Search results for: polymer substrate

Authors: Samir Lecheb, Ahmed Chellil, Hamza Mechakra, Brahim Safi, Houcine Kebir

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In this paper we studied fracture and dynamic behavior of vertical axis wind turbine blade, the VAWT is a historical machine, it has many properties, structure, advantage, component to be able to produce the electricity. We modeled the blade design then imported to Abaqus software for analysis the modes shapes, frequencies, stress, strain, displacement and stress intensity factor SIF, after comparison we chose the idol material. Finally, the CTS test of glass epoxy reinforced polymer plates to obtain the material fracture toughness Kc.

Keywords: blade, crack, frequency, material, SIF

Procedia PDF Downloads 536

Authors: Ahmed Nassim Moulai Khatir

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Fin field effect transistors (FinFETs) deliver superior levels of scalability than the classical structure of MOSFETs by offering the elimination of short channel effects. Modern FinFETs are 3D structures that rise above the planar substrate, but some of these structures have inclined surfaces, which results in trapezoidal cross sections instead of rectangular sections usually used. Fin cross section shape of FinFETs results in some device issues, like potential distribution performance. This work analyzes that impact with three-dimensional numeric simulation of several triple-gate FinFETs with various top and bottom widths of fin. Results of the simulation show that the potential distribution and the electrical field in the fin depend on the sidewall inclination angle.

Keywords: FinFET, cross section shape, SILVACO, trapezoidal FinFETs

Procedia PDF Downloads 33

Authors: Antoine Lauvray, Fabien Poulhaon, Pierre Michaud, Pierre Joyot, Emmanuel Duc

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Additive Friction Stir Manufacturing (AFSM) is a new industrial process that follows the emergence of friction-based processes. The AFSM process is a solid-state additive process using the energy produced by the friction at the interface between a rotating non-consumable tool and a substrate. Friction depends on various parameters like axial force, rotation speed or friction coefficient. The feeder material is a metallic rod that flows through a hole in the tool. Unlike in Friction Stir Welding (FSW) where abundant literature exists and addresses many aspects going from process implementation to characterization and modeling, there are still few research works focusing on AFSM. Therefore, there is still a lack of understanding of the physical phenomena taking place during the process. This research work aims at a better AFSM process understanding and implementation, thanks to numerical simulation and experimental validation performed on a prototype effector. Such an approach is considered a promising way for studying the influence of the process parameters and to finally identify a process window that seems relevant. The deposition of material through the AFSM process takes place in several phases. In chronological order these phases are the docking phase, the dwell time phase, the deposition phase, and the removal phase. The present work focuses on the dwell time phase that enables the temperature rise of the system composed of the tool, the filler material, and the substrate and due to pure friction. Analytic modeling of heat generation based on friction considers as main parameters the rotational speed and the contact pressure. Another parameter considered influential is the friction coefficient assumed to be variable due to the self-lubrication of the system with the rise in temperature or the materials in contact roughness smoothing over time. This study proposes, through numerical modeling followed by experimental validation, to question the influence of the various input parameters on the dwell time phase. Rotation speed, temperature, spindle torque, and axial force are the main monitored parameters during experimentations and serve as reference data for the calibration of the numerical model. This research shows that the geometry of the tool as well as fluctuations of the input parameters like axial force and rotational speed are very influential on the temperature reached and/or the time required to reach the targeted temperature. The main outcome is the prediction of a process window which is a key result for a more efficient process implementation.

Keywords: numerical model, additive manufacturing, friction, process

Procedia PDF Downloads 136

Authors: Safa Ladhari, Alireza Saidi, Phuong Nguyen-Tri

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During health crises, such as COVID-19, using disposable protective equipment (PEs) (masks, gowns, etc.) causes long-term problems, increasing the volume of hazardous waste that must be handled safely and expensively. Therefore, producing textiles for antimicrobial and reusable materials is highly desirable to decrease the use of disposable PEs that should be treated as hazardous waste. In addition, if these items are used regularly in the workplace or for daily activities by the public, they will most likely end up in household waste. Furthermore, they may pose a high risk of contagion to waste collection workers if contaminated. Therefore, to protect the whole population in times of sanitary crisis, it is necessary to equip these materials with tools that make them resilient to the challenges of carrying out daily activities without compromising public health and the environment and without depending on them external technologies and producers. In addition, the materials frequently used for EPs are plastics of petrochemical origin. The subject of the present work is replacing petroplastics with bioplastic since it offers better biodegradability. The chosen polymer is polyhydroxybutyrate (PHB), a family of polyhydroxyalkanoates synthesized by different bacteria. It has similar properties to conventional plastics. However, it is renewable, biocompatible, and has attractive barrier properties compared to other polyesters. These characteristics make it ideal for EP protection applications. The current research topic focuses on the preparation and rapid evaluation of the biological activity of nanotechnology-based antimicrobial agents to treat textile surfaces used for PE. This work will be carried out to provide antibacterial solutions that can be transferred to a workplace application in the fight against short-term biological risks. Three main objectives are proposed during this research topic: 1) the development of suitable methods for the deposition of antibacterial agents on the surface of textiles; 2) the development of a method for measuring the antibacterial activity of the prepared textiles and 3) the study of the biodegradability of the prepared textiles. The studied textile is a non-woven fabric based on a biodegradable polymer manufactured by the electrospinning method. Indeed, nanofibers are increasingly studied due to their unique characteristics, such as high surface-to-volume ratio, improved thermal, mechanical, and electrical properties, and confinement effects. The electrospun film will be surface modified by plasma treatment and then loaded with hybrid antibacterial silver and titanium dioxide nanoparticles by the dip-coating method. This work uses simple methods with emerging technologies to fabricate nanofibers with suitable size and morphology to be used as components for protective equipment. The antibacterial agents generally used are based on silver, zinc, copper, etc. However, to our knowledge, few researchers have used hybrid nanoparticles to ensure antibacterial activity with biodegradable polymers. Also, we will exploit visible light to improve the antibacterial effectiveness of the fabric, which differs from the traditional contact mode of killing bacteria and presents an innovation of active protective equipment. Finally, this work will allow for the innovation of new antibacterial textile materials through a simple and ecological method.

Keywords: protective equipment, antibacterial textile materials, biodegradable polymer, electrospinning, hybrid antibacterial nanoparticles

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Authors: Lei Zhao, Yi Song, Tim Dunne, Jiaxiang (Jason) Ren, Wenhan Yue, Lei Yang, Li Wen, Yu Liu

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Fasting dissolving magnesium (DM) alloy technology has contributed significantly to the “Shale Revolution” in oil and gas industry. This application requires DM downhole tools dissolving initially at a slow rate, rapidly accelerating to a high rate after certain period of operation time (typically 8 h to 2 days), a contradicting requirement that can hardly be addressed by traditional Mg alloying or processing itself. Premature disintegration has been broadly reported in downhole DM tool from field trials. To address this issue, “temporary” thin polymers of various formulations are currently coated onto DM surface to delay its initial dissolving. Due to conveying parts, harsh downhole condition, and high dissolving rate of the base material, the current delay coatings relying on pure polymers are found to perform well only at low temperature (typical < 100 ℃) and parts without sharp edges or corners, as severe geometries prevent high quality thin film coatings from forming effectively. In this study, a coating technology combining Plasma Electrolytic Oxide (PEO) coatings with advanced thin film deposition has been developed, which can delay DM complex parts (with sharp corners) in corrosive fluid at 150 ℃ for over 2 days. Synergistic effects between porous hard PEO coating and chemical inert elastic-polymer sealing leads to its delaying dissolution improvement, and strong chemical/physical bonding between these two layers has been found to play essential role. Microstructure of this advanced coating and compatibility between PEO and various polymer selections has been thoroughly investigated and a model is also proposed to explain its delaying performance. This study could not only benefit oil and gas industry to unplug their High Temperature High Pressure (HTHP) unconventional resources inaccessible before, but also potentially provides a technical route for other industries (e.g., bio-medical, automobile, aerospace) where primer anti-corrosive protection on light Mg alloy is highly demanded.

Keywords: dissolvable magnesium, coating, plasma electrolytic oxide, sealer

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Authors: Ashraf Nawaz Khan, R. Alagirusamy, Apurba Das, Puneet Mahajan

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The thermoplastic-based fibre composites are acquiring a market sector of conventional as well as thermoset composites. However, replacing the thermoset with a thermoplastic composite has never been an easy task. The inherent high viscosity of thermoplastic resin reveals poor interface properties. In this work, a homo-polymer towpreg is produced through an electrostatic powder spray coating methodology. The produced flexible towpreg offers a low melt-flow distance during the consolidation of the laminate. The reduced melt-flow distance demonstrates a homogeneous fibre/matrix distribution (and low void content) on consolidation. The composite laminate has been fabricated with two manufacturing techniques such as conventional film stack (FS) and powder-coated (PC) technique. This helps in understanding the distinct response of produced laminates on applying load since the laminates produced through the two techniques are comprised of the same constituent fibre and matrix (constant fibre volume fraction). The changed behaviour is observed mainly due to the different fibre/matrix configurations within the laminate. The interface adhesion influences the load transfer between the fibre and matrix. Therefore, it influences the elastic, plastic, and failure patterns of the laminates. Moreover, the effect of preform geometries (plain weave and satin weave structure) are also studied for corresponding composite laminates in terms of various mechanical properties. The fracture analysis is carried out to study the effect of resin at the interlacement points through micro-CT analysis. The PC laminate reveals a considerably small matrix-rich and deficient zone in comparison to the FS laminate. The different load tensile, shear, fracture toughness, and drop weight impact test) is applied to the laminates, and corresponding damage behaviour is analysed in the successive stage of failure. The PC composite has shown superior mechanical properties in comparison to the FS composite. The damage that occurs in the laminate is captured through the SEM analysis to identify the prominent mode of failure, such as matrix cracking, fibre breakage, delamination, debonding, and other phenomena.

Keywords: composite, damage, fibre, manufacturing

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Authors: Grigoria Athanasaki, Veerarajan Vimala, A. M. Kannan, Louis Cindrella

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Energy usage has been increased throughout the years, leading to severe environmental impacts. Since the majority of the energy is currently produced from fossil fuels, there is a global need for clean energy solutions. Proton Exchange Membrane Fuel Cells (PEMFCs) offer a very promising solution for transportation applications because of their solid configuration and low temperature operations, which allows them to start quickly. One of the main components of PEMFCs is the Gas Diffusion Layer (GDL), which manages water and gas transport and shows direct influence on the fuel cell performance. In this work, a novel dual-layer GDL with gradient porosity was prepared, using polyethylene glycol (PEG) as pore former, to improve the gas diffusion and water management in the system. The microporous layer (MPL) of the fabricated GDL consists of carbon powder PUREBLACK, sodium dodecyl sulfate as a surfactant, 34% wt. PTFE and the gradient porosity was created by applying one layer using 30% wt. PEG on the carbon substrate, followed by a second layer without using any pore former. The total carbon loading of the microporous layer is ~ 3 mg.cm-2. For the assembly of the catalyst layer, Nafion membrane (Ion Power, Nafion Membrane NR211) and Pt/C electrocatalyst (46.1% wt.) were used. The catalyst ink was deposited on the membrane via microspraying technique. The Pt loading is ~ 0.4 mg.cm-2, and the active area is 5 cm2. The sample was ex-situ characterized via wetting angle measurement, Scanning Electron Microscopy (SEM), and Pore Size Distribution (PSD) to evaluate its characteristics. Furthermore, for the performance evaluation in-situ characterization via Fuel Cell Testing using H2/O2 and H2/air as reactants, under 50, 60, 80, and 100% relative humidity (RH), took place. The results were compared to a single layer GDL, fabricated with the same carbon powder and loading as the dual layer GDL, and a commercially available GDL with MPL (AvCarb2120). The findings reveal high hydrophobic properties of the microporous layer of the GDL for both PUREBLACK based samples, while the commercial GDL demonstrates hydrophilic behavior. The dual layer GDL shows high and stable fuel cell performance under all the RH conditions, whereas the single layer manifests a drop in performance at high RH in both oxygen and air, caused by catalyst flooding. The commercial GDL shows very low and unstable performance, possibly because of its hydrophilic character and thinner microporous layer. In conclusion, the dual layer GDL with PEG appears to have improved gas diffusion and water management in the fuel cell system. Due to its increasing porosity from the catalyst layer to the carbon substrate, it allows easier access of the reactant gases from the flow channels to the catalyst layer, and more efficient water removal from the catalyst layer, leading to higher performance and stability.

Keywords: gas diffusion layer, microporous layer, proton exchange membrane fuel cells, relative humidity

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Authors: Meriem Hamla, Mohamed Benaicha, Sabrine Derbal

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In the present work, several materials such as M/glass (M = Pt, Mo) were investigated to test their suitability for studying the early nucleation stages and growth of copper-tin clusters. It was found that most of these materials stand as good substrates to be used in the study of the nucleation and growth of electrodeposited Cu-Sn alloys from aqueous solution containing CuCl2, SnCl2 as electroactive species and Na3C6H5O7 as complexing agent. Among these substrates, Pt shows instantaneous models followed by 3D diffusion-limited growth. On the other hand, the electrodeposited copper-tin thin films onto Mo substrate followed progressive nucleation. The deposition mechanism of the Cu-Sn films has been studied using stationary electrochemical techniques (cyclic voltammetery (CV) and chronoamperometry (CA). The structural, morphological and compositional of characterization have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and EDAX techniques respectively.

Keywords: electrodeposition, CuSn, nucleation, mechanism

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Authors: Hyeong-Jin Kim, Jong Kook Lee

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Zirconia has biological, mechanical and optical properties, so, it used as a dental implant material in human body. But, it is difficult to form directly bonding with living tissues after the procedure and induces the falling away from implanted parts of the body. To improve this phenomenon, it is essential to increase the surface roughness of zirconia implants and induce a forming-ability of strong bonds. In this study, we performed a room temperature spray coating on zirconia specimen to obtain a highly roughened zirconia surface. To get optimal surface roughness, we controlled the distance between the nozzle and the substrate, coating times and powder condition. Bonding microstructure, surface roughness, and chemical composition of the coating layer were observed by SEM, XRD and roughness tester.

Keywords: implant, aerosoldeposition, zirconia, dental

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Authors: Dagmara Malina, Katarzyna Bialik-Wąs, Klaudia Pluta

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The growing significance of transdermal systems, in which skin is a route for systemic drug delivery, has generated a considerable amount of data which has resulted in a deeper understanding of the mechanisms of transport across the skin in the context of the controlled and prolonged release of active substances. One of such solutions may be the use of carrier systems based on intelligent polymers with different physicochemical properties. In these systems, active substances, e.g. drugs, can be conjugated (attached), immobilized, or encapsulated in a polymer matrix that is sensitive to specific environmental conditions (e.g. pH or temperature changes). Intelligent polymers can be divided according to their sensitivity to specific environmental stimuli such as temperature, pH, light, electric, magnetic, sound, or electromagnetic fields. Materials & methods—The first stage of the presented research concerned the synthesis of pH-sensitive polymeric carriers by a radical polymerization reaction. Then, the selected active substance (hydrocortisone) was introduced into polymeric carriers. In a further stage, bio-hybrid sodium alginate/poly(vinyl alcohol) – SA/PVA-based hydrogel matrices modified with various carrier-drug systems were prepared with the chemical cross-linking method. The conducted research included the assessment of physicochemical properties of obtained materials i.e. degree of hydrogel swelling and degradation studies as a function of pH in distilled water and phosphate-buffered saline (PBS) at 37°C in time. The gel fraction represents the insoluble gel fraction as a result of inter-molecule cross-linking formation was also measured. Additionally, the chemical structure of obtained hydrogels was confirmed using FT-IR spectroscopic technique. The dynamic light scattering (DLS) technique was used for the analysis of the average particle size of polymer-carriers and carrier-drug systems. The nanocarriers morphology was observed using SEM microscopy. Results & Discussion—The analysis of the encapsulated polymeric carriers showed that it was possible to obtain the time-stable empty pH-sensitive carrier with an average size 479 nm and the encapsulated system containing hydrocortisone with an average 543 nm, which was introduced into hydrogel structure. Bio-hybrid hydrogel matrices are stable materials, and the presence of an additional component: pH-sensitive carrier – hydrocortisone system, does not reduce the degree of cross-linking of the matrix nor its swelling ability. Moreover, the results of swelling tests indicate that systems containing higher concentrations of the drug have a slightly higher sorption capacity in each of the media used. All analyzed materials show stable and statically changing swelling values in simulated body fluids - there is no sudden fluid uptake and no rapid release from the material. The analysis of FT-IR spectra confirms the chemical structure of the obtained bio-hybrid hydrogel matrices. In the case of modifications with a pH-sensitive carrier, a much more intense band can be observed in the 3200-3500 cm⁻¹ range, which most likely originates from the strong hydrogen interactions that occur between individual components.

Keywords: hydrogels, polymer nanocarriers, sodium alginate/poly(vinyl alcohol) matrices, wound dressings.

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Authors: Hussein Hakim, Zainab Al-Ramadhan, Ahmed Hashim

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Polymer nano composites of polyvinylpyrrolidone and poly-ethylene glycol with different concentrations of aluminum oxide (Al2O3) nano particles have been prepared by solution cast method. The optical characterizations have been done by analyzing the absorption (A) spectra in the 300–800 nm spectral region. It was found that the optical energy gap decreases with the increasing of Al2O3 nano particles content. The optical constants (refractive index, extinction coefficient, real and imaginary parts of the dielectric constant) are changing with increasing aluminum oxide nano particle concentrations.

Keywords: nanocomposites, polyvinylpyrrolidone, optical constants, polymers, blend

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Authors: S. Abdullahi, M. Momoh, K. U. Isah

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Zinc oxide (ZnO) thin films of 75.5 nm and 130.5 nm were deposited at room temperature onto chemically and ultrasonically cleaned corning glass substrate by radio frequency technique and annealed at 150°C under nitrogen atmosphere for 60 minutes. The optical properties of the films were ascertained by UV-VIS-NIR spectrophotometry. Influence of the thickness of the films on the optical properties was studied keeping other deposition parameters constant. The optical transmittance spectra reveal a maximum transmittance of 81.49% and 84.26% respectively. The band gap of the films is found to be direct allowed transition and decreases with the increase in thickness of the films. The band gap energy (Eg) is in the range of 3.28 eV to 3.31 eV, respectively. These thin films are suitable for solar cell applications.

Keywords: optical constants, RF sputtering, Urbach energy, zinc oxide thin film

Procedia PDF Downloads 447

Authors: Krittapast Dara-Opast, Sureeporn Ruengsangtongkul, Jumreang Tummatorn, Kittipong Chainok, Onrapak Reamtong, Somsak Ruchirawat, Charnsak Thongsornkleeb

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Selective synthesis of gem-dihalo spiroisobenzofuran and spiroisocoumarin can be performed via halogenative double cyclization of methyl 2-(hydroxyalk-1-yn-1-yl) benzoates in the presence of either N-chlorosuccinimide (NCS) or N-bromosuccinimide (NBS) and chlorotrimethylsilane (TMSCl). The combination of NCS and TMSCl led to the generation of electrophilic chlorine in situ, which activated the alkyne functional group of the substrate leading to the cyclization via either 5-exo-dig or 6-endo-dig mode of cyclization to produce the target compounds in moderate yields. The protocol could be carried on a broad scope of substrates under mild conditions (0 °C to rt). The parent compounds showed good antiparasitic activity compared to standard drug albendazole. Further investigation of the scope of the reaction and their antiparasitic activities is underway.

Keywords: antiparasitic activities, halogenative annulation, spirocycles, spirocyclization

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Authors: C. C. Castro, T. Senechal, D. Lahem, A. L. Hantson

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Formaldehyde is one of the most representative volatile organic compounds present in the indoor air of residential units and workplaces. Increased attention has been given to this toxic compound because of its carcinogenic effect in health. Biological or enzymatic transformation is being explored to degrade this pollutant. Pseudomonas putida is a bacteria able to synthesize formaldehyde dehydrogenase, an enzyme known to use formaldehyde as a substrate and transform it into less toxic compounds. The immobilization of bacterial cells in the surface of different supports through spraying or dip-coating is herein proposed. The determination of the enzymatic activity on the coated surfaces was performed as well as the study of its effect on formaldehyde degradation in an isolated chamber. Results show that the incorporation of microbial cells able to synthesize depolluting enzymes can be an innovative, low-cost, effective and environmentally friendly solution for indoor air depollution.

Keywords: cells encapsulation, formaldehyde, formaldehyde dehydrogenase, indoor air depollution

Procedia PDF Downloads 161

Authors: Jamal Abd Awadallak, Thiago Olinek Reinehr, Eduardo Raizer, Deise Molinari, Edson Antonio, Camila da Silva da Silva

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The hydrolysis of soy oil catalyzed by 1,3-specific enzyme (Lecitase Ultra) in a well-stirred bioreactor was studied. Two forms of applications of the ultrasound were evaluated aiming to increase reaction rates, wherein the use of probe ultrasound associated with the use of surfactant to pre-emulsify the substrate showed the best results. Two different reaction periods were found: the first where the ultrasound has great influence on reaction rates, and the second where ultrasound influence is minimal. Studies on the time of pre-emulsification, surfactant concentration and enzyme concentration showed that the initial rate of hydrolysis depends on the interfacial area between the oil phase and the aqueous phase containing the enzyme.

Keywords: specific enzyme, free fatty acids, Hydrolysis, lecitase ultra, ultrasound

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Authors: Erwin San Juan Martinez, Miguel Angel Aguilar Mendez, Manuel Sandoval Villa, Libia Iris Trejo Tellez

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Some nanomaterials may improve the vegetal growth in certain concentration intervals, and could be used as nanofertilizers in order to increase crops yield, and decreasing the environmental pollution due to non-controlled use of conventional fertilizers, therefore the present investigation’s objective was to synthetize and characterize gelatin nanoparticles loaded with calcium generated through pulverization technique and be used as nanofertilizers. To obtain these materials, a fractional factorial design 27-4 was used in order to evaluate the largest number of factors (concentration of Ca2+, temperature and agitation time of the solution and calcium concentration, drying temperature, and % spray) with a possible effect on the size, distribution and morphology of nanoparticles. For the formation of nanoparticles, a Nano Spray-Dryer B - 90® (Buchi, Flawil, Switzerland), equipped with a spray cap of 4 µm was used. Size and morphology of the obtained nanoparticles were evaluated using a scanning electron microscope (JOEL JSM-6390LV model; Tokyo, Japan) equipped with an energy dispersive x-ray X (EDS) detector. The total quantification of Ca2+ as well as its release by the nanoparticles was carried out in an equipment of induction atomic emission spectroscopy coupled plasma (ICP-ES 725, Agilent, Mulgrave, Australia). Of the seven factors evaluated, only the concentration of fertilizer, % spray and concentration of polymer presented a statistically significant effect on particle size. Micrographs of SEM from six of the eight conditions evaluated in this research showed particles separated and with a good degree of sphericity, while in the other two particles had amorphous morphology and aggregation. In all treatments, most of the particles showed smooth surfaces. The average size of smallest particle obtained was 492 nm, while EDS results showed an even distribution of Ca2+ in the polymer matrix. The largest concentration of Ca2+ in ICP was 10.5%, which agrees with the theoretical value calculated, while the release kinetics showed an upward trend within 24 h. Using the technique employed in this research, it was possible to obtain nanoparticles loaded with calcium, of good size, sphericity and with release controlled properties. The characteristics of nanoparticles resulted from manipulation of the conditions of synthesis which allow control of the size and shape of the particles, and provides the means to adapt the properties of the materials to an specific application.

Keywords: calcium, controlled release, gelatin, nano spraydryer, nanofertilizer

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Authors: Amine Benmoussa, Mebrouk Rebhi, Rahmani Lakhdar

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Mechanically agitated vessels are commonly used for various operations within a wide range process in chemical, pharmaceutical, polymer, biochemical, mineral, petroleum industries. Depending on the purpose of the operation carried out in mixer, the best choice for geometry of the tank and agitator type can vary widely. In this paper, the laminar 2D agitation flow and power consumption of viscoplastic fluids with straight and circular gate impellers in a stirring tank is studied by using computational fluid dynamics (CFD), where the velocity profile, the velocity fields and power consumption was analyzed.

Keywords: CFD, mechanical stirring, power consumption, yield stress fluid

Procedia PDF Downloads 339

Authors: K. Kefif, Y. Bouizem, A. Belfedal, D. J. Sib, K. Zellama, l. Chahed

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Hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared by radio frequency magnetron sputtering at relatively low growth temperatures (Ts=100 °C). The films grown on glass substrate in order to use the new generation of substrates sensitive to elevated temperatures. Raman spectroscopy was applied to investigate the effect of the argon gas diluted in hydrogen, on the structural properties and the evolution of the micro structure in the films. Raman peak position, intensity and line width were used to characterize the quality and the percentage of the crystallites in the films. The results of this investigation suggest the existence of a threshold dilution around a gas mixture of argon (40%) and hydrogen (60%) for which the crystallization occurs, even at low deposition temperatures. The difference between the amorphous and the crystallized structures is well confirmed by spectroscopic ellipsometry (SE) technique.

Keywords: Silicon, Thin films, Structural properties, Raman spectroscopy, Ellipsometry

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Authors: Michael Tupý, Alice Tesaříková-Svobodová, Dagmar Měřínská, Vít Petránek

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Polyethylene (PE), Polypropylene (PP), Polyethylene (vinyl acetate) (EVA) and Surlyn (modif-PE) nano composite samples were prepared with montmorillonite fillers Cloisite 93A and Dellite 67G. The amount of modified Na+ montmorillonite (MMT) was fixed to 5 % (w/w). For the compounding of polymer matrix and chosen nano fillers twin-screw kneader was used. The level of MMT intercalation or exfoliation in the nano composite systems was studied by transmission electron microscopy (TEM) observations. The properties of samples were evaluated by dynamical mechanical analysis (E* modulus at 30 °C) and by the measurement of tensile properties (stress and strain at break).

Keywords: polyethylene, polypropylene, polyethylene(vinyl acetate), clay, nanocomposite, montmorillonite

Procedia PDF Downloads 524

Authors: Y. Alqaheem, A. Alomair, F. Altarkait, F. Alswaileh, Nusrat Tanoli

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Helium market is continuously growing due to its essential uses in the electronic and healthcare sectors. Currently, helium is produced by cryogenic distillation but the process is uneconomical especially for low production volumes. On the other hand, polymeric membranes can provide a cost-effective solution for helium purification due to their low operating energy. However, the preparation of membranes involves the use of very toxic solvents such as chloroform. In this work, polyetherimide membranes were prepared using a less toxic solvent, n-methylpyrrolidone with a polymer-to-solvent ratio of 27 wt%. The developed membrane showed a superior helium permeability of 15.9 Barrer that surpassed the permeability of membranes made by chloroform.

Keywords: helium separation, polyetherimide, dense membrane, gas permeability

Procedia PDF Downloads 158

Authors: Catariny C. Aleman, Flavio B. Campos, Matheus A. Caliman, Everardo C. Mantovani

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The seedling production stage is a critical point in the vegetable production system. Obtaining high-quality seedlings is a prerequisite for subsequent cropping to occur well and productivity optimization is required. The water management is an important step in agriculture production. The adequate water requirement in horticulture seedlings can provide higher quality and increase field production. The practice of irrigation is indispensable and requires a duly adjusted quality irrigation system, together with a specific water management plan to meet the water demand of the crop. Irrigation management in seedling management requires a great deal of specific information, especially when it involves the use of inputs such as hydrorentering polymers and automation technologies of the data acquisition and irrigation system. The experiment was conducted in a greenhouse at the Federal University of Viçosa, Viçosa - MG. Tomato seedlings (Lycopersicon esculentum Mill) were produced in plastic trays of 128 cells, suspended at 1.25 m from the ground. The seedlings were irrigated by 4 micro sprinklers of fixed jet 360º per tray, duly isolated by sideboards, following the methodology developed for this work. During Phase 1, in January / February 2017 (duration of 24 days), the cultivation coefficient (Kc) of seedlings cultured in the presence and absence of hydrogel was evaluated by weighing lysimeter. In Phase 2, September 2017 (duration of 25 days), the seedlings were submitted to 4 irrigation managements (Kc, timer, 0.50 ETo, and 1.00 ETo), in the presence and absence of hydrogel and then evaluated in relation to quality parameters. The microclimate inside the greenhouse was monitored with the use of air temperature, relative humidity and global radiation sensors connected to a microcontroller that performed hourly calculations of reference evapotranspiration by Penman-Monteith standard method FAO56 modified for the balance of long waves according to Walker, Aldrich, Short (1983), and conducted water balance and irrigation decision making for each experimental treatment. Kc of seedlings cultured on a substrate with hydrogel (1.55) was higher than Kc on a pure substrate (1.39). The use of the hydrogel was a differential for the production of earlier tomato seedlings, with higher final height, the larger diameter of the colon, greater accumulation of a dry mass of shoot, a larger area of crown projection and greater the rate of relative growth. The handling 1.00 ETo promoted higher relative growth rate.

Keywords: automatic system; efficiency of water use; precision irrigation, micro sprinkler.

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Authors: Barrera C. Monserrat, Sierra-Alvarez Reyes, Pat-Espadas Aurora, Moreno Andrade Ivan

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Antimony is a toxic and carcinogenic metalloid considered a pollutant of priority interest by the United States Environmental Protection Agency. It is present in the environment in two oxidation states: antimonite (Sb (III)) and antimony (Sb (V)). Sb (III) is toxic to several aquatic organisms, but the potential inhibitory effect of Sb species for microorganisms has not been extensively evaluated. The fate and possible toxic impact of antimony on aerobic and anaerobic wastewater treatment systems are unknown. For this reason, the objective of this study was to evaluate the microbial toxicity of Sb (V) and Sb (III) in aerobic and anaerobic environments. Sb(V) and Sb(III) were used as potassium hexahydroxoantimonate (V) and potassium antimony tartrate, respectively (Sigma-Aldrich). The toxic effect of both Sb species in anaerobic environments was evaluated on methanogenic activity and the inhibition of hydrogen production of microorganisms from a wastewater treatment bioreactor. For the methanogenic activity, batch experiments were carried out in 160 mL serological bottles; each bottle contained basal mineral medium (100 mL), inoculum (1.5 g of VSS/L), acetate (2.56 g/L) as substrate, and variable concentrations of Sb (V) or Sb (III). Duplicate bioassays were incubated at 30 ± 2°C on an orbital shaker (105 rpm) in the dark. Methane production was monitored by gas chromatography. The hydrogen production inhibition tests were carried out in glass bottles with a working volume of 0.36 L. Glucose (50 g/L) was used as a substrate, pretreated inoculum (5 g VSS/L), mineral medium and varying concentrations of the two species of antimony. The bottles were kept under stirring and at a temperature of 35°C in an AMPTSII device that recorded hydrogen production. The toxicity of Sb on aerobic microorganisms (from a wastewater activated sludge treatment plant) was tested with a Microtox standardized toxicity test and respirometry. Results showed that Sb (III) is more toxic than Sb (V) for methanogenic microorganisms. Sb (V) caused a 50% decrease in methanogenic activity at 250 mg/L. In contrast, exposure to Sb (III) resulted in a 50% inhibition at a concentration of only 11 mg/L, and an almost complete inhibition (95%) at 25 mg/L. For hydrogen-producing microorganisms, Sb (III) and Sb (V) inhibited 50% of this production with 12.6 mg/L and 87.7 mg/L, respectively. The results for aerobic environments showed that 500 mg/L of Sb (V) do not inhibit the Allivibrio fischeri (Microtox) activity or specific oxygen uptake rate of activated sludge. In the case of Sb (III), this caused a loss of 50% of the respiration of the microorganisms at concentrations below 40 mg/L. The results obtained indicate that the toxicity of the antimony will depend on the speciation of this metalloid and that Sb (III) has a significantly higher inhibitory potential compared to Sb (V). It was shown that anaerobic microorganisms can reduce Sb (V) to Sb (III). Acknowledgments: This work was funded in part by grants from the UA-CONACYT Binational Consortium for the Regional Scientific Development and Innovation (CAZMEX), the National Institute of Health (NIH ES- 04940), and PAPIIT-DGAPA-UNAM (IN105220).

Keywords: aerobic inhibition, antimony reduction, hydrogen inhibition, methanogenic toxicity

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Authors: Gong Zhang, Hong Cai, Bin Dong, Jifang Tao, Aiqun Liu, Dim-Lee Kwong, Yuandong Gu

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An on-chip refractive index sensor with high sensitivity and large measurement range is demonstrated in this paper. The sensing structures are based on Mach-Zehnder interferometer configuration, built on the SOI substrate. The wavelength sensitivity of the sensor is estimated to be 3129 nm/RIU. Meanwhile, according to the interference pattern period changes, the measured period sensitivities are 2.9 nm/RIU (TE mode) and 4.21 nm/RIU (TM mode), respectively. As such, the wavelength shift and the period shift can be used for fine index change detection and larger index change detection, respectively. Therefore, the sensor design provides an approach for large index change measurement with high sensitivity.

Keywords: Mach-Zehnder interferometer, nanotechnology, refractive index sensing, sensors

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Authors: Okpala Charles Chikwendu, Ezeanyim Okechukwu Chiedu, Onukwuli Somto Kenneth

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The demand for lightweight and fuel-efficient automobiles has led to the use of fiber-reinforced polymer composites in place of traditional metal parts. Coir, a natural fiber, offers qualities such as low cost, good tensile strength, and biodegradability, making it a potential filler material for automotive components. However, poor interfacial adhesion between coir and polymeric matrices has been a challenge. To address poor interfacial adhesion with polymeric matrices due to their moisture content and method of preparation, the extracted coir was chemically treated using NaOH. To develop a side view mirror encasement by investigating the mechanical effect of fiber percentage composition, fiber length and percentage composition of Epoxy in a coir fiber reinforced composite, polyester was adopted as the resin for the mold, while that of the product is Epoxy. Coir served as the filler material for the product. Specimens with varied compositions of fiber loading (15, 30 and 45) %, length (10, 15, 20, 30 and 45) mm, and (55, 70, 85) % weight of epoxy resin were fabricated using hand lay-up technique, while those specimens were later subjected to mechanical tests (Tensile, Flexural and Impact test). The results of the mechanical test showed that the optimal solution for the input factors is coir at 45%, epoxy at 54.543%, and 45mm coir length, which was used for the development of a vehicle’s side view mirror encasement. The optimal solutions for the response parameters are 49.333 Mpa for tensile strength, flexural for 57.118 Mpa, impact strength for 34.787 KJ/M2, young modulus for 4.788 GPa, stress for 4.534 KN, and 20.483 mm for strain. The models that were developed using Design Expert software revealed that the input factors can achieve the response parameters in the system with 94% desirability. The study showed that coir is quite durable for filler material in an epoxy composite for automobile applications and that fiber loading and length have a significant effect on the mechanical behavior of coir fiber-reinforced epoxy composites. The coir's low density, considerable tensile strength, and bio-degradability contribute to its eco-friendliness and potential for reducing the environmental hazards of synthetic automotive components.

Keywords: coir, composite, coir fiber, coconut husk, polymer, automobile, mechanical test

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Authors: Ariadna Manresa, Ines Ferrer

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Introduction: Ultrasonic moulding process (USM) is a recent injection technology used to manufacture micro components. It is able to melt small amounts of material so the waste of material is certainly reduced comparing to microinjection molding. This is an important advantage when the materials are expensive like medical biopolymers. Micro-scaled components are involved in a variety of uses, such as biomedical applications. It is required replication fidelity so it is important to stabilize the process and minimize the variability of the responses. The aim of this research is to investigate the influence of the main process parameters on the filling behaviour, the dimensional accuracy and the cavity pressure when a micro-plate is manufactured by biomaterials such as PLA and PCL. Methodology or Experimental Procedure: The specimens are manufactured using a Sonorus 1G Ultrasound Micro Molding Machine. The used geometry is a rectangular micro-plate of 15x5mm and 1mm of thickness. The materials used for the investigation are PLA and PCL due to biocompatible and degradation properties. The experimentation is divided into two phases. Firstly, the influence of process parameters (vibration amplitude, sonotrodo velocity, ultrasound time and compaction force) on filling behavior is analysed, in Phase 1. Next, when filling cavity is assured, the influence of both cooling time and force compaction on the cavity pressure, part temperature and dimensional accuracy is instigated, which is done in Phase. Results and Discussion: Filling behavior depends on sonotrodo velocity and vibration amplitude. When the ultrasonic time is higher, more ultrasonic energy is applied and the polymer temperature increases. Depending on the cooling time, it is possible that when mold is opened, the micro-plate temperature is too warm. Consequently, the polymer relieve its stored internal energy (ultrasonic and thermal) expanding through the easier direction. This fact is reflected on dimensional accuracy, causing micro-plates thicker than the mold. It has also been observed the most important fact that affects cavity pressure is the compaction configuration during the manufacturing cycle. Conclusions: This research demonstrated the influence of process parameters on the final micro-plated manufactured. Future works will be focused in manufacturing other geometries and analysing the mechanical properties of the specimens.

Keywords: biomaterial, biopolymer, micro injection molding, ultrasound

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Authors: Majid Eslami

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Functionally graded materials (FGMs) exhibit heterogeneous microstructures in which the composition and properties gently change in specified directions. The common type of FGMs consist of a metal in which ceramic particles are distributed with a graded concentration. There are many processing routes for FGMs. An important group of these methods is casting techniques (gravity or centrifugal). However, the main problem of casting molten metal slurry with dispersed ceramic particles is a destructive chemical reaction between these two phases which deteriorates the properties of the materials. In order to overcome this problem, in the present investigation a suspension of 6061 aluminum and alumina powders in a liquid polymer was used as the starting material and subjected to centrifugal force for making FGMs. The size rang of these powders was 45-63 and 106-125 μm. The volume percent of alumina in the Al/Al2O3 powder mixture was in the range of 5 to 20%. PMMA (Plexiglas) in different concentrations (20-50 g/lit) was dissolved in toluene and used as the suspension liquid. The glass mold contaning the suspension of Al/Al2O3 powders in the mentioned liquid was rotated at 1700 rpm for different times (4-40 min) while the arm length was kept constant (10 cm) for all the experiments. After curing the polymer, burning out the binder, cold pressing and sintering , cylindrical samples (φ=22 mm h=20 mm) were produced. The density of samples before and after sintering was quantified by Archimedes method. The results indicated that by using the same sized alumina and aluminum powders particles, FGM sample can be produced by rotation times exceeding 7 min. However, by using coarse alumina and fine alumina powders the sample exhibits step concentration. On the other hand, using fine alumina and coarse alumina results in a relatively uniform concentration of Al2O3 along the sample height. These results are attributed to the effects of size and density of different powders on the centrifugal force induced on the powders during rotation. The PMMA concentration and the vol.% of alumina in the suspension did not have any considerable effect on the distribution of alumina particles in the samples. The hardness profiles along the height of samples were affected by both the alumina vol.% and porosity content. The presence of alumina particles increased the hardness while increased porosity reduced the hardness. Therefore, the hardness values did not show the expected gradient in same sample. The sintering resulted in decreased porosity for all the samples investigated.

Keywords: FGM, powder metallurgy, centrifugal method, polymeric suspension

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Authors: K. Daoudi, Z. Othmen, S. El Helali, M.Oueslati, M. Oumezzine

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La0.7Sr0.3CoO3 thin films have been epitaxially grown on LaAlO3 and SrTiO3 (001) single-crystal substrates by metal organic deposition process. The structural and micro structural properties of the obtained films have been investigated by means of high resolution X-ray diffraction, Raman spectroscopy and transmission microscopy observations on cross-sections techniques. We noted a close dependence of the crystallinity on the used substrate and the film thickness. By increasing the annealing temperature to 1000ºC and the film thickness to 100 nm, the electrical resistivity was decreased by several orders of magnitude. The film resistivity reaches approximately 3~4 x10-4 Ω.cm in a wide interval of temperature 77-320 K, making this material a promising candidate for a variety of applications.

Keywords: cobaltite, thin films, epitaxial growth, MOD, TEM

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Authors: Zafar Mahmood, Fahimullah Babar, Surriyia Naz, Hafiz Ur Rehman

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Cadmium Sulphide (CdS) was deposited on a Tec 15 glass substrate with the help of CBD (chemical bath deposition process) and then cadmium telluride CdTe was deposited on CdS with the help of CSS (closed spaced sublimation technique) for the construction of a solar cell. The thicknesses of all the deposited materials were measured with the help of Elipsometry. The IV graphs were drawn in order to observe the current voltage output. The efficiency of the cell was graphed with the fill factor as well (graphs not given here).The efficiency came out to be approximately 16.5 % and the CIGS (copper- indium –gallium- selenide) maximum efficiency is 20 %.The efficiency of a solar cell can further be enhanced by adapting quality materials, good experimental devices and proper procedures. The grain size was analyzed with the help of scanning electron microscope using RBS (Rutherford backscattering spectroscopy).

Keywords: CBD, CdS, CdTe, CSS

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Authors: Prashant Sharma, Jyotsna Dutta Majumdar

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The present study concerns development of a composite thermal barrier coating consisting of a mixture of La2O3 and YSZ (with 8 wt.%, 32 wt.% and 50 wt.% 50% La2O3) by plasma spray deposition technique on a CoNiCrAlY based bond coat deposited on Inconel 718 substrate by high velocity oxy-fuel deposition (HVOF) technique. The addition of La2O3 in YSZ causes the formation of pyrochlore (La2Zr2O7) phase in the inter splats boundary along with the presence of LaYO3 phase. The coefficient of thermal expansion is significantly reduced from due to the evolution of different phases and structural defects in the sprayed coating. The activation energy for TGO growth under isothermal and cyclic oxidation was increased in the composite coating as compared to YSZ coating.

Keywords: plasma spraying, oxidation resistance, thermal barrier coating, microstructure, X-ray method

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Authors: A. N. Moulai Khatir

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SOI-Multifin-FETs are placed to be the workhorse of the industry for the coming few generations, and thus, in a few years because their excellent transistor characteristics, ideal sub-threshold swing, low drain induced barrier lowering (DIBL) without pocket implantation, and negligible body bias dependency. The corner effect may also exist in the two lower corners; this effect is called the BOX effect, which can also occur in the direction X-Z. The electric field lines from the source and drain cross the bottom oxide and arrive in the silicon. This effect is also called DIVSB (Drain Induced Virtual Substrate Basing). The potential in the silicon film in particular near the drain is increased by the drain bias. It is similar to DIBL and result in a decrease of the threshold voltage. This work provides an understanding of the limitation of this effect by reducing the fin width for components with increased fin number.

Keywords: SOI, finFET, corner effect, dual-gate, tri-gate, BOX, multi-finFET

Procedia PDF Downloads 482