This study reports the fabrication and characterization of electrospun polyvinylidene fluoride (PVdF)and
polyvinylpyrrolidone (PVP) nanofiber separators embedded with carbon black nanoparticles. Different weight
percentages (0, 0.25, 0.5, 1, 2, and 4wt%) of carbon black nanoparticles were dispersed in N, Ndimethylacetamide
(DMAC) and ethanol using sonication and high-speed agitations, and then PVdF and PVP
polymers were added to the dispersions prior to the mixing and electrospinning processes. The morphological,
dielectric constant, ionic conductivity, and surface hydrophobic properties of the PVdF/PVP nanofiber
separators were analyzed using various techniques. SEM micrograms showed that the fiber diameter was
around 100-200 nm. The ionic conductivity test clearly revealed a significant increase in conductivity valueof
4.28 x 10-4
S/cm for 4 wt. % carbon black loading. However, the contact angle values were decreased with
increasing weight percent of carbon black particles. The dielectric constant was increased with the carbon black
loading. As can be seen, overall physical properties of the nanocomposite separators were significantly
enhanced as a function of carbon black inclusions, which may be useful for supercapacitor separators and other
energy storage devices
Analysis of Conducting Polymer:Polypyrrole::Part 3Debajyoti Biswas
The document discusses the measurement and importance of various response functions in composite structures made of polypyrrole (PPy) and polydimethylsiloxane (PDMS). It describes the dielectric response, viscoelastic response, and Young's modulus of these composites. The dielectric constant of PPy-PDMS composites is significantly higher than pure PDMS due to interfacial polarization. The viscoelastic properties and creep depth increase with electrolyte concentration, influenced by dopant ions. Elastic modulus increases with higher PPy nanowire concentration, providing enhanced electrical and mechanical properties while maintaining mechanical compliance.
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.
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 summarizes the fabrication, characterization, and performance evaluation of a dye-sensitized solar cell (DSSC). It was submitted as a project report by three students to fulfill their degree requirements in energy engineering at Central University of Jharkhand. The report provides background on DSSCs, describes the experimental methodology used to assemble a DSSC, and presents results and discussion of testing the fabricated DSSC. Key aspects covered include the use of TiO2 semiconductor, ruthenium dye sensitizer, carbon counter electrode, and testing under Ranchi, India weather conditions.
In tech polymer-based_nanodielectric_compositesMohsen Fayik
The document discusses polymer-based nanodielectric composites for applications requiring high energy density and high temperature dielectric materials. It describes how nanodielectric composites aim to leverage the high breakdown strength of polymers and high permittivity of ceramic fillers. The challenges of maintaining breakdown strength in multi-phase systems are discussed. Well-dispersed, low defect fillers and good particle-polymer interfaces are needed to prevent localized breakdowns. High-K ceramic or ferroelectric fillers could increase permittivity but require optimization to avoid decreasing breakdown strength.
Organic field-effect transistors (OFETs) use organic semiconductors like pentacene that can be deposited through low-cost solution processing. OFETs have the potential for applications requiring flexibility and large-area coverage. Pentacene has shown high carrier mobility, with mobilities on par with amorphous silicon in the best OFETs. While progress has been made, understanding charge transport and developing n-type and ambipolar materials remains an area of ongoing research to further improve organic electronics.
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.
Conducting polymers based nanocomposites for flexible supercapacitorsCharu Lakshmi
This document discusses conducting polymer-based nanocomposites for flexible supercapacitors. It begins by classifying supercapacitors and explaining why flexibility is needed. Nanocomposites contain at least one nano-dimensional component and can be made of polymers, ceramics, or metals. Specifically, the document explores carbon nanotube, graphene, and metal oxide reinforced polymer nanocomposites. It notes these materials increase conductivity, surface area, and flexibility while reducing weight and cost. The document concludes that incorporating carbon nanomaterials that form networks while retaining mesoporosity, along with two-dimensional materials and open structures, can further improve supercapacitor performance.
Analysis of Conducting Polymer:Polypyrrole::Part 3Debajyoti Biswas
The document discusses the measurement and importance of various response functions in composite structures made of polypyrrole (PPy) and polydimethylsiloxane (PDMS). It describes the dielectric response, viscoelastic response, and Young's modulus of these composites. The dielectric constant of PPy-PDMS composites is significantly higher than pure PDMS due to interfacial polarization. The viscoelastic properties and creep depth increase with electrolyte concentration, influenced by dopant ions. Elastic modulus increases with higher PPy nanowire concentration, providing enhanced electrical and mechanical properties while maintaining mechanical compliance.
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.
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 summarizes the fabrication, characterization, and performance evaluation of a dye-sensitized solar cell (DSSC). It was submitted as a project report by three students to fulfill their degree requirements in energy engineering at Central University of Jharkhand. The report provides background on DSSCs, describes the experimental methodology used to assemble a DSSC, and presents results and discussion of testing the fabricated DSSC. Key aspects covered include the use of TiO2 semiconductor, ruthenium dye sensitizer, carbon counter electrode, and testing under Ranchi, India weather conditions.
In tech polymer-based_nanodielectric_compositesMohsen Fayik
The document discusses polymer-based nanodielectric composites for applications requiring high energy density and high temperature dielectric materials. It describes how nanodielectric composites aim to leverage the high breakdown strength of polymers and high permittivity of ceramic fillers. The challenges of maintaining breakdown strength in multi-phase systems are discussed. Well-dispersed, low defect fillers and good particle-polymer interfaces are needed to prevent localized breakdowns. High-K ceramic or ferroelectric fillers could increase permittivity but require optimization to avoid decreasing breakdown strength.
Organic field-effect transistors (OFETs) use organic semiconductors like pentacene that can be deposited through low-cost solution processing. OFETs have the potential for applications requiring flexibility and large-area coverage. Pentacene has shown high carrier mobility, with mobilities on par with amorphous silicon in the best OFETs. While progress has been made, understanding charge transport and developing n-type and ambipolar materials remains an area of ongoing research to further improve organic electronics.
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.
Conducting polymers based nanocomposites for flexible supercapacitorsCharu Lakshmi
This document discusses conducting polymer-based nanocomposites for flexible supercapacitors. It begins by classifying supercapacitors and explaining why flexibility is needed. Nanocomposites contain at least one nano-dimensional component and can be made of polymers, ceramics, or metals. Specifically, the document explores carbon nanotube, graphene, and metal oxide reinforced polymer nanocomposites. It notes these materials increase conductivity, surface area, and flexibility while reducing weight and cost. The document concludes that incorporating carbon nanomaterials that form networks while retaining mesoporosity, along with two-dimensional materials and open structures, can further improve supercapacitor performance.
This document provides an overview of electrospinning functional materials for biomedical applications and tissue engineering. It discusses how electrospinning can be used to create ultrathin polymer fibers with properties that mimic the extracellular matrix, including large surface area to volume ratio and control over mechanical properties. The document also describes how electrospinning parameters can be modified to control fiber properties, and how fiber surfaces can be modified through treatments like plasma treatment, chemical modification, and immobilization of bioactive molecules to enhance cell interactions.
This document provides a short review of polypyrrole synthesis and the factors affecting its electrical conductivity. It discusses various methods for synthesizing polypyrrole, including chemical oxidative polymerization, electrochemical polymerization, and ultrasonic-assisted polymerization. Chemical oxidative polymerization is the most common method due to its ability to produce large quantities of polypyrrole. The conductivity of polypyrrole is influenced by synthesis parameters like the oxidant, dopants, and reaction conditions. Despite extensive research, no prior study has comprehensively covered both polypyrrole fabrication techniques and the key factors that determine its electrical conductivity.
Organic electronics is a branch of electronics dealing with conductive polymers and small molecules. Conductive polymers are lighter, more flexible, and less expensive than inorganic conductors, making them desirable for many applications. Significant developments include the discovery that doping polyacetylene with iodine increases its conductivity by 12 orders of magnitude, and the invention of the organic light-emitting diode and organic photovoltaic cell. Organic electronics utilize carbon-based materials and offer advantages over traditional silicon-based electronics such as lower cost, mechanical flexibility, and lower processing temperatures.
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
Dye-sensitized solar cells (DSSCs) have gained increasing attention
with regard to photovoltaic devices, because of their low
cost and simple fabrication methods; they are mostly investigated
in indoor light-harvesting and portable applications. The
focus has been on three main parameters of photovoltaic devices,
that is, lifetime, and cost effectiveness. A DSSC consists of
four prominent components including a photoanode, a photosensitizer,
a redox electrolyte, and a counter electrode. The
counter electrode is a crucial component, in which triiodide is
reduced to iodide by electrons flowing through the external
circuit. An effective approach to improve the performance of
a counter electrode is to enhance the power conversion efficiency
and to reduce the cost of the device. Platinum-coated
conducting glass electrodes give the best performance, but
their high cost and the scarcity of platinum restricts large-scale
application in DSSCs. This has prompted researchers to develop
low-costing platinum-free electrodes for DSSCs. In this
review, we focus mainly on counter electrode materials for the
electrocatalytic redox reaction for the I¢/I¢
3 electrolyte, and
apart from this, other counter electrode materials for iodinefree
redox electrolytes are discussed. Different counter electrode
materials are highlighted in different categories such as
carbon materials, conducting polymers, oxide and sulfide materials,
transition-metal nitrides and carbides, and composite
materials. The stability of counter electrodes in DSSCs is also
presented.
This document summarizes a study on the electrical properties of electrodeposited zinc-copper-telluride (ZnCuTe) ternary nanowires embedded in polycarbonate membranes. Scanning electron microscopy confirmed the formation of uniform diameter nanowires equal to the pore diameters of 200nm, 100nm, and 50nm templates used. Electrical measurements found the nanowires exhibited linear and ohmic characteristics. Larger diameter nanowires showed higher electron transport than smaller ones. Temperature-dependent measurements from 308K-423K revealed electrical conductivity increased with temperature and decreased with smaller nanowire size, with ZnCuTe nanowires exhibiting negative temperature coefficients of resistance.
This PhD thesis investigates the integration of YBa2Cu3O7-x (YBCO) superconducting films with silicon substrates using buffer layers. Cerium oxide (CeO2) and yttria-stabilized zirconia (YSZ) are chosen as buffer layers due to their structural compatibility with silicon and YBCO. Various multilayer structures including CeO2/Si, YSZ/Si, CeO2/YSZ/Si, YBCO/CeO2/Si and YBCO/CeO2/YSZ/Si are grown using magnetron sputtering and characterized structurally and electrically. The goal is to optimize the structural properties at the interfaces and
Organic electronics such as organic LEDs (OLEDs) and organic photovoltaics (OPVs) offer advantages over traditional electronics like being lightweight, flexible, and having low-cost production. The document discusses the electronic structures of organic materials used in these applications and how they enable charge transport. It reviews the state-of-the-art in OLED and OPV technologies and processing techniques like solution processing and vapor deposition. Photocrosslinking is highlighted as a method to improve device performance. Challenges in improving material properties, device efficiencies, and reducing costs are also outlined.
Tungsten oxide nanostructures for energy storage and field emission applicationseSAT Journals
Abstract
Single crystalline tungsten oxide (WO3) nanorods were synthesized over flexible carbon fabric via simple hydrothermal method
and used directly as supercapacitor (SC) electrode. WO3 nanorods with their peculiar structural features over the fabric exhibited
excellent electrochemical performance with a high specific capacitance of 481.34 F/g at scan speed 10 mV s-1. Additionally, these
nanorods showed propitious as electron field emitters where the registered turn on field and estimated field enhancement values
were 3.6 V/μm and 4550 respectively. These results indicate that present unique WO3 nanorods arrays over flexible carbon cloth
substrate are a promising candidate for constructing high-performance solid state electronics and electrochromic devices.
Key Words: Semiconductor compounds, Nanorods, carbon fabric, Supercapacitors, Field emitters and arrays
Pentacene-Based Organic Field-Effect Transistors: Analytical Model and Simula...IDES Editor
Organic Field-Effect Transistors, OFETs, attract
much interest recently and their proficiency and hence
applications are being enhanced increasingly. However, only
analytical model of old field-effect transistors, developed for
silicon-based transistors, and their relevant numerical
analyses have been used for such devices, so far. Increasing
precision of such models and numerical methods are essential
now in order to modify OFETs and propose more effective
models and methods. This study pegs at comparing current
analytical model, simulation methods and experiment data
and their fitness with each other. Certainly, four aspects of
results of three abovementioned approaches were examined
comparatively: sub-threshold slope, on-state drain current,
threshold voltage and carrier mobility. We embark to analyze
related experiment data of OFETs made by pentacene, as the
organic material, along with various organic gate insulators
including CyEP, PVP, PMMA, Parylene-C and Polyimide and
then to offer their results, comparatively.
Electrospinning, a broadly used technology for electrostatic fiber formation which utilizes electrical forces to produce polymer fiber with diameters ranging from 2 nm to several micrometers using polymer solutions of both natural and synthetic polymers.
The electrical profiles of the renewable polymer graphite (PG) composites upon ultra violet (UV) curing were investigated. Renewable PG films were prepared by mixing with varying weight percent of graphite (with an increment of 5 wt. % of prepared graphite) up to 30 wt.% and crosslinker. Then, the composites solution was slip casted and cured upon stimulated UV irradiation (UV accelerated weathering tester) at different time exposure (up to 1000 hours) was applied. Small changes on the functional groups of the composites were observed due to UV exposure time by Fourier Transform Infrared Spectroscopy (FTIR). Suggesting that chemical crosslink and chain scissions occurred within renewable polymer graphite composites. Further electrical profile through two point probe and four point probe method recorded visibly fluctuating values for both resistivity and conductivity within its composites range. Proposed here that the removal of organic contaminants and weak materials form both renewable polymer and graphite particles through the UV curing may have an effect on the formation of conductive network stability.
This document discusses the use of carbon nanotubes in solar panels to improve efficiency. It provides background on solar panels and carbon nanotubes, explaining their properties. It then details the history of carbon nanotube solar panels, how they are constructed, and how double-walled carbon nanotubes can be used as both light absorbers and charge carriers. Using carbon nanotubes allows solar panels to utilize infrared light and increase efficiency to potentially 80%. Their properties like high mobility and strength make them suitable for more efficient solar energy conversion.
Analysis of Conducting Polymer:Polypyrrole::Part 1Debajyoti Biswas
Polypyrrole is a conducting polymer that can be synthesized through oxidation of its monomer, pyrrole. When oxidized, polypyrrole becomes conductive and has applications in electronic devices and chemical sensors. It has potential uses for radar absorbing materials and as a vehicle for drug delivery. Polypyrrole's conductivity ranges from 2-100 S/cm and depends on the reagents and conditions used during oxidation. It is being investigated for applications such as artificial muscles due to its ability to swell and accommodate ions through doping.
This document summarizes recent developments in nanostructured paper for flexible energy applications. It discusses how cellulose fibers can be disintegrated into nano fibrillated cellulose (NFC) to create paper with a hierarchical structure at different length scales. Conductive materials like carbon nanotubes (CNTs), graphene, and conductive polymers can be integrated into the paper to enable applications in electrical energy storage. Specifically, CNTs and NFC can be uniformly mixed at the nanoscale to create highly conductive and porous composite electrodes. Conductive paper maintains good mechanical properties and flexibility compared to metal-coated papers.
This document discusses organic field effect transistors (OFETs). It describes how the first OFET was invented in 1986 using a polythiophene film, and four years later one was made using a small conjugated molecule called sexithiophene. OFETs have three terminals - source, drain, and gate - as well as a semiconductor layer and insulating layer between the semiconductor and gate. There are two common configurations: top contact, where electrodes are deposited on top of the organic material, and bottom contact, where electrodes are deposited on the dielectric before the organic layer. OFETs operate by applying a voltage to the gate to induce an electric field and form an accumulation layer of charges at the semiconductor-dielectric interface. Characteristics include
Analysis of Stress and Deflection of Cantilever Beam and its Validation Using...IJERA Editor
This document analyzes the stress and deflection of a cantilever beam under different loading conditions using analytical calculations and finite element analysis in ANSYS. Analytical calculations are performed for three cases: a point load at the free end, uniform distributed load, and uniform varying load. Computational analysis using 8-node brick and 10-node tetrahedral elements in ANSYS is conducted for the same cases. Results show that the 10-node tetrahedral element more accurately calculates deflection while the 8-node brick element better calculates stresses when compared to analytical solutions.
A Survey on Hidden Markov Model (HMM) Based Intention Prediction Techniques IJERA Editor
The extensive use of virtualization in implementing cloud infrastructure brings unrivaled security concerns for
cloud tenants or customers and introduces an additional layer that itself must be completely configured and
secured. Intruders can exploit the large amount of cloud resources for their attacks.
This paper discusses two approaches In the first three features namely ongoing attacks, autonomic prevention
actions, and risk measure are Integrated to our Autonomic Cloud Intrusion Detection Framework (ACIDF) as
most of the current security technologies do not provide the essential security features for cloud systems such as
early warnings about future ongoing attacks, autonomic prevention actions, and risk measure. The early
warnings are signaled through a new finite State Hidden Markov prediction model that captures the interaction
between the attackers and cloud assets. The risk assessment model measures the potential impact of a threat on
assets given its occurrence probability. The estimated risk of each security alert is updated dynamically as the
alert is correlated to prior ones. This enables the adaptive risk metric to evaluate the cloud’s overall security
state. The prediction system raises early warnings about potential attacks to the autonomic component,
controller. Thus, the controller can take proactive corrective actions before the attacks pose a serious security
risk to the system.
In another Attack Sequence Detection (ASD) approach as Tasks from different users may be performed on the
same machine. Therefore, one primary security concern is whether user data is secure in cloud. On the other
hand, hacker may facilitate cloud computing to launch larger range of attack, such as a request of port scan in
cloud with multiple virtual machines executing such malicious action. In addition, hacker may perform a
sequence of attacks in order to compromise his target system in cloud, for example, evading an easy-to-exploit
machine in a cloud and then using the previous compromised to attack the target. Such attack plan may be
stealthy or inside the computing environment, so intrusion detection system or firewall has difficulty to identify
it.
Effect of Fines on Liquefaction Resistance in Fine Sand and Silty SandIJERA Editor
It is required to recognize the conditions that exist in a soil deposit before an earthquake in order to identify
liquefaction. Soil is basically an assemblage of many soil particles which stay in contact with many neighboring
soil. The contact forces produced by the weight of the overlying particles holds individual soil particle in its
place and provide strength. Occurrence of liquefaction is the result of rapid load application and break down of
the loose and saturated sand and the loosely-packed individual soil particles tries to move into a denser
configuration. However, there is not enough time for the pore-water of the soil to be squeezed out in case of
earthquake. Instead, the water is trapped and prevents the soil particles from moving closer together. Thus, there
is an increase in water pressure which reduces the contact forces between the individual soil particles causing
softening and weakening of soil deposit. In extreme conditions, the soil particles may lose contact with each
other due to the increased pore-water pressure. In such cases, the soil will have very little strength, and will
behave more like a liquid than a solid - hence, the name "liquefaction".
Identifying Structures in Social Conversations in NSCLC Patients through the ...IJERA Editor
The exploration of social conversations for addressing patient’s needs is an important analytical task in which
many scholarly publications are contributing to fill the knowledge gap in this area. The main difficulty remains
the inability to turn such contributions into pragmatic processes the pharmaceutical industry can leverage in
order to generate insight from social media data, which can be considered as one of the most challenging source
of information available today due to its sheer volume and noise. This study is based on the work by Scott
Spangler and Jeffrey Kreulen and applies it to identify structure in social media through the extraction of a
topical taxonomy able to capture the latent knowledge in social conversations in health-related sites. The
mechanism for automatically identifying and generating a taxonomy from social conversations is developed and
pressured tested using public data from media sites focused on the needs of cancer patients and their families.
Moreover, a novel method for generating the category’s label and the determination of an optimal number of
categories is presented which extends Scott and Jeffrey’s research in a meaningful way. We assume the reader is
familiar with taxonomies, what they are and how they are used.
This document provides an overview of electrospinning functional materials for biomedical applications and tissue engineering. It discusses how electrospinning can be used to create ultrathin polymer fibers with properties that mimic the extracellular matrix, including large surface area to volume ratio and control over mechanical properties. The document also describes how electrospinning parameters can be modified to control fiber properties, and how fiber surfaces can be modified through treatments like plasma treatment, chemical modification, and immobilization of bioactive molecules to enhance cell interactions.
This document provides a short review of polypyrrole synthesis and the factors affecting its electrical conductivity. It discusses various methods for synthesizing polypyrrole, including chemical oxidative polymerization, electrochemical polymerization, and ultrasonic-assisted polymerization. Chemical oxidative polymerization is the most common method due to its ability to produce large quantities of polypyrrole. The conductivity of polypyrrole is influenced by synthesis parameters like the oxidant, dopants, and reaction conditions. Despite extensive research, no prior study has comprehensively covered both polypyrrole fabrication techniques and the key factors that determine its electrical conductivity.
Organic electronics is a branch of electronics dealing with conductive polymers and small molecules. Conductive polymers are lighter, more flexible, and less expensive than inorganic conductors, making them desirable for many applications. Significant developments include the discovery that doping polyacetylene with iodine increases its conductivity by 12 orders of magnitude, and the invention of the organic light-emitting diode and organic photovoltaic cell. Organic electronics utilize carbon-based materials and offer advantages over traditional silicon-based electronics such as lower cost, mechanical flexibility, and lower processing temperatures.
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
Dye-sensitized solar cells (DSSCs) have gained increasing attention
with regard to photovoltaic devices, because of their low
cost and simple fabrication methods; they are mostly investigated
in indoor light-harvesting and portable applications. The
focus has been on three main parameters of photovoltaic devices,
that is, lifetime, and cost effectiveness. A DSSC consists of
four prominent components including a photoanode, a photosensitizer,
a redox electrolyte, and a counter electrode. The
counter electrode is a crucial component, in which triiodide is
reduced to iodide by electrons flowing through the external
circuit. An effective approach to improve the performance of
a counter electrode is to enhance the power conversion efficiency
and to reduce the cost of the device. Platinum-coated
conducting glass electrodes give the best performance, but
their high cost and the scarcity of platinum restricts large-scale
application in DSSCs. This has prompted researchers to develop
low-costing platinum-free electrodes for DSSCs. In this
review, we focus mainly on counter electrode materials for the
electrocatalytic redox reaction for the I¢/I¢
3 electrolyte, and
apart from this, other counter electrode materials for iodinefree
redox electrolytes are discussed. Different counter electrode
materials are highlighted in different categories such as
carbon materials, conducting polymers, oxide and sulfide materials,
transition-metal nitrides and carbides, and composite
materials. The stability of counter electrodes in DSSCs is also
presented.
This document summarizes a study on the electrical properties of electrodeposited zinc-copper-telluride (ZnCuTe) ternary nanowires embedded in polycarbonate membranes. Scanning electron microscopy confirmed the formation of uniform diameter nanowires equal to the pore diameters of 200nm, 100nm, and 50nm templates used. Electrical measurements found the nanowires exhibited linear and ohmic characteristics. Larger diameter nanowires showed higher electron transport than smaller ones. Temperature-dependent measurements from 308K-423K revealed electrical conductivity increased with temperature and decreased with smaller nanowire size, with ZnCuTe nanowires exhibiting negative temperature coefficients of resistance.
This PhD thesis investigates the integration of YBa2Cu3O7-x (YBCO) superconducting films with silicon substrates using buffer layers. Cerium oxide (CeO2) and yttria-stabilized zirconia (YSZ) are chosen as buffer layers due to their structural compatibility with silicon and YBCO. Various multilayer structures including CeO2/Si, YSZ/Si, CeO2/YSZ/Si, YBCO/CeO2/Si and YBCO/CeO2/YSZ/Si are grown using magnetron sputtering and characterized structurally and electrically. The goal is to optimize the structural properties at the interfaces and
Organic electronics such as organic LEDs (OLEDs) and organic photovoltaics (OPVs) offer advantages over traditional electronics like being lightweight, flexible, and having low-cost production. The document discusses the electronic structures of organic materials used in these applications and how they enable charge transport. It reviews the state-of-the-art in OLED and OPV technologies and processing techniques like solution processing and vapor deposition. Photocrosslinking is highlighted as a method to improve device performance. Challenges in improving material properties, device efficiencies, and reducing costs are also outlined.
Tungsten oxide nanostructures for energy storage and field emission applicationseSAT Journals
Abstract
Single crystalline tungsten oxide (WO3) nanorods were synthesized over flexible carbon fabric via simple hydrothermal method
and used directly as supercapacitor (SC) electrode. WO3 nanorods with their peculiar structural features over the fabric exhibited
excellent electrochemical performance with a high specific capacitance of 481.34 F/g at scan speed 10 mV s-1. Additionally, these
nanorods showed propitious as electron field emitters where the registered turn on field and estimated field enhancement values
were 3.6 V/μm and 4550 respectively. These results indicate that present unique WO3 nanorods arrays over flexible carbon cloth
substrate are a promising candidate for constructing high-performance solid state electronics and electrochromic devices.
Key Words: Semiconductor compounds, Nanorods, carbon fabric, Supercapacitors, Field emitters and arrays
Pentacene-Based Organic Field-Effect Transistors: Analytical Model and Simula...IDES Editor
Organic Field-Effect Transistors, OFETs, attract
much interest recently and their proficiency and hence
applications are being enhanced increasingly. However, only
analytical model of old field-effect transistors, developed for
silicon-based transistors, and their relevant numerical
analyses have been used for such devices, so far. Increasing
precision of such models and numerical methods are essential
now in order to modify OFETs and propose more effective
models and methods. This study pegs at comparing current
analytical model, simulation methods and experiment data
and their fitness with each other. Certainly, four aspects of
results of three abovementioned approaches were examined
comparatively: sub-threshold slope, on-state drain current,
threshold voltage and carrier mobility. We embark to analyze
related experiment data of OFETs made by pentacene, as the
organic material, along with various organic gate insulators
including CyEP, PVP, PMMA, Parylene-C and Polyimide and
then to offer their results, comparatively.
Electrospinning, a broadly used technology for electrostatic fiber formation which utilizes electrical forces to produce polymer fiber with diameters ranging from 2 nm to several micrometers using polymer solutions of both natural and synthetic polymers.
The electrical profiles of the renewable polymer graphite (PG) composites upon ultra violet (UV) curing were investigated. Renewable PG films were prepared by mixing with varying weight percent of graphite (with an increment of 5 wt. % of prepared graphite) up to 30 wt.% and crosslinker. Then, the composites solution was slip casted and cured upon stimulated UV irradiation (UV accelerated weathering tester) at different time exposure (up to 1000 hours) was applied. Small changes on the functional groups of the composites were observed due to UV exposure time by Fourier Transform Infrared Spectroscopy (FTIR). Suggesting that chemical crosslink and chain scissions occurred within renewable polymer graphite composites. Further electrical profile through two point probe and four point probe method recorded visibly fluctuating values for both resistivity and conductivity within its composites range. Proposed here that the removal of organic contaminants and weak materials form both renewable polymer and graphite particles through the UV curing may have an effect on the formation of conductive network stability.
This document discusses the use of carbon nanotubes in solar panels to improve efficiency. It provides background on solar panels and carbon nanotubes, explaining their properties. It then details the history of carbon nanotube solar panels, how they are constructed, and how double-walled carbon nanotubes can be used as both light absorbers and charge carriers. Using carbon nanotubes allows solar panels to utilize infrared light and increase efficiency to potentially 80%. Their properties like high mobility and strength make them suitable for more efficient solar energy conversion.
Analysis of Conducting Polymer:Polypyrrole::Part 1Debajyoti Biswas
Polypyrrole is a conducting polymer that can be synthesized through oxidation of its monomer, pyrrole. When oxidized, polypyrrole becomes conductive and has applications in electronic devices and chemical sensors. It has potential uses for radar absorbing materials and as a vehicle for drug delivery. Polypyrrole's conductivity ranges from 2-100 S/cm and depends on the reagents and conditions used during oxidation. It is being investigated for applications such as artificial muscles due to its ability to swell and accommodate ions through doping.
This document summarizes recent developments in nanostructured paper for flexible energy applications. It discusses how cellulose fibers can be disintegrated into nano fibrillated cellulose (NFC) to create paper with a hierarchical structure at different length scales. Conductive materials like carbon nanotubes (CNTs), graphene, and conductive polymers can be integrated into the paper to enable applications in electrical energy storage. Specifically, CNTs and NFC can be uniformly mixed at the nanoscale to create highly conductive and porous composite electrodes. Conductive paper maintains good mechanical properties and flexibility compared to metal-coated papers.
This document discusses organic field effect transistors (OFETs). It describes how the first OFET was invented in 1986 using a polythiophene film, and four years later one was made using a small conjugated molecule called sexithiophene. OFETs have three terminals - source, drain, and gate - as well as a semiconductor layer and insulating layer between the semiconductor and gate. There are two common configurations: top contact, where electrodes are deposited on top of the organic material, and bottom contact, where electrodes are deposited on the dielectric before the organic layer. OFETs operate by applying a voltage to the gate to induce an electric field and form an accumulation layer of charges at the semiconductor-dielectric interface. Characteristics include
Analysis of Stress and Deflection of Cantilever Beam and its Validation Using...IJERA Editor
This document analyzes the stress and deflection of a cantilever beam under different loading conditions using analytical calculations and finite element analysis in ANSYS. Analytical calculations are performed for three cases: a point load at the free end, uniform distributed load, and uniform varying load. Computational analysis using 8-node brick and 10-node tetrahedral elements in ANSYS is conducted for the same cases. Results show that the 10-node tetrahedral element more accurately calculates deflection while the 8-node brick element better calculates stresses when compared to analytical solutions.
A Survey on Hidden Markov Model (HMM) Based Intention Prediction Techniques IJERA Editor
The extensive use of virtualization in implementing cloud infrastructure brings unrivaled security concerns for
cloud tenants or customers and introduces an additional layer that itself must be completely configured and
secured. Intruders can exploit the large amount of cloud resources for their attacks.
This paper discusses two approaches In the first three features namely ongoing attacks, autonomic prevention
actions, and risk measure are Integrated to our Autonomic Cloud Intrusion Detection Framework (ACIDF) as
most of the current security technologies do not provide the essential security features for cloud systems such as
early warnings about future ongoing attacks, autonomic prevention actions, and risk measure. The early
warnings are signaled through a new finite State Hidden Markov prediction model that captures the interaction
between the attackers and cloud assets. The risk assessment model measures the potential impact of a threat on
assets given its occurrence probability. The estimated risk of each security alert is updated dynamically as the
alert is correlated to prior ones. This enables the adaptive risk metric to evaluate the cloud’s overall security
state. The prediction system raises early warnings about potential attacks to the autonomic component,
controller. Thus, the controller can take proactive corrective actions before the attacks pose a serious security
risk to the system.
In another Attack Sequence Detection (ASD) approach as Tasks from different users may be performed on the
same machine. Therefore, one primary security concern is whether user data is secure in cloud. On the other
hand, hacker may facilitate cloud computing to launch larger range of attack, such as a request of port scan in
cloud with multiple virtual machines executing such malicious action. In addition, hacker may perform a
sequence of attacks in order to compromise his target system in cloud, for example, evading an easy-to-exploit
machine in a cloud and then using the previous compromised to attack the target. Such attack plan may be
stealthy or inside the computing environment, so intrusion detection system or firewall has difficulty to identify
it.
Effect of Fines on Liquefaction Resistance in Fine Sand and Silty SandIJERA Editor
It is required to recognize the conditions that exist in a soil deposit before an earthquake in order to identify
liquefaction. Soil is basically an assemblage of many soil particles which stay in contact with many neighboring
soil. The contact forces produced by the weight of the overlying particles holds individual soil particle in its
place and provide strength. Occurrence of liquefaction is the result of rapid load application and break down of
the loose and saturated sand and the loosely-packed individual soil particles tries to move into a denser
configuration. However, there is not enough time for the pore-water of the soil to be squeezed out in case of
earthquake. Instead, the water is trapped and prevents the soil particles from moving closer together. Thus, there
is an increase in water pressure which reduces the contact forces between the individual soil particles causing
softening and weakening of soil deposit. In extreme conditions, the soil particles may lose contact with each
other due to the increased pore-water pressure. In such cases, the soil will have very little strength, and will
behave more like a liquid than a solid - hence, the name "liquefaction".
Identifying Structures in Social Conversations in NSCLC Patients through the ...IJERA Editor
The exploration of social conversations for addressing patient’s needs is an important analytical task in which
many scholarly publications are contributing to fill the knowledge gap in this area. The main difficulty remains
the inability to turn such contributions into pragmatic processes the pharmaceutical industry can leverage in
order to generate insight from social media data, which can be considered as one of the most challenging source
of information available today due to its sheer volume and noise. This study is based on the work by Scott
Spangler and Jeffrey Kreulen and applies it to identify structure in social media through the extraction of a
topical taxonomy able to capture the latent knowledge in social conversations in health-related sites. The
mechanism for automatically identifying and generating a taxonomy from social conversations is developed and
pressured tested using public data from media sites focused on the needs of cancer patients and their families.
Moreover, a novel method for generating the category’s label and the determination of an optimal number of
categories is presented which extends Scott and Jeffrey’s research in a meaningful way. We assume the reader is
familiar with taxonomies, what they are and how they are used.
Improved Reliability Memory’s Module Structure for Critical Application Systems IJERA Editor
For critical application systems, which control nuclear power plants and other energy facilities, air, sea and
ground vehicles, the needs to ensure their operability are increased. To fulfill this requirement, it is necessary to
increase the technical readiness coefficient, the value of which increases with decreasing recovery time control
system in case of fault of its constituent units. The main control system components critical applications are
memory devices, which store programs and used for performing algorithms control. Semiconductor memory
modules with automatic recovery functionality at multiple faults can be used in systems of critical applications
protection and management where the use of fault-tolerant digital devices is a necessity due to the inability of
traditional methods of repair by replacing the failed elements.
Online Votes and Fund analysis for political parties with Data SecurityIJERA Editor
With the traditional fund management and vote bank analysis, it was difficult to manage and analyze the details
of fund collection and vote bank where all the records and relevant details were maintained at manual level,
which is always a troublesome process. To overcome these problems, an online web application is being
developed which provide the means of maintaining the funds gathered, Analyzing vote bank generated, Analysis
of area wise grievances and providing data security using encryption algorithms like Advanced Encryption
standard enabling two step verification mechanisms such as legitimate user authentication and secured access to
data. Also various reports will be generated depicting graphical assessment of information gathered.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
The Effect of Chitosan, Sorbitol, and Heating Temperature Bioplastic Solution...IJERA Editor
Nowadays, bioplastics is often researched to substitute the conventional plastics because bioplastics come from
raw materials that is very enviromentally friendly and bioplastics is degradable. The purposes of this research are
to know the characteristics of starch from durian seed and to know the effect of additional chitosan as filler,
sorbitol as plasticizer, and variation of heating temperature bioplastic solution on mechanical properties of
bioplastics. In process, the ratio between durian-seed starch and chitosan are 7:3, 8:2 and 9:1 gram, while the
concentration of sorbitol are 20%, 30%, and 40%. The heating temperature of bioplastic solution is varied at 70
oC, 80 oC and 90 oC. Result of bioplastic FTIR shows there is increation of wave number N-H from 1570.06 cm-
1
to 1589.34 cm-1 and O-H from 3352.28 cm-1
to 3653.18 cm-1
. The characteristic of durian seed starch has water
content 12.73%, ash content 0,51%, starch content 76,65%, amylose content 22.34%, amylopectin content
54.32%, protein content 11.61%, and fat content 0.61%. Optimum mechanical properties of bioplastic from
durian seed starch occurs in heating temperature 70 oC with composition between durian-seed starch and
chitosan is 7:3 grams and sorbitol 20.0 grams.
A Framework for Curved Videotext Detection and ExtractionIJERA Editor
Proposed approach explores a new framework for curved video text detection and extraction. The algorithm first
utilizes a Gaussian filter based Color Edge Enhancement followed by a Gray level Co-occurrence matrix feature
extraction method for text detection. Secondly, a Connected Component filtering method is utilized to generate
clear localization result and at last, a Round Scan method is performed to extract curved text and generate binary
result for recognition by OCR. Experiments on various curved video data and Hua’s horizontal video text
dataset shows the effectiveness and robustness of the proposed method.
Assessment of Performance Characteristic of Solar Air Heater with Assorted Ge...IJERA Editor
Artificial roughness is an efficient way for increasing the heat transfer rate in solar air heater with the
corresponding improvement in its thermal performance. A viscous sub-layer is responsible for the low heat
transfer coefficient between absorber plate and flowing air. Repeated ribs in form of artificial roughness are an
effective way to increase the heat transfer rate and improving the performance of solar air heater. Artificial
roughness of the absorber plate is much economical and effective way to improve the thermal performance of
solar air heater. Several investigators have done various investigations to improve heat transfer coefficient with
little penalty of friction factor. They have also developed different correlation for heat transfer coefficient and
friction factor. The correlations developed for heat transfer and friction factor by various investigators have been
reviewed and presented.
Nanofluid Flow past an Unsteady Permeable Shrinking Sheet with Heat Source or...IJERA Editor
The consideration of nanofluids has been paid a good attention on the forced convection; the analysis focusing
nanofluids in porous media are limited in literature. Thus, the use of nanofluids in porous media would be very
much helpful in heat and mass transfer enhancement. In this paper, the influence of variable suction, Newtonian
heating and heat source or sink heat and mass transfer over a permeable shrinking sheet embedded in a porous
medium filled with a nanofluid is discussed in detail. The solutions of the nonlinear equations governing the
velocɨty, temperature and concentration profiles are solved numerically using Runge-Kutta Gill procedure
together with shooting method and graphical results for the resulting parameters are displayed and discussed.
The influence of the physical parameters on skin-friction coefficient, local Nusselt number and local Sherwood
number are shown in a tabulated form.
Absorption Reduction Capacity with Chromium (Cr) and Cadmium (Cd) Contaminant...IJERA Editor
This study aims to analyze the large of reduction capacity of chromium metals and cadmium in the soil compost
media and absorption capacity of chrome and cadmium in phytoremediation process of vetiver; to compare the
reduction-absorption capacities of chromium and cadmium metals in phytoremediation process of vetiver
(Vetivera zizanioides). The study was carried out for 2 months with a range of sampling every 7 days, and then
analyzed by using Atomic Absorption Spectrophotometer (AAS). Contaminants used as artificial contaminants
containing heavy metals chromium (Cr) and cadmium (Cd). This study is an experimental research includes two
variables. First, the variations of Cr concentrations used were 400 ppm, 600 ppm and 800 ppm and Cd
concentrations used were 40 ppm, 60 ppm, 800 ppm. Secondly, the variations of total plant are 3, 6, and 9 plant.
The period of observation is made every week. Planting media used is compost soil with compost and clay
composition of 20%, 30% and 40%. The results of study showed that there are a significant relationship between
the reduction capacity of Cr and Cd of compost soil and the absorption capacity of Cr and Cd for vetiver
(Vetiveria zizanioides). The higher of Cr and Cd decreases in soil followed by increased levels of Cr and Cd in
vetiver (Vetiveria zizanioides). The capacity of Cr reduction varies between 57% - 86% and Cd 36% - 64%
where as the absorption capacity of vetiver on Cr between 38% - 75% and Cd between 34%-74%. The capacity
of reduction-absorption of Cr is relatively higher than Cd in phytoremediation process of vetiver.
Ergonomic Evaluation of the Angle of Abduction in Laptops EnvironmentIJERA Editor
Laptops in 21st century are an integral part of every professional in vivid fields. Off late there has been
emergence of several ergonomic injuries such as repetitive strain injuries (RSIs) due to extensive usage of
laptops, which can be closely linked with applied force and postures. This study investigated the effect of
various angles of keyboard on the applied force and motor action plus response time while performing five
distinct tasks. On the basis of literature two different laptops were selected for performing different tasks. For
each case the three levels of platform angle were considered as 0°, 5°, and 10°. Male subjects were selected to
perform five distinct tasks for each platform angle for both laptops. The force applied (in milli-volts) and the
motor action plus response time (milli-seconds) were recorded using an oscilloscope. The data collected were
analyzed through ANOVA using MINITAB software. The abduction angle with the least mean response time
and applied force were considered as the best from ergonomics viewpoint. The ANOVA results showed that the
angle of abduction for both laptops (small and large) do have significant effect on applied force but not on motor
action plus response time. The analysis of results indicate that 10° angle of abduction in case of small laptops
should be applied to minimize musculoskeletal disorder and repetitive strain injuries.
Research relevance: This work suggests that those responsible for the function and operation of laptops would
have to redesign the system to reduce injuries, as far as musculoskeletal disorder, repetitive strain injuries and
other related problems are concerned. The present work can be quite useful for the system designers of
tomorrow.
Performance Analysis of Enhanced Opportunistic Minimum Cost Routingin Mobile ...IJERA Editor
Mobile Ad-Hoc Network (MANET) is a collection of wireless mobile nodes forming a temporary network with
infrastructure less environment to establish a data transmission between nodes within the network. A routing
protocol is used to discover routes between nodes. In this paper, we study the three existing routing protocols
namely AODV, DSDV and DSR to analyze theirperformance based on set of parameters.AODV and DSR
deliver almost all the packets compared to DSDV. Hence we try to modify the AODVprotocol and use in the
cooperative transmission.
In this paper, we study the cooperative transmission at the network layer and cooperative diversity at the
physical layer as a joint optimization of the transmission power in a Mobile Ad-Hoc Network (MANET) with
static channel. However due to variable wireless channels static routing is suboptimal. Proposed protocol
proactively selects forwarding nodes that work cooperatively forwarding the packet towards the destination.
Cooperative transmission side diversity helps in reducing interference. Diversity can be achieved at the physical
layer by coordinating the multiple nodes. Nodes are equipped with Omni-directional antenna and take the
advantages of transmission side diversity to achieve energy saving, under the assumption that channel gains are
available at the transmitters.
The proposed Opportunistic Minimum Cost Cooperative Transmission Shortest Path (OMCTSP) algorithms
select the best optimum route with minimum cost in terms of energy, number of hops, available bandwidth, link
quality (SNR) and outage probability. As the network becomes larger, finding optimal routes becomes
computationally intractable as the complexity of the dynamic programming (DP) approach increases as o (2
2n)
where n is the number of nodes in the networks. Hence we develop two suboptimal algorithms have complexity
of o (n2) perform as same as optimal algorithm. Also developthe Opportunistic Cooperative Routing in MANET
(O_CORMAN), which is a network layer opportunistic routing scheme for mobile ad hoc networks. Nodes in
the network use the components proactive routing protocol, forwarder list update and local re-transmission. We
evaluate the performance using NS 2.32 simulator there is significant performance improvement with respect to
energy, throughput packet delivery, and delay compared with Modified AODV (OMCTSP).
Evaluation the Impact of Human Interaction/Debate on Online News to Improve U...IJERA Editor
The average of many people trust online comments for any news as much as personal recommendations [1], [2].
In this paper, we analyzed the impact of the online news’s comments to evaluating the threading models of
electronic debates by using online surveys. In this paper, based on the results of our online survey of 500
participants, we evaluated whether forums with comments concerning online news are appropriate for the study
of debates. In particular, we have to verify whether the nature of discussions around news is argumentative and
whether the participating people expect to engage in multiple rounds of arguments. We presented
DirectDemocracyP2P application as a user interface for decentralized debates. In this paper, we evaluated and
analyzed the comments that were collected from online surveys to improve the DirectDemocracyP2P
applications. Also we have to verify whether the actual comments commonly submitted around news do go
beyond the simple advertisement of one own’s merchandise and attacks of competitors, into fair reviews of
news features and quality.
Nanofluid Flow past an Unsteady Permeable Shrinking Sheet with Heat Source or...IJERA Editor
The consideration of nanofluids has been paid a good attention on the forced convection; the analysis focusing
nanofluids in porous media are limited in literature. Thus, the use of nanofluids in porous media would be very
much helpful in heat and mass transfer enhancement. In this paper, the influence of variable suction, Newtonian
heating and heat source or sink heat and mass transfer over a permeable shrinking sheet embedded in a porous
medium filled with a nanofluid is discussed in detail. The solutions of the nonlinear equations governing the
velocɨty, temperature and concentration profiles are solved numerically using Runge-Kutta Gill procedure
together with shooting method and graphical results for the resulting parameters are displayed and discussed.
The influence of the physical parameters on skin-friction coefficient, local Nusselt number and local Sherwood
number are shown in a tabulated form.
Analysis and Design of One Dimensional Periodic Foundations for Seismic Base ...IJERA Editor
This document presents research on the analysis and design of one-dimensional (1D) periodic foundations for seismic base isolation of structures. It begins with an introduction to periodic materials and their unique property of frequency band gaps that can block incoming waves of certain frequencies. It then provides the basic theory and analytical framework for studying 1D periodic materials, including the concept of dispersion curves derived from Bloch-Floquet theory. The document presents parametric studies investigating the effects of material properties and geometric parameters on frequency band gaps. It finds that increasing the rubber modulus or concrete density widens band gaps, while increasing unit cell thickness reduces band gaps. Considering finite structures, it models different plane sizes and finds band gaps are maintained for structures up to 3
Optimization of Ultrasound-Assisted Extraction of Arbutin from Leaves of Pyru...IJERA Editor
Pyrus elaeagnifolia Pallas. ssp. elaeagnifolia is a medicinal plant used in traditional medicine for the treatment
of various diseases in Turkey. The leaves of Pyrus elaeagnifolia ssp. elaeagnifolia are a rich source of arbutin,
which is a naturally occurring derivative of hydroquinone. It is found in various plant species belonging to
diverse families, such as Lamiaceae, Ericaceae, Saxifragaceae and Rosaceae. It inhibits tyrosinase and has
been employed as a cosmetic skin whitening agent. In this study, Response Surface Methodology (RSM) using a
Box Behnken Design (BBD) was employed to optimize the condition for extraction of arbutin from the leaves of
Pyrus elaeagnifolia ssp. elaeagnifolia. Three influencing factors; methanol concentration, period of ultrasoundassisted
extraction and extraction temperature were investigated in the ultrasonic aqueous extraction. The
Response Surface Methodology was applied to optimize the extraction process focused on arbutin content with
respect to the above influencing factors. The best combination of each significant factor was determined by
RSM design and optimum pretreatment conditions for maximum arbutin content were established to be
methanol concentration of 48.54 %, extraction time of 39.32 min. And extraction temperature of 43.71 0C.
Under these conditions 5.37 % of arbutin content was observed experimentally, similar to the theoretical
prediction of 5.30 %.
Double layer energy storage in graphene a studytshankar20134
This document summarizes research on using graphene for energy storage in electrochemical double layer capacitors (EDLCs). Graphene has potential as an EDLC electrode material due to its high surface area and electrical conductivity. Studies have found specific capacitances of graphene electrodes ranging from tens of F/g to over 1000 F/g depending on preparation methods and electrolytes. However, graphene sheets tend to restack reducing surface area availability. Methods to prevent restacking like adding metal oxides or curving graphene sheets have improved capacitance. Research is optimizing graphene properties and composites to enhance energy and power densities for applications requiring high power such as filtering alternating current.
Enhancing Electrochemical Performance of V2O5 Thin Film by using Ultrasonic W...iosrjce
Ultrasonic weltering was used to enhance the electrochemical performance of V2O5 thin films deposited on stainless steel substrates for use as electrodes in supercapacitors. Structural, morphological, physical and electrochemical characterization showed that ultrasonic weltering resulted in more crystalline and porous films with increased specific surface area. This led to improved ion transport and a 19% increase in specific capacitance from 333 F/g to 397 F/g. Energy density also increased from 2.44 Wh/kg to 2.97 Wh/kg, while power density rose from 3.11 kW/kg to 3.52 kW/kg. Therefore, ultrasonic weltering produced structural and morphological changes that enhanced the supercapacitive properties
1. The document describes a new nanohybrid material composed of polyoxomolybdate, polypyrrole, and graphene oxide for use as a high-power symmetric supercapacitor electrode.
2. The nanohybrid was synthesized via a one-pot reaction where polyoxomolybdate acted as an oxidizing agent to polymerize pyrrole monomers onto graphene oxide nanosheets.
3. Structural and morphological analysis showed the nanohybrid had an excellent architecture with good interfacial contact between components, enabling fast redox reactions for high capacitive performance.
Clarification of the optimum silica nanofiller amount for electrical treeing ...TELKOMNIKA JOURNAL
This paper aims to clarify the optimum amount of fumed silica (SiO2) nanofiller in resisting the initiation and propagation of electrical treeing in silicone rubber (SiR). Unlike other works, SiR/SiO2 nanocomposites containing seven different weight percentages of SiO2 nanofiller were prepared for this purpose. To achieve the objective, the electrical tree characteristics of the SiR/SiO2 nanocomposites were investigated by comparing the tree initiation voltage, tree breakdown time, tree propagation length and tree growth rate with its equivalent unfilled SiR. Moreover, the structural and morphological analyses were conducted on the SiR/SiO2 nanocomposite samples. The results showed that the SiR, when added with an appropriate amount of SiO2 nanofiller, could result in an improved electrical tree resistance. It implies that the 5 wt% of silica is the optimum amount to achieve the optimal electrical tree resistance such that above 5 wt%, the tree resistance performance has been abruptly reduced, subjected to the agglomeration issue.
A review on_electrospinning_design_and_nanofibre_assembliesMahbubul Hassan
This document reviews different designs for electrospinning that produce various nanofibre assemblies. Electrospinning uses electric fields to draw polymer solutions into continuous nanofibre meshes. Researchers have developed new setups to control fibre flight and collection, producing nonwoven meshes, aligned fibres, patterns, and 3D structures. A dynamic collector like a rotating drum can align fibres for applications requiring orientation, while multiple spinnerets or electrodes can generate patterns. Understanding these assembly methods allows tailoring fibres for specific applications in areas like tissue engineering and filtration.
A survey on supercapacitors and their applicationseSAT Journals
Abstract The need for more sustainable, capable energy storage has motivated a transformed scientific and commercial concern in advanced capacitor designs in which the suite of experimental techniques and ideas that comprise nanotechnology are playing a vital role. Capacitors might be charged and discharged speedily and are one of the primary building blocks of many types of electrical circuit, from microprocessors to large-scale power supplies, but generally have reasonably low energy storage potential when compared with batteries. The blende of nanorange materials with bespoke morphologies and properties to electrochemical supercapacitors is being intensively studied and observed .Recuperating and preserving energy of a moving vehicle as it slows down and accelerate the vehicle later by means of that preserved energy, can significantly increase fuel efficiencies of automobiles. Capacitors are one of the primary and basic building blocks of many types of electrical circuit. Therefore, an effort here is done to present a survey on supercapacitors. Key Words: Super capacitors, EDLC, Grapheme, nanocomposites
This document discusses piezoelectric energy harvesting. Chapter 1 introduces piezoelectricity and the piezoelectric effect, as well as the need for energy harvesting. Piezoelectric materials convert mechanical energy into electrical energy. Chapter 2 provides a literature survey, discussing available piezoelectric materials like PVDF polymer, as well as components used in energy harvesting systems, such as piezoelectric cells, sensors, actuators, DC converters, and amplifiers. Chapter 3 will describe a piezoelectric energy harvesting system and its engineering design process. The document examines applications of piezoelectric energy harvesting.
This document summarizes a presentation on using carbon nanotubes in solar panel technology. It discusses how carbon nanotubes can improve the efficiency of solar cells compared to traditional organic solar cells. Carbon nanotubes are classified as single-walled or multi-walled nanotubes. Carbon nanotubes and a polymer called MEH-PPV-CN are used as materials in constructing a carbon solar cell. The cell works by generating electrons when exposed to light, which are transferred between energy bands and build up voltage. Adding carbon nanotubes can increase the cell's efficiency by improving light absorption and electron transport. Potential applications include using carbon nanotubes in the photoactive layer or as transparent electrodes.
Conducting polymer based flexible super capacitors [autosaved]Jishana Basheer
Conducting polymers have potential in flexible supercapacitors due to their redox properties. Polyaniline, polypyrrole and polythiophene are promising conducting polymers. Graphene composites with these polymers improve performance by preventing aggregation and enabling fast ion transport. Future work aims to develop ternary composites and asymmetric capacitors to further increase energy density without sacrificing power. Conducting polymers work best in asymmetric configurations using different polymers or a polymer-carbon composite to expand the operating voltage window.
1) Carbon nanotube tissues were coated with a polymer electrolyte via electrodeposition to improve their performance as anodes in flexible lithium-ion microbatteries.
2) Cyclic voltammetry was used to deposit p-sulfonated poly(allyl phenyl ether) polymer electrolyte into the carbon nanotube tissues.
3) The polymer-coated carbon nanotube tissue delivered a higher reversible capacity of 750 mAh/g compared to 450 mAh/g for the uncoated tissue, maintaining higher capacity even at fast charge/discharge rates, demonstrating its potential for flexible lithium-ion microbatteries.
The document discusses the synthesis and characterization of nickel-manganese phosphate (NiMn(PO4)2) as an electrode material for supercapattery devices. NiMn(PO4)2 nanocomposites were synthesized via a sono-chemical method and tested as the positive electrode in an asymmetric supercapattery device with activated carbon as the negative electrode. Electrochemical measurements showed the NiMn(PO4)2 electrode had a high specific capacitance of 678 C/g and the supercapattery device delivered a maximum specific energy of 63.8 Wh/kg and specific power of 11,892 W/kg, with 99.2% capacity retention after 5000 cycles. Analysis of the charge
Impact of Gamma Irradiation on Structural and Dielectric Properties of CuI-PV...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Electrochemical performance of supercapacitor with glass wool separator under...journalBEEI
The paper presents the electrochemical performance of supercapacitor with glass wool separator under organic electrolyte of tetraethylammonium tetrafluoroborate (TEABF4). The performance was evaluated using symmetrical two-electrode system and compared to an identical supercapacitor with commercially available cellulose paper separator under 1 M TEABF4. The application of glass wool separator reduces the bulk resistance of supercapacitor by 19.6%, promotes more efficient ions transfer across active surface of electrode and significantly improves specific capacitance by 19.1% compared to cellulose paper. The application of higher concentration TEABF4 (1.5 M) even improves the overall performance of glass wool-based supercapacitor by 32.2% reduction of bulk resistance and 61.9% increment in specific capacitance compared to 1 M TEABF4. In addition, the energy and power densities are significantly improved by 64% and 165%, respectively for the one with 1.5 M TEABF4. In general, the low-cost material glass wool material has great potential to replace commercially available cellulose paper as separator in developing much better supercapacitor.
Design And Development of Low-Cost Electrospinning Machine for NanoFabricatio...MuhammadHaseebAshiq
This document is a final year project proposal submitted by four students for their BS in Electrical Engineering. They propose to design and develop a low-cost electrospinning machine for nanofabrication. Their objectives are to build a prototype machine with mechanical and electrical components including a stepper motor syringe pump and DC motor collector drum. They will calibrate the machine to optimize spinning parameters. An extensive literature review covers the history of electrospinning development from 1902 to the present and describes the basic electrospinning process of using high voltage to eject charged polymer fibers from a needle tip onto a grounded collector.
Porous carbon in Supercapacitor Shameel Farhan 090614shameel farhan
- The document discusses the history and development of supercapacitors from the 1950s to current research. It provides an overview of how supercapacitors work and their advantages over batteries, including higher power densities and greater cycle life. Current research is focused on improving energy density and reducing costs by developing new electrode materials like graphene.
Here's an abstract for the presentation titled "Integration of Mxene Supercapacitor and Li-ion Battery"
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**Abstract**
The integration of Mxene supercapacitors and Li-ion batteries represents a promising advancement in energy storage technology, combining the high power density of supercapacitors with the high energy density of Li-ion batteries. This presentation explores the working principles, challenges, and potential solutions for enhancing the performance of these hybrid systems.
Mxenes, a class of two-dimensional materials comprising transition metal carbides, nitrides, and carbonitrides, exhibit unique properties such as high electrical conductivity, large specific surface area, and tunable surface chemistry, making them suitable for supercapacitor applications. However, issues such as aggregation, hydrophilicity, and synthesis challenges must be addressed to fully leverage their potential.
The presentation delves into various approaches to overcome the energy density limitations of traditional supercapacitors, including the use of asymmetric supercapacitors, graphene hybrids, and nanostructured materials. It also highlights the synthesis processes for Mxenes, comparing methods like hydrofluoric acid etching, fluoride salt etching, molten salt etching, ionic liquid etching, and electrochemical etching, along with their respective advantages and disadvantages.
A detailed comparison of Mxene supercapacitors, Li-ion batteries, and hybrid systems is provided, focusing on parameters such as capacitance, energy density, power density, cycle life, conductivity, and structural stability. The integration challenges, including electrolyte compatibility, electrode balancing, and safety concerns, are discussed, emphasizing the need for efficient and scalable synthesis techniques and a deeper understanding of charge storage mechanisms.
Finally, the future potential of Mxene-carbon hybrids for supercapacitors is explored, outlining prospective directions for research and development in this field. The findings presented underscore the significant role of Mxene-based hybrid systems in advancing energy storage solutions for applications requiring high power and energy density, such as portable electronics and electric vehicles.
Electrospinning for nanofibre production Akila Asokan
This presentation provides u some knowledge about the nanofibre (advantage ,disadvantage and applications) and also the method of production of those fibres using a novel technique called electospinning .And also some charecterisation techniques are exained here .then some factors that governs the fibre shape and size also discussed here .
22 9752 cable paper id 0022 edit septianIAESIJEECS
1. The document discusses several experiments conducted to determine the breakdown voltage and aging effects of XLPE cable insulation at different temperatures. In one experiment, the breakdown voltage of XLPE cable samples decreased as the temperature increased from 30°C to 70°C.
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Tuning the Ionic and Dielectric Properties of Electrospun Nanocomposite Fibers for Supercapacitor Applications
1. A. Jabbarnia. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -1) June 2016, pp.65-73
www.ijera.com 65 | P a g e
Tuning the Ionic and Dielectric Properties of Electrospun
Nanocomposite Fibers for Supercapacitor Applications
A. Jabbarnia1
*, W. S. Khan2
, A. Ghazinezami1
and R. Asmatulu1
*
1
Department of Mechanical Engineering, Wichita State University, 1845 Fairmount, Wichita, KS 67260-0133
2
Department of Mechanical and Industrial Engineering, Majmaah University, Majmaah, P.O. Box. 66, Saudi
Arabia
ABSTRACT
This study reports the fabrication and characterization of electrospun polyvinylidene fluoride (PVdF)and
polyvinylpyrrolidone (PVP) nanofiber separators embedded with carbon black nanoparticles. Different weight
percentages (0, 0.25, 0.5, 1, 2, and 4wt%) of carbon black nanoparticles were dispersed in N, N-
dimethylacetamide (DMAC) and ethanol using sonication and high-speed agitations, and then PVdF and PVP
polymers were added to the dispersions prior to the mixing and electrospinning processes. The morphological,
dielectric constant, ionic conductivity, and surface hydrophobic properties of the PVdF/PVP nanofiber
separators were analyzed using various techniques. SEM micrograms showed that the fiber diameter was
around 100-200 nm. The ionic conductivity test clearly revealed a significant increase in conductivity valueof
4.28 x 10-4
S/cm for 4 wt. % carbon black loading. However, the contact angle values were decreased with
increasing weight percent of carbon black particles. The dielectric constant was increased with the carbon black
loading. As can be seen, overall physical properties of the nanocomposite separators were significantly
enhanced as a function of carbon black inclusions, which may be useful for supercapacitor separators and other
energy storage devices.
Keywords: Carbon Black Nanopowders, Electrospun Nanofibers,Ionic Conductivity, Supercapacitor Separators.
I. Introduction
1.1. General Background
Supercapacitors or electrochemical
capacitors have been considered as alternative
energy storage devices. They can be utilized as
backup source devices due to their high power
levels, large specific surface area, low electrical
resistivity, high charging-discharging rate, and
long cyclic lives compared to conventional
capacitors and conventional batteries. They have
demonstrated great potential in a wide range of
applications such as power backup for mobile
phones or laptops, and a power source for hybrid
vehicles[1-8].Research on novel energy storage
devices has attracted substantial attention recently.
Traditional batteries have slow discharge rates and
a high energy density; therefore, it is important to
develop storage devices having high energy
density and high power density. Electrochemical
supercapacitors possess high power density and
reasonably good energy density. Currently,
researchers have focused their attention on
increasing the energy density of supercapacitors by
finding suitable materials for the
separator/electrode and lowering the overall cost
[9]. Many researchers have fabricated
separators/electrodes for supercapacitors using a
wide variety of materials, such as metal-
based oxides, graphene, carbon nanotubes,
carbonized wood, etc. Some researchers have used
carbonaceous compositions and metal oxides, and
incorporated them with various polymers for
separator applications [3-12]. Carbon-based
nanocomposites with conducting polymers have
high capacitance values and better cyclic
performance in supercapacitors. They also possess
high capacitance values due to their functional
groups containing phosphorus, nitrogen, and
oxygen, which are referred to as
thepseudocapacitance effect [13].
Electrospinning is a promising technique
used to fabricate nano/micro membrane separators
in a very short period of time with minimum
investment. Polymeric separators fabricated by the
electrospinning possess a unique texture with
micro and/or nanosize fiber arrangements,
flexibility, and high surface area and porosity. This
can be a promising material for various types of
separators.The main focus here is the fabrication of
a separator with high ionic conductivity and
electrochemical stability. Among many polymers,
PVdF has presented better results due to its high
electrochemical stability and particularly excellent
electrical properties, which can be useful in
supercapacitor applications,although the flexibility
of PVdF is not sufficient due to its high crystalline
structure and may eventually cause some
difficulties [14].
Electrospun polymer such as PVdF and its
derivatives, can be used as nanofiber mats in
RESEARCH ARTICLE OPEN ACCESS
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ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -1) June 2016, pp.65-73
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separators of Li-ion batteries, due to its nanoporous
structure leading to increased ionic conductivity
[15]. Uniform electrospun PVdF membrane
thickness and fiber diameter can be obtained by
using high polymer concentrations and
electrospinning at relatively high spinning voltage.
This improves mechanical strength and provides
the PVdF separator with charge and discharge
capacities that generally exceed commercial
polypropylene separators, while resulting in little
capacity loss [15].
Karabelli et al. [16] prepared PVdF
separators for supercapacitor applications, and
studied the different properties of PVdF separator
such as thermal, mechanical and ionic conductivity.
Polymeric materials are widely used as separators
and as electrodes in batteries and in ultracapacitors.
PVdF contains various phases, the most common
being the α-phase. The pyroelectric and
piezoelectric features of the β-phase of PVdF
provide better material properties [17]. The
purpose of this study was to fabricate separators
for supercapacitors using the electrospinning
technique and investigate their ionic, dielectric,
and surface properties.
1.2. Electrospinning
Electrospinning is an effective method to
produce woven and non-woven micro/nanoscale
fibers from a polymeric solution. The process
parameters can be optimized to prepare separators
having extraordinary properties. The resultant
fibers generally have a large surface area,
flexibility, and uniform porosity [18, 19]. Some
conventional fiber-spinning methods, such as melt
spinning, dry spinning, and gel spinning, are
capable of producing fibers with diameters in the
range of micrometers, but the electrospinning
technique produces non-woven polymeric fibers in
the micro to nanometer range. It also presents a
high surface area compared to conventional fiber-
forming methods [20].
In electrospinning, a high-voltage or high-
electric field is used to overcome the surface
tension of the polymeric solution. When the
intensity of the electric field is increased beyond a
certain limit, called threshold intensity, the
hemispherical surface of the polymer solution at
the tip of the capillary tube begins to elongate into
a structure known as the Taylor cone.Electrospun
fibers form from the plastic stretching of a
polymeric solution jet while the solvent evaporates,
and the polymer solidifies at micro and nanolevels.
In this technique, a polymer solution is transferred
into a syringe, and a continuous filament is drawn
from the nozzle to the collector by utilizing a high
electrostatic field. A charged polymer jet is ejected
from the nozzle due to electrostatic repulsion.
Afterward, the filaments are deposited on the
collector surface, which is located some distance
from the capillary tube [20].
Lewandowski et al. [21] studied the
electrochemical performance of a totally solid state
electric double – layer capacitor using a polymer
electrolyte and an activated carbon powder as
electrode material in which polymer electrolyte
serves as separator as well as electrode material.
Sivaraman et al. [22] reported all-solid-
supercapacitor based on chemically synthesized
polyaniline (PANI) and sulfonated polymers
having fluorinated ethylene propylene copolymer
grafted with acrylic acid and sulfonated (FEP-g-
AA-SO3H) membrane (separator). Electrospun
polymers such as polyvinylidene fluoride (PVdF)
and polyacrylonitrile (PAN) and many other, can
be used as nanofiber mats in separator applications
in electronic devices [15]. These separators
provide nanoporous structure leading to increased
ionic conductivity of membrane soaked with liquid
electrolyte [15]. A separator should be
mechanically, chemically, and thermally stable and
should allow ions to transfer, but prevent electrical
short circuit. However, a separator has two main
functions: the first one is to provide electronic
insulation between electrodes of opposite
polarization and the second one is to allow ionic
conduction from one electrode to another.
A uniform electrospun PVdF membrane
thickness can be achieved by using high polymer
concentration and carrying out electrospinning at
high voltage. This provides mechanical strength
and also results in charge and discharge capacities
that exceed many commercially available
separators [15]. High crystallinity of PVdF
generally impedes conductivity. Therefore, PVP
was added in polymeric solution in order to
account for conductivity limitation caused by
PVdF high crystallinity and also it increases
electrospinnability of polymeric solution.PVP is
ahydrophobicizer and stabilizer, and it can greatly
improve membrane oxidative stability and
chemical stability [23, 24].Qiao et al. [23]
determined the chemical stability of PVA/PVP
membrane by immersing it in different
concentration of KOH at elevated temperature, in
order to test the tolerance of the membrane at
elevated temperature in KOH solution.
Conventional capacitor technology has
focused on minimizing the area of electrode plates
and then combining these plates with thin layers of
insulating separator having high dielectric constant
possibly resulting in high capacitance values [25].
This methodology has certain limits, as separator
film can be of minimum thickness before it fails
and there are also limits on the dielectric constant
of film material [25]. Usingthe electrospun PVdF
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and PVP membranes incorporated with carbon
black not only increase the surface area of
separator and wettability, but also provide the
mechanical stability to the separator and increase
the dielectric constant values of separators, as well.
Figure 1 shows a schematic illustration of an
electrospinning process. Fibers produced by this
method can be used for many industrial
applications, such as sensors, filters, biomedical
purposes, compositereinforcement, solar cells, fuel
cells, batteries, supercapacitors, and membrane
technology [20, 26].
II. Experimental Procedure
2.1. Materials
PVdF and PVP with molecular weights of
180,000 g/mole and 130,000 g/mole, respectively,
were purchased from Sigma-Aldrich and used
without any modification or purification. Carbon
black (ELFTEX8) was purchased from the Cabot
Company and used as reinforcement nanoparticles
(15–60 nm). N, N-dimethylacetamide (DMAC)
and acetone, were purchased from Fisher Scientific
and used as solvents. Figure 2 shows SEM images
of the carbon black powder. As can be seen, the
particles are mainly aggregated and need to be
dispersed prior to the electrospinning process.
2.2. Methods
2.2.1. Fabrication of Nanocomposite Fibers
Different weight percentages (0, 0.25, 0.5,
1, 2, and 4 wt%) of carbon black nanopowders
were dispersed in the DMAC/acetone solvent and
sonicated for 90 minutes; then PVdF and 2 wt%of
PVP were added separately to the dispersions. The
weight ratio was 80 wt. % solvents (including
DMAC and acetone, were 70/30 in weight
proportions respectively) and 20 wt. % of polymers
(including 18 wt. % PVdF and 2 wt. % PVP). The
solution was constantly stirred at 550 rpm and
60C for five hours before the electrospinning
process. Special care was taken to ensure a
homogeneous blend of the mixture. The dispersed
solution was transferred to a 10 ml plastic syringe
connected to a capillary needle having an inside
diameter of 0.5 mm. The electrospinning
parameters of voltage, distance between tip and
collector, and syringe pump speed were 25 kV DC,
25 cm, and 2 ml/hr, respectively. The theoretical
density of polymeric solution with 4 wt. % of
carbon black was calculated as 1.069 g/cm3
, based
on rule of mixtures. Electrospun fibers were then
collected on an aluminum screen and dried in an
oven at 60C for eight hours to remove all residual
solvents.The theoretical density of electrospun
fibers with 4 wt. % of carbon black was calculated
as 1.72 g/cm3
, based on rule of mixtures. PVP is a
very good adhesive agent and it is used in batteries
as a special additive. PVP is used to glue the
membrane together for efficient electrochemical
performance of supercapacitors. The reason for
using PVdF is that it generally performs
significantly better in many applications where
strength, resistance to solvents and heat are
required. PVdF is also used as insulator on
electrical wires due to its combination of low
weight, low thermal conductivity and high thermal
and chemical resistance. Additionally, PVdF is a
binder material usually used in the production of
composite electrodes in lithium ion batteries.
Figure 3 shows the SEM images of PVdF/PVP
nanofibers incorporated with carbon black
nanopowders, indicating that most of PVdF
nanofibers are in nanosize(100 and 200 nm).
However, some beads were formed during the
electrospinning of 4 wt% carbon black, as shown
in Figure 3(f), which may have been due to the
mixture’s high carbon content. A good
combination of PVdF/PVP and carbon black
nanopowders is observed in all samples.A
membrane thickness of 0.5 mm was used in this
experiment. As can be seen in all SEM images
(Figure 3), there was no pronounced difference in
the fiber diameter as the weight % of carbon black
increased. In electrospinning, the fiber diameter
depends on the viscosity of the polymeric solution
and the distance between the capillary tube and
collector screen distance. The viscosity generally
depends on the molecular weight of the polymers
and solvent types used for dissolution. In the
present study, a constant distance of 25 cm was
maintained between the capillary tube and
collector screen throughout the experiment. A
higher distance will lower the intensity of the
electrostatic field. There could be some shrinkage
during the heat treatment at 60C for eight hours to
remove all residual solvents and polymer change
alignments. However, this shrinkage is very minute,
so fibers retained their shape and morphology after
the heat treatment. The average diameter of fibers
was observed to be between 100 and 200 nm in all
the cases.
2.2.2. Capacitance Measurements
The dielectric constant values of the
PVdF/ PVP nanocomposite fibers as a function of
carbon black were calculated using a parallel-plate
capacitor. An Andeen Hagerling 2550A Ultra
Precision capacitance bridge was used to measure
the capacitance of the parallel-plate capacitor.
Figure 4 represents a schematic of the dielectric
constant measurement following the ASTM D 150
test. The dielectric constant r can be obtained
from the measured capacitance C with the help of
electrodes of a known cross-section area A, layer
thickness d, and vacuum dielectric constant o
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ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -1) June 2016, pp.65-73
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(8.85 x 10-12
pF/m), using the following equation
[18]:
0
.
r
C d
A
(1)
The metal parallel-plate capacitor was
composed of 0.5-cm-thick aluminum. PVdF/PVP
nanocomposite fibers samples containing different
weight percent of carbon black were placed
between the aluminum conductor plates, which
were tightly held together by hard and rigid plastic
clips to ensure a complete contact between them
and the fiber samples. After the setup was
completed, the conductor plates were connected to
the capacitance bridge, which also served as a DC
power supply. As the current flowed, the
aluminum plates connected to the positive and
negative electrodes of the capacitance bridges were
negatively and positively charged, respectively,
creating a potential difference between the plates.
2.2.3. Water Contact Angle Measurements
The water contact angle values of the
PVdF/PVP samples as a function of carbon black
concentration were determined with an optical
contact angle goniometer, purchased from KSV
Instruments Ltd. (Model #CAM 100). This
compact, video-based instrument is used to
measure contact angles between 1 and 180 with
an accuracy of ±1. Computer software provided
by KSV Instruments Ltd. precisely measured and
also took pictures of the contact angles. Samples
were cleaned with deionized water and dried in a
vacuum overnight. Then they were placed on the
goniometer stage, and a droplet of water was
gently dropped on the sample from a syringe
attached to the goniometer.
2.2.4. Ionic Conductivity Measurements
Electrochemical impedance spectroscopy
(EIS) is an important tool for defining the electrical
properties of materials. A Gamry instrument
(Reference 600, Potentiostat/Galvanostat/ZRA)
was utilized to characterize the ionic conductivity
of the PVdF and PVP electrospun nanofibers. An
aqueous solution of 6M KOH, which is a common
electrolyte for liquid supercapacitors [2, 3, 23],
was used during the ionic conductivity
measurements. The conductivity values of the
polymeric fibers were calculated using the
resistance obtained from a slope of the I-V plot, a
known area of the film (A), and the measured
thickness of the film (L) [27] using the following
equation:
L
R A
(2)
WhereR represents resistance obtained from the
slope of the I-V plot.
III. Results And Discussion
3.1. Capacitance Measurement Tests
Dielectric materials are used in almost all
electrical equipment. They have low conduction
and the capability of storing an electric charge. The
dielectric properties of polymers are very
important in many industrial applications, such as
cable insulation, encapsulates for electronic
components, and wiring board materials.Dielectric
materials can store an electric charge in different
forms depending on theirstructure [18, 28]. Higher
filler material loadings will generally increase the
dielectric constant values to a notable limit, so that
the material can be used for various industrial
applications. However, some properties of
composites, such as thermal, electrical, and
mechanical, may degrade due to higher filler
loadings. Accordingly, the weight percentage of
carbon black nanopowders was limited to 4 wt% in
the present studies.
Figure 5 shows the dielectric constant
values of the obtained PVdF/PVP nanocomposite
fibers as a function of carbon black concentration.
As can be seen, the addition of carbon black in
PVdF/PVP nanofibers results in higher dielectric
constants. Generally, the dielectric propertiesof a
polymer depend on temperature, frequency,
structure, and composition of the polymer and
filler materials.
The measured dielectric constants of the
nanocomposite fibers remarkably increased from
1.59 to 3.97, when the carbon black concentration
reached 4 wt% in the PVdF/PVP nanocomposites.
As observed in Figure 5, the dielectric constant
values of PVdF/PVP samples were significantly
increased by adding 1 wt% of carbon black in the
fibers. By increasing the carbon black weight
percentage to 4 wt% in the PVdF/PVP fibers, the
dielectric constant values were slightly enhanced to
3.97.
This drastic improvement in dielectric
constant values of PVdF/PVP fibers is attributed to
the charge carrier concentration of carbon black
embedded into the polymer structures [27]. The
addition of carbon black to a polymer will certainly
increase the charge carrier concentration, thereby
increasing the polarizability of the electrospun
fibers [18]. The relationship between the dielectric
constant εr and the molecular polarizability αt is
given by [29]
0
1 ( )
t
r
N
(3)
Where 𝑁 is the concentration of
molecules, and 𝜀0 is the permittivity of free space.
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ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -1) June 2016, pp.65-73
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According to this relation, the dielectric constant
must increase by increasing the polarizability.
3.2. Surface Hydrophobicity
Contact angle measurements were
conducted on the PVdF/PVP nanocomposite
samples in order to determine the effects of carbon
black nanopowders on the surface properties of the
fibrous separators. Hydrophobicity and
hydrophilicity are terms related to the behavior of
solid surfaces when placed in contact with water
droplets. A hydrophobic surface is one on which a
droplet of water forms a contact angle greater than
90o
, whereas a hydrophilic surface is one on which
a droplet of water forms a contact angle less than
90o
[30]. Polymer surfaces with contact angles
between 150o
and 180o
are called super-
hydrophobic. This phenomenon is also known as
the “lotus effect”, which exhibits self-cleaning and
anti-contamination features [31].
The hydrophobicity or wettability of a
separator plays an important role in the
performance of a supercapacitor because a
separator with high wettability can retain the
electrolyte solutions and facilitate the diffusion of
electrolytes. Table 1 shows the contact angles of
PVdF/PVP fibers at different carbon black
loadings.
Contact angles values of the PVdF/PVP
fibers were slightly decreased by adding carbon
black nanopowders. However, nanocomposite
fibers indicated hydrophobic behaviors when the
carbon black concentration reached 0.5 wt%. Then,
increasing the carbon black percentages in the
PVdF/PVP fibers exhibited hydrophilic behaviors,
which may be more suitable for supercapacitor
separators. The addition of 4 wt% of carbon black
into PVdF/PVP fibers improved the wetting
property of the surface and showed a contact angle
of 78.51.
PVP has higher wettability characteristics
than PVdF because the surface tension of PVP (68
mN/m) fibers is much higher than that of PVdF
(33.2 mN/m). Therefore, it is obvious that a
combination of PVdF and PVP can provide better
properties for supercapacitor separators. Increasing
the carbon black content improved the surface
wettability of membranes which might be due the
high surface area of carbon black (1500 m2
g-1
),
surface energy and accessible surface to perform
higher hydrophilicity [7, 32, 33]. The membrane
should soak quickly and completely in typical
aqueous electrolytes to transport ions, but should
not dissolve in the electrolytes and change the
physical and chemical properties during charging
and discharging.
3.3. Ionic Conductivity Tests
Generally, encapsulation of a polymer
matrix with conducting elements can also increase
the ionic conductivity [34, 35]. Figure 6 shows the
ionic conductivity values of PVdF/PVP nano
composite fibers as a function of carbon black
nanoparticles. As can be seen, the ionic
conductivity of the carbon black-based PVdF/PVP
nanocomposite fiber samples increased 76.86% at
4 wt% carbon black loading.The calculated ionic
conductivity values of PVdF/PVP nanofibers are
given in Table 2.
Test results clearly indicate that the
incorporation of carbon black raises the ionic
conductivity, which may considerably increase the
functionality of supercapacitor separators. The
measured ionic conductivity value for the
PVdF/PVP fibers without the addition of carbon
black was 2.42 × 10-4
S cm-1
, which increased to
4.28 × 10-4
S cm-1
by adding 4 wt% of carbon
black to the fibers.Increasing the ionic conductivity
with a higher carbon black percentage is also
confirmed with a higher value of capacitance in the
presence of 4 wt% carbon black compared to
PVdF/PVP fibers without the addition of carbon
black. The high ionic conductivity may be
attributed to the interconnected pores by carbon
black nanopowders and the molecular structure of
PVdF. Carbon blacknanoparticles are found to be
highly branched with open structures, and high
porosity which might assist ionsto move faster,
resulting in higher ionic conductivity at higher
carbon black contents in the microstructure
[7].Porous separators with an accessible
transportation path will provide better movement
for ions between anode and cathode electrodes.
Due to their nanoscale size, conducting polymer
nanostructures are expected to improve
performance and shorten the diffusion path length
for transporting ions.
IV. Conclusions
The electrospinning method was
employed to fabricate various polymeric
PVdF/PVP separators incorporated with different
percentages of carbon black nanoparticles for
supercapacitors with high porosity, surface area,
and ionic conductivity. Following the
electrospinning process, the nanofiber samples
were characterized using SEM, the capacitance
bridge, the water contact angle, and GAMRY/EIS.
The PVdF/PVP nanofibers were mainly nanosize
(between 100 and 200 nm). The ionic conductivity
of the PVdF/PVP electrospun membranes reached
4.28 × 10-4
S cm-1
by adding 4 wt% of carbon
black. The dielectric constant values of the fibers
were significantly increased in the presence of
carbon black nanopowders, which may have been
the result of the charge-carrying nanoinclusions
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embedded into the polymer structure. The
wettability of the PVdF/PVP nanofibers improved
by adding carbon black nanoparticles in the
polymer structure. The present study clearly shows
that electrospun nanocomposite fibers have
excellent physical and chemical properties, which
may be effectively utilized for the fabrication of
supercapacitor separators.
V. Acknowledgment
The authors gratefully acknowledge the
Kansas NSF EPSCoR (#R51243/700333), and
Wichita State Universityfor the financial and
technical support of this work.
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Table Captions:
Table 1: Water contact angle values of electrospun
PVdF/PVP nanocomposite fibers as a function of
carbon black concentrations.
Table 2: Ionic conductivity values of electrospun
PVdF/PVP nanocomposite fibersas a function of
carbon black concentrations.
Figure Captions:
Figure 1: Schematic view of electrospinning
process.
Figure 2: SEM images of carbon black (ELFTEX8)
powderat low (left) and high (right) magnifications.
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ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -1) June 2016, pp.65-73
www.ijera.com 72 | P a g e
Figure 3:EDX SEM images: (a) electrospun
PVdF/PVP fibers, and incorporated with (b)
0.25wt%, (c) 0.5wt%, (d) 1wt%, (e) 2wt%,and (f)
4 wt%carbon black.
Figure 4: Schematic view of capacitance
measurement of dielectric materials using ASTM
D 150 test.
Figure 5: (Color online) Dielectric constant values
of PVdF/PVP fibers as a function of carbon
blackconcentrations.
Figure 6: (Color online) Linear sweep
voltammogram curves for PVdF/PVP
nanocomposite fibersas a function of carbon black
concentrations.
Table 1:
Carbon Black
Concentration (wt %)
Water Contact
Angle (o
)
0 112
0.25 111
0.5 95
1 81
2 80
4 78
Table 2:
Carbon Black
Concentration (wt %)
Ionic Conductivity
(Scm-1
)×10-4
0 2.42±0.04
0.25 2.90±0.03
0.5 3.56±0.04
1 3.87±0.05
2 4.05±0.03
4 4.28±0.05
Figure 1:
Figure 2:
(a)
(b)
(c)
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(d)
(e)
(f)
Figure 3:
Figure 4:
Figure 5:
Figure 6: