In this paper the effect of temperature range of 298 K to 348 K and volume filler content ф on
electrical properties of polyethylene PE filled with nickel Ni powders has been investigated .The volume
electrical resistivity
V
of such composites decreases suddenly by several orders of magnitude at a critical
volume concentration (i.e. фc=14.27 Vol.%) ,whereas the dielectric constant and the A.C electrical
conductivity AC of such composites increase suddenly at a critical volume concentration (i.e. фc=14.27
Vol.%).For volume filler content lower than percolation threshold ф<фc> фc there is increase in the value of their
resistivity, and decrease in the value of their dielectric constant and the A.C electrical conductivity AC with
increasing temperature indicating metallic-conduction.
the effect of nickel incorporation on some physical properties of epoxy resinINFOGAIN PUBLICATION
The J-E characteristics of samples of epoxy resins mixed with nickel powder in different concentrations have been tested and a log-log straight line behaviour in both the low- and high field regions is observed. Ni-concentration has significant influence on the calculated constants of the J-E relationship. The d.c. electrical resistivity (ρ) of the samples are measured from the room temperature up to about 400 K. The variation of ρ with T obeys the exponential relation of ordinary dielectrics in three temperature regions. The parameters characterizing the ρ -T dependence change considerably with Ni-concentration. Due to the existence of nickel in different concentration a "true" compensation effect is observed with three characteristic compensation temperatures. The mechanical hardness of the samples was investigated as a function of Ni-concentration.
This document discusses a study on the effect of curing on the activation energy and dielectric properties of carbon black-epoxy composites at different temperatures and frequencies. The key findings are:
1) The activation energy was found to be higher for room temperature cured carbon black-epoxy samples compared to thermally cured samples, indicating curing behavior affects activation energy.
2) Dielectric constants of thermally cured samples were higher than room temperature cured samples.
3) Activation energy decreased with increasing carbon black concentration in the composite, likely due to increased polarization energy and charge carrier density.
4) Dielectric constant increased with temperature but decreased with increasing frequency for both cured sample types.
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Space charge and dielectric behavior of epoxy composite with si o2 al2o3 nano...Oussama Elbouadi
The document discusses a study of the space charge distribution, complex dielectric permittivity, and conduction current of an epoxy resin and its composite with SiO2-Al2O3 nano-micro fillers at temperatures ranging from 20 to 200°C. The results show that below the glass transition temperature (Tg), space charge behavior is dominated by electronic charge transport, while above Tg it is dominated by ion transport. Both the real and imaginary parts of complex permittivity increase dramatically above Tg, which can be attributed to ion accumulation at the electrodes. The conduction current also increases with temperature and transitions from electronic to ionic charge transport above Tg. The composite exhibits weaker space charge accumulation, lower complex permit
10.1016-j.mssp.2015.01.037-Electrochemical investigation of graphene_nanoporo...Mahdi Robat Sarpoushi
This study investigated the effect of mixing graphene nanosheets and nanoporous carbon black on the surface morphology and electrochemical performance of electrodes prepared for supercapacitors. Electrodes containing 80% nanoporous carbon black, 10% graphene nanosheets, and 10% PTFE binder showed the highest specific capacitance of 10.22 F/g. The addition of nanoporous carbon black increased the proportion of outer charge stored on the electrode relative to the total charge stored, indicating higher current response and voltage reversal at the end potentials. Scanning electron microscopy images showed that adding nanoporous carbon black particles arranged the graphene nanosheets in different directions, increasing the specific surface area and changing diffusion characteristics to improve capacitance and reversibility
Designing the Shape of Graphite Anode for Microbial Fuel Cells to Increase it...IRJET Journal
This document discusses the design of graphite anode shapes for microbial fuel cells to increase efficiency. It begins with background on microbial fuel cells and how they convert chemical energy to electrical energy using bacteria. Electrode design is important for improving performance, specifically designs that increase surface area to enhance current generation while reducing material costs. The document proposes a new anode shape designed using CAD tools to theoretically increase surface area and decrease the amount of graphite required, lowering operation costs. In summary, the proposed anode shape aims to boost microbial fuel cell efficiency and cost-effectiveness.
This document summarizes a study that compared a single chamber microbial fuel cell (SC-MFC) to a double chamber microbial fuel cell (DC-MFC) using different electron acceptors. The SC-MFC used oxygen from the air as the cathode, while the DC-MFC used diluted hydrogen peroxide. Testing found the DC-MFC produced a higher open circuit voltage of 448mV compared to 200mV for the SC-MFC. The DC-MFC also generated more power, with a maximum power of 7.57mW and coulombic efficiency of 9.2%, versus 0.46mW and 1.88% respectively for the SC-MFC. This suggests hydrogen per
Activated carbon monoliths (ACMs) with average pore diameters in the meso- and micropore regions were successfully produced from biomass material. ACM synthesis uses chemical activation with KOH and ZnCl2 activating agents. The carbon and activating agent mass ratios were 1:1, 1:3, 1:5 and 1:7. Both activating materials produced an ACM with an average pore diameter of 3.2 nm. The specific capacitance, specific surface area, energy and power were as high as 63 F/g, 650 m2/g, and 0.23 Wh/kg for KOH and 73 F/g, and 522 m2/g, and 19 W/kg for ZnCl2 activating agents, respectively. For comparison, we also studied the physical and electrochemical properties of ACM with an average pore size in the micropore range from the same raw material.
the effect of nickel incorporation on some physical properties of epoxy resinINFOGAIN PUBLICATION
The J-E characteristics of samples of epoxy resins mixed with nickel powder in different concentrations have been tested and a log-log straight line behaviour in both the low- and high field regions is observed. Ni-concentration has significant influence on the calculated constants of the J-E relationship. The d.c. electrical resistivity (ρ) of the samples are measured from the room temperature up to about 400 K. The variation of ρ with T obeys the exponential relation of ordinary dielectrics in three temperature regions. The parameters characterizing the ρ -T dependence change considerably with Ni-concentration. Due to the existence of nickel in different concentration a "true" compensation effect is observed with three characteristic compensation temperatures. The mechanical hardness of the samples was investigated as a function of Ni-concentration.
This document discusses a study on the effect of curing on the activation energy and dielectric properties of carbon black-epoxy composites at different temperatures and frequencies. The key findings are:
1) The activation energy was found to be higher for room temperature cured carbon black-epoxy samples compared to thermally cured samples, indicating curing behavior affects activation energy.
2) Dielectric constants of thermally cured samples were higher than room temperature cured samples.
3) Activation energy decreased with increasing carbon black concentration in the composite, likely due to increased polarization energy and charge carrier density.
4) Dielectric constant increased with temperature but decreased with increasing frequency for both cured sample types.
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Space charge and dielectric behavior of epoxy composite with si o2 al2o3 nano...Oussama Elbouadi
The document discusses a study of the space charge distribution, complex dielectric permittivity, and conduction current of an epoxy resin and its composite with SiO2-Al2O3 nano-micro fillers at temperatures ranging from 20 to 200°C. The results show that below the glass transition temperature (Tg), space charge behavior is dominated by electronic charge transport, while above Tg it is dominated by ion transport. Both the real and imaginary parts of complex permittivity increase dramatically above Tg, which can be attributed to ion accumulation at the electrodes. The conduction current also increases with temperature and transitions from electronic to ionic charge transport above Tg. The composite exhibits weaker space charge accumulation, lower complex permit
10.1016-j.mssp.2015.01.037-Electrochemical investigation of graphene_nanoporo...Mahdi Robat Sarpoushi
This study investigated the effect of mixing graphene nanosheets and nanoporous carbon black on the surface morphology and electrochemical performance of electrodes prepared for supercapacitors. Electrodes containing 80% nanoporous carbon black, 10% graphene nanosheets, and 10% PTFE binder showed the highest specific capacitance of 10.22 F/g. The addition of nanoporous carbon black increased the proportion of outer charge stored on the electrode relative to the total charge stored, indicating higher current response and voltage reversal at the end potentials. Scanning electron microscopy images showed that adding nanoporous carbon black particles arranged the graphene nanosheets in different directions, increasing the specific surface area and changing diffusion characteristics to improve capacitance and reversibility
Designing the Shape of Graphite Anode for Microbial Fuel Cells to Increase it...IRJET Journal
This document discusses the design of graphite anode shapes for microbial fuel cells to increase efficiency. It begins with background on microbial fuel cells and how they convert chemical energy to electrical energy using bacteria. Electrode design is important for improving performance, specifically designs that increase surface area to enhance current generation while reducing material costs. The document proposes a new anode shape designed using CAD tools to theoretically increase surface area and decrease the amount of graphite required, lowering operation costs. In summary, the proposed anode shape aims to boost microbial fuel cell efficiency and cost-effectiveness.
This document summarizes a study that compared a single chamber microbial fuel cell (SC-MFC) to a double chamber microbial fuel cell (DC-MFC) using different electron acceptors. The SC-MFC used oxygen from the air as the cathode, while the DC-MFC used diluted hydrogen peroxide. Testing found the DC-MFC produced a higher open circuit voltage of 448mV compared to 200mV for the SC-MFC. The DC-MFC also generated more power, with a maximum power of 7.57mW and coulombic efficiency of 9.2%, versus 0.46mW and 1.88% respectively for the SC-MFC. This suggests hydrogen per
Activated carbon monoliths (ACMs) with average pore diameters in the meso- and micropore regions were successfully produced from biomass material. ACM synthesis uses chemical activation with KOH and ZnCl2 activating agents. The carbon and activating agent mass ratios were 1:1, 1:3, 1:5 and 1:7. Both activating materials produced an ACM with an average pore diameter of 3.2 nm. The specific capacitance, specific surface area, energy and power were as high as 63 F/g, 650 m2/g, and 0.23 Wh/kg for KOH and 73 F/g, and 522 m2/g, and 19 W/kg for ZnCl2 activating agents, respectively. For comparison, we also studied the physical and electrochemical properties of ACM with an average pore size in the micropore range from the same raw material.
A Nano Capacitor Including Graphene Layers Composed with Doped Boron and Nitr...CrimsonPublishersRDMS
A Nano Capacitor Including Graphene Layers Composed with Doped Boron and Nitrogen by Majid Monajjemi* in Crimson Publishers: Peer Reviewed Material Science Journals
Environment-Friendly, Self-Sensing Concrete Blended with Byproduct WastesTalalSalem5
This document summarizes research on developing an environmentally friendly self-sensing concrete using byproduct wastes. Concrete samples were made with additions of coal fly ash, blast furnace slag, and red mud at volumes up to 25% to partially replace Portland cement. The samples were cured for 3, 7, and 28 days and then tested to evaluate how the byproduct wastes affected mechanical strength and electrical resistance. Experimental results showed the byproduct wastes could improve the concrete's electrical properties to enable self-sensing abilities while maintaining adequate strength levels, providing an environmentally friendly self-sensing concrete material.
Optimization of electric energy density in epoxy aluminium nanocompositeiaemedu
This document summarizes research on optimizing the electric energy density of epoxy-aluminum nanocomposites. It models the nanocomposite as a three-phase material and evaluates how aluminum particle size and filler loading affect permittivity, breakdown strength, and energy density. Numerical results show permittivity increases drastically near the percolation threshold. As filler volume increases, breakdown strength decreases but energy density notably increases. The optimal filler size and concentration for maximum energy density are evaluated, with inter-particle distance controlling breakdown strength significantly impacting energy storage capacity.
Optimization of electric energy density in epoxy aluminiumiaemedu
This document discusses optimizing the electric energy density of epoxy-aluminum nanocomposites for use as dielectric materials. It presents a three-phase model to characterize the nanocomposite's dielectric properties as a function of aluminum particle size and volume fraction. Numerical results show that permittivity increases drastically near the percolation threshold. While breakdown strength decreases with higher volume fractions, the overall energy density is significantly higher than pure epoxy. Maximum energy density occurs at an optimal particle size and concentration balancing high permittivity and maintaining breakdown strength. Careful control of microstructure is important to avoid defects and achieve expected energy density gains.
1) The document investigates the effect of cation and anion sizes on the charge storage capabilities of graphite nanosheets as electrode materials for electrochemical double layer capacitors.
2) Scanning electron microscope images confirm the layered structure of the graphite nanosheets used, which are 12nm thick with 3.36 Angstrom spacing between layers.
3) Electrochemical measurements using cyclic voltammetry and impedance spectroscopy indicate that the graphite electrodes exhibited better charge storage and delivery in 3M NaCl electrolyte compared to NaOH and KOH electrolytes, due to the smaller ion sizes matching better with the graphite structure.
Graphene Supported Metal Oxide for Non-Enzymatic H2O2 Sensing - Crimson Publi...CrimsonPublishersRDMS
This document summarizes research on using graphene as a support material for metal oxides in producing sensors for detecting hydrogen peroxide. Graphene is well-suited as a support due to its large surface area, high conductivity, and ability to prevent metal oxide nanoparticle aggregation. Several studies are described that synthesized composites of graphene with various metal oxides like iron oxide, cobalt oxide, zinc oxide, and copper oxide. The graphene-metal oxide composites showed enhanced sensitivity, detection limits, stability, and electrochemical performance compared to metal oxides alone, due to the properties graphene provides as a support.
Enhanced thermal conductivity of epoxy matrix composites filled with boron ni...IAEME Publication
This document summarizes research on enhancing the thermal conductivity of epoxy composites by adding boron nitride (BN) microparticles. Epoxy composites containing 0-11.3% BN by volume were prepared and their thermal conductivities were measured experimentally. Numerical simulations using ANSYS found the effective thermal conductivity increased by 27.82% for 11.3% BN and 440% for 30% BN, compared to neat epoxy. The results showed BN particles exhibited a percolation behavior, with a sudden jump in thermal conductivity occurring at 20% BN volume.
Composites combine multiple materials to create new materials with improved properties. Nanocomposites embed nanoscale particles in a matrix material. Epoxy resins are commonly used as the matrix for nanocomposites due to their versatility. Incorporating nanoscale fillers like graphene and carbon nanotubes into epoxy matrices can enhance the material's thermal and electrical conductivity compared to using microscale or no fillers. The type and concentration of filler, as well as the fabrication method, influence the degree of enhancement in the epoxy composite's properties.
Bruce Decker Journal of Thermal EngineeringBruce Decker
This document summarizes the results of experiments testing the thermoelectric properties of bismuth telluride filled silicone composite wires created via electrospinning. Bismuth telluride and silicone rubber were mixed and extruded into millimeter-sized wires. The electrical resistance of the composite wires was measured to be as high as 2.9*1010 ohms. Seebeck coefficient measurements also showed the composite material exhibited a high Seebeck effect due to the low thermal conductivity of the silicone rubber matrix. The flexibility of the composite material and enhancement of bismuth telluride's thermoelectric properties indicates potential for flexible alternative energy applications.
Dielectric Constant of nano- CCTO / Epoxy CompositeIOSR Journals
Nanocrystalline multiphase CaCu3Ti4O12 (CCTO) was prepared using Ca(NO3)2.4H2O, Cu(NO3)2.3H2O, TiO2 and C2H2O4.2H2O. The X-Ray differection and SEM analysed of the prepared CCTO powder sintered at 900oC and 950oC. A homogeneous ceramics-polymer nanocomposites consisting of CCTO particles as fillers and epoxy polymer as matrix have been prepared using a casting process. The nanocomposites exhibit enhanced dielectric constant and dielectric loss. Dielectric properties of CCTO ceramics were characterized in a broad frequency range (100 Hz-1 MHz) and at a temperature ranged from 25 oC to 150 oC. As a result of increasing the content of CCTO, the dielectric constant and dielectric loss of composites are increased. The increase of dielectric loss at high frequencies is due to the relaxation process in the polymer matrix.
This document summarizes research investigating graphene/cerium oxide nanoparticles as an electrode material for supercapacitors. Scanning electron microscopy images showed the layered structure of graphene with cerium oxide nanoparticles dispersed across the surface. Electrochemical testing found the electrode achieved a maximum specific capacitance of 11.09 F g−1 in 3 M NaCl electrolyte. Charge/discharge cycling showed good reversibility and 37% increase in capacitance after 500 cycles. The graphene/cerium oxide composite performed better than cerium oxide alone due to graphene's conductivity and the formation of an electrical double layer at the electrode interface.
This document summarizes a study investigating the effects of morphology and pore size distribution on the physicochemical properties of graphite nanosheets/nanoporous carbon black/cerium oxide nanoparticle electrodes for electrochemical capacitors. Electrodes with different compositions of these materials were fabricated and their surfaces and pores were characterized using SEM. Electrochemical testing showed that electrodes with a mixture of materials exhibited the highest capacitance due to having macro, micro, and nano pores that increased the accessible surface area. Introducing cerium oxide nanoparticles created micro pores, while carbon black particles created macro pores and rearranged the graphite nanosheets. This nanoporous structure resulted in an electrode with the highest capacitance of 16.2 F/
A new poling method for piezoelectric ceramics with thick film (1)praptome
A new poling method is proposed for piezoelectric ceramics with thick films that uses ITO glass instead of metal electrodes. Using ITO glass overcomes the constraints of applying high electric fields, which can cause cracking in conventional poling methods. ITO glass allows for higher electric fields during poling due to its high energy band, resulting in better alignment of dipoles and higher piezoelectric constants compared to conventional methods. The article discusses energy band concepts and the advantages of ITO glass for piezoelectric poling.
This document describes a new nanocomposite material called SuCoLEx that combines high thermal conductivity and very low thermal expansion. The composite is made of copper with highly aligned graphite platelets added. Spark plasma sintering is used to create an excellent interface between the copper and graphite. Testing found the composite has a thermal conductivity of 500 W/m-K, which is 140% of copper's conductivity. Remarkably, its thermal expansion was found to be just 2 ppm/K, much lower than graphite or copper on their own. This combination of properties makes SuCoLEx promising for applications requiring heat sinks and thermal management.
Highly thermally conductive dielectric coatings produced by Plasma Electrolyt...Tamires Tah
The document describes research on producing highly thermally conductive dielectric coatings on aluminum substrates using plasma electrolytic oxidation (PEO). Key findings:
1. PEO was used to produce porous oxide coatings on aluminum in sodium silicate solutions. Coatings contained Al2O3, silicon, and had electrical resistivities suitable for heat sinks.
2. Thermal diffusivity and conductivity of coatings were significantly higher than aluminum, Al2O3, and AlN - up to 900% higher for some coatings.
3. The best performing coatings had thermal diffusivity of 1.38 x 10-4 m2/s and conductivity of 287 Wm-1K-
SYNTHESIS AND DIELECTRIC CHARACTERIZATION OF BARIUM SUBSTITUTED STRONTIUM BIS...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
Manindra's Paper - Effect of Silver coating on electrical properties of sisal...manindra trihotri
1) The document studies the effect of silver coating and fibre length on the electrical properties of sisal fibre-reinforced epoxy composites.
2) Samples with silver-coated 5mm sisal fibres exhibited higher dielectric constants than samples with 10mm fibres, due to the increased surface area of shorter fibres.
3) Dielectric constant increased with temperature and decreased with frequency for all samples, following trends seen in other fibre-epoxy composites.
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
This document discusses waste heat recovery using thermoelectric generators. It begins by introducing the Seebeck effect which allows heat to be directly converted to electricity via a temperature gradient across conductors. The key factors for good thermoelectric materials - high Seebeck coefficient, electrical conductivity and low thermal conductivity - are discussed. Lead telluride is identified as a suitable high performance material for recovering waste heat between 200-600°C. A thermoelectric couple model is analyzed using ANSYS software, showing a voltage of 0.074806V, current of 19.083A and power of 1.4275W can be generated. The summary concludes the analysis demonstrates the potential of thermoelectric generation to recover low grade waste heat as
Fabrication and studying the dielectric properties of (polystyrene-copper oxi...journalBEEI
This document summarizes a study that fabricated (polystyrene-copper oxide) nanocomposites for potential piezoelectric applications. Copper oxide nanoparticles were added to polystyrene at concentrations of 0, 4, 8 and 12 wt.%. The dielectric constant, dielectric loss, and AC electrical conductivity increased with higher copper oxide concentrations and increased frequency. The electrical resistance of the nanocomposites decreased with increasing pressure, showing piezoelectric behavior. The nanocomposites showed potential for use in piezoelectric sensors due to their sensitivity to pressure changes.
The document describes the design and application of powder composite electrodes made of Cu, Co, Ni, Pt and Ir for use in electrosynthesis and electroanalysis in alkaline solutions. The electrodes were prepared by mixing 95% metal powder with 5% polyvinyl chloride binder. Characterization showed the electrodes had a rough, porous surface and good electrochemical stability, with higher current densities than metal sheet electrodes. Cyclic voltammetry testing demonstrated the composite electrodes had good stability over multiple cycles for electrooxidation reactions like ethanol oxidation in KOH solution. The composite electrodes are suitable for electrochemistry research applications requiring stable, conductive electrodes.
A Nano Capacitor Including Graphene Layers Composed with Doped Boron and Nitr...CrimsonPublishersRDMS
A Nano Capacitor Including Graphene Layers Composed with Doped Boron and Nitrogen by Majid Monajjemi* in Crimson Publishers: Peer Reviewed Material Science Journals
Environment-Friendly, Self-Sensing Concrete Blended with Byproduct WastesTalalSalem5
This document summarizes research on developing an environmentally friendly self-sensing concrete using byproduct wastes. Concrete samples were made with additions of coal fly ash, blast furnace slag, and red mud at volumes up to 25% to partially replace Portland cement. The samples were cured for 3, 7, and 28 days and then tested to evaluate how the byproduct wastes affected mechanical strength and electrical resistance. Experimental results showed the byproduct wastes could improve the concrete's electrical properties to enable self-sensing abilities while maintaining adequate strength levels, providing an environmentally friendly self-sensing concrete material.
Optimization of electric energy density in epoxy aluminium nanocompositeiaemedu
This document summarizes research on optimizing the electric energy density of epoxy-aluminum nanocomposites. It models the nanocomposite as a three-phase material and evaluates how aluminum particle size and filler loading affect permittivity, breakdown strength, and energy density. Numerical results show permittivity increases drastically near the percolation threshold. As filler volume increases, breakdown strength decreases but energy density notably increases. The optimal filler size and concentration for maximum energy density are evaluated, with inter-particle distance controlling breakdown strength significantly impacting energy storage capacity.
Optimization of electric energy density in epoxy aluminiumiaemedu
This document discusses optimizing the electric energy density of epoxy-aluminum nanocomposites for use as dielectric materials. It presents a three-phase model to characterize the nanocomposite's dielectric properties as a function of aluminum particle size and volume fraction. Numerical results show that permittivity increases drastically near the percolation threshold. While breakdown strength decreases with higher volume fractions, the overall energy density is significantly higher than pure epoxy. Maximum energy density occurs at an optimal particle size and concentration balancing high permittivity and maintaining breakdown strength. Careful control of microstructure is important to avoid defects and achieve expected energy density gains.
1) The document investigates the effect of cation and anion sizes on the charge storage capabilities of graphite nanosheets as electrode materials for electrochemical double layer capacitors.
2) Scanning electron microscope images confirm the layered structure of the graphite nanosheets used, which are 12nm thick with 3.36 Angstrom spacing between layers.
3) Electrochemical measurements using cyclic voltammetry and impedance spectroscopy indicate that the graphite electrodes exhibited better charge storage and delivery in 3M NaCl electrolyte compared to NaOH and KOH electrolytes, due to the smaller ion sizes matching better with the graphite structure.
Graphene Supported Metal Oxide for Non-Enzymatic H2O2 Sensing - Crimson Publi...CrimsonPublishersRDMS
This document summarizes research on using graphene as a support material for metal oxides in producing sensors for detecting hydrogen peroxide. Graphene is well-suited as a support due to its large surface area, high conductivity, and ability to prevent metal oxide nanoparticle aggregation. Several studies are described that synthesized composites of graphene with various metal oxides like iron oxide, cobalt oxide, zinc oxide, and copper oxide. The graphene-metal oxide composites showed enhanced sensitivity, detection limits, stability, and electrochemical performance compared to metal oxides alone, due to the properties graphene provides as a support.
Enhanced thermal conductivity of epoxy matrix composites filled with boron ni...IAEME Publication
This document summarizes research on enhancing the thermal conductivity of epoxy composites by adding boron nitride (BN) microparticles. Epoxy composites containing 0-11.3% BN by volume were prepared and their thermal conductivities were measured experimentally. Numerical simulations using ANSYS found the effective thermal conductivity increased by 27.82% for 11.3% BN and 440% for 30% BN, compared to neat epoxy. The results showed BN particles exhibited a percolation behavior, with a sudden jump in thermal conductivity occurring at 20% BN volume.
Composites combine multiple materials to create new materials with improved properties. Nanocomposites embed nanoscale particles in a matrix material. Epoxy resins are commonly used as the matrix for nanocomposites due to their versatility. Incorporating nanoscale fillers like graphene and carbon nanotubes into epoxy matrices can enhance the material's thermal and electrical conductivity compared to using microscale or no fillers. The type and concentration of filler, as well as the fabrication method, influence the degree of enhancement in the epoxy composite's properties.
Bruce Decker Journal of Thermal EngineeringBruce Decker
This document summarizes the results of experiments testing the thermoelectric properties of bismuth telluride filled silicone composite wires created via electrospinning. Bismuth telluride and silicone rubber were mixed and extruded into millimeter-sized wires. The electrical resistance of the composite wires was measured to be as high as 2.9*1010 ohms. Seebeck coefficient measurements also showed the composite material exhibited a high Seebeck effect due to the low thermal conductivity of the silicone rubber matrix. The flexibility of the composite material and enhancement of bismuth telluride's thermoelectric properties indicates potential for flexible alternative energy applications.
Dielectric Constant of nano- CCTO / Epoxy CompositeIOSR Journals
Nanocrystalline multiphase CaCu3Ti4O12 (CCTO) was prepared using Ca(NO3)2.4H2O, Cu(NO3)2.3H2O, TiO2 and C2H2O4.2H2O. The X-Ray differection and SEM analysed of the prepared CCTO powder sintered at 900oC and 950oC. A homogeneous ceramics-polymer nanocomposites consisting of CCTO particles as fillers and epoxy polymer as matrix have been prepared using a casting process. The nanocomposites exhibit enhanced dielectric constant and dielectric loss. Dielectric properties of CCTO ceramics were characterized in a broad frequency range (100 Hz-1 MHz) and at a temperature ranged from 25 oC to 150 oC. As a result of increasing the content of CCTO, the dielectric constant and dielectric loss of composites are increased. The increase of dielectric loss at high frequencies is due to the relaxation process in the polymer matrix.
This document summarizes research investigating graphene/cerium oxide nanoparticles as an electrode material for supercapacitors. Scanning electron microscopy images showed the layered structure of graphene with cerium oxide nanoparticles dispersed across the surface. Electrochemical testing found the electrode achieved a maximum specific capacitance of 11.09 F g−1 in 3 M NaCl electrolyte. Charge/discharge cycling showed good reversibility and 37% increase in capacitance after 500 cycles. The graphene/cerium oxide composite performed better than cerium oxide alone due to graphene's conductivity and the formation of an electrical double layer at the electrode interface.
This document summarizes a study investigating the effects of morphology and pore size distribution on the physicochemical properties of graphite nanosheets/nanoporous carbon black/cerium oxide nanoparticle electrodes for electrochemical capacitors. Electrodes with different compositions of these materials were fabricated and their surfaces and pores were characterized using SEM. Electrochemical testing showed that electrodes with a mixture of materials exhibited the highest capacitance due to having macro, micro, and nano pores that increased the accessible surface area. Introducing cerium oxide nanoparticles created micro pores, while carbon black particles created macro pores and rearranged the graphite nanosheets. This nanoporous structure resulted in an electrode with the highest capacitance of 16.2 F/
A new poling method for piezoelectric ceramics with thick film (1)praptome
A new poling method is proposed for piezoelectric ceramics with thick films that uses ITO glass instead of metal electrodes. Using ITO glass overcomes the constraints of applying high electric fields, which can cause cracking in conventional poling methods. ITO glass allows for higher electric fields during poling due to its high energy band, resulting in better alignment of dipoles and higher piezoelectric constants compared to conventional methods. The article discusses energy band concepts and the advantages of ITO glass for piezoelectric poling.
This document describes a new nanocomposite material called SuCoLEx that combines high thermal conductivity and very low thermal expansion. The composite is made of copper with highly aligned graphite platelets added. Spark plasma sintering is used to create an excellent interface between the copper and graphite. Testing found the composite has a thermal conductivity of 500 W/m-K, which is 140% of copper's conductivity. Remarkably, its thermal expansion was found to be just 2 ppm/K, much lower than graphite or copper on their own. This combination of properties makes SuCoLEx promising for applications requiring heat sinks and thermal management.
Highly thermally conductive dielectric coatings produced by Plasma Electrolyt...Tamires Tah
The document describes research on producing highly thermally conductive dielectric coatings on aluminum substrates using plasma electrolytic oxidation (PEO). Key findings:
1. PEO was used to produce porous oxide coatings on aluminum in sodium silicate solutions. Coatings contained Al2O3, silicon, and had electrical resistivities suitable for heat sinks.
2. Thermal diffusivity and conductivity of coatings were significantly higher than aluminum, Al2O3, and AlN - up to 900% higher for some coatings.
3. The best performing coatings had thermal diffusivity of 1.38 x 10-4 m2/s and conductivity of 287 Wm-1K-
SYNTHESIS AND DIELECTRIC CHARACTERIZATION OF BARIUM SUBSTITUTED STRONTIUM BIS...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
Manindra's Paper - Effect of Silver coating on electrical properties of sisal...manindra trihotri
1) The document studies the effect of silver coating and fibre length on the electrical properties of sisal fibre-reinforced epoxy composites.
2) Samples with silver-coated 5mm sisal fibres exhibited higher dielectric constants than samples with 10mm fibres, due to the increased surface area of shorter fibres.
3) Dielectric constant increased with temperature and decreased with frequency for all samples, following trends seen in other fibre-epoxy composites.
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
This document discusses waste heat recovery using thermoelectric generators. It begins by introducing the Seebeck effect which allows heat to be directly converted to electricity via a temperature gradient across conductors. The key factors for good thermoelectric materials - high Seebeck coefficient, electrical conductivity and low thermal conductivity - are discussed. Lead telluride is identified as a suitable high performance material for recovering waste heat between 200-600°C. A thermoelectric couple model is analyzed using ANSYS software, showing a voltage of 0.074806V, current of 19.083A and power of 1.4275W can be generated. The summary concludes the analysis demonstrates the potential of thermoelectric generation to recover low grade waste heat as
Fabrication and studying the dielectric properties of (polystyrene-copper oxi...journalBEEI
This document summarizes a study that fabricated (polystyrene-copper oxide) nanocomposites for potential piezoelectric applications. Copper oxide nanoparticles were added to polystyrene at concentrations of 0, 4, 8 and 12 wt.%. The dielectric constant, dielectric loss, and AC electrical conductivity increased with higher copper oxide concentrations and increased frequency. The electrical resistance of the nanocomposites decreased with increasing pressure, showing piezoelectric behavior. The nanocomposites showed potential for use in piezoelectric sensors due to their sensitivity to pressure changes.
The document describes the design and application of powder composite electrodes made of Cu, Co, Ni, Pt and Ir for use in electrosynthesis and electroanalysis in alkaline solutions. The electrodes were prepared by mixing 95% metal powder with 5% polyvinyl chloride binder. Characterization showed the electrodes had a rough, porous surface and good electrochemical stability, with higher current densities than metal sheet electrodes. Cyclic voltammetry testing demonstrated the composite electrodes had good stability over multiple cycles for electrooxidation reactions like ethanol oxidation in KOH solution. The composite electrodes are suitable for electrochemistry research applications requiring stable, conductive electrodes.
IRJET- Development of MGO-EPOXY Composites with Enhanced Thermal ConductivityIRJET Journal
This document discusses the development of MgO-epoxy composites with enhanced thermal conductivity. Researchers successfully prepared MgO-epoxy composites by infiltrating magnesium oxide (MgO) powder into epoxy resin. Testing found that thermal conductivity increased with MgO content, reaching a maximum of 0.207 W/(mK) at 20 wt% MgO, higher than neat epoxy. This demonstrates a potential method for manufacturing epoxy composites with extremely high thermal conductivity suitable for electronic device packaging and heat dissipation applications. The document provides background on thermal interface materials and discusses various ceramic fillers used to increase the thermal conductivity of polymer composites.
Synthesis of (Poly-methyl Methacrylate-lead Oxide) Nanocomposites and Studyin...journalBEEI
Piezoelectric materials have been prepared from (poly-methyl methacrylate-lead oxide) nanocomposites for electronic applications. The lead oxide nanoparticles were added to poly-methyl methacrylate by different concentrations are (4, 8, and 12) wt%. The structural and dielectric properties of nanocomposites were studied. The results showed that the dielectric constant and dielectric loss of nanocomposites decrease with increase in frequency of applied electric field. The A.C electrical conductivity increases with increase in frequency. The dielectric constant, dielectric loss and A.C electrical conductivity of poly-methyl methacrylate increase with increase in lead oxide nanoparticles concentrations. The results of pressure sensor showed that the electrical resistance of (PMMA-PbO2) nanocomposites decreases with increase in pressure.
Optimization of electric energy density in epoxy aluminium nanocompositeIAEME Publication
This document summarizes a study that models epoxy-aluminum nanocomposites as a three-phase material to investigate their dielectric properties. It evaluates how aluminum particle size and filler loading influence permittivity, breakdown strength, and electric energy density. The model accounts for the polymer matrix, interfacial phase between polymer and particles, and nanoparticle fillers. Numerical results show permittivity increases drastically near a transition threshold. While breakdown strength decreases with higher volume fraction, energy density notably increases. An optimal filler size and concentration for maximum energy density is determined.
Enhanced thermal conductivity of epoxy matrix composites filled with boron ni...IAEME Publication
This document summarizes research on enhancing the thermal conductivity of epoxy matrix composites by filling them with boron nitride (BN) particles. The researchers prepared epoxy composites with BN content ranging from 0-11.3% by volume and measured their thermal conductivities experimentally. They also used finite element analysis to model heat transfer in the composites and validate the simulated effective thermal conductivities. Their results showed that an 11.3% BN filling increased thermal conductivity by 27.82% while a 30% filling increased it by 440%, demonstrating BN's ability to significantly improve an epoxy matrix's heat dissipation capabilities.
Evaluation Performance ofan Annular Composite Fin by UsingMATLAB ProgrammingIJERA Editor
The aim of this project is analysis the efficiency ratio in an annular fin by the variation of heat transfer coefficient for any surface condition by using MATLAB software to calculate the base fin efficiency and the coated fin efficiency by the variation of heat transfer coefficient, radius ratio and base fin thickness of an annular fin and compare the coating fin efficiency to base fin efficiency. If the heat transfer coefficient is 50W/m2K the increase efficiency ratio is 10.46 – 28.02% for zinc coating fin from the literature but the MATLAB result is 9.3 - 25.54% , the gain efficiency ratio at thicker base fin (d=0.001m) is 11.72%, at the thinner base fin (d=0.0002m) is 33.57% from the literature but the MATLAB result is 7.45% (d=0.001m) and 32.14% (d=0.0002m) for zinc coating fin and the gain efficiency ratio at thicker base fin (d=0.001m) is 11.92%, at the thinner base fin (d=0.0002m) is 33.61% from the literature but the MATLAB result is 7.51% (d=0.001m) and 32.16% (d=0.0002m) for zinc alloy coating fin.
Potential enhancement of thermoelectric energy conversion in cobaltite superl...Anastasios Englezos
This document is a master's thesis submitted by Tasos Englezos investigating the potential enhancement of thermoelectric energy conversion in cobaltite oxide superlattices. The thesis aims to grow superlattices composed of alternating layers of NaxCoO3 and Ca3Co4O9 using pulsed laser deposition, as both materials show promise for thermoelectric applications but also have limitations. Characterization of the superlattices shows the structures maintain crystalline coherence while electrical and thermal properties are preserved at a good level. Further measurements of thermal conductivity are needed to determine if the superlattice approach reduces thermal conductivity and thereby improves thermoelectric efficiency in these cobaltite oxides.
This document summarizes research on developing electrically conductive concrete using waste coke powder. Coke powder was partially substituted for cement at dosages of 2%, 4%, 6%, 8%, 10%, and 12% by weight. Fresh concrete workability decreased with higher coke content due to its high surface area. Compressive strength was slightly reduced at 8% coke, with a more significant decrease above 10%. Conductivity and temperature rise increased continuously with higher coke. The optimum coke dosage was 8%, as it provided increased conductivity and temperature effects without compromising strength or causing electric shocks. This "Cokecrete" has applications for grounding in transmission towers.
This document summarizes recent developments in materials, design, and concepts for bipolar/end plates in polymer electrolyte membrane fuel cells. It discusses experimental results showing iron- and copper-based alloys can be used as cheaper alternatives to conventional graphite bipolar plates. Models for optimizing gas flow field design parameters in these plates are discussed. New concepts like using metal foams and corrugated thin sheets in bipolar plates are presented, with experimental results comparing to model predictions. Applications of these new concepts in developing commercial fuel cell stacks for a hydrogen economy are considered.
This document summarizes research into optimizing the design of lithium-ion battery cells for electric vehicles to minimize costs. The researchers created a cell model that can flexibly simulate different electrode designs and materials. Their analysis shows that matching a cell's power-to-energy ratio to the requirements of an electric vehicle leads to the lowest costs. However, providing a unique cell for each vehicle model would be impractical for automakers. Therefore, the researchers use an algorithm to determine the optimal number and specifications of cell types that can cost-effectively meet the needs of a range of vehicles. This modular battery design approach aims to help automakers and suppliers develop the most cost-competitive lithium-ion cell strategies.
The document summarizes a study comparing the electrical properties of platinum interconnects deposited by electron beam induced deposition using two different precursors: a carbon-free precursor (Pt(PF3)4) and a standard organometallic precursor ((CH3)3Pt(CpCH3)). Interconnects deposited with the carbon-free precursor exhibited significantly improved electrical performance, including lower resistivity (0.24 x 10-3 Ω cm vs 0.2 Ω cm for the standard precursor) and higher maximum current density (1.87 x 107 A/cm2 vs 9.44 x 105 A/cm2). Post-deposition annealing was found to further improve the electrical properties by inducing crystallization and
Influence of low temperature on heat transfer in epoxide nano compositesAlexander Decker
This document summarizes research on the influence of low temperatures on heat transfer in epoxide
nanocomposites. It discusses how adding nanofillers to epoxy polymers can significantly change their
mechanical, thermal, and electrical properties due to increased heterogeneity and interactions at the
polymer-filler interface. The document also describes the preparation and testing of epoxy nanocomposite
samples containing various nanofillers like carbon nanotubes and aerosil at low concentrations.
Influence of low temperature on heat transfer in epoxide nano compositesAlexander Decker
This document summarizes research on the influence of low temperatures on heat transfer in epoxide
nanocomposites. It discusses how adding nanofillers to epoxy polymers can significantly change their
mechanical, thermal, and electrical properties due to increased heterogeneity and interactions at the
polymer-filler interface. The document also describes the preparation and testing of epoxy nanocomposite
samples containing various nanofillers like carbon nanotubes and aerosil at low concentrations.
This document summarizes a study on the effect of crystallite size of zinc oxide (ZnO) filler on the properties of polypropylene (PP)/ZnO nanocomposites. ZnO nanoparticles were prepared using two different methods, resulting in nanoparticles with crystallite sizes of 13.4 nm (NZO) and 29.2 nm (CZO). PP/ZnO composites containing 0-5% ZnO were produced by melt mixing. Composites with NZO exhibited higher mechanical properties, dynamic properties, and thermal stability than those with CZO, due to the smaller crystallite size and more uniform dispersion of NZO in PP. Transparency of the composites improved with decreasing ZnO crystallite
Synthesis and Dielectric Characterization of Barium Substituted Strontium Bis...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
TRIBOLOGICAL CHARACTERISTICS,ELECTRICAL PROPERTIES Arjun K Gopi
This document discusses tribological and electrical properties and provides summaries of several documents on related topics. It begins by defining tribological properties like wear resistance and coefficient of friction and electrical properties like dielectric strength. It then summarizes a document about polycarbazole nanocomposites with metal oxides for transparent electrode applications, describing their preparation, transparent and conductive properties. Following this, it summarizes documents about nanocomposites containing inorganic nanoparticles and conducting polymers and their various synthesis techniques and applications. It also briefly summarizes documents about carbon nanotube composites and their electrical properties and enhanced thermoelectric performance of single-walled carbon nanotube and polyaniline hybrid nanocomposites.
Similar to Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polyethylene-Nickel Composites (20)
A Novel Method for Prevention of Bandwidth Distributed Denial of Service AttacksIJERD Editor
Distributed Denial of Service (DDoS) Attacks became a massive threat to the Internet. Traditional
Architecture of internet is vulnerable to the attacks like DDoS. Attacker primarily acquire his army of Zombies,
then that army will be instructed by the Attacker that when to start an attack and on whom the attack should be
done. In this paper, different techniques which are used to perform DDoS Attacks, Tools that were used to
perform Attacks and Countermeasures in order to detect the attackers and eliminate the Bandwidth Distributed
Denial of Service attacks (B-DDoS) are reviewed. DDoS Attacks were done by using various Flooding
techniques which are used in DDoS attack.
The main purpose of this paper is to design an architecture which can reduce the Bandwidth
Distributed Denial of service Attack and make the victim site or server available for the normal users by
eliminating the zombie machines. Our Primary focus of this paper is to dispute how normal machines are
turning into zombies (Bots), how attack is been initiated, DDoS attack procedure and how an organization can
save their server from being a DDoS victim. In order to present this we implemented a simulated environment
with Cisco switches, Routers, Firewall, some virtual machines and some Attack tools to display a real DDoS
attack. By using Time scheduling, Resource Limiting, System log, Access Control List and some Modular
policy Framework we stopped the attack and identified the Attacker (Bot) machines
Hearing loss is one of the most common human impairments. It is estimated that by year 2015 more
than 700 million people will suffer mild deafness. Most can be helped by hearing aid devices depending on the
severity of their hearing loss. This paper describes the implementation and characterization details of a dual
channel transmitter front end (TFE) for digital hearing aid (DHA) applications that use novel micro
electromechanical- systems (MEMS) audio transducers and ultra-low power-scalable analog-to-digital
converters (ADCs), which enable a very-low form factor, energy-efficient implementation for next-generation
DHA. The contribution of the design is the implementation of the dual channel MEMS microphones and powerscalable
ADC system.
Influence of tensile behaviour of slab on the structural Behaviour of shear c...IJERD Editor
-A composite beam is composed of a steel beam and a slab connected by means of shear connectors
like studs installed on the top flange of the steel beam to form a structure behaving monolithically. This study
analyzes the effects of the tensile behavior of the slab on the structural behavior of the shear connection like slip
stiffness and maximum shear force in composite beams subjected to hogging moment. The results show that the
shear studs located in the crack-concentration zones due to large hogging moments sustain significantly smaller
shear force and slip stiffness than the other zones. Moreover, the reduction of the slip stiffness in the shear
connection appears also to be closely related to the change in the tensile strain of rebar according to the increase
of the load. Further experimental and analytical studies shall be conducted considering variables such as the
reinforcement ratio and the arrangement of shear connectors to achieve efficient design of the shear connection
in composite beams subjected to hogging moment.
Gold prospecting using Remote Sensing ‘A case study of Sudan’IJERD Editor
Gold has been extracted from northeast Africa for more than 5000 years, and this may be the first
place where the metal was extracted. The Arabian-Nubian Shield (ANS) is an exposure of Precambrian
crystalline rocks on the flanks of the Red Sea. The crystalline rocks are mostly Neoproterozoic in age. ANS
includes the nations of Israel, Jordan. Egypt, Saudi Arabia, Sudan, Eritrea, Ethiopia, Yemen, and Somalia.
Arabian Nubian Shield Consists of juvenile continental crest that formed between 900 550 Ma, when intra
oceanic arc welded together along ophiolite decorated arc. Primary Au mineralization probably developed in
association with the growth of intra oceanic arc and evolution of back arc. Multiple episodes of deformation
have obscured the primary metallogenic setting, but at least some of the deposits preserve evidence that they
originate as sea floor massive sulphide deposits.
The Red Sea Hills Region is a vast span of rugged, harsh and inhospitable sector of the Earth with
inimical moon-like terrain, nevertheless since ancient times it is famed to be an abode of gold and was a major
source of wealth for the Pharaohs of ancient Egypt. The Pharaohs old workings have been periodically
rediscovered through time. Recent endeavours by the Geological Research Authority of Sudan led to the
discovery of a score of occurrences with gold and massive sulphide mineralizations. In the nineties of the
previous century the Geological Research Authority of Sudan (GRAS) in cooperation with BRGM utilized
satellite data of Landsat TM using spectral ratio technique to map possible mineralized zones in the Red Sea
Hills of Sudan. The outcome of the study mapped a gossan type gold mineralization. Band ratio technique was
applied to Arbaat area and a signature of alteration zone was detected. The alteration zones are commonly
associated with mineralization. The alteration zones are commonly associated with mineralization. A filed check
confirmed the existence of stock work of gold bearing quartz in the alteration zone. Another type of gold
mineralization that was discovered using remote sensing is the gold associated with metachert in the Atmur
Desert.
Reducing Corrosion Rate by Welding DesignIJERD Editor
This document summarizes a study on reducing corrosion rates in steel through welding design. The researchers tested different welding groove designs (X, V, 1/2X, 1/2V) and preheating temperatures (400°C, 500°C, 600°C) on ferritic malleable iron samples. Testing found that X and V groove designs with 500°C and 600°C preheating had corrosion rates of 0.5-0.69% weight loss after 14 days, compared to 0.57-0.76% for 400°C preheating. Higher preheating reduced residual stresses which decreased corrosion. Residual stresses were 1.7 MPa for optimal X groove and 600°C
Router 1X3 – RTL Design and VerificationIJERD Editor
Routing is the process of moving a packet of data from source to destination and enables messages
to pass from one computer to another and eventually reach the target machine. A router is a networking device
that forwards data packets between computer networks. It is connected to two or more data lines from different
networks (as opposed to a network switch, which connects data lines from one single network). This paper,
mainly emphasizes upon the study of router device, it‟s top level architecture, and how various sub-modules of
router i.e. Register, FIFO, FSM and Synchronizer are synthesized, and simulated and finally connected to its top
module.
Active Power Exchange in Distributed Power-Flow Controller (DPFC) At Third Ha...IJERD Editor
This paper presents a component within the flexible ac-transmission system (FACTS) family, called
distributed power-flow controller (DPFC). The DPFC is derived from the unified power-flow controller (UPFC)
with an eliminated common dc link. The DPFC has the same control capabilities as the UPFC, which comprise
the adjustment of the line impedance, the transmission angle, and the bus voltage. The active power exchange
between the shunt and series converters, which is through the common dc link in the UPFC, is now through the
transmission lines at the third-harmonic frequency. DPFC multiple small-size single-phase converters which
reduces the cost of equipment, no voltage isolation between phases, increases redundancy and there by
reliability increases. The principle and analysis of the DPFC are presented in this paper and the corresponding
simulation results that are carried out on a scaled prototype are also shown.
Mitigation of Voltage Sag/Swell with Fuzzy Control Reduced Rating DVRIJERD Editor
Power quality has been an issue that is becoming increasingly pivotal in industrial electricity
consumers point of view in recent times. Modern industries employ Sensitive power electronic equipments,
control devices and non-linear loads as part of automated processes to increase energy efficiency and
productivity. Voltage disturbances are the most common power quality problem due to this the use of a large
numbers of sophisticated and sensitive electronic equipment in industrial systems is increased. This paper
discusses the design and simulation of dynamic voltage restorer for improvement of power quality and
reduce the harmonics distortion of sensitive loads. Power quality problem is occurring at non-standard
voltage, current and frequency. Electronic devices are very sensitive loads. In power system voltage sag,
swell, flicker and harmonics are some of the problem to the sensitive load. The compensation capability
of a DVR depends primarily on the maximum voltage injection ability and the amount of stored
energy available within the restorer. This device is connected in series with the distribution feeder at
medium voltage. A fuzzy logic control is used to produce the gate pulses for control circuit of DVR and the
circuit is simulated by using MATLAB/SIMULINK software.
Study on the Fused Deposition Modelling In Additive ManufacturingIJERD Editor
Additive manufacturing process, also popularly known as 3-D printing, is a process where a product
is created in a succession of layers. It is based on a novel materials incremental manufacturing philosophy.
Unlike conventional manufacturing processes where material is removed from a given work price to derive the
final shape of a product, 3-D printing develops the product from scratch thus obviating the necessity to cut away
materials. This prevents wastage of raw materials. Commonly used raw materials for the process are ABS
plastic, PLA and nylon. Recently the use of gold, bronze and wood has also been implemented. The complexity
factor of this process is 0% as in any object of any shape and size can be manufactured.
Spyware triggering system by particular string valueIJERD Editor
This computer programme can be used for good and bad purpose in hacking or in any general
purpose. We can say it is next step for hacking techniques such as keylogger and spyware. Once in this system if
user or hacker store particular string as a input after that software continually compare typing activity of user
with that stored string and if it is match then launch spyware programme.
A Blind Steganalysis on JPEG Gray Level Image Based on Statistical Features a...IJERD Editor
This paper presents a blind steganalysis technique to effectively attack the JPEG steganographic
schemes i.e. Jsteg, F5, Outguess and DWT Based. The proposed method exploits the correlations between
block-DCTcoefficients from intra-block and inter-block relation and the statistical moments of characteristic
functions of the test image is selected as features. The features are extracted from the BDCT JPEG 2-array.
Support Vector Machine with cross-validation is implemented for the classification.The proposed scheme gives
improved outcome in attacking.
Secure Image Transmission for Cloud Storage System Using Hybrid SchemeIJERD Editor
- Data over the cloud is transferred or transmitted between servers and users. Privacy of that
data is very important as it belongs to personal information. If data get hacked by the hacker, can be
used to defame a person’s social data. Sometimes delay are held during data transmission. i.e. Mobile
communication, bandwidth is low. Hence compression algorithms are proposed for fast and efficient
transmission, encryption is used for security purposes and blurring is used by providing additional
layers of security. These algorithms are hybridized for having a robust and efficient security and
transmission over cloud storage system.
Application of Buckley-Leverett Equation in Modeling the Radius of Invasion i...IJERD Editor
A thorough review of existing literature indicates that the Buckley-Leverett equation only analyzes
waterflood practices directly without any adjustments on real reservoir scenarios. By doing so, quite a number
of errors are introduced into these analyses. Also, for most waterflood scenarios, a radial investigation is more
appropriate than a simplified linear system. This study investigates the adoption of the Buckley-Leverett
equation to estimate the radius invasion of the displacing fluid during waterflooding. The model is also adopted
for a Microbial flood and a comparative analysis is conducted for both waterflooding and microbial flooding.
Results shown from the analysis doesn’t only records a success in determining the radial distance of the leading
edge of water during the flooding process, but also gives a clearer understanding of the applicability of
microbes to enhance oil production through in-situ production of bio-products like bio surfactans, biogenic
gases, bio acids etc.
Gesture Gaming on the World Wide Web Using an Ordinary Web CameraIJERD Editor
- Gesture gaming is a method by which users having a laptop/pc/x-box play games using natural or
bodily gestures. This paper presents a way of playing free flash games on the internet using an ordinary webcam
with the help of open source technologies. Emphasis in human activity recognition is given on the pose
estimation and the consistency in the pose of the player. These are estimated with the help of an ordinary web
camera having different resolutions from VGA to 20mps. Our work involved giving a 10 second documentary to
the user on how to play a particular game using gestures and what are the various kinds of gestures that can be
performed in front of the system. The initial inputs of the RGB values for the gesture component is obtained by
instructing the user to place his component in a red box in about 10 seconds after the short documentary before
the game is finished. Later the system opens the concerned game on the internet on popular flash game sites like
miniclip, games arcade, GameStop etc and loads the game clicking at various places and brings the state to a
place where the user is to perform only gestures to start playing the game. At any point of time the user can call
off the game by hitting the esc key and the program will release all of the controls and return to the desktop. It
was noted that the results obtained using an ordinary webcam matched that of the Kinect and the users could
relive the gaming experience of the free flash games on the net. Therefore effective in game advertising could
also be achieved thus resulting in a disruptive growth to the advertising firms.
Hardware Analysis of Resonant Frequency Converter Using Isolated Circuits And...IJERD Editor
-LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region[5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits.
Simulated Analysis of Resonant Frequency Converter Using Different Tank Circu...IJERD Editor
LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region [5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits. The supported simulation
is done through PSIM 6.0 software tool
Amateurs Radio operator, also known as HAM communicates with other HAMs through Radio
waves. Wireless communication in which Moon is used as natural satellite is called Moon-bounce or EME
(Earth -Moon-Earth) technique. Long distance communication (DXing) using Very High Frequency (VHF)
operated amateur HAM radio was difficult. Even with the modest setup having good transceiver, power
amplifier and high gain antenna with high directivity, VHF DXing is possible. Generally 2X11 YAGI antenna
along with rotor to set horizontal and vertical angle is used. Moon tracking software gives exact location,
visibility of Moon at both the stations and other vital data to acquire real time position of moon.
“MS-Extractor: An Innovative Approach to Extract Microsatellites on „Y‟ Chrom...IJERD Editor
Simple Sequence Repeats (SSR), also known as Microsatellites, have been extensively used as
molecular markers due to their abundance and high degree of polymorphism. The nucleotide sequences of
polymorphic forms of the same gene should be 99.9% identical. So, Microsatellites extraction from the Gene is
crucial. However, Microsatellites repeat count is compared, if they differ largely, he has some disorder. The Y
chromosome likely contains 50 to 60 genes that provide instructions for making proteins. Because only males
have the Y chromosome, the genes on this chromosome tend to be involved in male sex determination and
development. Several Microsatellite Extractors exist and they fail to extract microsatellites on large data sets of
giga bytes and tera bytes in size. The proposed tool “MS-Extractor: An Innovative Approach to extract
Microsatellites on „Y‟ Chromosome” can extract both Perfect as well as Imperfect Microsatellites from large
data sets of human genome „Y‟. The proposed system uses string matching with sliding window approach to
locate Microsatellites and extracts them.
Importance of Measurements in Smart GridIJERD Editor
- The need to get reliable supply, independence from fossil fuels, and capability to provide clean
energy at a fixed and lower cost, the existing power grid structure is transforming into Smart Grid. The
development of a smart energy distribution grid is a current goal of many nations. A Smart Grid should have
new capabilities such as self-healing, high reliability, energy management, and real-time pricing. This new era
of smart future grid will lead to major changes in existing technologies at generation, transmission and
distribution levels. The incorporation of renewable energy resources and distribution generators in the existing
grid will increase the complexity, optimization problems and instability of the system. This will lead to a
paradigm shift in the instrumentation and control requirements for Smart Grids for high quality, stable and
reliable electricity supply of power. The monitoring of the grid system state and stability relies on the
availability of reliable measurement of data. In this paper the measurement areas that highlight new
measurement challenges, development of the Smart Meters and the critical parameters of electric energy to be
monitored for improving the reliability of power systems has been discussed.
Study of Macro level Properties of SCC using GGBS and Lime stone powderIJERD Editor
The document summarizes a study on the use of ground granulated blast furnace slag (GGBS) and limestone powder to replace cement in self-compacting concrete (SCC). Tests were conducted on SCC mixes with 0-50% replacement of cement with GGBS and 0-20% replacement with limestone powder. The results showed that replacing 30% of cement with GGBS and 15% with limestone powder produced SCC with the highest compressive strength of 46MPa, meeting fresh property requirements. The study concluded that this ternary blend of cement, GGBS and limestone powder can improve SCC properties while reducing costs.
Enchancing adoption of Open Source Libraries. A case study on Albumentations.AIVladimir Iglovikov, Ph.D.
Presented by Vladimir Iglovikov:
- https://www.linkedin.com/in/iglovikov/
- https://x.com/viglovikov
- https://www.instagram.com/ternaus/
This presentation delves into the journey of Albumentations.ai, a highly successful open-source library for data augmentation.
Created out of a necessity for superior performance in Kaggle competitions, Albumentations has grown to become a widely used tool among data scientists and machine learning practitioners.
This case study covers various aspects, including:
People: The contributors and community that have supported Albumentations.
Metrics: The success indicators such as downloads, daily active users, GitHub stars, and financial contributions.
Challenges: The hurdles in monetizing open-source projects and measuring user engagement.
Development Practices: Best practices for creating, maintaining, and scaling open-source libraries, including code hygiene, CI/CD, and fast iteration.
Community Building: Strategies for making adoption easy, iterating quickly, and fostering a vibrant, engaged community.
Marketing: Both online and offline marketing tactics, focusing on real, impactful interactions and collaborations.
Mental Health: Maintaining balance and not feeling pressured by user demands.
Key insights include the importance of automation, making the adoption process seamless, and leveraging offline interactions for marketing. The presentation also emphasizes the need for continuous small improvements and building a friendly, inclusive community that contributes to the project's growth.
Vladimir Iglovikov brings his extensive experience as a Kaggle Grandmaster, ex-Staff ML Engineer at Lyft, sharing valuable lessons and practical advice for anyone looking to enhance the adoption of their open-source projects.
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GitHub: https://github.com/albumentations-team/albumentations
Website: https://albumentations.ai/
LinkedIn: https://www.linkedin.com/company/100504475
Twitter: https://x.com/albumentations
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Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polyethylene-Nickel Composites
1. International Journal of Engineering Research and Development
e-ISSN: 2278-067X, p-ISSN: 2278-800X, www.ijerd.com
Volume 11, Issue 02 (February 2015), PP.29-38
29
Effect of Temperature and Nickel Concentration on the Electrical
and Dielectric Properties of Polyethylene-Nickel Composites
Ghassan Adnan Naeem
Physics Department, College of Education for Pure Science, AL-Anbar University, Anbar/Ramady, Iraq
Abstract:- In this paper the effect of temperature range of 298 K to 348 K and volume filler content ф on
electrical properties of polyethylene PE filled with nickel Ni powders has been investigated .The volume
electrical resistivity
V
of such composites decreases suddenly by several orders of magnitude at a critical
volume concentration (i.e. фc=14.27 Vol.%) ,whereas the dielectric constant and the A.C electrical
conductivity AC of such composites increase suddenly at a critical volume concentration (i.e. фc=14.27
Vol.%).For volume filler content lower than percolation threshold ф<фc the resistivity decreases with
increasing temperature, whereas the dielectric constant and the A.C electrical conductivity of such composites
increase indicating a semi-conducting behavior, where for ф> фc there is increase in the value of their
resistivity, and decrease in the value of their dielectric constant and the A.C electrical conductivity AC with
increasing temperature indicating metallic-conduction.
Keywords:- conducting polymer, filler, polymer matrix, polyethylene, CPCM, percolation threshold.
I. INTRODUCTION
In our daily life we are surrounded by more and more articles produced of polymers rather than
traditional materials such as wood, metals or ceramics. One of the main drivers contributing to the
popularization of polymers is their ease of processing into complexly shaped parts at high speeds and low costs
via relatively simple processes, such as extrusion, injection and compression modelling . Complementary
advantages of polymers are their low density and large range of specific properties due to these properties
polymers are becoming attractive .Conducting polymer composite materials (CPCM), that consist of a random
distribution of a conducting filler throughout an insulating polymer, deserve interest in several application fields
[2].They have emerged as a new group of engineering materials lately. Possible applications include (a)
discharging static electricity, (b) heat conduction, (c) electrical shielding, (d) converting mechanical to electrical
signals, (f) absorbing electrical waves, and (g) friction-antifriction materials. The materials are likely to have the
following advantages in comparison with metals: high corrosion resistance, lower specific weight, ease of
workability when manufacturing products of complex shapes are desired, cheapness, and great accessibility [3].
The purpose of use of fillers can be divided into two basic categories, first, to improve the properties of
the material and second, to reduce the cost of component. Metal-polymer composites are a relative new of
technological materials; their electrical characteristics are close to those of metals, whereas the mechanical
properties and processing methods are typical for plastics. The conditions of electric charge transfer determine
the electrical conductivity level and the dielectric properties of the heterogeneous system, in which polymer
forms the matrix and conductive phase is formed by the dispersed metallic filler. The electrical properties of
(CPCM) depend on several factors, including the kind of conducting filler, the spatial distribution of filler
particles, the interaction between polymer and filler, and the contact interaction between particles [4]. By
gradually increasing the filler content in a metal-polymer composite, the most significant changes in electrical
and dielectric properties occur in a certain, relatively narrow critical region of filler content Фc (percolation
concentration).Usually the percolation model is used for explaining the observed effects in metal-polymer
composite[5].
The percolation theory is the most adequate for modelling conductivity of CPCM .It involves
convergence of particles to distances at which the probability of transfer of current carriers between them
becomes higher than zero. The so-called percolation threshold фc, i.e. the lowest concentration of conduction
particles at which continuous conducting chains are formed, is easily determined from the experimental
dependence of conductivity on the filler concentration. It is a very useful tool to probe the filler distribution
within a polymer matrix [6].
Increased attention has been paid in recent years to the researches on polymeric composites in general
and PE- metal composite in particular .A brief summary of various experimental studies on PE- metal composite
is given below. Turner and co-workers [6-9] reported early works on polyethylene-Ni composites. They made
2. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
30
preliminary investigations on polyethylene-Ni and polyurethane-Ni systems. Their studies showed that the
critical composition of metal could be reduced considerably by segregation of the metallic particles. Segregation
was effected by admixture of large particles of polymer with smaller particles of metal followed by compaction.
Horibe et-al [10] investigated the effect of the content and particle size of carbon black filler on the electrical
conductivity of the PE-C.B composite .the study of composites showed that the resistivity of PE-C.B composites
decreased with increasing C.B content, and the smaller the C.B. particle size is the lower resistivity of the PE-
C.B composites. Ismail [11] studied the electrical resistivity and tensile properties of composites formed by the
incorporation of metal such as Al, Cu & Fe in PE matrix. It is found that the electrical resistivity of the
composites is governed by the shape of filler and amount of filler content.
The aim of this paper is to focus on study of the effect of filler concentration and the effect of
temperature on the electrical properties of PE-Ni composites. It is important from the practical point of view
because composites are used extensively in many industrial applications.
II. EXPERIMENTAL PART
1. Materials
The materials used in this work were:
a. High-density polyethylene is used as polymer matrix, a non polar polymer. It is light polymer with a density
approaching 0.95-0.97 gm/cm3
.Polyethylene is commercially available , the commonly used polyethylene due to
its ability for modelling in various ways and tempting properties such as high density, good mechanical
properties, good dielectric in high frequency and possesses a good resistance against corrosion because it is
inert against chemicals . Its chemical formula is shown in the following [12]:
b. Nickel powder from (Metco Ltd. England) of particle size 75-100 microns with a density8.902 gm/cm3
.
2. Preparation of PE-Ni composites
Weighed amounts of polyethylene and nickel powders were mixed by a rotary blender until a
homogeneous product was obtained. The mixture was compacted in steel cylindrical of diameter 3 cm under a
pressure of 110 bar for 10 min at 110o
C, the die was then cooled to 50o
C by tapped water. The compacted
sample was ejected from the die and allowed to cool to room temperature. The specimens were modelled in
disc-shape with a diameter of about 30 mm and a thickness ranged between 0.9 and 1.5 mm. Table1 gives the
list of weight percentage of all the PE-Ni specimens and their equivalent volume percentage. The weight
percentage of Ni powder is given by:
%100.%
T
Ni
W
W
Niofwt ……...…(1)
Whereas The weight percentage of PE powder is:
%100.%
T
NiPE
W
WW
PEofwt …(2)
Where TW : the total weight of sample, NiW : weight of Ni powder and PEW : weight of PE powder .The
volume percentage of Ni powder is given by:
%100.%
PE
PE
Ni
Ni
D
W
D
W
NiofVol ……(3)
Where NiD : density of Ni powder and PED : density of PE powder.
Table I: List of weight percentage of all the PE-Ni specimens and their equivalent volume percentage.
3. Optical Micrograph
3. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
31
All samples of PE-Ni composites were examined by the optical microscope from (Olympus – BH-22)
which have a maximum magnification power of ( 500 ) and equipped with light intensity automatic
controlled camera.
4. Measurement of DC electrical properties
The resistivity data were obtained with specimens shaped according to ASTM, D257- 66 standard.
Figure.1a by means of the Three electrodes arrangement [13].This technique has been used to decrease the effect
of the fringing of the electric field at edges ,and to distinguish between the surface and the volume resistivity of
the sample ,therefore it permits measuring the bulk resistivity of the material.
In Figure1b a schematic representation of the preferential current paths and the equivalent electric
circuit are shown .RS represent the surface resistance between the guard and the guarded electrodes ,Rv the
volume resistance between the guarded and the bottom electrodes ,and Rg is the guard resistance between the
guard and the bottom electrodes.
Fig. 1: (a) Shape of the specimen and of the electrodes. (b) Schematic representation of the preferential
current paths and equivalent electric circuit.
The complete system of the D.C. volume resistivity measurement is shown in Figure 2.The electrodes
were made of copper metal, and a uniform pressure on the specimen was applied by Four adjustable screws, the
electrical input was provided by means of stabilized D.C. power supply (Philip Harris Limited) which provide
an output voltage from 0 to 3000 volt .The output current was measured by Keithley 616C / digital solid state
electrometer.
Fig. 2: Schematic diagram of the DC volume resistivity measurements.
Volume percentage of the
filler
Weight percentage of
the filler
Symbol of
sample
1.6315
1
3.0925
2
4.9935
3
11.3355
4
17.2265
5
21.6370
6
4. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
32
The Keithley electrometer provides direct reading current ranges to 10-12
ampere full scale .The test
samples are in the form of disc like shape, the disc surfaces were covered by a (AL) leaf to ensure uniform
electrical contact and to minimize the contact resistance. The test sample is placed between the two electrodes
and left at a desired temperature for half hour, then the desired test voltage is selected from the voltage supply
and the current passing through the bulk of the test sample at this selected temperature ,is measured by the
electrometer. The volume resistivity measurements were performed in the temperature range between298 K –
348 K by using a temperature controlled oven (MLW) which has been shield against external electromagnetic
field.
5. Measurement of AC electrical properties
Figure 3 shows the guard electrode specimen holder which is situated in temperature controlled oven
(MLW).As shown in the figure ,the high and low specimen holder terminals are connected to Multi-Frequency
LCR Meters(Models hp-4274A & hp-4275A),and the third specimen holder terminal is connected to earth. The
hp-4274A & hp-4275A are able to measure several parameters among them, the specimen capacitance C,
dissipation factor tan , and the phase angle ф. The HP covers a frequency range of 100Hz to 10MHz. In this
paper we use only 1KHz because the dielectric constant is generally insensitive to the frequency increasing in
the low and intermediate frequency range for non polar polymers[14].
Fig. 3: Schematic diagram for the A.C. measurements.
All the wiring was shielded to reduce the noise which is readily detectable especially in case of high
resistance measurements.
III. RESULTS AND DISCUSSION
Figure 4 shows the optical micrographs of different composites. At 1.63 Vol. % and 3.09 Vol. %
(fig.4a, 4b), the Ni particles are randomly distributed and the matrix in whose lattice sites are made of metallic
and no metallic particle sites, this means that if two metallic particles are at neighbouring lattice sites, there is
interaction, but if they are separated by at least, one non-metallic particle, there is no interaction. At 11.33
Vol. % (fig.4c), the concentration of filler sites is slightly below the threshold value, the Ni particles tend to
form conductive network so that a finite clusters are existed. At 17.22 Vol. % and 21.63 Vol. % (fig.4d, 4e), the
conductive network have been form by touching conductive particles, the conductive network consists of
infinite chains of interconnected sites.
Fig. 4: Photomicrographs of PE-Ni composites )100( :
(a) 1.63 Vol. %, (b) 3.09 Vol. %, (c) 11.33 Vol. %, (d) 17.22 Vol. % & (e) 21.63 Vol.%.
5. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
33
A. D.C. Electrical Resistivity Results
The volume resistance for composites of various volume filler concentrations (0, 1.63,3.09,4.99,11.33,
17.22 and 21.63 Vol. %) were measured during heating by the guard ring electrode method. The volume
resistivity v was determined from the equation [15]:
v =R v
L
A
……………….…………(4)
Where Rv is the volume resistance between the guarded and the bottom electrodes in ohm measured as
the ratio between desired applied test voltage and the current passing through the test sample, L is the average
thickness of the sample; A is the guarded electrode effective area.
Figure 5 shows the electrical resistivity enhancement of the composite by increasing the volume filler
concentration of the nickel filler at (T=298 k).
Fig. 5: The volume electrical resistivity, V
, of PE-Ni composites as a function of Ni concentration.
At lower concentration of the filler [0, 1.63,3.09,4.99,11.33vol.% < Фc=14.27 Vol.%], the electrical
resistivity of the composite decreases slightly; while at higher concentrations[Фc=14.27 Vol.%< 17.22 ,21.63
Vol.% ], the resistivity decreases sharply where the composite becomes a good conductive substance. The slight
decrease in resistivity may be due to the space charge effect caused by the addition of a small amount of nickel
filler, in addition to the matrix impurities existing in the used commercial polyethylene. At high filler content
[17.22 21.63 Vol.%], the amount of the interconnecting networks is increased ( see figures.4d, 4e) and the
contact resistance between the filler is decreased, and hence a good electron conduction is achieved resulting in
transformation of the polymer insulator to a good conductive polymer composite.
Figure 6 shows the variation of the electrical resistivity of various prepared composites over a
temperature range of 298 K to 348 K .At filler concentrations [0, 1.63,3.09,4.99,11.33Vol.% < Фc=14.27
Vol.%], the resistivity of the substance is high and decreases with increasing temperature, i.e. the temperature
coefficient of resistance is negative, similar to typical semiconductors. For specimens highly concentrated with
nickel filler[17.22 ,21.63 Vol.% > Фc=14.27 Vol.%], the resistivity increases slightly over the testing
temperature range and the temperature coefficient of resistance becomes positive, similar to typical metals .As a
summary of the thermal behavior of resistivity of the composites, we can say that the observed decrease of the
resistivity of low filler content specimens with temperature results from two contributions in the conduction
mechanism .The first one is hopping that arises from the space charge effect in the contact regions because of
the presence of free ions in commercial polymers, and the second is the addition of a small amount of nickel
filler. The slight increase of the electrical resistivity of highly filler composites with temperature indicates a
metallic-type conduction mechanism due to conductive networks, where the thermal expansion and result in
increasing resistivity with temperature effects cause a reduction in contacts between the fillers in the
network[7].
0.00 5.00 10.00 15.00 20.00 25.00
Volume percent of Ni (Vol.%)
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
1E+9
1E+10
1E+11
1E+12
1E+13
1E+14
1E+15
1E+16
1E+17
1E+18
1E+19
Resistivity(Ohm-cm)
At T=298 K
6. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
34
Fig. 6: The volume electrical resistivity, v , of PE-Ni composites as a function of temperature.
Figures 7&8 show the relation of Log
V
against the reciprocal temperature, from the slopes of best
fit of these curves the activation energy Ea for PE-Ni specimens can be calculated by using the equation [16]:
V = 0 exp (-
RT
Ea
)…..…………. (5)
Where ρ is the measured electrical resistivity, 0 is constant, R is the universal gas constant, and T is
the absolute temperature.
Fig. 7: Variation of the volume electrical resistivity, v , with reciprocal temperature for PE specimens of
low and medium Ni concentration(i.e. ф<фc).
290.00 300.00 310.00 320.00 330.00 340.00 350.00
Temperature (K)
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
1E+9
1E+10
1E+11
1E+12
1E+13
1E+14
1E+15
1E+16
1E+17
1E+18
1E+19
Resistivity(Ohm-cm)
Pure PE
1.63Vol.%
3.09 Vol.%
4.99 Vol.%
11.33 Vol.%
17.22 Vol.%
21.63 Vol.%
2.80 3.00 3.20 3.40
1000/T (K )
2.00
2.40
2.80
3.20
3.60
LogResistivity
17.22 Vol.%
21.63 Vol.%
7. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
35
Fig.8: Variation of the volume electrical resistivity, v , with reciprocal temperature for PE specimens of
high nickel concentration(i.e. 17.22 & 21.63 Vol.%).
Figure 9 shows the variation of the activation energy and filler content, that Ea decreases rapidly with
the filler concentration of composites. The Ea of the thermal activated rate process decreases from about 21.44
KCal.mol-1
(typical for polymers) to about 1.92 KCal. mol-1
(typical for conductive or semi-conductive
composites).The same effect has been reported by some researchers [16,17] .
It can be seen from Figure9 that there are mainly three different trends of behavior of the bulk
resistance with temperature and filler content. These three trends correspond physically to different electrical
conduction process occurring in the polymer composite and depend on their modified structure. One process
with specimens low filler concentrations [0,1.63,3.09,4.99 vol.% < Фc=14.27 Vol.%] which have high
activation energy value [21.44 KCal.mol-1
,20.2 KCal.mol-1
,17.32 KCal.mol-1
&14.84 KCal.mol-1
] result from the
existence of large resistance contact gives the composites more insulating behavior. The second process with
specimen's medium filler concentration [11.33 vol. % < Фc=14.27 Vol.%] which have medium activation
energy value [12.11 KCal.mol-1
. 1
] arises from the hopping mechanism. While the third process with specimens
high filler concentration [17.22, 21.63 Vol. % > Фc=14.27 Vol.%] which have low activation energy value
[2.16 KCal.mol-1
, 1.92 KCal.mol-1
] result from a metallic-type conduction mechanism due to conductive
networks, a case which reflects that a new conductive polymer composite is constructed from the insulating
polymer polyethylene.
Fig. 9: Variation of the activation energy, aE , of PE-Ni composites with the filler concentration.
0.00 5.00 10.00 15.00 20.00 25.00
Volume percent of Ni ( Vol.%)
0.00
5.00
10.00
15.00
20.00
25.00
ActivationEnergy(KCal/mol)
2.80 2.90 3.00 3.10 3.20 3.30 3.40
1000/T (K )
12.00
13.00
14.00
15.00
16.00
17.00
18.00
19.00
LogResistivity
Pure PE
1.63 Vol.%
3.09 Vol.%
4.99 Vol.%
11.33 Vol.%
8. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
36
B. A.C. Electrical Conductivity Results
The Variation of dielectric constant, , as function of nickel concentration and temperature is shown
in figure 10.The values of the real component , ,were calculated from the equation [18]:
=
OC
C
………………….……..… (6)
When the nickel concentration is below the threshold value (i.e.0,1.63,3.09,4.99,11.33 vol.% <
Фc=14.27 Vol.%) the , , values are low, characteristics of dielectric behaviours, the figure show that the ,
, value in first and second doped specimens are slightly lower than that of pure material. This could be
attributed to oxidation effect, which may be eliminated in higher nickel concentration. Increasing the nickel
concentration results in increasing the average number of contacts among the nickel conductive particles which
results increasing, ,value. When Ni concentration equal or above the threshold value (Фc=14.27 Vol.%)
dielectric constant of very high value approaching infinity, This case can be explained by
Bruggeman's[16]formula, when Ni concentration equal or above the threshold value (Фc=14.27 Vol.%) the long
chain emerging through connecting nickel particles will be formed ,i.e. One cluster consisting of infinite number
of metal particle will be formed. , the value in this case will be approaching One 1 , when substituting
the value in the Bruggeman's formula:
3
1
3
1
111
…..… (7)
(where 1 is the permittivity of the matrix) ,this makes dielectric constant of very high value approaching
infinity. Locking back to the figure(10) the effect of increasing temperature on the value is shown. Heating
up the specimens result in slightly increasing value of specimens of nickel concentration below the threshold
value (Фc=14.27 Vol.%) ,characteristics of semiconductor-type behaviours. Whereas for specimens Ni
concentration equal or above the threshold value (Фc=14.27 Vol.%) the , , values are decreased with
increasing temperature are characteristics of metallic-type behaviours.
Fig.10: Variation of the activation energy, aE , of PE-Ni composites with the filler concentration.
The variation of A.C electrical conductivity, AC , as function of the volumetric filler content of PE-Ni
composites in temperature range from 298 K to 348 K is shown in figure 11, The data were calculated from the
equation :
AC = 2 ƒ O …..……...……… (8)
0.00 5.00 10.00 15.00 20.00 25.00
Volume percent of Ni ( Vol.%)
0.00
5.00
10.00
15.00
20.00
25.00
ActivationEnergy(KCal/mol)
9. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
37
Where O is the permittivity of free space { O =8.854 x10-12
F. m-1
}, ƒ is the frequency and is dielectric
loss.
= . tan ………………...…...(9)
Where tan is loss angle δ [18].
The A.C conductivity, AC , of PE-Ni composites is increased slightly when the filler concentration is
below threshold value (i.e. Фc=14.27 Vol.%),this behavior can be explained by the polarization effect and
hopping, i.e. a polarization effect since the nickel concentration is insufficient to form an infinite conducting
network ,i.e. the polarization between these finite networks (clusters) as well as the hopping of the electron
between adjacent states, randomly distributed within these finite network. Whereas for specimens Ni
concentration equal or above the threshold value Фc the A.C conductivity, AC , increases sharply with
increasing the filler concentration. This increase in the A.C conductivity, AC , could be attributed possibly to
the formation of continues conducting cluster, hence a good electron conduction is achieved between the metal
particles. The behavior of the A.C conductivity, AC , as function of temperature through heating can
characterized by two kinds .The first kind occur at low filler concentration, the A.C conductivity, AC , of
samples is low essentially ,of insulating polymer, and increase slowly with increasing temperature. The second
kind at higher nickel concentration, the A.C conductivity, AC , decreases slightly over the testing temperature
range.
Fig.10: Variation of dielectric constant, , of PE-Ni composites with the filler concentration &
temperature at F=1KHz .
IV. CONCLUSIONS
From the results presented above the following conclusions may be drawn:
1. The electrical resistivity, dielectric constant and A.C conductivity of PE-Ni composites are enhanced by
increasing the filler concentration.
2. The electrical resistivity of PE-Ni composites decrease suddenly by thirteen orders of magnitude from
cm.10419.1 16
to cm.10332.9 2
when the filler concentration reach the threshold value
Фc=14.27 Vol.% .
3. The electrical resistivity, dielectric constant and A.C conductivity of PE-Ni composites showed temperature
dependence in the range under investigation.
4. The calculated activation energy for the composites was found to decrease with increasing filler
concentration
5. Addition of nickel filler alter the electrical conduction mechanism of PE-Ni composites.
0.00 5.00 10.00 15.00 20.00 25.00
Volume percent of Ni ( Vol.%)
1E+0
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
DielectricConstant
at F=1KHz
at T=298 K
at T=308 K
at T=318 K
at T=328 K
at T=338 K
at T=348 K
10. Effect of Temperature and Nickel Concentration on the Electrical and Dielectric Properties of Polye...
38
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