Search results for: materials properties

Authors: Kazui Sasakii, Seira Mormune-Moriya, Hiroaki Tanahashi, Shigeji Kongaya

Abstract:

Poly (3.4-ethylenedioxythiophene) doped with poly (4-styrene sulfonate) (PEDOT: PSS) attracted a great deal of attention because of its unique characteristics of flexibility, optical properties, heat resistance and colloidal dispersion in water. It is well known that when high boiling solvents such as ethylene glycol or dimethyl sulfoxide are added as a secondary dopant to the micellar structure, PEDOT microcrystallizes and becomes highly conductive. In previous study bis(4-hydroxyphenyl) sulfone (BPS) was used as a secondary dopant for PEDOT:PSS and the enhancement of the conductivity was revealed. However, ductility is one of the serious issues which limited the application of PEDOT:PSS/BPS. So far, the composition with polymer binders has been conducted, however, polymer binders decrease the conductivity of the materials. In this study, PEDOT: PSS composites with polyester (PEs) were prepared by a simple aqueous process using PEs emulsion. The structural studies revealed that PEDOT:PSS and PEs were homogeneously distributed in the composites. It was found that the properties of PEDOT:PSS were remarkably enhanced by the incorporation of PEs. According to the tensile test, the ductility of PEDOT:PSS was remarkably improved. Interestingly, the conductivity of PEDOT:PSS/PEs composites was higher than that of neat PEDOT:PSS. For example, the conductivity increased by 8% at PEs content of 25 wt%. Since PEDOT:PSS were homogeneously dispersed on the surface of PEs particles, it was assumed that the conductive pathway was constructed by PEs particles in the nanocomposites. Therefore, a significant increase in conductivity was achieved.

Keywords: polymer composites, conductivity, PEDOT:PSS, polyester

Procedia PDF Downloads 115

Authors: Weeradej Cheewapattananuwong, Keeree Srivichian, Godchamon Somchai, Wasin Phusanong, Nontawat Yoddamnern

Abstract:

Natural rubber used for traffic devices in Thailand has been developed and researched for several years. When compared with Dry Rubber Content (DRC), the quality of Rib Smoked Sheet (RSS) is better. However, the cost of admixtures, especially CaCO₃ and sulphur, is higher than the cost of RSS itself. In this research, Flexible Guideposts and Rubber Fender Barriers (RFB) are taken into consideration. In case of flexible guideposts, the materials used are both RSS and DRC60%, but for RFB, only RSS is used due to the controlled performance tests. The objective of flexible guideposts and RFB is to decrease a number of accidents, fatal rates, and serious injuries. Functions of both devices are to save road users and vehicles as well as to absorb impact forces from vehicles so as to decrease of serious road accidents. This leads to the mitigation methods to remedy the injury of motorists, form severity to moderate one. The solution is to find the best practice of traffic devices using natural rubber under the engineering concepts. In addition, the performances of materials, such as tensile strength and durability, are calculated for the modulus of elasticity and properties. In the laboratory, the simulation of crashes, finite element of materials, LRFD, and concrete technology methods are taken into account. After calculation, the trials' compositions of materials are mixed and tested in the laboratory. The tensile test, compressive test, and weathering or durability test are followed and based on ASTM. Furthermore, the Cycle-Repetition Test of Flexible Guideposts will be taken into consideration. The final decision is to fabricate all materials and have a real test section in the field. In RFB test, there will be 13 crash tests, 7 Pickup Truck tests, and 6 Motorcycle Tests. The test of vehicular crashes happens for the first time in Thailand, applying the trial and error methods; for example, the road crash test under the standard of NCHRP-TL3 (100 kph) is changed to the MASH 2016. This is owing to the fact that MASH 2016 is better than NCHRP in terms of speed, types, and weight of vehicles and the angle of crash. In the processes of MASH, Test Level 6 (TL-6), which is composed of 2,270 kg Pickup Truck, 100 kph, and 25 degree of crash-angle is selected. The final test for real crash will be done, and the whole system will be evaluated again in Korea. The researchers hope that the number of road accidents will decrease, and Thailand will be no more in the top tenth ranking of road accidents in the world.

Keywords: LRFD, load and resistance factor design, ASTM, american society for testing and materials, NCHRP, national cooperation highway research program, MASH, manual for assessing safety hardware

Procedia PDF Downloads 128

Authors: Felipe Aguirre

Abstract:

In this paper some of the relevant features of the πλῆκτρον within GrecoLatin tradition will be analyzed. Starting from the formal aspects (shape, materials, technical properties) and the archaeological evidence, some of its symbolic implications that emerge in the light of literary and iconographic analysis will be discussed. I shall expose that, in addition to fulfilling a purely physical function within the process of sound production, the πλῆκτρον was the object of a rich imaginery that provided it with an allegorical, metaphorical-poetic and even metaphysical dimension.

Keywords: musicology, ethnomusicology, ancient greek music, plectrum, stringed instruments

Procedia PDF Downloads 144

Authors: A. N. Fouda

Abstract:

A novel well identified hexagonal graphene oxide (GO) nano-sheets were synthesized using modified Hummer method. Low temperature thermal reduction at 350°C in air ambient was performed. After thermal reduction, typical few layers of thermal reduced GO (TRGO) with dimension of few hundreds nanometers were observed using high resolution transmission electron microscopy (HRTEM). GO has a lot of structure models due to variation of the preparation process. Determining the atomic structure of GO is essential for a better understanding of its fundamental properties and for realization of the future technological applications. Structural characterization was identified by x-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR) measurements. A comparison between exper- imental and theoretical IR spectrum were done to confirm the match between experimentally and theoretically proposed GO structure. Partial overlap of the experimental IR spectrum with the theoretical IR was confirmed. The electrochemical properties of TRGO nano-sheets as electrode materials for supercapacitors were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements. An enhancement in supercapacitance after reduction was confirmed and the area of the CV curve for the TRGO electrode is larger than those for the GO electrode indicating higher specific capacitance which is promising in super-capacitor applications

Keywords: hexagonal graphene oxide, thermal reduction, cyclic voltammetry

Procedia PDF Downloads 493

Authors: Suresh Kumar Verma, Jugal Kishore Das, Ealisha Jha, Mrutyunjay Suar, SKS Parashar

Abstract:

In recent years nanoforms of inorganic metallic oxides has attracted a lot of interest due to their small size and significantly improved physical, chemical and biological properties compared to their molecular precursor. Some of the inorganic materials such as TiO2, ZnO, MgO, CaO, Al2O3 have been extensively used in biological applications. Zinc Oxide is a Wurtzite-type semiconductor and piezo-electric material exhibiting excellent electrical, optical and chemical properties with a band energy gap of 3.1-3.4 eV. Nanoforms of Zinc Oxide (ZnO) are increasingly recognised for their utility in biological application. The significant physical parameters such as surface area, particle size, surface charge and Zeta potential of Zinc Oxide (ZnO) nanoparticles makes it suitable for the uptake, persistance, biological, and chemical activities inside the living cells. The present study shows the effect of intrinsic defects of ZnO nanocrystals synthesized by high energy ball milling (HEBM) technique in their antibacterial activities. Bulk Zinc oxide purchased from market were ball milled for 7 h, 10 h, and 15 h respectively to produce nanosized Zinc Oxide. The structural and optical modification of such synthesized particles were determined by X-ray diffraction (XRD), Scanning Electron Microscopy and Electron Paramagnetic Resonance (EPR). The antibacterial property of synthesized Zinc Oxide nanoparticles was tested using well diffusion, minimum inhibitory Concentration, minimum bacteriocidal concentration, reactive oxygen species (ROS) estimation and membrane potential determination methods. In this study we observed that antibacterial activity of ZnO nanoparticles is because of the intrinsic defects that exist as a function of difference in size and milling time.

Keywords: high energy ball milling, ZnO nanoparticles, EPR, Antibacterial properties

Procedia PDF Downloads 428

Authors: Salwa Mowafi, Mohamed Rehan, Hany Kafafy

Abstract:

In this study, three different systems including room temperature, conventional water bath heating and microwave irradiation technique will be employed in the fabrication of silver nanoparticle-wool fibers. The silver nanoparticles will be synthesized in-situ incorporated into wool fibers under redox active bio-template of wool protein which facilitates the reduction of Ag+ to nanoparticulate Ag0. Silver NPs incorporated wool fiber will be characterized by scanning electron microscopy, energy dispersive X-ray, FTIR, TGA, silver content and X-ray photoelectron spectroscopy. The mechanism of binding Ag NPs in-situ incorporated wool fibers matrix will be discussed. The effect of silver nanoparticles on the coloration, antimicrobial, UV-protection and catalytic properties of the wool fibers will be evaluated. The overall results of this study indicate that the Ag NPs in-situ incorporated wool fibers will be applied as colorants for wool fibers with improving in its multi-functionality properties. So, this study provides a simple approach for innovative protein fibers design by applying the optical properties of Plasmonic noble metal nanoparticles.

Keywords: microwave irradiation technique, multi-functionality properties, silver nanoparticles, wool fibers

Procedia PDF Downloads 207

Authors: Jos Olijve

Abstract:

Introduction and Purpose: Endotoxins are found in the outer membrane of gram-negative bacteria and have profound in vitro and in vivo responses. They can trigger strong immune responses and negatively affect various cellar activities particular cells expressing toll-like receptors. They are therefore unwanted contaminants of biomaterials sourced from natural raw materials, and their activity must be as low as possible. Collagen and gelatin are natural extracellular matrix components and have, due to their low allergenic potential, suitable biological properties, and tunable physical characteristics, high potential in biomedical applications. The purpose of this study was to determine the influence of autoclave sterilization of gelatin on physical properties and endotoxin level compared to surfactant purified gelatin. Methods: Type A gelatin from Sigma-Aldrich (G1890) with endotoxin level of 35000 endotoxin units (EU) per gram gelatin and type A gelatins from Rousselot Gent with endotoxin activity of 30000 EU per gram were used. A 10 w/w% G1890 gelatin solution was autoclave sterilized during 30 minutes at 121°C and 1 bar over pressure. The physical properties and the endotoxin level of the sterilized G1890 gelatin were compared to a type A gelatin from Rousselot purified with Triton X100 surfactant. The Triton X100 was added to a concentration of 0.5 w/w% which is above the critical micellar concentration. The gelatin surfactant mixtures were kept for 30-45 minutes under constant stirring at 55-60°C. The Triton X100 was removed by active carbon filtration. The endotoxin levels of the gelatins were measured using the Endozyme recombinant factor C method from Hyglos GmbH (Germany). Results and Discussion: Autoclave sterilization significantly affect the physical properties of gelatin. Molecular weight of G1890 decreased from 140 to 50kDa, and gel strength decreased from 300 to 40g. The endotoxin level of the gelatin reduced after sterilization from 35000 EU/g to levels of 400-500 EU/g. These endotoxin levels are however still far above the upper endotoxin level of 0.05 EU/ml, which resembles 5 EU/g gelatin based on a 1% gelatin solution, to avoid cell proliferation alteration. Molecular weight and gel strength of Rousselot gelatin was not altered after Triton X100 purification and remained 150kDa and 300g respectively. The endotoxin levels of Triton X100 purified Rousselot gelatin was < 5EU/g gelatin. Conclusion: Autoclave sterilization of gelatin is, in comparison to Triton X100 purification, not efficient to inactivate endotoxin levels in gelatin to levels below the upper limit to avoid cell proliferation alteration. Autoclave sterilization gave a significant decrease in molecular weight and gel strength which makes autoclave sterilized gelatin, in comparison to Triton X100 purified gelatin, not suitable for 3D printing.

Keywords: endotoxin, gelatin, molecular weight, sterilization, Triton X100

Procedia PDF Downloads 233

Authors: Bashar Mudhaffar Abdullah, Hasniza Zaman Huri, Nany Hairunisa

Abstract:

This study was carried out to determine the thermal properties and spectroscopy study of Malaysian Jatropha curcas seed oil. The J. curcas seed oil physicochemical properties such as free fatty acid (FFA %), acid value, saponification value, iodine value, unsaponifiable matter, and viscosity (cp) gave values of 1.89±0.10%, 3.76±0.07, 203.36±0.36 mg/g, 4.90±0.25, 1.76±0.03%, and 32, respectively. Gas chromatography (GC) was used to determine the fatty acids (FAs) composition. J. curcas seed oil is consisting of saturated FAs (19.55%) such as palmitic (13.19%), palmitoleic (0.40%), and stearic (6.36%) acids and unsaturated FAs (80.42%) such as oleic (43.32%) and linoleic (36.70%) acids. The thermal properties using differential scanning calorimetry (DSC) showed that crystallized TAG was observed at -6.79°C. The melting curves displayed three major exothermic regions of J. curcas seed oil, monounsaturated (lower-temperature peak) at -31.69°C, di-unsaturated (medium temperature peak) at -20.23°C and tri-unsaturated (higher temperature peak) at -12.72°C. The results of this study showed that the J. curcas seed oil is a plausible source of polyunsaturated fatty acid (PUFA) to be developed in the future for pharmaceutical applications.

Keywords: Jatropha curcas seed oil, thermal properties, crystallization, melting, spectroscopy

Procedia PDF Downloads 478

Authors: Esra Turker, Umit Hakan Yildiz, Ahu Arslan Yildiz

Abstract:

The key of regenerative medicine is mimicking natural three dimensional (3D) microenvironment of tissues by utilizing appropriate biomaterials. In this study, a synthetic biodegradable polymer; poly (L-lactide-co-ε-caprolactone) (PLLCL) and a natural polymer; collagen was used to mimic the biochemical structure of the natural extracellular matrix (ECM), and by means of electrospinning technique the real physical structure of ECM has mimicked. PLLCL/Collagen biocomposite scaffolds enables cell attachment, proliferation and nutrient transport through fabrication of micro to nanometer scale nanofibers. Biocomposite materials are commonly preferred due to limitations of physical and biocompatible properties of natural and synthetic materials. Combination of both materials improves the strength, degradation and biocompatibility of scaffold. Literature studies have shown that collagen is mostly solved with heavy chemicals, which is not suitable for cell culturing. To overcome this problem, a new approach has been developed in this study where polyvinylpyrrolidone (PVP) is used as co-electrospinning agent. PVP is preferred due to its water solubility, so PLLCL/collagen biocomposite scaffold can be easily and rapidly produced. Hydrolytic and enzymatic biodegradation as well as mechanical strength of scaffolds were examined in vitro. Cell adhesion, proliferation and cell morphology characterization studies have been performed as well. Further, on-chip drug screening analysis has been performed over 3D tumor models. Overall, the developed biocomposite scaffold was used for 3D tumor model formation and obtained results confirmed that developed model could be used for drug screening studies to predict clinical efficacy of a drug.

Keywords: biomaterials, 3D cell culture, drug screening, electrospinning, lab-on-a-chip, tissue engineering

Procedia PDF Downloads 312

Authors: R. Dangtungee, A. Rattanapan, S. Siengchin

Abstract:

Waste silicon carbide (waste SiC) filled high-density polyethylene (HDPE) with and without surface modifiers were studied. Two types of surface modifiers namely; high-density polyethylene-grafted-maleic anhydride (HDPE-g-MA) and 3-aminopropyltriethoxysilane have been used in this study. The composites were produced using a two roll mill, extruder and shaped in a hydraulic compression molding machine. The mechanical properties of polymer composites such as flexural strength and modulus, impact strength, tensile strength, stiffness and hardness were investigated over a range of compositions. It was found that, flexural strength and modulus, tensile modulus and hardness increased, whereas impact strength and tensile strength decreased with the increasing in filler contents, compared to the neat HDPE. At similar filler content, the effect of both surface modifiers increased flexural modulus, impact strength, tensile strength and stiffness but reduced the flexural strength. Morphological investigation using SEM revealed that the improvement in mechanical properties was due to enhancement of the interfacial adhesion between waste SiC and HDPE.

Keywords: high-density polyethylene, HDPE-g-MA, mechanical properties, morphological properties, silicon carbide, waste silicon carbide

Procedia PDF Downloads 363

Authors: Suresh Vidyasagar Chevuri, D. B. Karunakar Chevuri

Abstract:

The main advantages of 'Metal Matrix Nano Composites (MMNCs)' include excellent mechanical performance, good wear resistance, low creep rate, etc. The method of fabrication of MMNCs is quite a challenge, which includes processing techniques like Spark Plasma Sintering (SPS), etc. The objective of the present work is to fabricate aluminum based MMNCs with the addition of small amounts of yttrium using Spark Plasma Sintering and to evaluate their mechanical and microstructure properties. Samples of 2024 AA with yttrium ranging from 0.1% to 0.5 wt% keeping 1 wt% TiB2 constant are fabricated by Spark Plasma Sintering (SPS). The mechanical property like hardness is determined using Vickers hardness testing machine. The metallurgical characterization of the samples is evaluated by Optical Microscopy (OM), Field Emission Scanning Electron Microscopy (FE-SEM) and X-Ray Diffraction (XRD). Unreinforced 2024 AA sample is also fabricated as a benchmark to compare its properties with that of the composite developed. It is found that the yttrium addition increases the above-mentioned properties to some extent and then decreases gradually when yttrium wt% increases beyond a point between 0.3 and 0.4 wt%. High density is achieved in the samples fabricated by spark plasma sintering when compared to any other fabrication route, and uniform distribution of yttrium is observed.

Keywords: spark plasma sintering, 2024 AA, yttrium addition, microstructure characterization, mechanical properties

Procedia PDF Downloads 224

Authors: Hyun-Sook Lee, Hongjae Moon, Hwaebong Jung, Sumin Kim, Wooyoung Lee

Abstract:

Low-temperature phase (LTP) of MnBi has attracted much attention because it has a larger coercivity than that of Nd-Fe-B at high temperature, which gives high potential as a permanent magnet material that can be used at such high temperature. We present variation in magnetic properties of MnBi films by controlling the numbers of Bi/Mn bilayer. The thin films of LTP-MnBi were fabricated onto glass substrates by UHV sputtering, followed by in-situ annealing process at an optimized condition of 350 °C and 1.5 hours. The composition ratio of Bi/Mn was adjusted by varying the thickness of Bi and Mn layers. The highest value of (BH)max ~ 8.6 MGOe at room temperature was obtained in one Bi/Mn bilayer with 34 nm Bi and 16 nm Mn. To investigate the effect of Bi/Mn multilayers on the magnetic properties, we increased the numbers of Bi/Mn bilayer up to five at which the total film thicknesses of Bi and Mn were fixed with 34 nm and 16 nm. The increase of coercivity was observed up to three layers from 4.8 kOe to 15.3 kOe and then suppression was appeared. A reversed behavior was exhibited in the magnetization. We found that these were closely related to a microstructural change of LTP-MnBi and a reduction of growth rate of LTP-MnBi by analyzing XRD and TEM results. We will discuss how the multilayered MnBi affects the magnetic properties in details.

Keywords: coercivity, MnBi, multilayer film, permanent magnet

Procedia PDF Downloads 334

Authors: Hisashi Imai, Kuan-Yu Chen, Katsuyoshi Kondoh, Hung-Yin Tsai, Junko Umeda

Abstract:

Microstructural and electrical properties of copper-chromium alloy (Cu-Cr) dispersed with vapor-grown carbon fiber (VGCF) prepared by powder metallurgy (P/M) process have been investigated. Cu-0.7 mass% Cr pre-alloyed powder (Cu-Cr) made by water atomization process was used as raw materials, which contained solid solute Cr elements in Cu matrix. The alloy powder coated with un-bundled VGCF by using oil coating process was consolidated at 1223 K in vacuum by spark plasma sintering, and then extruded at 1073 K. The extruded Cu-Cr alloy (monolithic alloy) had 209.3 MPa YS and 80.4 IACS% conductivity. The extruded Cu-Cr with 0.1 mass% VGCF composites revealed a small decrease of YS compared to the monolithic Cu-Cr alloy. On the other hand, the composite had a higher electrical conductivity than that of the monolithic alloy. For example, Cu-Cr with 0.1 mass% VGCF composite sintered for 5 h showed 182.7 MPa YS and 89.7 IACS% conductivity. In the case of Cu-Cr with VGCFs composites, the Cr concentration was observed around VGCF by SEM-EDS analysis, where Cr23C6 compounds were detected by TEM observation. The amount of Cr solid solution in the matrix of the Cu-Cr composites alloy was about 50% compared to the monolithic Cu-Cr sintered alloy, and resulted in the remarkable increment of the electrical conductivity.

Keywords: powder metallurgy Cu-Cr alloy powder, vapor-grown carbon fiber, electrical conductivity

Procedia PDF Downloads 493

Authors: Afiqah Shafify Amran, Siti Aisyah Shamsudin, Nurul Yuziana Mohd Yusof

Abstract:

Cadmium Sulphide (CdS) from group II-IV quantum dots with good optical properties was successfully synthesized by using the simple colloidal method. Capping them with ligand Polyethylinamine (PEI) alters the surface defect of CdS while, thioglycolic acid (TGA) was added to the reaction as a stabilizer. Due to their cytotoxicity, we decided to conjugate them with the protein cage nanoparticles. In this research, we used capsid of Cowpea Chlorotic Mottle Virus (CCMV) to package the CdS because they have the potential to serve in drug delivery, cell targeting and imaging. Adding Sodium Hydroxide (NaOH) changes the pH of the systems hence the isoelectric charge is adjusted. We have characterized and studied the morphology and the optical properties of CdS and CdS-CCMV by transmitted electron microscopic (TEM), UV-Vis spectroscopy, photoluminescence spectroscopy, UV lamp and Fourier transform infrared spectroscopy (FTIR), respectively. The results obtained suggest that the protein cage nanoparticles do not affect the optical properties of CdS.

Keywords: cadmium sulphide, cowpea chlorotic mottle virus, protein cage nanoparticles, quantum dots

Procedia PDF Downloads 338

Authors: A. Sacko, H. Nyoni, T. A. M. Msagati, B. Ntsendwana

Abstract:

Carbon based materials to target environmental pollutants have become increasingly recognized in science. Electrochemical methods using carbon based materials are notable methods for high sensitive detection of organic pollutants in air. It is therefore in this light that exfoliated graphite electrode was fabricated for electrochemical analysis of PAHs in urban atmospheric air. The electrochemical properties of the graphite electrode were studied using CV and EIS in the presence of acetate buffer supporting electrolyte with 2 Mm ferricyanide as a redox probe. The graphite electrode showed enhanced current response which confirms facile kinetics and enhanced sensitivity. However, the peak to peak (DE) separation increased as a function of scan rate. The EIS showed a high charger transfer resistance. The detection phenanthrene on the exfoliated graphite was studied in the presence of acetate buffer solution at PH 3.5 using DPV. The oxidation peak of phenanthrene was observed at 0.4 V. Under optimized conditions (supporting electrolyte, pH, deposition time, etc.). The detection limit observed was at 5x 10⁻⁸ M. Thus the results demonstrate with further optimization and modification lower concentration detection can be achieved.

Keywords: electrochemical detection, exfoliated graphite, PAHs (polycyclic aromatic hydrocarbons), urban air

Procedia PDF Downloads 204

Authors: Anastasia Beketova, Emmanouil-George C. Tzanakakis, Ioannis G. Tzoutzas, Eleana Kontonasaki

Abstract:

In restorative dentistry, yttria-stabilized zirconia (YSZ) nanoparticles can be applied as fillers to improve the mechanical properties of various resin-based materials. Using sol-gel based synthesis as simple and cost-effective method, nano-sized YSZ particles with high purity can be produced. The aim of this study was to synthesize YSZ nanoparticles by the Pechini sol-gel method at different temperatures and to investigate their composition, structure, and morphology. YSZ nanopowders were synthesized by the sol-gel method using zirconium oxychloride octahydrate (ZrOCl₂.8H₂O) and yttrium nitrate hexahydrate (Y(NO₃)₃.6H₂O) as precursors with the addition of acid chelating agents to control hydrolysis and gelation reactions. The obtained powders underwent TG_DTA analysis and were sintered at three different temperatures: 800, 1000, and 1200°C for 2 hours. Their composition and morphology were investigated by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction Analysis (XRD), Scanning Electron Microscopy with associated with Energy Dispersive X-ray analyzer (SEM-EDX), Transmission Electron Microscopy (TEM) methods, and Dynamic Light Scattering (DLS). FTIR and XRD analysis showed the presence of pure tetragonal phase in the composition of nanopowders. By increasing the calcination temperature, the crystallinity of materials increased, reaching 47.2 nm for the YSZ1200 specimens. SEM analysis at high magnifications and DLS analysis showed submicron-sized particles with good dispersion and low agglomeration, which increased in size as the sintering temperature was elevated. From the TEM images of the YSZ1000 specimen, it can be seen that zirconia nanoparticles are uniform in size and shape and attain an average particle size of about 50 nm. The electron diffraction patterns clearly revealed ring patterns of polycrystalline tetragonal zirconia phase. Pure YSZ nanopowders have been successfully synthesized by the sol-gel method at different temperatures. Their size is small, and uniform, allowing their incorporation of dental luting resin cements to improve their mechanical properties and possibly enhance the bond strength of demanding dental ceramics such as zirconia to the tooth structure. This research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme 'Human Resources Development, Education and Lifelong Learning 2014- 2020' in the context of the project 'Development of zirconia adhesion cements with stabilized zirconia nanoparticles: physicochemical properties and bond strength under aging conditions' (MIS 5047876).

Keywords: dental cements, nanoparticles, sol-gel, yttria-stabilized zirconia, YSZ

Procedia PDF Downloads 147

Authors: B. Roopa Sri, Y Lakshmi Naidu

Abstract:

Chemical Graph Theory (CGT) is the branch of mathematical chemistry in which molecules are modeled to study their physicochemical properties using molecular descriptors. Amongst these descriptors, topological indices play a vital role in predicting the properties by defining the graph topology of the molecule. Recently, the bond-additive topological index known as the Mostar index has been proposed. In this paper, we compute the Mostar-type indices of octane isomers and use the data obtained to perform QSPR analysis. Furthermore, we show the correlation between the Mostar type indices and the properties.

Keywords: chemical graph theory, mostar type indices, octane isomers, qspr analysis, topological index

Procedia PDF Downloads 130

Authors: Santiranjan Shannigrahi, Mohit Sharma, Ivan Tan Chee Kiang, Yong Anna Marie

Abstract:

Polymer-ceramics composites are gaining importance due to their high specific strength, corrosion resistance, and high mechanical properties, as well as low cost. As a result, polymer composites are suitable for various industrial applications, like automobiles, aerospace, and biomedical areas. The present work comprises the development of polymer-ceramic composite films and is tested for the harsh environment including weatherability and UV barrier property. The polymer composite films are kept in weather chamber for a fixed period of time followed by tested for their physical, mechanical and chemical properties. The composite films are fabricated using compounding followed by hot pressing. UV-visible spectroscopy results reveal that the pure polymer polyethylene (PE) films are transparent in the visible range and do not absorb UV. However, polymer ceramic composite films start absorbing UV completely even at very low filler loading amount of 5 wt.%. The changes in tensile properties of the various composite films before and after UV illuminations for 40 hrs at 60 degC are analyzed. The tensile strength of neat PE film has been observed 8% reduction, whereas the remarkable increase in tensile strength has been observed (18% improvement for 10 wt. % filled composites films). The UV exposure leads to strengthen the crosslinking among PE polymer chains in the filled composite films, which contributes towards the incremented tensile strength properties.

Keywords: polymer ceramic composite, processing, harsh environment, mechanical properties

Procedia PDF Downloads 383

Authors: Adil Tamimi

Abstract:

Limestone powder is a natural material that is available in many parts of the world. In this research self-compacting concrete was designed and prepared using limestone powder. The resulted concrete was exposed to the hydrochloric acid solution and compared with reference concrete. Mechanical properties of both fresh and hardened concrete have been evaluated. Scanning Electron Microscopy “SEM” has been unitized to analyse the morphological development of the hydration products. In sulphuric acid solution, a large formation of gypsum was detected in both samples of self-compacting concrete and conventional concrete. The Higher amount of thaumasite and ettringite was also detected in the SCC sample. In hydrochloric acid solution, monochloroaluminate was detected.

Keywords: self-compacting concrete, mechanical properties, Scanning Electron Microscopy, acid solution

Procedia PDF Downloads 511

Authors: Yousof Farrag, Sara Malmir, Rebeca Bouza, Maite Rico, Belén Montero, Luís Barral

Abstract:

Biopolymers are being extensively studied in the last years as a replacement of the conventional petroleum derived polymers, especially in packaging industry. They are natural, biodegradable materials. However, the lack of good mechanical and barrier properties is a problem in the way of this replacement. One of the most abundant biopolymers in the nature is the starch, its renewable, biocompatible low cost polysaccharide, it can be obtained from wide variety of plants, it has been used in food, packaging and other industries. This work is focusing on the production a high yield of starch nanoparticles via nanoprecipitation, to be used as reinforcement filling of biopolymer packaging matrices made of different types of starch improving their mechanical and barrier properties. Wheat and corn starch solutions were prepared in different concentrations. Absolute ethanol, acetone and different concentrations of hydrochloric acid were added as antisolvents dropwise under different amplitudes of sonication and different speeds of stirring, the produced particles were analyzed with dynamic light scattering DLS and scanning electron microscope SEM getting the morphology and the size distribution to study the effect of those factors on the produced particles. DLS results show that we have nanoparticles using low concentration of corn starch (0.5%) using 0.1M HCl as antisolvent, [Z average: 209 nm, PDI: 0,49], in case of wheat starch, we could obtain nanoparticles [Z average: 159 nm, PDI: 0,45] using the same starch solution concentration together with absolute ethanol as antisolvent.

Keywords: biopolymers, nanoparticles, DLS, starch

Procedia PDF Downloads 327

Authors: Abdelrahman Mohamed

Abstract:

The ancient Egyptians used canopic vessels in embalming operations in order to preserve the guts of the mummified corpse. Canopic vessels were made of many materials, including pottery and glazed pottery. In this research, we study a pottery canopic vessel and a glazed pottery vessel. An analysis to find out the compounds and elements of the materials from which the container is made and the colors, and also to make some analysis for the organic materials present inside it, such as the Fourier Transform Infrared Spectroscopy analysis and the Gas chromatograph mass spectrometers analysis of the organic residue. Through the study and analysis, it was proved that some of the materials present in the pot were coniferous oil and animal fats. In the other pot, the analysis showed the presence of some plant resins (mastic) inside rolls of linen. Restoration operations were carried out, such as mechanical cleaning, strengthening, and completing the reinforcement of the pots.

Keywords: canopic jar, embalming, FTIR, GCMS, linen.

Procedia PDF Downloads 85

Authors: Liaqat Ali, Furqan Ahmad

Abstract:

The heat losses should be controlled during the high temperature processes from energy conservation point of view. For this purpose, refractories with low thermal conductivity, high porosity and good mechanical strength along with low price are desirable. In this work, various combinations of naturally occurring, locally available, cheap raw materials, namely, clay, rice husk and saw dust were used. Locally produced insulating firebricks (IFBs) cannot be used at higher than a few hundred °C and possess low strength as well. Various process parameters were studied and the refractories with desirable properties were produced, which can be used up to 1200 °C.

Keywords: firebricks, mechanical strength, thermal conductivity, refractory bricks

Procedia PDF Downloads 328

Authors: Abeer A. Q. Ahmed, Tracey McKay

Abstract:

Biomass can provide a sustainable source for the production of high valued chemicals. Under the uncertain availability of fossil resources biomass could be the only available source for chemicals in future. Cellulose and hemicellulose can be hydrolyzed into their building blocks (hexsoses and pentoses) which can be converted later to the desired high valued chemicals. A cellulase- and xylanase- producing bacterial strain identified as Paenibacillus illinoisensis CX11 by 16S rRNA gene sequencing and phylogenetic analysis was found to have the ability to saccharify different lignocellulosic materials. Cellulase and xylanase activities were evaluated by 3,5-dinitro-salicylic acid (DNS) method using CMC and xylan as substrates. Results showed that P. illinoisensis CX11 have cellulase (2.63± 0.09 mg/ml) and xylanase (3.25 ± 0.2 mg/ml) activities. The ability of P. illinoisensis CX11 to saccharify lignocellulosic materials was tested using wheat straw (WS), wheat bran (WB), saw dust (SD), and corn stover (CS). DNS method was used to determine the amount of reducing sugars that were released from lignocellulosic materials. P. illinoisensis CX11 showed to have the ability to saccharify lignocellulosic materials and producing total reducing sugars as 2.34 ± 0.12, 2.51 ± 0.37, 1.86 ± 0.16, and 3.29 ± 0.20 mg/l from WS, WB, SD, and CS respectively. According to the author's knowledge, current findings are the first to report P. illinoisensis CX11 as a cellulase and xylanase producing species and that it has the ability to saccharify different lignocellulosic materials. This study presents P. illinoisensis CX11 that can be good source for cellulase and xylanase enzymes which could be introduced into lignocellulose bioconversion processes to produce high valued chemicals.

Keywords: cellulase, high valued chemicals, lignocellulosic materials, Paenibacillus illinoisensis CX11, Xylanase

Procedia PDF Downloads 246

Authors: Iliya Dimitrov Stoev, Benjamin Seelbinder, Elena Erben, Nicola Maghelli, Moritz Kreysing

Abstract:

Despite the revolutionizing impact of optical tweezers in materials science and cell biology up to the present date, trapping has so far extensively relied on specific material properties of the probe and local heating has limited applications related to investigating dynamic processes within living systems. To overcome these limitations while maintaining high sensitivity, here we present a new optofluidic approach that can be used to gently trap microscopic particles and measure femtoNewton forces in a contact-free manner and with thermally limited precision.

Keywords: optofluidics, force measurements, microrheology, FLUCS, thermoviscous flows

Procedia PDF Downloads 170

Authors: Marta Paszkiewicz, Justyna Łuczak, Martyna Marchelek, Adriana Zaleska-Medynska

Abstract:

In recent years, photocatalytical processes have been intensively investigated for destruction of pollutants, hydrogen evolution, disinfection of water, air and surfaces, for the construction of self-cleaning materials (tiles, glass, fibres, etc.). Titanium dioxide (TiO2) is the most popular material used in heterogeneous photocatalysis due to its excellent properties, such as high stability, chemical inertness, non-toxicity and low cost. It is well known that morphology and microstructure of TiO2 significantly influence the photocatalytic activity. This characteristics as well as other physical and structural properties of photocatalysts, i.e., specific surface area or density of crystalline defects, could be controlled by preparation route. In this regard, TiO2 particles can be obtained by sol-gel, hydrothermal, sonochemical methods, chemical vapour deposition and alternatively, by ionothermal synthesis using ionic liquids (ILs). In the TiO2 particles synthesis ILs may play a role of a solvent, soft template, reagent, agent promoting reduction of the precursor or particles stabilizer during synthesis of inorganic materials. In this work, the effect of the ILs anion type on morphology and photoactivity of TiO2 is presented. The preparation of TiO2 microparticles with spherical structure was successfully achieved by solvothermal method, using tetra-tert-butyl orthotitatane (TBOT) as the precursor. The reaction process was assisted by an ionic liquids 1-butyl-3-methylimidazolium bromide [BMIM][Br], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] and 1-butyl-3-methylimidazolium haxafluorophosphate [BMIM][PF6]. Various molar ratios of all ILs to TBOT (IL:TBOT) were chosen. For comparison, reference TiO2 was prepared using the same method without IL addition. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brenauer-Emmett-Teller surface area (BET), NCHS analysis, and FTIR spectroscopy were used to characterize the surface properties of the samples. The photocatalytic activity was investigated by means of phenol photodegradation in the aqueous phase as a model pollutant, as well as formation of hydroxyl radicals based on detection of fluorescent product of coumarine hydroxylation. The analysis results showed that the TiO2 microspheres had spherical structure with the diameters ranging from 1 to 6 µm. The TEM micrographs gave a bright observation of the samples in which the particles were comprised of inter-aggregated crystals. It could be also observed that the IL-assisted TiO2 microspheres are not hollow, which provides additional information about possible formation mechanism. Application of the ILs results in rise of the photocatalytic activity as well as BET surface area of TiO2 as compared to pure TiO2. The results of the formation of 7-hydroxycoumarin indicated that the increased amount of ·OH produced at the surface of excited TiO2 for samples TiO2_ILs well correlated with more efficient degradation of phenol. NCHS analysis showed that ionic liquids remained on the TiO2 surface confirming structure directing role of that compounds.

Keywords: heterogeneous photocatalysis, IL-assisted synthesis, ionic liquids, TiO2

Procedia PDF Downloads 267

Authors: Yahaya Taiwo, Adedayo M. Segun

Abstract:

This study investigated the effect of postweld soaking temperature on mechanical properties of AISI 1018 steel plate welded in aqueous environment. Pairs of 90 x 70 x 12 mm, AISI 1018 steel plates were welded with weld zone beyond distance 10 mm from weld centerline immersed in a water jacket at 25°C. The welded specimens were tempered at temperature of 200, 300, 400, 500 and 600°C for 1.5 hours. Tensile, hardness and toughness tests at distances 15, 30, 45 and 60 mm from the weld centreline with micro structural evaluation were carried out. The results show that the aqueous environment as-weld sample exhibited higher hardness and tensile strength values of 45.3 HV and 448.12 N/mm2 respectively while the hardness and tensile strength of aqueous environment postweld heat treated samples were 44.9 HV and 378.98 N/mm2. This revealed 0.82% and 15.4% reduction in hardness and strength respectively. The metallographic tests showed that the postweld heat treated AISI 1018 steel micro structure contained tempered martensite with ferritic structure and precipitation of carbides. Postweld heat treatment produced materials of lower hardness and improved toughness.

Keywords: air weld samples, aqueous environment weld samples, soaking temperature, water jacket

Procedia PDF Downloads 334

Authors: Berk Kiliç

Abstract:

In the medical and surgical fields, wound care is a critical and expansive industry. Hydrocolloid wound dressings have been introduced and are widely used due to their effectiveness in promoting healing, managing wound fluids, and protecting against infection. Hydrocolloid wound dressings have been introduced as effective solutions, adherence to wound surfaces and infection prevention. it fabricated different hydrocolloid wound dressings with myrrh resin, garlic and sorrel inorder to enhance healing properties. The physical and mechanical properties were evaluated to confirm which one is most suitable as a hydrocolloid wound dressing. it observations show that mirderm solution showed superior wound healing and fluid control properties compared to other prepared solutions. This indicates that “mirderm” could be a viable alternative to standard gauze and some commercial hydrocolloid dressings that do not contain myrrh.

Keywords: wound, hydrocolloid, myrrh, garlic, sorrel

Procedia PDF Downloads 25

Authors: Zawawi Daud

Abstract:

Agro waste can be defined as waste from agricultural plant. Oil palm leaf and corn stalk can be categorized as ago waste material. At first, the comparison between oil palm leaf and corn stalk by mechanical properties from soda pulping process. After that, focusing on surface characterization by Scanning Electron Microscopy (SEM). Both material have a potential due to mechanical properties (tensile, tear, burst and fold) and surface characterization but corn stalk shows more in strength and compactness due to fiber characterization compared to oil palm leaf. This study promoting the green technology in develop a friendly product and suitable to be used as an alternative pulp in paper making industry.

Keywords: fiber, oil palm leaf, corn stalk, green technology

Procedia PDF Downloads 490

Authors: Philippe Castaing, Thomas Jollivet

Abstract:

As a result of their advantages, i.e. recyclability, weld-ability, environmental compatibility, long (continuous) fiber thermoplastic composites (LFTPC) are increasingly used in many industrial sectors (mainly automotive and aeronautic) for structural applications. Indeed, in the next ten years, the environmental rules will put the pressure on the use of new structural materials like composites. In aerospace, more than 50% of the damage are due to stress impact and 85% of damage are repaired on the fuselage (fuselage skin panels and around doors). With the arrival of airplanes mainly of composite materials, replacement of sections or panels seems difficult economically speaking and repair becomes essential. The objective of the present study is to propose a solution of repair to prevent the replacement the damaged part in thermoplastic composites in order to recover the initial mechanical properties. The classification of impact damage is not so not easy : talking about low energy impact (less than 35 J) can be totally wrong when high speed or weak thicknesses as well as thermoplastic resins are considered. Crash and perforation with higher energy create important damages and the structures are replaced without repairing, so we just consider here damages due to impacts at low energy that are as follows for laminates : − Transverse cracking; − Delamination; − Fiber rupture. At low energy, the damages are barely visible but can nevertheless reduce significantly the mechanical strength of the part due to resin cracks while few fiber rupture is observed. The patch repair solution remains the standard one but may lead to the rupture of fibers and consequently creates more damages. That is the reason why we investigate the repair of thermoplastic composites impacted at low energy. Indeed, thermoplastic resins are interesting as they absorb impact energy through plastic strain. The methodology is as follows: - impact tests at low energy on thermoplastic composites; - identification of the damage by micrographic observations; - evaluation of the harmfulness of the damage; - repair by reconsolidation according to the extent of the damage ; -validation of the repair by mechanical characterization (compression). In this study, the impacts tests are performed at various levels of energy on thermoplastic composites (PA/C, PEEK/C and PPS/C woven 50/50 and unidirectional) to determine the level of impact energy creating damages in the resin without fiber rupture. We identify the extent of the damage by US inspection and micrographic observations in the plane part thickness. The samples were in addition characterized in compression to evaluate the loss of mechanical properties. Then the strategy of repair consists in reconsolidating the damaged parts by thermoforming, and after reconsolidation the laminates are characterized in compression for validation. To conclude, the study demonstrates the feasibility of the repair for low energy impact on thermoplastic composites as the samples recover their properties. At a first step of the study, the “repair” is made by reconsolidation on a thermoforming press but we could imagine a process in situ to reconsolidate the damaged parts.

Keywords: aerospace, automotive, composites, compression, damages, repair, structural applications, thermoplastic

Procedia PDF Downloads 304

Authors: Sandrine Cardinal, Jean-Marc Pelletier, Guang Xie, Florian Mercier, Florent Delmas

Abstract:

Bulk metallic glasses exhibit several superior properties, compared to their corresponding crystalline counterpart, such as high strength, high elastic limit or good corrosion resistance. Therefore they can be considered as good candidates for structural applications in many sectors. However, they are generally brittle and do not exhibit plastic deformation at room temperature. These materials are mainly obtained by rapid cooling from a liquid state to prevent crystallization, which limits their size. To overcome these two drawbacks: fragility and limited dimensions, composite metallic glass matrix reinforced by a second phase whose role is to slow crack growth are developed. Concerning the limited size of the pieces, the proposed solution is to get the material from amorphous powders by densifying under load. In this study, Cu50Zr45Al5 bulk metallic glassy matrix composites (MGMCs) containing different volume fraction (Vf) of Zr crystalline particles were manufactured by spark plasma sintering (SPS). Microstructure, thermal stability and mechanical properties of the MGMCs were investigated. Matrix of the composites remains a fully amorphous phase after consolidation at 420°C under 600 MPa. A good dispersion of the particles in the glassy matrix is obtained. Results show that the compressive strength decreases with Vf : 1670 MPa (Vf=0%) to 1300MPa (Vf=30%), the elastic modulus decreases but only slighty respectively 97.3GPa and 94.5 GPa and plasticity is improved from 0 to 4%. Fractographic investigation indicates a good bonding between amorphous and crystalline particles. In conclusion, present study has demonstrated that SPS method is useful for the synthesis of the bulk glassy composites. Large controlled microstructure specimens with interesting ductility can be obtained compared with others methods.

Keywords: composite, mechanical properties, metallic glasses, spark plasma sintering

Procedia PDF Downloads 280