The document summarizes research on copper oxide (CuO) dispersed polyvinyl alcohol (PVA) polymer films. Five films were prepared with varying concentrations of CuO nanoparticles (0 wt%, 2.5 wt%, 5 wt%, 7.5 wt%, and 10 wt%). The films were characterized through various analyses. X-ray diffraction and scanning electron microscopy showed the inclusion of CuO nanoparticles in the PVA matrix. Optical band gap decreased from 3.47 eV to 1.63 eV with increasing CuO concentration. Photoluminescence spectra showed increased wavelength emission with higher CuO content. Electrical conductivity increased with rising temperature and CuO concentration, indicating improved electronic conduction in the composites.
PPT on "Functionalization of Nanoparticles and Nanoplatelets" by Deepak rawalDeepak Rawal
Presentation on Functionalization of nanoparticles, magnetic nanoparticles, chemical funtionalization, funtionalization of carbon nanotubes and their applications. Introduction about graphite nanoplatelets.
The document discusses various topics related to composite materials including:
1. Composites are made of two or more materials combined to take advantage of distinct properties of each material. Fibers include glass, carbon, and synthetic fibers while matrices include polymer, metal, ceramic, and carbon.
2. Nanocomposites contain at least one constituent with dimensions less than 100 nm which can improve properties at the macroscale. Common nanofillers include clays, carbon nanotubes, and silica.
3. In situ polymerization involves dispersing nanoparticles in a monomer and polymerizing to form a thermoset composite with strong interfaces between the polymer and reinforcement.
This document discusses polymer nanocomposites, which combine a polymer matrix with nanoscale inorganic fillers. Polymer nanocomposites can overcome limitations of conventional composites and monolithic polymers by exhibiting improved mechanical, thermal, and optical properties due to the high surface area of nanoparticles. Properties of nanocomposites depend on the matrix polymer, nanoparticle fillers, and their dispersion within the polymer. Potential applications of nanocomposites include use in automobiles, electronics, packaging, and military equipment by exploiting their enhanced strength, thermal and chemical resistance.
This document discusses nanocomposites for solar energy storage. It defines nanocomposites as composite materials with at least one nanoscale component that produces different properties than the individual components. For solar energy storage, electron donor and acceptor materials are blended into a nanocomposite rather than using semiconductor p-n junctions. Popular donor and acceptor materials discussed are P3HT polymer and PCBM fullerene. Nanocomposites can be fabricated with organic donors paired with either inorganic oxide acceptors like ZnO or organic acceptors like PCBM. Poly(3-butylthiophene) nanowires are mentioned as an example donor material.
Patent Landscape Report on “Dielectric Polymer Nanocomposites” by DexPatentCaroline Charumathy
The Dielectric Property of Polymer Nanocomposite is an emerging and fast moving concept in electrical insulation. It is used in wide range of applications including Energy storage devices, Thin films, Semiconductor devices and Electromagnetic shielding or as radar- absorbent materials (RAMs). This landscape report will help in understanding the developments relating to preparation and use of Dielectric Polymer Nanocomposites
To get in-depth analysis of specific technology areas and the competitive patent landscape similar to this, contact us.
Boron nitride nanotubes (BNNTs) are structurally similar to carbon nanotubes but are electrically insulating. When added to polymer matrices as nanocomposites, BNNTs can improve the mechanical, thermal, and dielectric properties of polymers. BNNTs enhance stiffness, thermal conductivity, and breakdown voltage while maintaining the electrical insulation of polymers. They disperse well due to strong interfacial interactions and do not negatively impact polymer properties. BNNTs show promise as nanofillers for high performance polymer composites.
This seminar presentation summarizes polymer nanocomposites. It defines nanocomposites as multiphase solid materials with one phase having dimensions less than 100 nm. The major constituent is the polymer matrix and the minor constituent is nanoscale reinforcement materials like nanotubes, nanoplates, or nanoparticles. The advantages of nanoscale fillers over conventional fillers include low percolation thresholds, large interfacial areas, and short particle distances. Surface modification of nanofillers is important to prevent agglomeration and improve interfacial interactions. Common synthesis methods for polymer nanocomposites include melt compounding, solvent processing, and in situ polymerization. Polymer nanocomposites provide enhanced properties compared to
Synthesis and characterization of nanocompositessowmya sankaran
This document defines and discusses different types of nanocomposites. It begins by defining nanotechnology and some unique properties at the nanoscale. It then discusses different types of nanomaterials that can be used in nanocomposites like nanoparticles, nanotubes, and nanorods. The document outlines three main types of nanocomposites - metal matrix, ceramic matrix, and polymer matrix - and provides examples and processing methods for each type. It concludes by discussing several applications of nanocomposites in areas like food packaging, environmental protection, aerospace, automotive, and batteries.
PPT on "Functionalization of Nanoparticles and Nanoplatelets" by Deepak rawalDeepak Rawal
Presentation on Functionalization of nanoparticles, magnetic nanoparticles, chemical funtionalization, funtionalization of carbon nanotubes and their applications. Introduction about graphite nanoplatelets.
The document discusses various topics related to composite materials including:
1. Composites are made of two or more materials combined to take advantage of distinct properties of each material. Fibers include glass, carbon, and synthetic fibers while matrices include polymer, metal, ceramic, and carbon.
2. Nanocomposites contain at least one constituent with dimensions less than 100 nm which can improve properties at the macroscale. Common nanofillers include clays, carbon nanotubes, and silica.
3. In situ polymerization involves dispersing nanoparticles in a monomer and polymerizing to form a thermoset composite with strong interfaces between the polymer and reinforcement.
This document discusses polymer nanocomposites, which combine a polymer matrix with nanoscale inorganic fillers. Polymer nanocomposites can overcome limitations of conventional composites and monolithic polymers by exhibiting improved mechanical, thermal, and optical properties due to the high surface area of nanoparticles. Properties of nanocomposites depend on the matrix polymer, nanoparticle fillers, and their dispersion within the polymer. Potential applications of nanocomposites include use in automobiles, electronics, packaging, and military equipment by exploiting their enhanced strength, thermal and chemical resistance.
This document discusses nanocomposites for solar energy storage. It defines nanocomposites as composite materials with at least one nanoscale component that produces different properties than the individual components. For solar energy storage, electron donor and acceptor materials are blended into a nanocomposite rather than using semiconductor p-n junctions. Popular donor and acceptor materials discussed are P3HT polymer and PCBM fullerene. Nanocomposites can be fabricated with organic donors paired with either inorganic oxide acceptors like ZnO or organic acceptors like PCBM. Poly(3-butylthiophene) nanowires are mentioned as an example donor material.
Patent Landscape Report on “Dielectric Polymer Nanocomposites” by DexPatentCaroline Charumathy
The Dielectric Property of Polymer Nanocomposite is an emerging and fast moving concept in electrical insulation. It is used in wide range of applications including Energy storage devices, Thin films, Semiconductor devices and Electromagnetic shielding or as radar- absorbent materials (RAMs). This landscape report will help in understanding the developments relating to preparation and use of Dielectric Polymer Nanocomposites
To get in-depth analysis of specific technology areas and the competitive patent landscape similar to this, contact us.
Boron nitride nanotubes (BNNTs) are structurally similar to carbon nanotubes but are electrically insulating. When added to polymer matrices as nanocomposites, BNNTs can improve the mechanical, thermal, and dielectric properties of polymers. BNNTs enhance stiffness, thermal conductivity, and breakdown voltage while maintaining the electrical insulation of polymers. They disperse well due to strong interfacial interactions and do not negatively impact polymer properties. BNNTs show promise as nanofillers for high performance polymer composites.
This seminar presentation summarizes polymer nanocomposites. It defines nanocomposites as multiphase solid materials with one phase having dimensions less than 100 nm. The major constituent is the polymer matrix and the minor constituent is nanoscale reinforcement materials like nanotubes, nanoplates, or nanoparticles. The advantages of nanoscale fillers over conventional fillers include low percolation thresholds, large interfacial areas, and short particle distances. Surface modification of nanofillers is important to prevent agglomeration and improve interfacial interactions. Common synthesis methods for polymer nanocomposites include melt compounding, solvent processing, and in situ polymerization. Polymer nanocomposites provide enhanced properties compared to
Synthesis and characterization of nanocompositessowmya sankaran
This document defines and discusses different types of nanocomposites. It begins by defining nanotechnology and some unique properties at the nanoscale. It then discusses different types of nanomaterials that can be used in nanocomposites like nanoparticles, nanotubes, and nanorods. The document outlines three main types of nanocomposites - metal matrix, ceramic matrix, and polymer matrix - and provides examples and processing methods for each type. It concludes by discussing several applications of nanocomposites in areas like food packaging, environmental protection, aerospace, automotive, and batteries.
Nanocomposite biomaterials are multiphase solid materials where one phase has dimensions less than 100 nm. This nano-scale structure gives nanocomposites improved mechanical, electrical, thermal and other properties compared to their components. There are several types of nanocomposite biomaterials including ceramic-matrix nanocomposites, polymer-matrix nanocomposites, polymer-silicate nanocomposites, elastomeric nanocomposites, and bionanocomposites. Bionanocomposites are of particular interest for biomedical applications like tissue engineering due to their biocompatibility and ability to be biodegraded in the body.
This document discusses the use of nanocomposites to improve polymer properties by mixing carbon nanotubes (CNTs) or graphene into polymers. It summarizes that melt mixing is an effective way to disperse CNTs into polymers, and that the masterbatch dilution technique can achieve percolation between 1.0-0.5 wt% of multi-walled CNTs (MWNTs) in polycarbonate (PC), depending on processing conditions. Direct incorporation of CNTs results in percolation thresholds that depend on the type of CNT and processing method used. The document also reviews methods to fabricate graphene-polymer composites and their advantages in improving mechanical, thermal, barrier and electrical properties
1) A nanocomposite is a multiphase solid material where one of the phases has dimensions less than 100 nm.
2) Nanocomposites consist of a continuous matrix phase and one or more discontinuous reinforcement phases distributed within the matrix.
3) Polymer nanocomposites can have ceramic, metal, or polymer reinforcements and find applications in packaging, marine uses, and more due to properties like increased strength and melting temperature.
This document discusses the development of biomimetic materials through the continuous processing and surface modification of polycaprolactone (PCL) nanofibers. Specifically:
1) The goal is to introduce multiple orthogonal chemical modifications onto nanofibers to produce a surface capable of attaching various bioactive cues like peptides.
2) A coextrusion and photochemical modification procedure is used to introduce and spatially control functional groups on the fibers.
3) Initial results show the substrate with dual RGD and OGP peptide modifications is sufficient to induce bone cell differentiation and adhesion, demonstrating the potential of these biomimetic materials.
Morphological and Optical Study of Sol-Gel SpinCoated Nanostructured CdSThin ...iosrjce
Nanostructured CdS thin films of different thicknesses were deposited on a cleaned glass substrate
using sol-gel spin coating technique. CdS thin films were prepared using cadmium acetate as cadmium source
and thiourea as sulfur source. The Morphological, chemical composition, and optical properties of the spin- coated
CdS thin film were studied using field emission- scanning electron microscopy (FE-SEM), Energy dispersive X –ray
(EDX) spectroscopy, and a UV-Vis-NIR spectrophotometer.The morphological results revealed that the films consist
of agglomerated spherical CdS nanoparticles with diameter < 20 nm, which distributed uniformly on the substrate
surface.The films show high transmittance > 90% and very strong absorption edge at 295 nm.The absorption edge
shifts towards longer wavelength as the film thickness increased.
Nanotechnology involves adding small amounts (<10%) of nano-scale clay particles to plastics to dramatically improve their performance properties without increasing density or reducing light transmission. Nanoclay was first developed in the 1980s at Toyota and can strengthen, lighten, and make plastics less expensive and more versatile. Nanofillers have long been used in plastics to improve mechanical and physical properties by filling space, disrupting polymer structure, and immobilizing or orienting polymer groups. Polymer nanocomposites enhance mechanical and barrier properties with only minimal increases in density.
Effect of morphology on the photoelectrochemical performance of nanostructure...Pawan Kumar
This document discusses the effect of morphology on the photoelectrochemical performance of nanostructured Cu2O photocathodes. It summarizes that:
1) Different deposition methods including electroreduction, anodization, thermal oxidation, and chemical oxidation were used to deposit planar and 1D nanostructured Cu2O thin films on copper foil with varying morphologies.
2) Mesoscopic and planar Cu2O morphologies exhibited large differences in carrier density and charge transfer resistance, but these differences did not strongly influence their photoelectrochemical performance.
3) Planar Cu2O deposited via electroreduction provided the highest photocurrent density of 5.0 mA cm−2 at 0 V vs RHE,
Influence Of Gamma Irradiation On The Dielectric Properties Of PVA- PS Polyme...IJERA Editor
Pure Polyvinyl alcohol (PVA), Polystyrene (PS) and PVA0.5PS0.5 films were prepared by simple cost effective solution casting techniques. The as prepared films were subjected to gamma irradiation upto 1.5 kGy at room temperature. The irradiated and unradiated films were subjected to XRD and electrical analysis. The results revealed that gamma irradiation improves the crystallinity as well as electrical conduction of the films. Moreover, the PVA0.5PS0.5 polymer blend film showed enhanced behavior than pure PVA and PS in both the structural and electrical properties.
Karthik S.K. presented on nanocomposites and their applications in food packaging. The presentation covered the history of nanocomposites, definitions of composites and nanocomposites, methods for preparing polymer nanocomposites, various types of nanocomposites including clay, polymer, biobased, starch, cellulose, and protein nanocomposites. The presentation discussed characterization techniques for nanocomposites and concluded that nanocomposites can improve mechanical, barrier and antimicrobial properties of food packaging materials.
Remarkable self-organization and unusual conductivity behavior in cellulose n...Pawan Kumar
Aqueous suspensions of cellulose nanocrystals were blended with Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) [PEDOT:PSS], and cast into thin films. The morphology, structure and electrical properties of the resulting nanocomposite thin films were thoroughly characterized. We found that the CNC–PEDOT:PSS blends self-organize into a layered vertical stack with a pitch of 100–200 nm while retaining a continuous percolation network for PEDOT. Atomic force microscopy, dynamic light scattering and multi-angle light scattering measurements confirmed the wrapping of polymer chains around the rod-like CNCs. The blended films exhibited improved molecular ordering of the PEDOT chains with concomitant improvement in the carrier mobility. The remarkable self-organization and enhanced structural order enabled the CNC–PEDOT:PSS blends to exhibit a high conductivity typical of PEDOT:PSS even when the content of the insulating CNCs in the nanocomposite was as high as 50 wt%.
This document summarizes research on fabricating and characterizing nanostructured films containing both conducting poly(o-ethoxyaniline) (POEA) and magnetic maghemite nanoparticles. The layer-by-layer technique was used to deposit films by alternately dipping substrates in POEA and sulfonated polystyrene (PSS) solutions, with some POEA solutions additionally containing maghemite nanoparticles. Characterization found the POEA remained doped in the films and a similar conductivity was observed even when maghemite nanoparticles were incorporated. Magnetic measurements also indicated the maghemite nanoparticles were incorporated in the film. The research demonstrates the feasibility of obtaining nanocomposite films exhibiting both conducting and magnetic properties using the layer
Study of highly broadening Photonic band gaps extension in one-dimensional Me...IOSR Journals
This document discusses the theoretical study of enhancing the reflectance spectra of one-dimensional metallo-organic multilayer photonic structures. It examines structures composed of alternating thin layers of silver and the organic material N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine. The transfer matrix method is used to calculate the reflectance spectra for different configurations of layer thicknesses and incident angles of light. Tuning of the photonic band gap is observed by varying the thickness of either the metal or organic layers. Broadening and shifting of the band edges from ultraviolet to visible and infrared regions occurs due to the optical absorption properties of both the
This document provides an overview of nanocomposite materials. It defines nanocomposites as materials with at least one component that has dimensions between 1-100 nm. Nanocomposites consist of inorganic or organic nanoparticles embedded in a matrix. They exhibit enhanced and unique properties compared to bulk materials due to quantum effects and high surface area. The document discusses various synthesis methods for nanomaterials and nanocomposites, as well as their advantages and limitations.
Polymeric carbon nitride-based photocatalysts for photoreforming of biomass d...Pawan Kumar
Photoreforming of biomass to value-added chemicals and fuels is a chemical approach to extract photosynthetically-trapped energy in complex biomolecules which otherwise disintegrate naturally in the environment. Designing precise photocatalytic materials that can selectively break the sturdy, nature-designed biomass with multiplex chemical composition/bonding and inaccessible sites is central to deploying this technology. Polymeric carbon nitride (CN) comprised of a 2D network of condensed heptazine/triazine (C6N7/C3N3) core has shown great promise for photoreforming of biomass derivatives due to intriguing physicochemical and optical properties. This review comprehensively summarizes the state-of-the-art applications of CN-based photocatalysts for the conversion of lignocellulosic biomass derivatives. Various chemical and structural modifications in CN structure such as doping, surface functionalization, hybridization entailing to higher selectivity and conversion have been discussed aiming at providing valuable guidance for future CN-based materials design.
Bio nanocomposites are materials produced from biological raw materials and principles or having biological applications. They can be synthesized through self-assembly of biomolecules and inorganic nanomaterials, mimicking nature. Applications include novel nanocomposites for artificial bone implants, carbon composites like carbon nanotubes and buckminsterfullerene, and controlled assembly of bioinorganic materials using live cells. These materials have properties dependent on their nanoscale structures, and future research aims to develop adaptive and intelligent macrostructures using nano and biotechnologies.
Water-splitting photoelectrodes consisting of heterojunctions of carbon nitri...Pawan Kumar
Quinary and senary non-stoichiometric double perovskites such as Ba2Ca0.66Nb1.34−xFexO6−δ (BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical CO2 reduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, Ba2Ca0.66Nb0.68Fe0.33Co0.33O6−δ (BCNFCo), exhibited an optical absorption edge at ∼800 nm, p-type conduction and a distinct photoresponse up to 640 nm while demonstrating high thermochemical stability. A nanocomposite of BCNFCo and g-C3N4 (CN) was prepared via a facile solvent-assisted exfoliation/blending approach using dichlorobenzene and glycerol at a moderate temperature. The exfoliation of g-C3N4 followed by wrapping on perovskite established an effective heterojunction between the materials for charge separation. The conjugated 2D sheets of CN enabled better charge migration resulting in increased photoelectrochemical performance. A blend composed of 40 wt% perovskites and CN performed optimally, whilst achieving a photocurrent density as high as 1.5 mA cm−2 for sunlight-driven water-splitting with a Faradaic efficiency as high as ∼88%.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
El alcoholismo se caracteriza por una fuerte necesidad de ingerir alcohol y una dependencia física manifestada a través de síntomas de abstinencia, con un consumo excesivo que va en aumento debido a la tolerancia y sin control sobre los límites de consumo. El alcoholismo es una de las principales causas de consulta en salud mental, pero muchos alcohólicos no reconocen su problema y no buscan ayuda a pesar de las graves consecuencias que tiene para la salud y la vida de las personas.
Este projeto visa desenvolver habilidades de leitura e escrita de estudantes através da criação de um jornal mural. Os objetivos incluem formar leitores autônomos de jornais, ampliar capacidades de leitura e escrita, e estimular análise crítica. As atividades envolverão pesquisa em jornais, recorte e colagem de notícias, produção de textos, e avaliação final dos resultados do projeto do jornal mural.
Nanocomposite biomaterials are multiphase solid materials where one phase has dimensions less than 100 nm. This nano-scale structure gives nanocomposites improved mechanical, electrical, thermal and other properties compared to their components. There are several types of nanocomposite biomaterials including ceramic-matrix nanocomposites, polymer-matrix nanocomposites, polymer-silicate nanocomposites, elastomeric nanocomposites, and bionanocomposites. Bionanocomposites are of particular interest for biomedical applications like tissue engineering due to their biocompatibility and ability to be biodegraded in the body.
This document discusses the use of nanocomposites to improve polymer properties by mixing carbon nanotubes (CNTs) or graphene into polymers. It summarizes that melt mixing is an effective way to disperse CNTs into polymers, and that the masterbatch dilution technique can achieve percolation between 1.0-0.5 wt% of multi-walled CNTs (MWNTs) in polycarbonate (PC), depending on processing conditions. Direct incorporation of CNTs results in percolation thresholds that depend on the type of CNT and processing method used. The document also reviews methods to fabricate graphene-polymer composites and their advantages in improving mechanical, thermal, barrier and electrical properties
1) A nanocomposite is a multiphase solid material where one of the phases has dimensions less than 100 nm.
2) Nanocomposites consist of a continuous matrix phase and one or more discontinuous reinforcement phases distributed within the matrix.
3) Polymer nanocomposites can have ceramic, metal, or polymer reinforcements and find applications in packaging, marine uses, and more due to properties like increased strength and melting temperature.
This document discusses the development of biomimetic materials through the continuous processing and surface modification of polycaprolactone (PCL) nanofibers. Specifically:
1) The goal is to introduce multiple orthogonal chemical modifications onto nanofibers to produce a surface capable of attaching various bioactive cues like peptides.
2) A coextrusion and photochemical modification procedure is used to introduce and spatially control functional groups on the fibers.
3) Initial results show the substrate with dual RGD and OGP peptide modifications is sufficient to induce bone cell differentiation and adhesion, demonstrating the potential of these biomimetic materials.
Morphological and Optical Study of Sol-Gel SpinCoated Nanostructured CdSThin ...iosrjce
Nanostructured CdS thin films of different thicknesses were deposited on a cleaned glass substrate
using sol-gel spin coating technique. CdS thin films were prepared using cadmium acetate as cadmium source
and thiourea as sulfur source. The Morphological, chemical composition, and optical properties of the spin- coated
CdS thin film were studied using field emission- scanning electron microscopy (FE-SEM), Energy dispersive X –ray
(EDX) spectroscopy, and a UV-Vis-NIR spectrophotometer.The morphological results revealed that the films consist
of agglomerated spherical CdS nanoparticles with diameter < 20 nm, which distributed uniformly on the substrate
surface.The films show high transmittance > 90% and very strong absorption edge at 295 nm.The absorption edge
shifts towards longer wavelength as the film thickness increased.
Nanotechnology involves adding small amounts (<10%) of nano-scale clay particles to plastics to dramatically improve their performance properties without increasing density or reducing light transmission. Nanoclay was first developed in the 1980s at Toyota and can strengthen, lighten, and make plastics less expensive and more versatile. Nanofillers have long been used in plastics to improve mechanical and physical properties by filling space, disrupting polymer structure, and immobilizing or orienting polymer groups. Polymer nanocomposites enhance mechanical and barrier properties with only minimal increases in density.
Effect of morphology on the photoelectrochemical performance of nanostructure...Pawan Kumar
This document discusses the effect of morphology on the photoelectrochemical performance of nanostructured Cu2O photocathodes. It summarizes that:
1) Different deposition methods including electroreduction, anodization, thermal oxidation, and chemical oxidation were used to deposit planar and 1D nanostructured Cu2O thin films on copper foil with varying morphologies.
2) Mesoscopic and planar Cu2O morphologies exhibited large differences in carrier density and charge transfer resistance, but these differences did not strongly influence their photoelectrochemical performance.
3) Planar Cu2O deposited via electroreduction provided the highest photocurrent density of 5.0 mA cm−2 at 0 V vs RHE,
Influence Of Gamma Irradiation On The Dielectric Properties Of PVA- PS Polyme...IJERA Editor
Pure Polyvinyl alcohol (PVA), Polystyrene (PS) and PVA0.5PS0.5 films were prepared by simple cost effective solution casting techniques. The as prepared films were subjected to gamma irradiation upto 1.5 kGy at room temperature. The irradiated and unradiated films were subjected to XRD and electrical analysis. The results revealed that gamma irradiation improves the crystallinity as well as electrical conduction of the films. Moreover, the PVA0.5PS0.5 polymer blend film showed enhanced behavior than pure PVA and PS in both the structural and electrical properties.
Karthik S.K. presented on nanocomposites and their applications in food packaging. The presentation covered the history of nanocomposites, definitions of composites and nanocomposites, methods for preparing polymer nanocomposites, various types of nanocomposites including clay, polymer, biobased, starch, cellulose, and protein nanocomposites. The presentation discussed characterization techniques for nanocomposites and concluded that nanocomposites can improve mechanical, barrier and antimicrobial properties of food packaging materials.
Remarkable self-organization and unusual conductivity behavior in cellulose n...Pawan Kumar
Aqueous suspensions of cellulose nanocrystals were blended with Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) [PEDOT:PSS], and cast into thin films. The morphology, structure and electrical properties of the resulting nanocomposite thin films were thoroughly characterized. We found that the CNC–PEDOT:PSS blends self-organize into a layered vertical stack with a pitch of 100–200 nm while retaining a continuous percolation network for PEDOT. Atomic force microscopy, dynamic light scattering and multi-angle light scattering measurements confirmed the wrapping of polymer chains around the rod-like CNCs. The blended films exhibited improved molecular ordering of the PEDOT chains with concomitant improvement in the carrier mobility. The remarkable self-organization and enhanced structural order enabled the CNC–PEDOT:PSS blends to exhibit a high conductivity typical of PEDOT:PSS even when the content of the insulating CNCs in the nanocomposite was as high as 50 wt%.
This document summarizes research on fabricating and characterizing nanostructured films containing both conducting poly(o-ethoxyaniline) (POEA) and magnetic maghemite nanoparticles. The layer-by-layer technique was used to deposit films by alternately dipping substrates in POEA and sulfonated polystyrene (PSS) solutions, with some POEA solutions additionally containing maghemite nanoparticles. Characterization found the POEA remained doped in the films and a similar conductivity was observed even when maghemite nanoparticles were incorporated. Magnetic measurements also indicated the maghemite nanoparticles were incorporated in the film. The research demonstrates the feasibility of obtaining nanocomposite films exhibiting both conducting and magnetic properties using the layer
Study of highly broadening Photonic band gaps extension in one-dimensional Me...IOSR Journals
This document discusses the theoretical study of enhancing the reflectance spectra of one-dimensional metallo-organic multilayer photonic structures. It examines structures composed of alternating thin layers of silver and the organic material N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine. The transfer matrix method is used to calculate the reflectance spectra for different configurations of layer thicknesses and incident angles of light. Tuning of the photonic band gap is observed by varying the thickness of either the metal or organic layers. Broadening and shifting of the band edges from ultraviolet to visible and infrared regions occurs due to the optical absorption properties of both the
This document provides an overview of nanocomposite materials. It defines nanocomposites as materials with at least one component that has dimensions between 1-100 nm. Nanocomposites consist of inorganic or organic nanoparticles embedded in a matrix. They exhibit enhanced and unique properties compared to bulk materials due to quantum effects and high surface area. The document discusses various synthesis methods for nanomaterials and nanocomposites, as well as their advantages and limitations.
Polymeric carbon nitride-based photocatalysts for photoreforming of biomass d...Pawan Kumar
Photoreforming of biomass to value-added chemicals and fuels is a chemical approach to extract photosynthetically-trapped energy in complex biomolecules which otherwise disintegrate naturally in the environment. Designing precise photocatalytic materials that can selectively break the sturdy, nature-designed biomass with multiplex chemical composition/bonding and inaccessible sites is central to deploying this technology. Polymeric carbon nitride (CN) comprised of a 2D network of condensed heptazine/triazine (C6N7/C3N3) core has shown great promise for photoreforming of biomass derivatives due to intriguing physicochemical and optical properties. This review comprehensively summarizes the state-of-the-art applications of CN-based photocatalysts for the conversion of lignocellulosic biomass derivatives. Various chemical and structural modifications in CN structure such as doping, surface functionalization, hybridization entailing to higher selectivity and conversion have been discussed aiming at providing valuable guidance for future CN-based materials design.
Bio nanocomposites are materials produced from biological raw materials and principles or having biological applications. They can be synthesized through self-assembly of biomolecules and inorganic nanomaterials, mimicking nature. Applications include novel nanocomposites for artificial bone implants, carbon composites like carbon nanotubes and buckminsterfullerene, and controlled assembly of bioinorganic materials using live cells. These materials have properties dependent on their nanoscale structures, and future research aims to develop adaptive and intelligent macrostructures using nano and biotechnologies.
Water-splitting photoelectrodes consisting of heterojunctions of carbon nitri...Pawan Kumar
Quinary and senary non-stoichiometric double perovskites such as Ba2Ca0.66Nb1.34−xFexO6−δ (BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical CO2 reduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, Ba2Ca0.66Nb0.68Fe0.33Co0.33O6−δ (BCNFCo), exhibited an optical absorption edge at ∼800 nm, p-type conduction and a distinct photoresponse up to 640 nm while demonstrating high thermochemical stability. A nanocomposite of BCNFCo and g-C3N4 (CN) was prepared via a facile solvent-assisted exfoliation/blending approach using dichlorobenzene and glycerol at a moderate temperature. The exfoliation of g-C3N4 followed by wrapping on perovskite established an effective heterojunction between the materials for charge separation. The conjugated 2D sheets of CN enabled better charge migration resulting in increased photoelectrochemical performance. A blend composed of 40 wt% perovskites and CN performed optimally, whilst achieving a photocurrent density as high as 1.5 mA cm−2 for sunlight-driven water-splitting with a Faradaic efficiency as high as ∼88%.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
El alcoholismo se caracteriza por una fuerte necesidad de ingerir alcohol y una dependencia física manifestada a través de síntomas de abstinencia, con un consumo excesivo que va en aumento debido a la tolerancia y sin control sobre los límites de consumo. El alcoholismo es una de las principales causas de consulta en salud mental, pero muchos alcohólicos no reconocen su problema y no buscan ayuda a pesar de las graves consecuencias que tiene para la salud y la vida de las personas.
Este projeto visa desenvolver habilidades de leitura e escrita de estudantes através da criação de um jornal mural. Os objetivos incluem formar leitores autônomos de jornais, ampliar capacidades de leitura e escrita, e estimular análise crítica. As atividades envolverão pesquisa em jornais, recorte e colagem de notícias, produção de textos, e avaliação final dos resultados do projeto do jornal mural.
Este documento describe los conceptos clave de la vista estructural, incluyendo diagramas de clases y objetos. Explica que los diagramas de clases representan las clases y sus asociaciones, mientras que los diagramas de objetos muestran las instancias de clases en un momento dado. También cubre la identificación de clases, atributos, métodos y relaciones, así como la notación para diagramas de clases y objetos.
Improvement Structural and Optical Properties of ZnO/ PVA Nanocompositesiosrjce
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.
Optical Properties of PVA:CdCl2.H2O Polymer ElectrolytesIOSR Journals
Polymer electrolytes based on Polyvinyl alcohol – Cadmium Chloride were prepared by solution cast
technique. Results of optical absorption, transmission spectra, refractive index, optical band gaps, optical
conductance, single oscillator energy, dispersion energy, real and imaginary parts of dielectric constants
studies are presented. The optical properties were obtained using UV-VIS Double Beam Spectrophotometer in
the wavelength range (190-1100) nm. The optical transmittance at wavelength ≈ 190nm for pure PVA was
nearly at 78%, while it was 50% for all doped samples. The optical transmittance was increased with increasing
wavelength up to 98% for all films beyond ≈240nm. The calculated energy band gap changes from 6.42eV (pure
PVA) to 5.80eV (PVA-20%CdCl2.H2O). The optical conductance and band-gap indicated that the films are
almost transmitting within the visible range. The single oscillator expression has been used to obtain the
information about disorder degree. The real and imaginary parts of dielectric constant of the doped films
increases with increasing CdCl2.H2O concentration, and it shows decreases abruptly in the wavelength (200-
220) nm, and finally becomes constant with increase in photon energy.
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.
This document summarizes a study that analyzed the structural characterization of gamma irradiated poly-(diamino naphthalene) doped poly-(vinyl alcohol) films. The researchers irradiated film samples with different doses and dose rates of gamma radiation and then used X-ray diffraction to analyze changes in crystallinity, peak intensity and width, and domain size before and after irradiation. The results showed that gamma irradiation increased crystallinity, caused peaks to become sharper and shift to lower degrees, occur at higher intensities, and increased domain size. This indicates that gamma irradiation induced cross-linking and formation of helical structures in the polymer films.
Remarkable self-organization and unusual conductivity behavior in cellulose n...Pawan Kumar
Aqueous suspensions of cellulose nanocrystals were blended with Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)
[PEDOT:PSS], and cast into thin films. The morphology, structure and electrical properties of the resulting nanocomposite
thin films were thoroughly characterized. We found that the CNC–PEDOT:PSS blends self-organize into a layered vertical
stack with a pitch of 100–200 nm while retaining a continuous percolation network for PEDOT. Atomic force microscopy,
dynamic light scattering and multi-angle light scattering measurements confirmed the wrapping of polymer chains around
the rod-like CNCs. The blended films exhibited improved molecular ordering of the PEDOT chains with concomitant
improvement in the carrier mobility. The remarkable self-organization and enhanced structural order enabled the CNC–
PEDOT:PSS blends to exhibit a high conductivity typical of PEDOT:PSS even when the content of the insulating CNCs in
the nanocomposite was as high as 50 wt%.
Remarkable self-organization and unusual conductivity behavior in cellulose n...Pawan Kumar
The document describes research on nanocomposites made from blending cellulose nanocrystals (CNCs) with PEDOT:PSS. Key findings include:
1) CNC-PEDOT:PSS blends self-organize into layered vertical stacks with a pitch of 100-200nm while maintaining a continuous polymer network.
2) Atomic force microscopy, dynamic light scattering, and multi-angle light scattering confirm wrapping of polymer chains around rod-like CNCs.
3) Blended films exhibit improved molecular ordering of PEDOT chains and enhanced structural order, enabling high conductivity even at 50wt% insulating CNC content.
Remarkable self-organization and unusual conductivity behavior in cellulose n...Pawan Kumar
The document describes research on nanocomposites made of cellulose nanocrystals (CNCs) blended with PEDOT:PSS. Key findings include:
1) CNC-PEDOT:PSS blends were found to self-organize into layered vertical stacks with a pitch of 100-200nm, while maintaining electrical conductivity even at 50wt% CNC loading.
2) Measurements showed the PEDOT polymer chains wrapped around the rod-like CNCs.
3) The blended films exhibited improved molecular ordering of PEDOT chains and enhanced structural order, enabling high conductivity typical of PEDOT:PSS.
Unusual Electronic Properties of Cellulose Nanocrystals Conjugated to Cobalt ...Pawan Kumar
Octacarboxylated cobalt phthalocyanine (CoPc) was covalently conjugated to cellulose nanocrystals (CNCs) by employing an esterification protocol. Solid-state NMR, X-ray photoelectron spectroscopy (XPS), Raman, and infrared spectra were used to verify and study the nature of covalent attachment responsible for the immobilization of CoPc on the CNC surface. The covalent attachment was investigated from a theoretical simulation perspective using dispersion-corrected density functional theory (DFT) calculations, which verified the stable bond formation between CNC and CoPc. CoPc is an organic semiconductor with a high exciton binding energy, and CNCs are known to be insulating. Yet, Kelvin probe force microscopy (KPFM) indicated charge carrier generation and long-lived charge separation in the CNC–CoPc conjugate compared to pristine CoPc under visible light illumination. Such behavior is more typical of a semiconductor nanocomposite. The CNC–CoPc conjugate exhibited superior performance in the visible-light-driven surface photocatalytic reduction of 4-nitrobenzenethiol (4-NBT) to p,p′-dimercaptoazobenzene (DMAB) and photodegradation of rhodamine B.
Effect of Microstructural, Optical and Electrical Properties of host PVA by Z...IRJET Journal
This document summarizes research on the effect of zinc ferrite nano fillers on the microstructural, optical, and electrical properties of polyvinyl alcohol (PVA) polymer composites. Zinc ferrite nanoparticles were synthesized using chemical precipitation and characterized. PVA composite films with varying concentrations of zinc ferrite filler from 0-2wt% were prepared by solvent casting. The composites were characterized using XRD, UV-Vis spectroscopy, and electrical conductivity measurements. XRD showed the polymer structure became more crystalline with doping. UV-Vis analysis found red shifts in absorption peaks and edges with increased doping, indicating charge transfer complexes forming between dopant and polymer. Electrical conductivity increased with doping concentration up to 6
Optical characterization of polyvinyl alcohol ammonium nitrate polymer elec...Alexander Decker
This document summarizes research on polyvinyl alcohol-ammonium nitrate polymer electrolyte films. The films were prepared using a solution casting method and their optical properties were characterized using UV-Vis spectroscopy. It was found that increasing the concentration of ammonium nitrate decreased the optical band gap of the films. Other optical properties that increased with salt concentration included refractive index, extinction coefficient, real and imaginary parts of the dielectric constant, and optical conductance. The document also discusses methods used to analyze properties like transmittance, absorption coefficient, and Urbach energy.
The document describes a study that introduces diethylammonium bromide (DABr) as a post-treatment material for pre-deposited methylammonium lead iodide (MAPbI3) perovskite films to fabricate a high-quality two-dimensional/three-dimensional (2D/3D) stacked perovskite film heterostructure. The DABr treatment improves the surface morphology, enlarges grain size, improves crystallinity, and forms a 2D capping layer. Perovskite solar cells made with the DABr-treated films showed significantly enhanced power conversion efficiency of 19.10% and stability compared to untreated films, demonstrating the potential of this
Facile Synthesis of CuO Nanoparticles by Hydrothermal Method and their Applic...IRJET Journal
The document describes a study that synthesized copper oxide (CuO) nanoparticles using a hydrothermal method. The CuO nanoparticles were characterized through various techniques and tested for their antibacterial properties. Specifically, the study synthesized CuO nanorods through a surfactant-free hydrothermal process. The nanoparticles were analyzed using XRD, SEM, EDX, FTIR, and UV-Vis spectroscopy. XRD analysis confirmed the nanoparticles had a monoclinic crystal structure. SEM showed they had a rod-like morphology. FTIR identified Cu-O bonds. UV-Vis determined the optical bandgap. Tests found the CuO nanoparticles showed good antibacterial activity against Staphylococcus aureus, with inhibition increasing at higher concentrations.
The PVA bulk solution was first prepared by dissolving PVA powder (5 wt %) in distilled water under controlling water bath temperature at 60-70 0C and continuous stirring for 3 hours, After the solution cooled down to ambient temperature, a concentration of (0.01and 0.03 wt%) of AgNO3 were added to solution in a darkroom and stirred for 2 hours, then the blend solution is poured into Petri dishes and allowed to dry to form films by casting under ambient temperature for 3 days in a darkroom, after draying the films were cut to 2cmx2cm and kept in black pags. The films were exposed to different doses (2, 4, 6, 8, 10 Gy) from a linear accelerator by constant energy 6 MeV with applicator cone and SSD (applicator surface distance) 50 cm, field size 10cmx10 cm. The characterization by by UV-visible spectroscopy showed that the pure PVA has an absorption peak in the range of ultraviolet at 275 nm and the absorption peak increases with radiation dose increment from 0 to 10 Gy and the composites films (PVA\AgNO3) showed an absorption peak coefficient at 420 nm (visible light) which is also increases as the radiation dose increases. Also the energy band gap of the composites irradiated films appeared to be decreases from 4.0E-19 down to 3.5E-19 eV. Moreover the optical density of the irradiated films showed significant correlation (R2 = 0.99) with the applied dose. While the tensile strength (TS) of the irradiated PVA film has been increases following the increment of radiation dose and peaking at 30 MPa at 6 Gy, then decreases as the dose increase. The study also revealed that there is a significant (R2 =96) linear proportional relationship between the absorption coefficient and the applied dose on the PVA film.
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
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Influence of Manganese doping on Structural, optical and ethanol sensing of S...IRJET Journal
This document summarizes research on the influence of manganese doping on the structural, optical, and ethanol sensing properties of copper oxide thin films synthesized using successive ion layer adsorption and reaction technique. Key findings include:
- X-ray diffraction analysis showed manganese doping reduced grain size up to 5% doping due to increased microstrain, beyond which grain size increased.
- Optical studies found the band gap increased with doping up to 5% due to the Burstein-Moss effect, then decreased with further doping likely due to excess manganese in interstitial sites.
- The 5% doped film exhibited the highest sensitivity of 87% for detecting 1500 ppm ethanol at
This document describes the fabrication and testing of a high-performance tandem organic solar cell with novel active layers. It utilizes a record-efficiency polymer, PBTI3T, in combination with other polymers like PTB7 and PSBTBT-Si to further enhance efficiency. Absorption spectra of the polymers show offset peaks that minimize spectral overlap when combined in a tandem device. Tandem devices were fabricated with PBTI3T and either PTB7 or PSBTBT-Si as the active layers. Results showed one of the highest open-circuit voltages reported and an overall power conversion efficiency above 6%, demonstrating the potential of tandem organic photovoltaics using high-efficiency polymers.
Preparation and study of optical properties of (polymer nickel nitrate) compo...Alexander Decker
This document summarizes an academic article that studied the optical properties of polymer-nickel nitrate composite materials. It discusses how composites of polyvinyl alcohol doped with different concentrations of nickel nitrate were prepared and their optical characteristics analyzed. The study found that absorption increased with higher nickel nitrate concentration, while the optical band gap decreased. The refractive index, extinction coefficient, and dielectric constants were also found to increase with greater amounts of the nickel nitrate dopant. The composites showed potential for applications in areas like integrated optics or holography due to their tunable optical properties.
This document summarizes a study analyzing the image profiles of poly-(diamino naphthalene) (PDAN) doped poly-(vinyl alcohol) (PVA) films using time-of-flight secondary ion mass spectrometry (ToF-SIMS). ToF-SIMS was used to obtain total ion images and positive ion images of PVA, diamino-naphthalene (DAN) doped PVA, and PDAN doped PVA films. The results showed that total ion counts and secondary ion intensities decreased with increasing molecular mass of species, indicating higher mass fragments are more affected by surface density. Positive ion images of different mass fragments for each film were obtained, with contrast and
Preparation and Characterization of Lithium Ion Conducting Solid Polymer Elec...IJERA Editor
Solid Polymer electrolyte films have been prepared from Starch-Poly vinyl alcohol (PVA) blend a well acknowledged biodegradable material. Solution cast technique was employed for the preparation of solid polymer electrolyte films added with Lithium Bromide (LiBr) salt. X-ray diffraction (XRD) studies of the prepared films portrayed the evolution of an amorphous structure with increasing content of salt which is an important factor that leads to the augmentation of conductivity. Electrochemical impedance spectroscopic analysis revealed noticeable ionic conductivity ~ 5x 10-3 S/cm for 20 wt% of salt at ambient conditions. Ionic conductivity showed an increasing trend with salt content at ambient conditions. Transference number measurements confirmed the ionic nature of the prepared solid polymer electrolyte films. Dielectric studies revealed a sharp increase in the number of charge carriers which contributed to enhancement in conductivity. Low values of activation energy extracted from temperature dependent conductivity measurements could be favorable for device applications. For the composition with highest conductivity a temperature independent relaxation mechanism was confirmed by electric modulus scaling.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
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However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Threats to mobile devices are more prevalent and increasing in scope and complexity. Users of mobile devices desire to take full advantage of the features
available on those devices, but many of the features provide convenience and capability but sacrifice security. This best practices guide outlines steps the users can take to better protect personal devices and information.
TrustArc Webinar - 2024 Global Privacy SurveyTrustArc
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In the fifth annual Global Privacy Benchmarks Survey, we asked over 1,800 global privacy professionals and business executives to share their perspectives on the current state of privacy inside and outside of their organizations. This year’s report focused on emerging areas of importance for privacy and compliance professionals, including considerations and implications of Artificial Intelligence (AI) technologies, building brand trust, and different approaches for achieving higher privacy competence scores.
See how organizational priorities and strategic approaches to data security and privacy are evolving around the globe.
This webinar will review:
- The top 10 privacy insights from the fifth annual Global Privacy Benchmarks Survey
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1. Insights into integrating generative AI.
2. Understanding how this integration enhances test automation within the UiPath platform
3. Practical demonstrations
4. Exploration of real-world use cases illustrating the benefits of AI-driven test automation for UiPath
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What is generative AI
Test Automation with generative AI and Open AI.
UiPath integration with generative AI
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20 Comprehensive Checklist of Designing and Developing a WebsitePixlogix Infotech
Dive into the world of Website Designing and Developing with Pixlogix! Looking to create a stunning online presence? Look no further! Our comprehensive checklist covers everything you need to know to craft a website that stands out. From user-friendly design to seamless functionality, we've got you covered. Don't miss out on this invaluable resource! Check out our checklist now at Pixlogix and start your journey towards a captivating online presence today.
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Partecipate alla presentazione per immergervi in una storia di interoperabilità, standard e formati aperti, per poi discutere del ruolo importante che i contributori hanno in una comunità open source sostenibile.
BIO: Sostenitrice del software libero e dei formati standard e aperti. È stata un membro attivo dei progetti Fedora e openSUSE e ha co-fondato l'Associazione LibreItalia dove è stata coinvolta in diversi eventi, migrazioni e formazione relativi a LibreOffice. In precedenza ha lavorato a migrazioni e corsi di formazione su LibreOffice per diverse amministrazioni pubbliche e privati. Da gennaio 2020 lavora in SUSE come Software Release Engineer per Uyuni e SUSE Manager e quando non segue la sua passione per i computer e per Geeko coltiva la sua curiosità per l'astronomia (da cui deriva il suo nickname deneb_alpha).
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The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
GraphSummit Singapore | The Future of Agility: Supercharging Digital Transfor...Neo4j
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GraphSummit Singapore | The Future of Agility: Supercharging Digital Transfor...
A045050107
1. M. Meena et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 5( Version 5), May 2014, pp.01-07
www.ijera.com 1 | P a g e
Investigation on CuO Dispersed PVA Polymer Films
R. Divya1
, M. Meena2
, C. K. Mahadevan2
and C. M. Padma1
1
Department of Physics, Women’s Christian College, Nagercoil – 629001, Tamilnadu, India.
2
Physics Research Centre, S.T. Hindu College, Nagercoil – 629002, Tamilnadu, India
Abstract
Addition of inorganic nanoparticles to polymers allows the modification of physical properties of
polymers as well as the implementation of new features in polymer matrix. In the present work, we have made
an attempt to disperse CuO nanoparticles in the polyvinyl alcohol (PVA) and to understand the change in
structural, optical and electrical properties of the polymer film. CuO nanoparticles were added in four different
concentrations, viz. 2.5, 5.0, 7.5 and 10 wt%. A total of 5 films were prepared (including the pure PVA film, for
comparison).The prepared films were subjected to XRD, FESEM, UV-Vis spectral, PL spectral and electrical
analyses. The results obtained are reported.
Keywords: Polymer thin films; Inorganic nanoparticles; Structural properties; Optical properties; Electrical
properties
I. INTRODUCTION
Fabrication of inorganic nanoparticles in
polymer matrices has attracted much attention,
because the combination of inorganic nanoparticles
and a polymer provides a simple route to stable and
processable composite materials, integrating the
promising properties of both components [1]. It is
well known that the electrical and optical properties
of polymers can be improved to a desired limit
through suitable doping [2]. Also the optical and
electrical properties of nanocomposites films can be
adjusted by varying the composition. Over the years,
Polyvinyl alcohol (PVA) polymer has attracted
attention due to its high dielectric strength, good
charge storage capacity and dopant dependent
electrical and optical properties [3].
PVA is a water soluble synthetic polymer
which has a melting point of 230 o
C and density 1.36
g/cm3
. Also, PVA has carbon chain backbone with
hydroxyl groups attached to methane carbons; these
OH groups can be a source of hydrogen bonding and
hence assist the formation of polymer composite [4].
However, the retention of homogenous dispersion of
nano-sized particle in the preparation process of
nanocomposites is very difficult, because of strong
tendency for nanoparticles to agglomerate [5]. To
prevent the formation of agglomeration of
nanoparticles in polymers, the combination of
inorganic particles with polymers is usually
accomplished by surface modification. CuO is the
simplest member in the family of Cu compounds and
exhibit a range of potential physical properties, such
as high temperature superconductivity, electron
correlation effects and spin dynamics [ 6,7]. It
possesses useful photovoltaic and photoconductive
properties because CuO crystal structure has a narrow
band gap [8]. CuO nanoparticles have been applied in
different areas including gas sensors [9], catalysis
[10], batteries [11], solar energy conversion [12], etc.
CuO is much cheaper than silver oxide and can be
mixed with polymer more easily to obtain composites
with unique chemical and physical properties,
because they can reduce friction and mend worn
surface [13,14].
The crucial factors for the use of a
semiconducting material as an active layer in the
solar cells are the band gap and optical absorption of
the material. The relatively large band gap of
polymer such as PVA limits the absorption of near-
infrared light and thus lowers the light harvesting and
therefore cannot be used as an active layer in organic
solar cells. The control over the band gap is
necessary while designing new materials for organic
solar cells. The band gap engineering allows one to
design and synthesize new materials with maximum
overlap of absorption spectrum with the solar
emission spectrum. It is often found that the synthesis
of low band gap polymer is not only the solution to
address this problem but also the position of highest
occupied molecular orbital (HOMO) and lowest
unoccupied molecular orbital (LUMO) limits the
open-circuit voltage (Voc) of the photovoltaic cell.
These two properties of organic materials can be
controlled by introducing nano-inorganic salts or
introducing alternative electron rich and electron-
deficient units in the polymer backbone [15,16].
Recently, synthesis and design of several important
low band gap polymers with enhanced absorption
abilities have been reported and researchers have
made a breakthrough in fabricating polymer solar
cells with conversion efficiency up to 5-7 % based on
the II-VI compounds filled polymers [17].
Keeping this in view, in order to find new
polymer composites with tuned properties for
RESEARCH ARTICLE OPEN ACCESS
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photonic and electronic applications, we have made
an attempt to prepare CuO dispersed PVA polymer
films with different concentrations of CuO by a
simple chemical method. The results obtained in the
present study are reported herein.
II. MATERIALS AND METHODS
Polyvinyl alchocol, dimethyl sulphoxide
(DMSO), demineralised water, copper acetate and
urea were purchased from Aldrich. Pure PVA thin
film was prepared by dissolving 2.5 g of PVA in a
mixed solvent of DMSO and water at 40 o
C and
stirred continuously for about 1 hour. The thin film
was made by evaporating the excess solvent by
pouring the solution in petri dish and dried it in
sunlight. For CuO dispersed PVA films, the above
prepared PVA solution was modified by adding 2.5
wt% of copper acetate and urea solution. The same
procedure was followed for the remaining
concentrations (5.0, 7.5 and 10 wt%) also. Pure and
CuO dispersed PVA thin films were characterized
by X-ray diffraction (XRD), field effect scanning
electron microscopic (FESEM), thickness and
refractive index, UV-Vis spectral,
photoluminescence (PL) spectral and electrical (both
DC and AC) measurements by using the standard
available procedures. The polymer films prepared in
the present study are represented as: Pure PVA for
the pure PVA polymer film and 2.5 % CuO, 5.0 %
CuO, 7.5 % CuO and 10 % CuO respectively for the
2.5 wt%, 5.0 wt%, 7.5 wt% and 10 wt% CuO
dispersed PVA polymer films.
III. RESULTS AND DISCUSSION
3.1 XRD Analysis
The X-ray diffraction measurements were
carried out on all the five films prepared in the
present study using X-ray powder diffractometer
(PANalytical X-ray diffractometer) with Cu Kα
radiation of wavelength 1.54056 Ǻ. The XRD
patterns of as-prepared pure and CuO dispersed PVA
polymer composites observed in the present study are
shown in Figure 1. Figure shows clearly that the
broad peak around 20 o
is the characteristic peak of
PVA [18]. As the concentration of CuO was
increased , new sharp peaks have appeared around 42
o
, 61 o
and 74 o
indicating clearly the inclusion of
CuO in the PVA host matrix. Also the position of
new peaks are well matched with the cubic structure
of CuO [JCPDS File No: 780428 ].
Fig 1: XRD patterns of pure and CuO dispersed
PVA films
3.2 FESEM Analysis
The FESEM images for all the five films
prepared were obtained using FESEM-SUPRA 55) -
CARL ZEISS, GERMANY. FESEM images of pure
and CuO dispersed PVA films observed in the
present study are shown in Figure 2. The images give
the information about the surface of the grown films.
Depending on the concentration of CuO presence in
the PVA matrix, the morphology of CuO-PVA
composite varies and greatly influences the
properties. Pure PVA shows smooth surface whereas
dispersion of CuO with different concentrations
shows remarkable changes in the surface. This
indicates the incorporation of CuO nanoparticles in
the PVA polymer (host) matrix endorsing the results
of XRD measurements. Moreover, homogeneity is
maintained with the increase in concentration of
CuO. The XRD and FESEM analyses indicate the
formation of proper CuO-PVA nanocomposites.
Thus, it is understood that the simple chemical
method adopted in the present study along with
copper acetate, urea and PVA as the precursors
favours the formation of films of proper CuO-PVA
nanocomposites.
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Fig 2: FESEM images of pure and CuO dispersed
PVA films
3.3 Thickness and Refractive Index Measurements
Spectroscopic reflectometry involves
illuminating samples with a white light (typically
tungsten halogen or deuterium- halogen) at an
incident angle which is normal to the sample and then
measuring the reflectance and interference from the
same geometry. Depending upon the nature of the
coating or film ultra-violet, visible or near infrared
wavelength measurements may be necessary to
obtain an optimum fitting of the measured curve
relative to the theoretical reflectance curve. The
theoretical curve is developed from a database of
optical constants (n and k). The “n” value is the
refractive index and “k” is the extinction coefficient.
The sampling process initially involves measuring a
reference uncoated substrate followed by the sample
measurement using the same conditions. The
thickness and refractive index of the films prepared
in the present study were measured using a US
Mprobe VIS spectroscopic reflectometer. The
thickness and refractive index were measured at
different places in every film and the average values
were determined.
Table 1: The average thicknesses and refractive
indices of pure and CuO dispersed PVA thin films
Sample Name Thickness (x
10-10
m)
Refractive
index
Pure PVA 1758 1.428
2.5 wt % CuO 1821 1.521
5.0 wt % CuO 1836 1.633
7.5 wt % CuO 1796 1.697
10 wt % CuO 1795 1.752
It is interesting to note that the thickness
does not vary significantly from one place to another
in the film. This indicates that the films formed in the
present study are of uniform thickness. The average
thickness and refractive index values observed for the
pure and CuO dispersed thin films are given in Table
1. The increase in refractive index observed due to
PURE PVA
5.0 % CuO
10.0 % CuO
2.5 % CuO
7.5 % CuO
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CuO dispersion proves the presence of CuO in the
PVA matrix, because CuO has higher refractive
index (n >2). Moreover, it can be seen that the
refractive index increases almost in proportion with
the increase in CuO concentration considered for the
preparation of films. Also, the measured value of n
for maximum CuO concentrated film well matches
with the reported one for CuO doped PVA thin films
( n=1.78 ) [19].
3.4 UV-Vis-NIR Spectral Analysis
The optical absorption is an important tool
to obtain optical energy band gap of crystalline and
amorphous materials. The fundamental absorption
corresponds to the electron excitation from the
valence band to the conduction band can be used to
determine the nature and value of the optical band
gap. UV-Vis-NIR spectral analysis was carried out
for all the five films prepared in the present study in
the wavelength range 190 – 900 nm using Jasco V –
630 spectrophotometer . Figure 3 shows the optical
absorption spectra (A) and the corresponding Tauc
plots (B) of pure and CuO dispersed PVA films
observed in the present study. The absorption spectra
reveal that the increase in concentration of CuO
produces red shift in the absorption peak and results
in low band gap.
The pure PVA nanocrystalline film has no
remarkable absorption in the visible light region with
a wavelength above 400 nm whereas the CuO
dispersed nanocrystalline film extends the absorption
spectrum obviously into the visible region. The result
indicates the ability of doped CuO crystalline films to
harvest the visible component of solar radiation.
Thus, the CuO dispersed PVA crystalline films could
be promising photocatalysts under visible light. Also
the optical band gap of the synthesized films were
determined from Tauc plot by taking energy along x-
axis and (αhν)2
along y-axis . CuO addition decreases
the band gap from 3.47 to 1. 63 eV with increasing
concentration which is similar to that observed for
PVA-CuI composite films [3]. This may be attributed
to salt complexation with polymer matrix besides the
expected nanaoparticle aggregation. Increase in
absorption and decrease in band gap may be due to
charge transfer transitions. Thus, the present study
indicates that CuO dispersion tunes the optical
absorption property of PVA significantly and
consequently makes the PVA film more useful.
Fig 3: (A) UV-Vis-NIR absorption spectra and (B)
Tauc plots of pure and CuO dispersed PVA films
3.5 PL Analysis
PL spectra were recorded for all the five
films prepared in the present study using Perkin
Elmer model: LS45 spectrophotometer . The PL
spectra of the prepared films with the excitation
wavelength of 280 nm are shown in Figure 4. Though
bulk CuO could not emit light, the nano structures
can emit visible and UV light [20]. PL emission is
mainly attributed to the presence of vacancies or
impurities. Vacancies may be copper or oxygen
vacancies while the defects may be interstitial copper
or anti-oxygen sites [20]. Vacancies present in the
material induces the formation of new energy levels
in the band gap and as a result emissions will arise
from these trap levels while exciting the sample.
Emission occurs due to radiative recombination of a
photo-excited hole with an electron and the emission
peaks are commonly referred to as deep level or trap
site emission due to oxygen vacancies [21]. The
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observed PL spectra show clearly the violet emission.
The CuO dispersion in PVA matrix increases the
wavelength of light emitted almost in proportion with
the concentration of CuO.
Results of optical (UV-Vis-NIR and PL
spectral) measurements indicate that the CuO
dispersed PVA polymer films prepared in the present
study are expected to be more useful in photonics
applications.
Fig 4: PL spectra of pure and CuO dispersed PVA
thin films
3.6 Electrical Properties
3.6.1DC electrical measurements
DC electrical conductivity measurements
were carried out on all the five films prepared in the
present study by using the conventional two-probe
technique in the temperature range 30 – 90 o
C. The
DC electrical conductivities observed in the present
study are shown in Figure 5. It is found that the DC
conductivity increases with the increase in
temperature as well as with the increase in CuO
concentration. This indicates that the electronic
conduction is increased significantly by dispersing
CuO in the PVA matrix indicating that the space
charge contribution may play an important role in the
charge transport process [22,23].
Fig 5: DC electrical conductivities of pure and
CuO dispersed PVA films
3.6.2 AC electrical measurements
Dielectric spectroscopy is sensitive to the
heterogeneous system and can provide insights into
the structures and electrical properties of the
materials at molecular and macroscopic levels [24].
The dielectric constant and dissipation (dielectric
loss) factor are crucial parameters required in the
design of electronic and other related electrical
devices and furthermore, as a function of temperature
or frequency, they reveal much information on the
chemical or physical state of the polymer [25].
The dielectric measurements were
performed using an impedance analyzer (Agilent
4284 A LCR meter) covering a frequency range from
20 to 1×106
Hz. The film samples were cut into
circular pieces of diameter 13 mm and coated with
silver paste and mounted between the electrodes of
the parallel plate capacitor. Capacitance (C) and
dielectric loss factor (tan δ) were measured for
various frequencies at room temperature. The real
part of the dielectric constant was calculated using
the relation
𝜀′ =
𝐶
𝐶0
where C and Co are the capacitance values with and
without sample, respectively; Co = [(0.08854 A)/d]
pF, where A (cm2
) is the area of the electrode and d
(cm) is the thickness of the film sample. The
imaginary part of the dielectric constant was
calculated using the relation
ε” = ε’ tan δ
The AC electrical conductivity was
calculated by using the relation
𝜎𝑎𝑐 = 𝜀0 ε′
tan 𝛿 𝜔
where ω is the angular frequency which is equal to
2πf (where f is the frequency of the applied field).
Variations of 𝜀′, ε” , tan δ and ζac with
frequency are shown in Figures 6 to 8 for all the 5
film samples considered in the present study. It can
be seen that the dielectric constant (both real and
imaginary parts) and dielectric loss factor decrease
while the AC electrical conductivity increases with
increasing frequency. Moreover, CuO dispersion
nearly decreases the real part of dielectric constant
and increases the imaginary part of dielectric
constant, dielectric loss factor and AC electrical
conductivity significantly. However, all the dielectric
parameters (except the real part of dielectric constant)
considered are found to vary nonlinearly with the
CuO concentration. This may be due to the
complexity involved in the charge transport and
polarization processes.
The rapid decrease in the dielectric constant
noticed over the low frequency range 1 -100 kHz
may be attributed to the tendency of dipoles in
macromolecules to orient themselves in the direction
of the applied field in the low frequency range.
However, in the high frequency range the dipoles will
hardly be able to orient themselves in the direction of
the applied field, and hence the value of the dielectric
constant decreases [26]. Also, CuO dispersion in
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PVA matrix nearly decreases the value of 𝜀′
with
increasing CuO concentration.
Fig 6 : Variations of ε’ and ε’’ with frequency for
pure and CuO dispersed films
The tan δ spectrum shows relaxation process
for all the film samples considered, and as the degree
of cross-linking increases, the magnitude of the
relaxation peak decreases [27] and the breadth
increases [28]. The observed tan δ values are below
1.0 which indicates that the dielectric phenomenon is
predominant in all the film samples considered.
Fig 7: Variation of tan δ with frequency for pure
and CuO dispersed PVA films
The increase of AC electrical conductivity
with frequency is common for polymeric and
semiconductor samples [29]. As the filler
concentration is increased, the inorganic filler
molecules start bridging the gap separating the two
localized states and lowering the potential barrier
between them, thereby facilitating the transfer of
charge carrier between two localized states [30]. The
frequency and temperature dependent conductivity is
caused by the hopping of charge carriers in the
localized state and also due to the excitation of
charge carriers to the states in the conduction band
[31]. The term hopping refers to the sudden
displacement of charge carriers from one position to
another neighboring site and, in general, includes
both jumps over a potential barrier and quantum
mechanical tunneling [32,33].
Fig 8: Variation of ζac with frequency for pure
and CuO dispersed PVA films
Results of electrical (both DC and AC)
measurements observed in the present study indicate
an increase of electronic conductivity and decrease of
the real part of dielectric constant with the increase in
concentration of CuO dispersion in the PVA polymer
matrix. This leads to an expectation that the CuO
dispersed PVA polymer films prepared in the present
study will find more utility in electronic and other
related electrical devices.
IV. Conclusions
Pure and CuO dispersed PVA polymer films
have been prepared successfully by a simple
chemical method and characterized structurally,
optically and electrically. The XRD and FESEM
analyses and thickness measurement indicate that the
simple chemical method adopted in the present study
favour the formation of good quality films of proper
CuO-PVA nanocomposites. Results of optical and
electrical measurements indicate respectively a
decrease of band gap and an increase of electronic
conductivity with CuO dispersion making the CuO-
PVA nanocomposites (films) prepared in the present
study expected to be more useful in photonic and
electronic device applications.
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