb 0.2 2+ and Pb
Abstract: In this work, superconducting samples of type (Bi1.8Pb0.4)Sr1.9Ca2.1Cu3O10+δ were prepared, with Pb0.4 composed of Pb0.2 2+ and Pb0.24+ , at different sintering temperatures ranging from 835℃to 855℃. The prepared samples were characterized using x-ray powder diffraction (XRD), scanning electron microscope (SEM), electron dispersive spectroscopy (EDS) and differential scanning calorimetery (DSC). The superconducting properties were investigated using electrical resistivity and transport critical current density. Our results showed that the sample prepared at sintering temperature 845?C has the optimum value of superconducting transition temperature Tc and transport critical current density Jc.
TL;DR: In this article, the herbicide was encapsulated in starch and chitosan beads reinforced with alginate, and the beads were characterized using SEM, DSC and FTIR.
Abstract: In a bid to make slow release formulations of imazaquin, the herbicide was encapsulated in starch and chitosan beads reinforced with alginate. The beads were characterized using SEM, DSC and FTIR. Two types of formulations were made by extrusion into 0.25 M calcium chloride solution: chitosan/alginate (LNCI) and starch/alginate (LNSI) beads, and the third was by gelatinization of starch at 75?C (LNSI2). Findings showed highly porous spherical beads, the starch/alginate beads bigger and less porous than the chitosan/alginate beads with diameters of 2.53 ± 0.01 and 2.31 ± 0.01 mm; porosity of 57.58% ± 0.2% and 81.28% ± 0.2% and swelling of 34.91% ± 0.2% and 80.35% ± 0.2%, respectively. FTIR revealed a reduction in intensity of the carboxylate peaks of alginate and the peak at 1058 cm?1, present in the FTIR of the matrices, is shifted to lower wave-numbers in the formulations, signifying interactions between the formulation components that make for good slow release. The DSC thermograms of all formulations showed evidence of interaction of imazaquin carboxylate group with the N-atoms of the macromolecules, which is indicative of reduced crystallinity of imazaquin.
TL;DR: In this paper, a fully densified in-situ reinforced (TiB + TiC)-Ti matrix composites have been produced from TiH2-B4C mixtures using pressure less sintering or hot pressing technique.
Abstract: Fully densified in-situ reinforced (TiB + TiC)-Ti matrix composites have been produced from TiH2-B4C mixtures using pressure less sintering or hot pressing technique. With increasing content of reinforcing components the sintering is retarded. The materials with more than 20 - 30 vol. % were only completely densified by hot pressing technique. Hardness values of the Ti matrix composites produced are up to 5 times higher than that of the sintered pure Ti produced from TiH2. This is caused beside the higher hardness of the inclusions also by hardening the matrix due to solubility of B and C in the titanium.
TL;DR: In this article, the effects of polyethylene terephthalate (PET) polymer, which is a waste material obtained by crushing of used PET bottles, on the mineralogical composition of composites after 28 days of casting are presented.
Abstract: The sheer amount of disposable bottles being produced nowadays makes it imperative to identify alternative procedures for recycling them since they are non-biodegradable. Experimental investigation on the effects of polyethylene terephthalate (PET) polymer, which is a waste material obtained by crushing of used PET bottles, on the mineralogical composition of composites after 28 days of casting are presented in this paper. Various weight fractions of cement 2.5%, 5% and 7.5% were replaced by the same weight of PET plastic; they were then moulded into specimens and cured. The fine powder samples obtained from broken specimens were subjected to X-ray diffraction, FT-IR spectroscopy, differential thermal analysis, thermogravimetric analysis and the composites were also observed by optical microscope. Thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to study the interaction between polymers and cements. Differential thermal analysis (DTA), X-ray diffraction and FT-IR were also used to investigate the cement hydration according to the additions. The results showed that an increase in polymer-cement ratio meets with a decrease in the quantity of Ca(OH)2; in terms of bonding, the rough surface of particle favours greater contact between PET and cement matrix and doesn’t seem to have chemical interaction between the mineral species and the organic molecules which could lead to the formation of new compounds. The present study highlights the capabilities of the different methods for the analysis of composites and opened new way for the recycling of PET in polymer-mortars.
TL;DR: In this paper, a modeling and experimental study was conducted to explore the effects of nanoparticle type (aluminum nanoparticles and carbon nanotubes), filler concentration and interactions between the nanoparticle and reinforcing fibers on through-thickness conductivity of nanoparticles/epoxy nanocomposites and nanoparticle/fiber-reinforced multiscale composites.
Abstract: In this research, a modeling and experimental study was conducted to explore the effects of nanoparticle type (aluminum nanoparticles and carbon nanotubes), filler concentration and interactions between the nanoparticle and reinforcing fibers on through-thickness conductivity of nanoparticle/epoxy nanocomposites and nanoparticle/fiber-reinforced multiscale composites. Multiple, notable micromechanical models were evaluated to predict through-thickness thermal conductivity of both composite systems, and then compared to the experimental results. The results showed that filler volume fraction ranges and thermal conductivity differences of the constituent materials for the thermal conductivity ratio (km/kf or kf/km) used in the models can affect the resulting predictions. Certain models were found to be suitable for varying conditions on the thermal conductivity ratio. Finite element models (FEM) were developed to reveal heat transport mechanisms of the resultant nanocomposites and multiscale composites. The nanocomposite design for finite element analysis (FEA) provided close predictions and performed better than the micromechanical models. On the multiscale composite system, predictions were concluded to be dependent upon the FEM design where the interactions between nanoparticles and fibers are critical to accurately determine the through-thickness thermal conductivity.
TL;DR: In this paper, the effect of the addition of hydrophilic surfactant Pluronic F127, Polyivinylpyrrolidone (PVP), and Tetronic 1307 on the performance of the final PES hollow-fiber membrane was investigated.
Abstract: Hydrophilic polyethersulfone (PES) hollow fiber membranes were prepared via non-solvent induced phase separation (NIPS) by addition of polymeric additives as a membrane modifying agent. The effect of the addition of hydrophilic surfactant Pluronic F127, Polyivinylpyrrolidone (PVP), and Tetronic 1307 on the performance of the final PES hollow-fiber membrane was investigated. The morphology of fabricated hollow fiber membrane observed by scanning electron microscopy (SEM) indicated that all of membrane had a skin layer on the surface and finger like macrovoid structure inside the hollow fiber. The addition of 5 wt% polymeric surfactant on the polymer solution results in membrane with improved length and number of macrovoid structure. Sponge formation both near inner surface and near outer surface of hollow fiber membrane was another impact of addition of polymeric additives, which is led to decrease of water permeability of these membrane. Water contact angle measurement was performed to investigate the hydrophilicity property of resulted membrane. It is confirmed that the modified PES hollow fiber membranes had lower water contact angle than that of the original membrane, which indicate that the modified PES membrane with additives has high hydrophilic.
TL;DR: A series of undoped nanocrystalline ZnO particles were successfully synthesized at various dry temperatures (100?C - 600?C) using coprecipitation method as discussed by the authors.
Abstract: A series of undoped nanocrystalline ZnO particles were successfully synthesized at various dry temperatures (100?C - 600?C) using coprecipitation method. The samples were characterized using a variety of experimental methods such as x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), thermal analysis TG-DTA, UV-vis spectroscopy, infrared absorption spectroscopy (FTIR) and electron spin resonance spectroscopy (ESR). According to XRD analysis, all of our ZnO samples posses the hexagonal wurzite structure with average crystallite size increased ranging from 19 - 23 nm as dry temperature increased. Optical absorption spectra show that the band gap shifted to the lower energy with increasing crystallite size. ESR measurements showed the resonance of electron centers with the g values of about 1.96. With increasing dry temperature we observed the decrease of the g values and the increase of the intensities of the ESR signal. In addition an increase in dry temperature results in a pronounce decrease of OH local vibrational modes. The results from ESR measurements are well supported by the results obtained from Infrared absorption spectroscopy and thermal analysis measurements.
TL;DR: In this paper, the effect of water absorption on hybrid fiber reinforcement for polypropylene composites was studied by immersion specimens in distilled water at room temperature for different time durations (24, 48, 72, 96, 120, 144, 168, 192 hours).
Abstract: The main objectives of this research were to study the effect of water absorption on mechanical properties of hybrid fiber reinforcement for polypropylene composites. The poor resistance towards water absorption is one of the draw- backs of natural fibers. Hybrid filler-polypropylene composites are subjected to water immersion tests in order to study the effects of water absorption on the mechanical properties. Composites specimens containing 30 phr and 40 phr fiber weight were prepared by melt blending process. Water absorption tests were conducted by immersion specimens in distilled water at room temperature for different time durations (24, 48, 72, 96, 120, 144, 168, 192 hours). The tensile, flexural and impact properties were investigated before and after water absorption. The percentage of moisture uptake increased as the increasing order of the filler loading due to the high cellulose content. The phase morphology of wood flour/wheat husk polypropylene hybrid composites were investigated by SEM, the dynamic mechanical properties of the composite are analyzed by DMA & wheat, wood filler interaction are analyzed by FT-IR.
TL;DR: In this paper, the influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated.
Abstract: The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using aluminum tri-sec-butoxide and zirconium n-propoxide as precursors. Ethanol (EtOH), isopropanol (iPrOH) and isobutanol (iBuOH) were used as solvents. The Al2O3-ZrO2 powders were characterized by nitrogen physisorption (SBET), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Prepared oxides calcined at 700℃ showed high specific surface area (200 - 240 m2/g). Obtained results suggest that the homogeneity of the mixed oxides is favored by using a water addition rate of 0.06 and 0.10 mL/min with ethanol as solvent.
TL;DR: In this article, the pyroelectric and dielectric properties of composite films were examined for their use in uncooled infrared detectors, and the results indicated Figures-of-merit of composite film were higher than pristine polyvinylidene fluoride films.
Abstract: Pyroelectric multi-walled carbon nanotubes:polyvinylidene fluoride (PVDF:MWCT) composite films have been fabriccated by the solution casting technique. The pyroelectric and dielectric properties of the composite films were examined for their use in uncooled infrared detectors. The properties measured include: 1) dielectric constants and 2) pyroelec- tric coefficient as a function of temperature. From the foregoing parameters, materials Figures-of-merit, for infrared detection and thermal-vidicons, were calculated. The results indicated Figures-of-merit of composite film were higher than pristine polyvinylidene fluoride films.
TL;DR: In this paper, the thermal properties of polyvinyl chloride and asbestos ceiling sheet were investigated in tropical regions with the view to establishing their suitability as ceiling materials in building designs for tropical regions.
Abstract: This work investigates the thermal properties of polyvinyl chloride and asbestos ceiling sheet. We have studied the thermal properties of these materials in terms of the thermal conductivity (TC), thermal resistivity (TR), thermaldiffusivity, thermalabsorptivity, and specific heat capacity (SHC). With the view to establishing their suitability as ceiling materials in building designs for tropical regions. The result showed that thermal conductivity, thermal resistivity, thermal absorptivity, thermal diffusivity and specific heat capacity values of PVC and asbestos ceiling sheets falls within the range of good insulating materials like pine fibre-board and oak wood. With these properties and further improvement, they possess properties that can be harnessed for possible usage as ceiling materials.
TL;DR: In this article, the influence of graphene nanoparticles (GNP) in concentrations from 2.0 to 10.0 phr on the dielectric and microwave properties of nanocomposites on the basis of natural rubber has been investigated in the wide frequency range (1 - 12 GHz).
Abstract: The development of carbon nanotubes based materials has been impeded by both their difficult dispersion in the polymer matrix and their high cost. The discovery of graphene and the subsequent development of graphene-based polymer nanocomposites is an important addition in the area of nanoscience and technology. In this study the influence of graphene nanoparticles (GNP) in concentrations from 2.0 to 10.0 phr on the dielectric (dielectric permittivity, dielectric loss angle tangent) and microwave (reflection coefficient, attenuation coefficient, shielding effectiveness) properties of nanocomposites on the basis of natural rubber has been investigated in the wide frequency range (1 - 12 GHz). The results achieved allow recommending graphene as a filler for natural rubber based composites to afford specific dielectric and microwave properties, especially when their loading with the much more expensive carbon nanotubes is not possible.
TL;DR: In this article, Cupric oxide nanoparticles (CuO NPs) were prepared by the chemical route and different nanofluid samples of CuONPs dispersed in PVA in dif- ferent concentrations were prepared using ultrasonication.
Abstract: Study of nanofluids is important for different types of heat transfer management systems. Cupric oxide nanoparticles (CuO NPs) were prepared by the chemical route and different nanofluid samples of CuO NPs dispersed in PVA in dif- ferent concentrations were prepared using ultrasonication. The apparatus acoustic particle sizer (APS-100) was used to make high precision measurements of the ultrasonic attenuation depending upon different frequencies in the frequency range 48 to 99 MHz. The ultrasonic attenuation data are inverted to particle size distribution (PSD) and are used for particle size determination of CuO NPs. Temperature dependent ultrasonic velocity in the samples is also measured. The results of ultrasonic spectroscopy are compared with the microscopic measurements such as transmission electron microscopy (TEM) and X-ray diffraction (XRD). There is good agreement between data produced by ultrasonic spec- troscopy and the microscopic measurements.
TL;DR: In this paper, the authors used a tribometer to measure the wear of a steel in industrial production as a tool for hot work on X38CrMoV5 (AISI H13).
Abstract: The present work is to characterize both processes of thermochemical treatments: plasma nitriding and gas. The tests were carried out in collaboration with the Franco-Tunisian heat treatment (F3T) applied to a widely used steel in industrial production as a tool for hot work on X38CrMoV5 (AISI H13). The material underwent a first cycle of hardening heat treatment at 1030℃ followed by two successive incomes at 550℃ and 590℃. After nitriding (ion and gas), the quantification of wear was performed in the laboratory of tribology at SUPMECA (St. Ouen). After defining the test conditions on the alternative tribometer ensuring on one hand a quantitatively sufficient wear and avoiding on the other hand, the phenomenon of jamming. The conditions chosen are: 58.8 N load, frequency 0.5 Hz, friction coefficient μ = 0.5. The wear tracks were scanned using the profilometer Talysurf 5 M type, which allowed us to assess the volume used and the wear rate. Moreover, these tracks were characterized by metallography. What emerges from this work is that the control parameters of ion nitriding ensures a better depth of treatment for the same holding time with a total absence of the white layer known for chipping and fragility.
TL;DR: In this article, nanoporous NiO was prepared using Ni(CH3COO)2,4H2O, folic acid and water as starting material, template and solvent respectively, by sol gel method followed by calcination at 400℃.
Abstract: In this study nanoporous NiO was prepared using Ni(CH3COO)2,4H2O, folic acid and water as starting material, template and solvent respectively, by sol gel method followed by calcination at 400℃. The solid product was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) Fourier transform infrared (FT-IR) and photoluminescence (PL) techniques. The particle size of the nanoparticles estimated by XRD was in good agreement with the particle size obtained by TEM analysis (4-5nm). It was also found that the prepared nanoporous NiO show very good activity for photodegredation of dye organic pollutants such as Congo red (91%) during 1.5 hours.
TL;DR: In this article, the authors investigated the effects of the addition of Sb (0, 3 and 6 wt%) on structure, melting, corrosion and mechanical properties of Sn-Bi eutectic solder alloys.
Abstract: The goal of the present work is to investigate the effects of the addition of Sb (0, 3 and 6 wt%) on structure, melting, corrosion and mechanical properties of Sn-Bi eutectic solder alloys The mechanical properties of the bulk Sn-Bi-Sb solders were higher as the amount of antimony increases, making compressive strength augment from 65 MPa to 100 MPa when 6 wt% Sb was incorporated to the Sn-Bi eutectic alloy The three alloys presented a melting temperature that is smaller to the one exhibited by the eutectic alloy Sn-38Pb (Tm = 183°C) According to the electrochemical results, the addition of higher contents of Sb to the Sn-Bi eutectic alloy had a positive effect: it ennobled the Ecorr values
TL;DR: In this paper, the physical characteristics of the films as a function of both water content in the starting solution and substrate temperature were studied, showing that the film structure was polycrystalline in all cases, and that the intensity of (200) peak increased with the water content.
Abstract: Fluorine doped tin oxide, SnO2:F, thin films were deposited by ultrasonic chemical spray starting from tin chloride and hydrofluoric acid. The physical characteristics of the films as a function of both water content in the starting solution and substrate temperature were studied. The film structure was polycrystalline in all cases, showing that the intensity of (200) peak increased with the water content in the starting solution. The electrical resistivity decreased with the water content, reaching a minimum value, in the order of 8 × 10-4 Ωcm, for films deposited at 450℃ from a starting solution with a water content of 10 ml per 100 ml of solution; further increase in water content increased the corresponding resistivity. Optical transmittances of SnO2:F films were high, in the order of 75%, and the band gap values oscillated around 3.9 eV. SEM analysis showed uniform surface morphologies with different geometries depending on the deposition conditions. Composition analysis showed a stoichiometric compound with a [Sn/O] ratio around 1:2 in all samples. The presence of F into the SnO2 lattice was detected, within 2 at % respect to Sn.
TL;DR: Aminocaproic acid (ACA) mixed methanolic lead acetate-thiourea (PbAc-TU) complex as precursor for fabrication of lead sulphide nanoparticles (NPs) has been explained.
Abstract: Aminocaproic acid (ACA) mixed methanolic lead acetate-thiourea (PbAc-TU) complex as precursor for fabrication of lead sulphide (PbS) nanoparticles (NPs) has been explained. The size, structure and morphology of as-prepared ACA-capped PbS NPs were systematically characterized by scanning electron microscopy (SEM), Transmission electron mi-croscopy (TEM), X-ray diffraction (XRD), Uv-vis spectroscopy and Brunauer-Emmett-Teller (BET) techniques. The obtained results show that the synthesized PbS NPs are nanocrystalline, size quantized and their agglomeration shows a mesoporous network of 8.7 nm in pore size. The binding nature of ACA molecules on PbS surface was studied by thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) techniques. Results indicate that ACA acts as a soft template that restricts the growth of PbS NPs through its binding to Pb surface via nitrogen lone pair.