Biofunctionalized gold nanoparticle-conducting polymer nanocomposite based bioelectrode for CRP detection.

Science.gov (United States)

Mishra, Sujeet K; Sharma, Vikash; Kumar, Devendra; Rajesh

2014-10-01

An electrochemical impedance immunosensing method for the detection and quantification of C-reactive protein (αCRP) in phosphate buffered saline (PBS) is demonstrated. The protein antibody, Ab-αCRP, has been covalently immobilized on a platform comprising of electrochemically deposited 3-mercaptopropionic acid-capped gold nanoparticles Au(MPA)-polypyrrole (PPy) nanocomposite film of controlled thickness onto an indium tin oxide-coated glass plate. The free carboxyl groups present on the nanocomposite film have been used to site-specifically immobilize the Ab-αCRP biomolecules through a stable acyl amino ester intermediate generated by N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride and N-hydroxysuccinimide. The nanocomposite film was characterized by atomic force microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and electrochemical techniques. The bioelectrode was electrochemically analyzed using modified Randles circuit in terms of constant phase element (CPE), electron transfer resistance (R et), and Warburg impedance (Z w). The value of n, a CPE exponent used as a gauge of heterogeneity, for the Au-PPy nanocomposite film was found to be 0.56 which is indicative of a rather rough morphology and porous structure. A linear relationship between the increased ∆R et values and the logarithmic value of protein antigen, Ag-αCRP, concentrations was found in the range of 10 ng to 10 μg mL(-1) with a R et sensitivity of 46.27 Ω cm(2)/decade of [Ag-αCRP] in PBS (pH 7.4).

Evaluation of synovium-derived mesenchymal stem cells and 3D printed nanocomposite scaffolds for tissue engineering

International Nuclear Information System (INIS)

Pan, Jian-Feng; Li, Shuo; Guo, Chang-An; Zhang, Feng; Yan, Zuo-Qin; Xu, Du-Liang; Mo, Xiu-Mei

2015-01-01

Stem cells and scaffolds play a very important role in tissue engineering. Here, we isolated synovium-derived mesenchymal stem cells (SMSCs) from synovial membrane tissue and characterized stem-cell properties. Gelatin nanoparticles (NP) were prepared using a two-step desolvation method and then pre-mixed into different host matrix (silk fibroin (SF), gelatin (Gel), or SF–Gel mixture) to generate various 3D printed nanocomposite scaffolds (NP/SF, NP/SF–Gel, NP/Gel-1, and NP/Gel-2). The microstructure was examined by scanning electron microscopy. Biocompatibility assessment was performed through CCK-8 assay by coculturing with SMSCs at 1, 3, 7 and 14 days. According to the results, SMSCs are similar to other MSCs in their surface epitope expression, which are negative for CD45 and positive for CD44, CD90, and CD105. After incubation in lineage-specific medium, SMSCs could differentiate into chondrocytes, osteocytes and adipocytes. 3D printed nanocomposite scaffolds exhibited a good biocompatibility in the process of coculturing with SMSCs and had no negative effect on cell behavior. The study provides a strategy to obtain SMSCs and fabricate 3D printed nanocomposite scaffolds, the combination of which could be used for practical applications in tissue engineering. (paper)

Chondrogenic potential of bone marrow–derived mesenchymal stem cells on a novel, auricular-shaped, nanocomposite scaffold

Directory of Open Access Journals (Sweden)

Kavi H Patel

2013-12-01

Full Text Available Reconstruction of the human auricle remains a challenge to plastic surgeons, and current approaches are not ideal. Tissue engineering provides a promising alternative. This study aims to evaluate the chondrogenic potential of bone marrow–derived mesenchymal stem cells on a novel, auricular-shaped polymer. The proposed polyhedral oligomeric silsesquioxane-modified poly(hexanolactone/carbonateurethane/urea nanocomposite polymer has already been transplanted in patients as the world’s first synthetic trachea, tear duct and vascular bypass graft. The nanocomposite scaffold was fabricated via a coagulation/salt-leaching method and shaped into an auricle. Adult bone marrow–derived mesenchymal stem cells were isolated, cultured and seeded onto the scaffold. On day 21, samples were sent for scanning electron microscopy, histology and immunofluorescence to assess for neocartilage formation. Cell viability assay confirmed cytocompatability and normal patterns of cellular growth at 7, 14 and 21 days after culture. This study demonstrates the potential of a novel polyhedral oligomeric silsesquioxane-modified poly(hexanolactone/carbonateurethane/urea scaffold for culturing bone marrow–derived mesenchymal stem cells in chondrogenic medium to produce an auricular-shaped construct. This is supported by scanning electron microscopy, histological and immunofluorescence analysis revealing markers of chondrogenesis including collagen type II, SOX-9, glycosaminoglycan and elastin. To the best of our knowledge, this is the first report of stem cell application on an auricular-shaped scaffold for tissue engineering purposes. Although many obstacles remain in producing a functional auricle, this is a promising step forward.

Probing localized strain in solution-derived YB a2C u3O7 -δ nanocomposite thin films

Science.gov (United States)

Guzman, Roger; Gazquez, Jaume; Mundet, Bernat; Coll, Mariona; Obradors, Xavier; Puig, Teresa

2017-07-01

Enhanced pinning due to nanoscale strain is unique to the high-Tc cuprates, where pairing may be modified with lattice distortion. Therefore a comprehensive understanding of the defect landscape is required for a broad range of applications. However, determining the type and distribution of defects and their associated strain constitutes a critical task, and for this aim, real-space techniques for atomic resolution characterization are necessary. Here, we use scanning transmission electron microscopy (STEM) to study the atomic structure of individual defects of solution-derived YB a2C u3O7 (YBCO) nanocomposites, where the inclusion of incoherent secondary phase nanoparticles within the YBCO matrix dramatically increases the density of Y1B a2C u4O8 (Y124) intergrowths, the commonest defect in YBCO thin films. The formation of the Y124 is found to trigger a concatenation of strain-derived interactions with other defects and the concomitant nucleation of intrinsic defects, which weave a web of randomly distributed nanostrained regions that profoundly transform the vortex-pinning landscape of the YBCO nanocomposite thin films.

Study of processing conditions on properties of ABS and clay organically modified nanocomposites

International Nuclear Information System (INIS)

Galvan, Danieli; Massucato, Felipe; Bartoli, Julio R.; D'Avila, Marcos A.; Fernandes, Elizabeth G.

2011-01-01

Nanocomposites of poly(acrylonitrile-butadiene-styrene) and organically modified montmorillonite clay were prepared by melt intercalation on a co-rotating twin-screw extruder. The independent variables studied were the kind of organoclay (Cloisite 20A and Cloisite 30B) and the screw torque at levels of 45 and 70%. The effect of these variables on the intercalation/exfoliation were accessed by means of the morphological characteristics using X-ray diffraction and the mechanical properties of uniaxial tensile test. The experimental results showed that the incorporation of clay in the polymeric matrix improved the mechanical properties of elastic modulus, yield stress and tensile strength of nanocomposites, being more significant for that containing Cloisite 30B. Torque was also a significant variable for the responses studied. (author)

CA 19-9 Pancreatic Tumor Marker Fluorescence Immunosensing Detection via Immobilized Carbon Quantum Dots Conjugated Gold Nanocomposite.

Science.gov (United States)

Alarfaj, Nawal Ahmad; El-Tohamy, Maha Farouk; Oraby, Hesham Farouk

2018-04-11

The clinical detection of carbohydrate antigen 19-9 (CA 19-9), a tumor marker in biological samples, improves and facilitates the rapid screening and diagnosis of pancreatic cancer. A simple, low cost, fast, and green synthesis method to prepare a viable carbon quantum dots/gold (CQDs/Au) nanocomposite fluorescence immunosensing solution for the detection of CA 19-9 was reported. The present method is conducted by preparing glucose-derived CQDs using a microwave-assisted method. CQDs were employed as reducing and stabilizing agents for the preparation of a CQDs/Au nanocomposite. The immobilized anti-CA 19-9-labeled horseradish peroxidase enzyme (Ab-HRP) was anchored to the surface of a CQDs/Au nanocomposite by a peptide interaction between the carboxylic and amine active groups. The CA 19-9 antigen was trapped by another monoclonal antibody that was coated on the surface of microtiter wells. The formed sandwich capping antibody-antigen-antibody enzyme complex had tunable fluorescence properties that were detected under excitation and emission wavelengths of 420 and 530 nm. The increase in fluorescence intensities of the immunoassay sensing solution was proportional to the CA 19-9 antigen concentration in the linear range of 0.01-350 U mL -1 and had a lower detection limit of 0.007 U mL -1 . The proposed CQDs/Au nanocomposite immunoassay method provides a promising tool for detecting CA 19-9 in human serum.

Investigation of the effect of nanoclay and processing parameters on the tensile strength and hardness of injection molded Acrylonitrile Butadiene Styrene–organoclay nanocomposites

International Nuclear Information System (INIS)

Mamaghani Shishavan, Sajjad; Azdast, Taher; Rash Ahmadi, Samrand

2014-01-01

Highlights: • Development of polymer/clay nanocomposites. • Compatibility of ABS and montmorillonite nanoclay and composition capability of them. • Effect of nanoclay content and process parameters on the mechanical properties of nanocomposite. • Analyzing the distribution of nanoclay layers using XRD test. • Dependency of tensile strength and hardness to the nanoclay content and processing conditions. - Abstract: Polymer–clay nanocomposites have attracted considerable interest over recent years due to their dramatic improved mechanical properties. In the present study, compatibility of Acrylonitrile Butadiene Styrene (ABS) and organically modified montmorillonite nanoclay (Cloisite 30B) and composition capability of them are investigated. Polymethylmethacrylate (PMMA) in varying amount (0, 2, and 4 wt%) is used as the compatibilizer. In order to produce nanocomposite parts, the material is first compounded using a twin-screw extruder and then injected into a mold. The effect of the nanoclay percentage and processing parameters on the tensile strength and hardness of nanocomposite parts is also explored using Taguchi Design of Experiments method. Nanoclay content (in three levels: 0, 2 and 4 wt%), melt temperature (in three levels: 190, 200 and 210 °C), holding pressure (in three levels: 80, 105 and 130 MPa) and holding pressure time (in three levels: 1, 2.5 and 4 s) are considered as the variable parameters. Moreover, distribution of nanoclay layers is analyzed using Wide Angle X-ray Diffraction (XRD) test. XRD results displayed that with the presence of PMMA, nanoclay in ABS matrix is compounded in more exfoliated and less intercalated dispersion mode. Adding PMMA also leads to a remarkable increase in the fluidity of the melt during injection molding process. Results also illustrated that nanocomposites with medium loading level (i.e. 2%) of nanoclay have the highest tensile strength, while the highest hardness number belongs to nanocomposites with

Ab initio pseudopotential theory

International Nuclear Information System (INIS)

Yin, M.T.; Cohen, M.L.

1982-01-01

The ab initio norm-conserving pseudopotential is generated from a reference atomic configuration in which the pseudoatomic eigenvalues and wave functions outside the core region agree with the corresponding ab initio all-electron results within the density-functional formalism. This paper explains why such pseudopotentials accurately reproduce the all-electron results in both atoms and in multiatomic systems. In particular, a theorem is derived to demonstrate the energy- and perturbation-independent properties of ab initio pseudopotentials

Research Progress in Graphene/Rubber Conducting Nanocomposites

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DONG Hui-min

2017-03-01

Full Text Available The conductive mechanism of graphene/rubber nanocomposites was introduced.Advances in the synthesis and properties of graphene and its derivatives, modifications of graphene, along with its hybrid fillers, as well as fabrication of related rubber conducting nanocomposites were reviewed.Many factors affecting the electrical properties, such as fabrication method, vulcanization, temperature, pressure, frequency and media etc. were also summarized.It was pointed out that the further research should be focused on multi-component graphene/rubber nanocomposites and its double percolation phenomenon.

Development of polylactic acid nanocomposite films reinforced with cellulose nanocrystals derived from coffee silverskin.

Science.gov (United States)

Sung, Soo Hyun; Chang, Yoonjee; Han, Jaejoon

2017-08-01

Bio-nanocomposite films based on polylactic acid (PLA) matrix reinforced with cellulose nanocrystals (CNCs) were developed using a twin-screw extruder. The CNCs were extracted from coffee silverskin (CS), which is a by-product of the coffee roasting process. They were extracted by alkali treatment followed by sulfuric acid hydrolysis. They were used as reinforcing agents to obtain PLA/CNC nanocomposites by addition at different concentrations (1%, 3%, and 5% CNCs). Morphological, tensile, and barrier properties of the bio-nanocomposites were analyzed. The tensile strength and Young's modulus increased with both 1% and 3% CNCs. The water vapor permeability decreased gradually with increasing addition of CNCs up to 3% and good oxygen barrier properties were found for all nanocomposites. These results suggest that CNCs from CS can improve the physical properties of PLA-based biopolymer film. The developed PLA/CNC bio-nanocomposite films can potentially be used for biopolymer materials with enhanced barrier and mechanical properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Growth suppression of colorectal cancer by plant-derived multiple mAb CO17-1A × BR55 via inhibition of ERK1/2 phosphorylation.

Science.gov (United States)

Kwak, Dong Hoon; Moussavou, Ghislain; Lee, Ju Hyoung; Heo, Sung Youn; Ko, Kisung; Hwang, Kyung-A; Jekal, Seung-Joo; Choo, Young-Kug

2014-11-14

We have generated the transgenic Tabaco plants expressing multiple monoclonal antibody (mAb) CO7-1A × BR55 by cross-pollinating with mAb CO17-1A and mAb BR55. We have demonstrated the anti-cancer effect of plant-derived multiple mAb CO17-1A × BR55. We find that co-treatment of colorectal mAbs (anti-epithelial cellular adhesion molecule (EpCAM), plant-derived monoclonal antibody (mAb(P)) CO17-1A and mAb(P) CO17-1A × BR55) with RAW264.7 cells significantly inhibited the cell growth in SW620 cancer cells. In particular, multi mAb(P) CO17-1A × BR55 significantly and efficiently suppressed the growth of SW620 cancer cells compared to another mAbs. Apoptotic death-positive cells were significantly increased in the mAb(P) CO17-1A × BR55-treated. The mAb(P) CO17-1A × BR55 treatment significantly decreased the expression of B-Cell lymphoma-2 (BCl-2), but the expression of Bcl-2-associated X protein (Bax), and cleaved caspase-3 were markedly increased. In vivo, the mAb(P) CO17-1A × BR55 significantly and efficiently inhibited the growth of colon tumors compared to another mAbs. The apoptotic cell death and inhibition of pro-apoptotic proteins expression were highest by treatment with mAb(P) CO17-1A × BR55. In addition, the mAb(P) CO17-1A × BR55 significantly inhibited the extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation in cancer cells and tumors. Therefore, this study results suggest that multiple mAb(P) CO17-1A × BR55 has a significant effect on apoptosis-mediated anticancer by suppression of ERK1/2 phosphorylation in colon cancer compared to another mAbs. In light of these results, further clinical investigation should be conducted on mAb(P) CO17-1A × BR55 to determine its possible chemopreventive and/or therapeutic efficacy against human colon cancer.

Synthesis and Characterization of Hydroxyapatite/Fullerenol Nanocomposites.

Science.gov (United States)

Djordjevic, Aleksandar; Ignjatovic, Nenad; Seke, Mariana; Jovic, Danica; Uskokovic, Dragan; Rakocevic, Zlatko

2015-02-01

Fullerenols are polyhydroxylated, water soluble derivatives of fullerene C60, with potential application in medicine as diagnostic agents, antioxidants or nano drug carriers. This paper describes synthesis and physical characterization of a new nanocomposite hydroxyapatite/fullerenol. Surface of the nanocomposite hydroxyapatite/fullerenol is inhomogeneous with the diameter of the particles in the range from 100 nm to 350 nm. The ζ potential of this nanocomposite is ten times lower when compared to hydroxyapatite. Surface phosphate groups of hydroxyapatite are prone to forming hydrogen bonds, when in close contact with hydroxyl groups, which could lead to formation of hydrogen bonds between hydroxyapatite and hydroxyl groups of fullerenol. The surface of hydroxyapatite particles (-2.5 mV) was modified by fullerenol particles, as confirmed by the obtained ζ potential value of the nanocomposite biomaterial hydroxyapatite/fullerenol (-25.0 mV). Keywords: Hydroxyapatite, Fullerenol, Nanocomposite, Surface Analysis.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

OpenAIRE

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-01-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Va...

Solid-State Synthesis and Photocatalytic Activity of Polyterthiophene Derivatives/TiO2 Nanocomposites

Directory of Open Access Journals (Sweden)

Ruxangul Jamal

2014-05-01

Full Text Available Poly(3,4-propylenedioxy-2,2':5',2"-terthiophene/TiO2 and poly(3,4-(2,2-dimethylenepropylenedioxy-2,2':5',2"-terthiophene/TiO2 nanocomposites were synthesized by a simple solid-state method. Additionally, the poly(3,4-propylenedioxy thiophene/TiO2 and poly(3,4-2,2-dimethylenepropylenedioxythiophene/TiO2 nanocomposites were synthesized in a similar manner for comparison. The structure and morphology were characterized by Fourier transform infrared (FTIR, ultraviolet-visible (UV-Vis absorption spectroscopy, X-ray diffraction (XRD and transmission electron microscopy (TEM. The photocatalytic activities of the nanocomposites were examined through the degradation processes of a methylene blue (MB solution under UV light and sunlight irradiation. The results of FTIR and UV-Vis spectra showed that the composites were successfully synthesized by solid-state method and the poly(3,4-propylenedioxy-2,2':5',2"-terthiophene/TiO2 and poly(3,4-(2,2-dimethylenepropylenedioxy-2,2':5',2"-terthiophene/TiO2 nanocomposite had a higher oxidation degree and conjugation length than others. The results also indicated that the TiO2 had no effect on the crystallinity of composites, but was well embedded in the polymer matrix. Additionally, the highest degradation efficiency of 90.5% occurred in the case of the poly(3,4-propylenedioxy-2,2':5',2"-terthiophene/TiO2 nanocomposite.

The 2-alkyl-2H-indazole regioisomers of synthetic cannabinoids AB-CHMINACA, AB-FUBINACA, AB-PINACA, and 5F-AB-PINACA are possible manufacturing impurities with cannabimimetic activities

OpenAIRE

Longworth, Mitchell; Banister, Samuel D.; Mack, James B. C.; Glass, Michelle; Connor, Mark; Kassiou, Michael

2016-01-01

Indazole-derived synthetic cannabinoids (SCs) featuring an alkyl substituent at the 1-position and l-valinamide at the 3-carboxamide position (e.g., AB-CHMINACA) have been identified by forensic chemists around the world, and are associated with serious adverse health effects. Regioisomerism is possible for indazole SCs, with the 2-alkyl-2H-indazole regioisomer of AB-CHMINACA recently identified in SC products in Japan. It is unknown whether this regiosiomer represents a manufacturing impurit...

Lead selenide quantum dot polymer nanocomposites

Science.gov (United States)

Waldron, Dennis L.; Preske, Amanda; Zawodny, Joseph M.; Krauss, Todd D.; Gupta, Mool C.

2015-02-01

Optical absorption and fluorescence properties of PbSe quantum dots (QDs) in an Angstrom Bond AB9093 epoxy polymer matrix to form a nanocomposite were investigated. To the authors’ knowledge, this is the first reported use of AB9093 as a QD matrix material and it was shown to out-perform the more common poly(methyl methacrylate) matrix in terms of preserving the optical properties of the QD, resulting in the first reported quantum yield (QY) for PbSe QDs in a polymer matrix, 26%. The 1-s first excitonic absorption peak of the QDs in a polymer matrix red shifted 65 nm in wavelength compared to QDs in a hexane solution, while the emission peak in the polymer matrix red shifted by 38 nm. The fluorescence QY dropped from 55% in hexane to 26% in the polymer matrix. A time resolved fluorescence study of the QDs showed single exponential lifetimes of 2.34 and 1.34 μs in toluene solution and the polymer matrix respectively.

Study of PVDF/Graphene oxide nanocomposites by UV-Vis analysis

International Nuclear Information System (INIS)

Pereira, Juliana V.

2013-01-01

In this work we have prepared nanocomposites made by mixing Poly (vinylidene fluoride) [PVDF] and grapheme oxide nanosheets (GO) aiming to find dosimetric properties for applications in high dose dosimetry. Graphene Oxides (GO) nanosheets were synthesized by the Hummers method, using graphite supplied by Aldrich as the starting material. Nanocomposites were produced by mixing solved PDVF in DMAc with GO dispersed in an aqueous solution by sonication. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h), with doses ranging from 50 to 1,000 kGy. The UV-Vis and spectrophotometry have been used to monitor the appearing of C=C conjugated bonds and radio-oxidation of carbon (C=O). The PVDF/OG nanocomposites prepared with 1.88 at.% of OG presented the best dosimetric properties. In this material, UVVis spectrometry has revealed that the absorbance intensities at 250 nm can be used for high dosimetry purposes for gamma doses ranging from 100 to 750 kGy. In this range, it is possible to observe a linear relationship between Abs and Dose. (author)

Cadmium Telluride-Titanium Dioxide Nanocomposite for Photodegradation of Organic Substance.

Science.gov (United States)

Ontam, Areeporn; Khaorapapong, Nithima; Ogawa, Makoto

2015-12-01

Cadmium telluride-titanium dioxide nanocomposite was prepared by hydrothermal reaction of sol-gel derived titanium dioxide and organically modified cadmium telluride. The crystallinity of titanium dioxide in the nanocomposite was higher than that of pure titanium dioxide obtained by the reaction under the same temperature and pressure conditions, showing that cadmium telluride induced the crystallization of titanium dioxide. Diffuse reflectance spectrum of the nanocomposite showed the higher absorption efficiency in the UV-visible region due to band-gap excitation of titanium dioxide. The nanocomposite significantly showed the improvement of photocatalytic activity for 4-chlorophenol with UV light.

SdAb heterodimer formation using leucine zippers

Science.gov (United States)

Goldman, Ellen R.; Anderson, George P.; Brozozog-Lee, P. Audrey; Zabetakis, Dan

2013-05-01

Single domain antibodies (sdAb) are variable domains cloned from camel, llama, or shark heavy chain only antibodies, and are among the smallest known naturally derived antigen binding fragments. SdAb derived from immunized llamas are able to bind antigens with high affinity, and most are capable of refolding after heat or chemical denaturation to bind antigen again. We hypothesized that the ability to produce heterodimeric sdAb would enable reagents with the robust characteristics of component sdAb, but with dramatically improved overall affinity through increased avidity. Previously we had constructed multimeric sdAb by genetically linking sdAb that bind non-overlapping epitopes on the toxin, ricin. In this work we explored a more flexible approach; the construction of multivalent binding reagents using multimerization domains. We expressed anti-ricin sdAb that recognize different epitopes on the toxin as fusions with differently charged leucine zippers. When the initially produced homodimers are mixed the leucine zipper domains will pair to produce heterodimers. We used fluorescence resonance energy transfer to confirm heterodimer formation. Surface plasmon resonance, circular dichroism, enzyme linked immunosorbent assays, and fluid array assays were used to characterize the multimer constructs, and evaluate their utility in toxin detection.

The Effect of Nanoparticles Percentage on Mechanical Behavior of Silica-Epoxy Nanocomposites

International Nuclear Information System (INIS)

Islam, M.S.; Masoodi, R.; Rostami, H.

2013-01-01

Silica-epoxy nanocomposites are very common among nanocomposites, which makes them very important. Several researchers have studied the effect of nanoparticle’s size, shape, and loading on mechanical behavior of silica-epoxy nanocomposites. This paper reviews the most important research done on the effect of nanoparticle loading on mechanical properties of silica-epoxy nanocomposites. While the main focus is the tensile behavior of nanocomposite, the compressive behavior and flexural behavior were also reviewed. Finally, some of the published experimental data were combined in the graphs, using dimensionless parameters. Later, the best fitted curves were used to derive some empirical formulas for mechanical properties of silica-epoxy nanocomposites as functions of weight or volume fraction of nanoparticles.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

Directory of Open Access Journals (Sweden)

Gabriela Mera

2015-04-01

Full Text Available The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs. Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers.

Science.gov (United States)

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-04-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

Science.gov (United States)

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-01-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail. PMID:28347023

Perspective: Ab initio force field methods derived from quantum mechanics

Science.gov (United States)

Xu, Peng; Guidez, Emilie B.; Bertoni, Colleen; Gordon, Mark S.

2018-03-01

It is often desirable to accurately and efficiently model the behavior of large molecular systems in the condensed phase (thousands to tens of thousands of atoms) over long time scales (from nanoseconds to milliseconds). In these cases, ab initio methods are difficult due to the increasing computational cost with the number of electrons. A more computationally attractive alternative is to perform the simulations at the atomic level using a parameterized function to model the electronic energy. Many empirical force fields have been developed for this purpose. However, the functions that are used to model interatomic and intermolecular interactions contain many fitted parameters obtained from selected model systems, and such classical force fields cannot properly simulate important electronic effects. Furthermore, while such force fields are computationally affordable, they are not reliable when applied to systems that differ significantly from those used in their parameterization. They also cannot provide the information necessary to analyze the interactions that occur in the system, making the systematic improvement of the functional forms that are used difficult. Ab initio force field methods aim to combine the merits of both types of methods. The ideal ab initio force fields are built on first principles and require no fitted parameters. Ab initio force field methods surveyed in this perspective are based on fragmentation approaches and intermolecular perturbation theory. This perspective summarizes their theoretical foundation, key components in their formulation, and discusses key aspects of these methods such as accuracy and formal computational cost. The ab initio force fields considered here were developed for different targets, and this perspective also aims to provide a balanced presentation of their strengths and shortcomings. Finally, this perspective suggests some future directions for this actively developing area.

Polymer-Layered Silicate Nanocomposites for Cryotank Applications

Science.gov (United States)

Miller, Sandi G.; Meador, Michael A.

2007-01-01

Previous composite cryotank designs have relied on the use of conventional composite materials to reduce microcracking and permeability. However, revolutionary advances in nanotechnology derived materials may enable the production of ultra-lightweight cryotanks with significantly enhanced durability and damage tolerance, as well as reduced propellant permeability. Layered silicate nanocomposites are especially attractive in cryogenic storage tanks based on results that have been reported for epoxy nanocomposite systems. These materials often exhibit an order of magnitude reduction in gas permeability when compared to the base resin. In addition, polymer-silicate nanocomposites have been shown to yield improved dimensional stability, strength, and toughness. The enhancement in material performance of these systems occurs without property trade-offs which are often observed in conventionally filled polymer composites. Research efforts at NASA Glenn Research Center have led to the development of epoxy-clay nanocomposites with 70% lower hydrogen permeability than the base epoxy resin. Filament wound carbon fiber reinforced tanks made with this nanocomposite had a five-fold lower helium leak rate than the corresponding tanks made without clay. The pronounced reduction observed with the tank may be due to flow induced alignment of the clay layers during processing. Additionally, the nanocomposites showed CTE reductions of up to 30%, as well as a 100% increase in toughness.

A light-driven modulation of electric conductance through the adsorption of azobenzene onto silicon-doped- and pyridine-like N3-vacancy graphene.

Science.gov (United States)

Zhao, Jun; Liu, Chunyan; Ma, Jing

2017-12-14

The ability to modulate the conductance of an electronic device under light irradiation is crucial to the practical applications of nanoscale electronics. Density functional theory calculations predict that the conductance of the photo-responsive graphene-based nanocomposites can be tuned through the noncovalent adsorption of an azobenzene (AB) derivative onto pristine, Si-doped, and pyridine-like N 3 -vacancy graphene. AB@graphene systems were found to exhibit a visible-light response within the low-frequency region, rendering the trans-to-cis isomerizations of these nanocomposites under the irradiation of solar light. The excellent solar light absorption performances of these hybrids can then be used to modulate the conductance of both N 3 -vacancy- and Si-doped-graphene AB hybrids effectively through the reversible change of the effective conjugate length of the AB molecule in the photoisomerization. In addition, the solar thermal energy up to 1.53 eV per AB molecule can be stored in the designed nanocomposites with the doped graphene. These findings provide clues for making multifunctional materials with potential applications as both optically controlled nanoelectronics and solar energy storage devices.

High performance, freestanding and superthin carbon nanotube/epoxy nanocomposite films.

Science.gov (United States)

Li, Jinzhu; Gao, Yun; Ma, Wenjun; Liu, Luqi; Zhang, Zhong; Niu, Zhiqiang; Ren, Yan; Zhang, Xiaoxian; Zeng, Qingshen; Dong, Haibo; Zhao, Duan; Cai, Le; Zhou, Weiya; Xie, Sishen

2011-09-01

We develop a facile, effective and filter free infiltration method to fabricate high performance, freestanding and superthin epoxy nanocomposite films with directly synthesized Sing-Walled Carbon Nanotubes (SWNTs) film as reinforcement skeleton. It is found that the thicknesses of the nanocomposite films can be easily controlled in the range of 0.5-3 μm by dripping target amount of acetone diluted epoxy through the skeleton film. The consequent measurements reveal that the mechanical and electrical properties of SWNTs/epoxy nanocomposite films could be tailored in a quite wide range. For examples, the Young's modulus of nanocomposite films can be tuned from 10 to 30 GPa, and the electrical conductivity can be ranged from 1000 S·cm(-1) to be insulated. Moreover, high load transfer efficiency in the nanocomposite films is demonstrated by the measured ultrahigh Raman bands shift rate (-30 ± 5 cm(-1)/% strain) under strain. The high effective modulus is derived as 774 ± 70 GPa for SWNTs inside this nanocomposite film.

Structural, mechanical and electrical properties biopolymer blend nanocomposites derived from poly (vinyl alcohol)/cashew gum/magnetite

Science.gov (United States)

Ramesan, M. T.; Jayakrishnan, P.; Manojkumar, T. K.; Mathew, G.

2018-01-01

Blending of poly vinyl alcohol (PVA) and natural biopolymers such as cashew gum (CG) with magnetite (Fe3O4) nanoparticles has been a promising way for preparing bio-degradable polymeric blend nanocomposites. PVA/CG/Fe3O4 blend nanocomposites have been prepared by a simple solution casting technique using water as the green solvent. The characterization of blend nanocomposites has been carried out by using Fourier transform infrared, UV, x-ray diffraction (XRD), high resolution transmission electron microscopy, scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis, mechanical properties and electrical conductivity. The interaction between nanoparticles and the blend segments was confirmed from the shift in characteristic absorption peaks of nanocomposites compared to PVA/CG blend. XRD analysis has shown the presence of crystalline peaks of nanoparticles in the blend matrix. The uniform distribution of Fe3O4 nanoparticles in the blend was revealed by TEM and SEM. The strong interaction of nanoparticles with the blend has been confirmed by the increase in glass transition temperature resulting from the reduced flexibility of the blend nanocomposite compared to that of the blend system. An increase in thermal stability and tensile strength and reduction in elongation at break of nanocomposites have been noticed with the increasing loading of nanoparticles. The AC electrical conductivity, dielectric constant and dielectric loss of the nanocomposites have been found to be higher than that of the blend. Generally, it can be stated that the magnetite nanoparticles acts as a potential filler in the PVA/CG blend at 7 wt% loading, giving the best balance of properties.

Sorption of different phenol derivatives on functionalized macroporous nanocomposite of poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate and acid modified bentonite

Directory of Open Access Journals (Sweden)

Marinović Sanja R.

2014-01-01

Full Text Available Macroporous nanocomposite of poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate and acid modified bentonite was prepared by radical suspension copolymerization. Nanocomposite was functionalized with diethylene triamine (deta, by ring-opening reaction of the pendant epoxy groups. Functionalization was performed in order to enable phenol derivatives sorption. This new, not sufficiently investigated material, with developed porous structure was denoted CP-SA-deta. In this study, the influence of temperature on 4-nitrophenol (4NP sorption on CP-SA-deta was investigated. The chemisorption was estimated as dominant process since activation energy of sorption of 4NP of 54.8 kJ mol-1 was obtained. After determining the optimal sorption conditions for 4NP, the sorption of 2-nitrophenol (2NP and 2-chloro 4-nitrophenol (2Cl4NP on CP-SA-deta was investigated with respect to pH, initial concentration and contact time. The 2NP sorption was seldom tested, while according to our knowledge, the 2Cl4NP sorption was not investigated. The isotherm data were best fitted with Langmuir model, while the sorption dynamics obeyed the pseudo-second-order kinetic model for all derivatives. [Projekat Ministarstva nauke Republike Srbije, br. III 45001 i br. III 43009

Strength and Magnetism of Nanocomposites Formed by 3D-Metal Nanochains Embedded in a Non-Magnetic Matrix

Czech Academy of Sciences Publication Activity Database

Káňa, Tomáš; Šob, Mojmír

2011-01-01

Roč. 8, Suppl. 1 (2011), s. 1033-1034 ISSN 1708-5284 R&D Projects: GA ČR GD106/09/H035; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z20410507 Institutional support: RVO:68081723 Keywords : nanocomposites * ab initio * mechanical properties * magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism

MicroPET/CT imaging of patient-derived pancreatic cancer xenografts implanted subcutaneously or orthotopically in NOD-scid mice using 64Cu-NOTA-panitumumab F(ab')2 fragments

International Nuclear Information System (INIS)

Boyle, Amanda J.; Cao, Ping-Jiang; Hedley, David W.; Sidhu, Sachdev S.; Winnik, Mitchell A.; Reilly, Raymond M.

2015-01-01

Introduction: Our objective was to study microPET/CT imaging of patient-derived pancreatic cancer xenografts in NOD-scid mice using F(ab') 2 fragments of the fully-human anti-EGFR monoclonal antibody, panitumumab (Vectibix) labeled with 64 Cu. More than 90% of pancreatic cancers are EGFR-positive. Methods: F(ab') 2 fragments were produced by proteolytic digestion of panitumumab IgG or non-specific human IgG, purified by ultrafiltration then modified with NOTA chelators for complexing 64 Cu. Panitumumab IgG and Fab fragments were similarly labeled with 64 Cu. EGFR immunoreactivity was determined in competition and direct (saturation) cell binding assays. The biodistribution of 64 Cu-labeled panitumumab IgG, F(ab') 2 and Fab was compared in non-tumor-bearing Balb/c mice. MicroPET/CT and biodistribution studies were performed in NOD-scid mice engrafted subcutaneously (s.c.) or orthotopically with patient-derived OCIP23 pancreatic tumors, or in NOD-scid with s.c. PANC-1 human pancreatic cancer xenografts. Results: Panitumumab F(ab') 2 fragments were produced in high purity (> 90%), derivitized with 3.2 ± 0.7 NOTA/F(ab') 2 , and labeled with 64 Cu (0.3–3.6 MBq/μg). The binding of 64 Cu-NOTA-panitumumab F(ab') 2 to OCIP23 or PANC-1 cells was decreased significantly by an excess of panitumumab IgG. The K d for binding of 64 Cu-NOTA-panitumumab F(ab') 2 to EGFR on PANC-1 cells was 0.14 ± 0.05 nmol/L. F(ab') 2 fragments exhibited more suitable normal tissue distribution for tumor imaging with 64 Cu than panitumumab IgG or Fab. Tumor uptake at 48 h post injection (p.i.) of 64 Cu-NOTA-panitumumab F(ab') 2 was 12.0 ± 0.9% injected dose/g (ID/g) in s.c. and 11.8 ± 0.9% ID/g in orthotopic OCIP23 tumors vs. 6.1 ± 1.1% ID/g in s.c. PANC-1 xenografts. Tumor/Blood (T/B) ratios were 5:1 to 9:1 for OCIP23 and 2.4:1 for PANC-1 tumors. Tumor uptake of 64 Cu-NOTA-non-specific F(ab') 2 in OCIP23 xenografts was 5-fold lower than 64

Processing, Microstructure, and Mechanical Properties of Si3N4/SiC Nanocomposites from Precursor Derived Ceramics

Science.gov (United States)

Strong, Kevin Thomas, Jr.

Polymer-derived ceramics (PDCs) provides a unique processing route to create Si3N4/SiC composites. Silazane precursor polyureasilazane (Ceraset PURS20) produce's an amorphous SiCN ceramic at temperatures of ~800 -- 1200 °C and crystallizes to a Si3N4/SiC nanocomposite at temperatures >1500 °C. A novel processing technique was developed where crosslinked polymers were heat-treated in a reactive NH3 atmosphere to control the stoichiometry of the pyrolyzed SiCN ceramic. Using this technique processing parameters were established to produce SiCN powders that resulted in nanocomposites with approximately 0, 5, 10, 20 and 30 vol. % SiC. Lu2O3 was added to these powders as a sintering aid and were densified using Hot Pressing and Field Assisted Sintering. The sintered nanocomposites resulted in microstructures with multiple-length scales. These length-scales included Si3N4 (0.1 -- 5 microm), SiC (10 -- 100 nm) and the intergranular grain boundary phase (<1 nm). Using a combination of SEM and TEM it was possible to quantify some of these microstructural features such as the size and location of the SiC. Hardness and fracture toughness testing was conducted to compared the room temperature mechanical properties of these resultant microstructures. This research was intended to develop robust processing approaches that can be used to control the nanostructures of Si3N4/SiC composites with significant structural features at multiple length scales. The control of their features and the investigation of their affect on the properties of composites can be used to simulate the affect of the structure on properties. These models can then be used to design optimal microstructures for specific applications.

Thermal Degradation of Nanocomposited PMMA/TiO2 Nanocomposites

International Nuclear Information System (INIS)

Hafizah, Nik Noor; Mamat, Mohamad Hafiz; Rusop, Mohamad; Said, Che Mohamad Som; Abidin, Mohd Hanafiah

2013-01-01

The polymer nanocomposite is a new choice to conventionally filled polymers. The lack of proper binding between the filler and the polymer can lead the decrease of the thermal and other properties of the nanocomposites. In this study, the nanocomposited PMMA/TiO 2 nanocomposites were prepared using sonication and solution casting method at different weight percent TiO 2 . The aims of adding TiO 2 in the PMMA is to study the effects of TiO 2 nanofiller on the thermal properties nanocomposites. FESEM results show the higher amounts of TiO 2 in PMMA increase the rough surface morphology of the samples. Further, the Raman results reveal that the TiO 2 nanofiller were successfully intercalated into the PMMA matrix. In addition, the thermal properties of nanocomposited PMMA/TiO 2 nanocomposites were increased with the addition of TiO 2 in the PMMA.

Study of processing conditions on properties of ABS and clay organically modified nanocomposites; Estudo das condicoes de processamento nas propriedades de nanocompositos de ABS e argilas organofilicas

Energy Technology Data Exchange (ETDEWEB)

Galvan, Danieli; Massucato, Felipe; Bartoli, Julio R., E-mail: bartoli@feq.unicamp.br [Fac. de Engenharia Quimica/Universidade Estadual de Campinas - DTP/FEQ/UNICAMP, Campinas, SP (Brazil); D' Avila, Marcos A. [Fac. de Engenharia Mecanica/Universidade Estadual de Campinas - DEMA/FEM/UNICAMP, Campinas, SP (Brazil); Fernandes, Elizabeth G. [Tezca P and D Celulas Solares, Campinas, SP (Brazil)

2011-07-01

Nanocomposites of poly(acrylonitrile-butadiene-styrene) and organically modified montmorillonite clay were prepared by melt intercalation on a co-rotating twin-screw extruder. The independent variables studied were the kind of organoclay (Cloisite 20A and Cloisite 30B) and the screw torque at levels of 45 and 70%. The effect of these variables on the intercalation/exfoliation were accessed by means of the morphological characteristics using X-ray diffraction and the mechanical properties of uniaxial tensile test. The experimental results showed that the incorporation of clay in the polymeric matrix improved the mechanical properties of elastic modulus, yield stress and tensile strength of nanocomposites, being more significant for that containing Cloisite 30B. Torque was also a significant variable for the responses studied. (author)

Novel synthesis of magnesium hydroxide nanoparticles modified with organic phosphate and their effect on the flammability of acrylonitrile-butadiene styrene nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Attia, Nour F., E-mail: drnour2005@yahoo.com [Fire Protection Laboratory, Chemistry Division, National Institute of Standards, 136, Giza 12211 (Egypt); Goda, Emad S.; Nour, M.A. [Fire Protection Laboratory, Chemistry Division, National Institute of Standards, 136, Giza 12211 (Egypt); Sabaa, M.W. [Chemistry Department, Faculty of Science, Cairo University, NahdetMisr Street, Giza 12613 (Egypt); Hassan, M.A., E-mail: Mohamed_a_hassan@hotmail.com [Fire Protection Laboratory, Chemistry Division, National Institute of Standards, 136, Giza 12211 (Egypt)

2015-11-15

New and facile method for the synthesis and modification of magnesium hydroxide nanoparticles has been developed. The organic phosphate was used to facilitate the synthesis and wrapping of magnesium hydroxide nanoparticles with organic phosphate shell. The size of the nanoparticles wrapped with phosphate has an average diameter range from 46 to 125 nm. The preparation method has governed the nanoparticles diameter based on reaction time. Thermal stability and morphological properties of the new nanoparticles coated phosphates were investigated. The developed magnesium hydroxide nanoparticles-organic phosphate achieved a very good compatibility when dispersed in acrylonitrile-butadiene styrene polymer (ABS) produced dispersed nanocomposites. The flammability and thermal properties of the new polymer nanocomposites were studied. The rate of burning of the nanocomposites was reduced to 9.8 mm/min compared to 15, 21.9 and 42.5 mm/min for polymer-conventional magnesium hydroxide composite, polymer-conventional magnesium hydroxide-organic phosphate composite and virgin polymer, respectively. The peak heat release rate (PHRR) and total heat release (THR) of the new nanocomposites were recorded as 243.4 kW/m{sup 2} and 19.2 MJ/m{sup 2}, respectively, achieved 71% reduction for PHRR and 55% for THR. The synergism between magnesium hydroxide nanoparticles and organic phosphates shell was also studied. The developed nanoparticles suppressed the emission of toxic gases. The different materials were characterized using thermal gravimetric analysis, fourier transform infrared spectroscopy, transmission electron microscopy. The flammability properties were evaluated using UL94 horizontal method and cone calorimeter. The dispersion of magnesium hydroxide nanoparticles-organic phosphate in ABS was studied using scanning electron microscope. - Highlights: • Novel and facile nanoparticles synthesis and modification have developed. • Magnesium hydroxide nanoparticles size has

Pharmacological Classification and Activity Evaluation of Furan and Thiophene Amide Derivatives Applying Semi-Empirical ab initio Molecular Modeling Methods

Directory of Open Access Journals (Sweden)

Leszek Bober

2012-05-01

Full Text Available Pharmacological and physicochemical classification of the furan and thiophene amide derivatives by multiple regression analysis and partial least square (PLS based on semi-empirical ab initio molecular modeling studies and high-performance liquid chromatography (HPLC retention data is proposed. Structural parameters obtained from the PCM (Polarizable Continuum Model method and the literature values of biological activity (antiproliferative for the A431 cells expressed as LD₅₀ of the examined furan and thiophene derivatives was used to search for relationships. It was tested how variable molecular modeling conditions considered together, with or without HPLC retention data, allow evaluation of the structural recognition of furan and thiophene derivatives with respect to their pharmacological properties.

CRY 1AB trangenic cowpea obtained by nodal electroporation ...

African Journals Online (AJOL)

Electroporation-mediated genetic transformation was used to introduce Cry 1 Ab insecticidal gene into cowpea. Nodal buds were electroporated in planta with a plasmid carrying the Cry 1Ab and antibiotic resistance npt II genes driven by a 35S CaMV promoter. T1 seeds derived from electroporated branches were selected ...

Investigating the property profile of polyamide-alumina nanocomposite materials

International Nuclear Information System (INIS)

Sarwar, Muhammad Ilyas; Zulfiqar, Sonia; Ahmad, Zahoor

2009-01-01

Transparent sol-gel-derived nanocomposites were prepared by incorporating an alumina network into a polyamide matrix. Different amounts of aluminum butoxide were hydrolyzed and condensed to produce the alumina network. Thin composite films were characterized in terms of their optical, morphological, mechanical and thermomechanical properties. Tensile modulus, stress at both yield and break points, improved for alumina loadings of 5-10 wt.%. The glass transition temperature increased to 140 o C for nanocomposites containing 15 wt.% alumina. Scanning electron microscopy investigations indicated a uniform distribution of alumina in the polyamide matrix.

Electrochromic nanocomposite films

Science.gov (United States)

Milliron, Delia; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2018-04-10

The present invention provides an electrochromic nanocomposite film. In an exemplary embodiment, the electrochromic nanocomposite film, includes (1) a solid matrix of oxide based material and (2) transparent conducting oxide (TCO) nanostructures embedded in the matrix. In a further embodiment, the electrochromic nanocomposite film farther includes a substrate upon which the matrix is deposited. The present invention also provides a method of preparing an electrochromic nanocomposite film.

Nanocomposites in food packaging – A review

Science.gov (United States)

A nanocomposite is a multiphase material derived from the combination of two or more components, including a matrix (continuous phase) and a discontinuous nano-dimensional phase with at least one nano-sized dimension (i.e. less than 100 nm). The main types of nanostructures are presented in this ch...

Smart Nacre-inspired Nanocomposites.

Science.gov (United States)

Peng, Jingsong; Cheng, Qunfeng

2018-03-15

Nacre-inspired nanocomposites with excellent mechanical properties have achieved remarkable attention in the past decades. The high performance of nacre-inspired nanocomposites is a good basis for the further application of smart devices. Recently, some smart nanocomposites inspired by nacre have demonstrated good mechanical properties as well as effective and stable stimuli-responsive functions. In this Concept, we summarize the recent development of smart nacre-inspired nanocomposites, including 1D fibers, 2D films and 3D bulk nanocomposites, in response to temperature, moisture, light, strain, and so on. We show that diverse smart nanocomposites could be designed by combining various conventional fabrication methods of nacre-inspired nanocomposites with responsive building blocks and interface interactions. The nacre-inspired strategy is versatile for different kinds of smart nanocomposites in extensive applications, such as strain sensors, displays, artificial muscles, robotics, and so on, and may act as an effective roadmap for designing smart nanocomposites in the future. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A systemic study on key parameters affecting nanocomposite coatings on magnesium substrates.

Science.gov (United States)

Johnson, Ian; Wang, Sebo Michelle; Silken, Christine; Liu, Huinan

2016-05-01

Nanocomposite coatings offer multiple functions simultaneously to improve the interfacial properties of magnesium (Mg) alloys for skeletal implant applications, e.g., controlling the degradation rate of Mg substrates, improving bone cell functions, and providing drug delivery capability. However, the effective service time of nanocomposite coatings may be limited due to their early delamination from the Mg-based substrates. Therefore, the objective of this study was to address the delamination issue of nanocomposite coatings, improve the coating properties for reducing the degradation of Mg-based substrates, and thus improve their cytocompatibility with bone marrow derived mesenchymal stem cells (BMSCs). The surface conditions of the substrates, polymer component type of the nanocomposite coatings, and post-deposition processing are the key parameters that contribute to the efficacy of the nanocomposite coatings in regulating substrate degradation and bone cell responses. Specifically, the effects of metallic surface versus alkaline heat-treated hydroxide surface of the substrates on coating quality were investigated. For the nanocomposite coatings, nanophase hydroxyapatite (nHA) was dispersed in three types of biodegradable polymers, i.e., poly(lactic-co-glycolic acid) (PLGA), poly(l-lactic acid) (PLLA), or poly(caprolactone) (PCL) to determine which polymer component could provide integrated properties for slowest Mg degradation. The nanocomposite coatings with or without post-deposition processing, i.e., melting, annealing, were compared to determine which processing route improved the properties of the nanocomposite coatings most significantly. The results showed that optimizing the coating processes addressed the delamination issue. The melted then annealed nHA/PCL coating on the metallic Mg substrates showed the slowest degradation and the best coating adhesion, among all the combinations of conditions studied; and, it improved the adhesion density of BMSCs

Organic/inorganic electrochromic nanocomposites with various interfacial interactions: A review

Energy Technology Data Exchange (ETDEWEB)

Xiong, Shanxin, E-mail: xiongsx@xust.edu.cn; Yin, Siyuan; Wang, Yuyun; Kong, Zhenzhen; Lan, Jinpeng; Zhang, Runlan; Gong, Ming; Wu, Bohua; Chu, Jia; Wang, Xiaoqin

2017-07-15

Highlights: • We review the effects of interfacial interactions in electrochromic nanocomposites. • Interfacial interactions are useful for film fabrication and property-enhancement. • The strong interaction can enhance the electron conduction and structural strength. • The weak interactions exist widely between organic and inorganic phases. • Multiple weak interactions can provide various performance-adjusting approaches. - Abstract: Electrochromic properties of organic or inorganic materials can be improved through preparing organic/inorganic electrochromic nanocomposites. In electrochromic nanocomposites, the interfacial interactions between the organic and inorganic phases play three important roles in preparation and application of the nanocomposites. Firstly, the interfacial interactions result in stable molecular structures. Secondly, they also improve the electron conduction and ion transport process in the nanocomposites. Thirdly, they enhance the electrochemical and electrochromic properties of the nanocomposites. In this paper, we review the common interfacial interactions including covalent bond, coordination bond, electrostatic interaction, hydrogen bond and π-π stacking interaction between the organic and inorganic phases in the electrochromic nanocomposites. The preparation method, the relationship between the structure and properties, and the mechanism of modulation of electrochromic effect in the nanocomposites with various interfacial interactions are surveyed. The strong interfacial interaction, e.g., covalent bond, is helpful for obtaining electrochromic nanocomposites with high electron conduction and high structural strength. However it is very complicated to construct covalent bond between the organic and inorganic phases. Another strong interfacial interaction, the coordination bond is mainly confined to preparation of electrochromic complex of metal ion and pyridine derivative. While, the weak interfacial interactions, e

Organic/inorganic electrochromic nanocomposites with various interfacial interactions: A review

International Nuclear Information System (INIS)

Xiong, Shanxin; Yin, Siyuan; Wang, Yuyun; Kong, Zhenzhen; Lan, Jinpeng; Zhang, Runlan; Gong, Ming; Wu, Bohua; Chu, Jia; Wang, Xiaoqin

2017-01-01

Highlights: • We review the effects of interfacial interactions in electrochromic nanocomposites. • Interfacial interactions are useful for film fabrication and property-enhancement. • The strong interaction can enhance the electron conduction and structural strength. • The weak interactions exist widely between organic and inorganic phases. • Multiple weak interactions can provide various performance-adjusting approaches. - Abstract: Electrochromic properties of organic or inorganic materials can be improved through preparing organic/inorganic electrochromic nanocomposites. In electrochromic nanocomposites, the interfacial interactions between the organic and inorganic phases play three important roles in preparation and application of the nanocomposites. Firstly, the interfacial interactions result in stable molecular structures. Secondly, they also improve the electron conduction and ion transport process in the nanocomposites. Thirdly, they enhance the electrochemical and electrochromic properties of the nanocomposites. In this paper, we review the common interfacial interactions including covalent bond, coordination bond, electrostatic interaction, hydrogen bond and π-π stacking interaction between the organic and inorganic phases in the electrochromic nanocomposites. The preparation method, the relationship between the structure and properties, and the mechanism of modulation of electrochromic effect in the nanocomposites with various interfacial interactions are surveyed. The strong interfacial interaction, e.g., covalent bond, is helpful for obtaining electrochromic nanocomposites with high electron conduction and high structural strength. However it is very complicated to construct covalent bond between the organic and inorganic phases. Another strong interfacial interaction, the coordination bond is mainly confined to preparation of electrochromic complex of metal ion and pyridine derivative. While, the weak interfacial interactions, e

Fracture Analysis of MWCNT/Epoxy Nanocomposite Film Deposited on Aluminum Substrate.

Science.gov (United States)

Her, Shiuh-Chuan; Chien, Pao-Chu

2017-04-13

Multi-walled carbon nanotube (MWCNT) reinforced epoxy films were deposited on an aluminum substrate by a hot-pressing process. Three-point bending tests were performed to determine the Young's modulus of MWCNT reinforced nanocomposite films. Compared to the neat epoxy film, nanocomposite film with 1 wt % of MWCNT exhibits an increase of 21% in the Young's modulus. Four-point-bending tests were conducted to investigate the fracture toughness of the MWCNT/epoxy nanocomposite film deposited on an aluminum substrate with interfacial cracks. Based on the Euler-Bernoulli beam theory, the strain energy in a film/substrate composite beam is derived. The difference of strain energy before and after the propagation of the interfacial crack are calculated, leading to the determination of the strain energy release rate. Experimental test results show that the fracture toughness of the nanocomposite film deposited on the aluminum substrate increases with the increase in the MWCNT content.

Synthesis and Antimicrobial Activities of Some Novel Quinoxalinone Derivatives

Directory of Open Access Journals (Sweden)

Y. A. Ammar

2000-06-01

Full Text Available Condensation of 4-benzoyl-1,2-phenylenediamine with sodium pyruvate in acetic acid furnished two products which were identified as 6-benzoyl and 7-benzoyl-3-methyl-2(1Hquinoxalinones (1a,b. Fusion of 1a with aromatic aldehydes furnished the styryl derivatives 2a-c. Alkylation of 1a,b with dimethyl sulphate or ethyl chloroacetate produced the N-alkyl derivatives 3a,b and 4a,b. Hydrazinolysis of the ester derivative 4a with hydrazine hydrate afforded the hydrazide derivative 5 which underwent condensation with aldehydes to give the corresponding hydrazone derivatives 6a,b. In addition, chlorination of 1a with thionyl chloride afforded the 2-chloro derivative 7 which was subjected to reaction with sodium azide and n-butylamine to yield the corresponding tetrazolo (8 and n-butylamino (9 derivatives, respectively. The structures of the compounds prepared were confirmed by analytical and spectral data. Also, some of the synthesized compounds were screened for antimicrobial activity.

Ab initio and Gordon--Kim intermolecular potentials for two nitrogen molecules

International Nuclear Information System (INIS)

Ree, F.H.; Winter, N.W.

1980-01-01

Both ab initio MO--LCAO--SCF and the electron-gas (or Gordon--Kim) methods have been used to compute the intermolecular potential (Phi) of N 2 molecules for seven different N 2 --N 2 orientations. The ab initio calculations were carried out using a [4s3p] contracted Gaussian basis set with and without 3d polarization functions. The larger basis set provides adequate results for Phi>0.002 hartree or intermolecular separations less than 6.5--7 bohr. We use a convenient analytic expression to represent the ab initio data in terms of the intermolecular distance and three angles defining the orientations of the two N 2 molecules. The Gordon--Kim method with Rae's self-exchange correction yields Phi, which agrees reasonably well over a large repulsive range. However, a detailed comparison of the electron kinetic energy contributions shows a large difference between the ab initio and the Gordon--Kim calculations. Using the ab initio data we derive an atom--atom potential of the two N 2 molecules. Although this expression does not accurately fit the data at some orientations, its spherical average agrees with the corresponding average of the ab initio Phi remarkably well. The spherically averaged ab initio Phi is also compared with the corresponding quantities derived from experimental considerations. The approach of the ab initio Phi to the classical quadrupole--quadrupole interaction at large intermolecular separation is also discussed

Biobased Epoxy Nanocomposites Derived from Lignin-Based Monomers.

Science.gov (United States)

Zhao, Shou; Abu-Omar, Mahdi M

2015-07-13

Biobased epoxy nanocomposites were synthesized based on 2-methoxy-4-propylphenol (dihydroeugenol, DHE), a molecule that has been obtained from the lignin component of biomass. To increase the content of hydroxyl groups, DHE was o-demethylated using aqueous HBr to yield propylcatechol (DHEO), which was subsequently glycidylated to epoxy monomer. Optimal conditions in terms of yield and epoxy equivalent weight were found to be 60 °C with equal NaOH/phenolic hydroxyl molar ratio. The structural evolution from DHE to cured epoxy was followed by (1)H NMR and Fourier transform infrared spectroscopy. The nano-montmorillonite modified DHEO epoxy exhibited improved storage modulus and thermal stability as determined from dynamic mechanical analysis and thermogravimetric analysis. This study widens the synthesis routes of biobased epoxy thermosets from lignin-based molecules.

Moving into advanced nanomaterials. Toxicity of rutile TiO{sub 2} nanoparticles immobilized in nanokaolin nanocomposites on HepG2 cell line

Energy Technology Data Exchange (ETDEWEB)

Bessa, Maria João, E-mail: mjbessa8@gmail.com [Department of Environmental Health, Portuguese National Institute of Health, Rua Alexandre Herculano, 321, 4000-055 Porto (Portugal); Costa, Carla, E-mail: cstcosta@gmail.com [Department of Environmental Health, Portuguese National Institute of Health, Rua Alexandre Herculano, 321, 4000-055 Porto (Portugal); EPIUnit - Institute of Public Health, University of Porto, Rua das Taipas 135, 4050-600, Porto (Portugal); Reinosa, Julian, E-mail: jjreinosa@icv.csic.es [Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Campus de Cantoblanco, Calle de Kelson, 5, 28049 Madrid (Spain); Pereira, Cristiana, E-mail: cristianacostapereira@gmail.com [Department of Environmental Health, Portuguese National Institute of Health, Rua Alexandre Herculano, 321, 4000-055 Porto (Portugal); EPIUnit - Institute of Public Health, University of Porto, Rua das Taipas 135, 4050-600, Porto (Portugal); Fraga, Sónia, E-mail: teixeirafraga@hotmail.com [Department of Environmental Health, Portuguese National Institute of Health, Rua Alexandre Herculano, 321, 4000-055 Porto (Portugal); EPIUnit - Institute of Public Health, University of Porto, Rua das Taipas 135, 4050-600, Porto (Portugal); Fernández, José, E-mail: jfernandez@icv.csic.es [Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Campus de Cantoblanco, Calle de Kelson, 5, 28049 Madrid (Spain); Bañares, Miguel A., E-mail: miguel.banares@csic.es [Catalytic Spectroscopy Laboratory, Instituto de Catálisis y Petroleoquímica, ICP-CSIC, Madrid (Spain); and others

2017-02-01

Immobilization of nanoparticles on inorganic supports has been recently developed, resulting in the creation of nanocomposites. Concerning titanium dioxide nanoparticles (TiO{sub 2} NPs), these have already been developed in conjugation with clays, but so far there are no available toxicological studies on these nanocomposites. The present work intended to evaluate the hepatic toxicity of nanocomposites (C-TiO{sub 2}), constituted by rutile TiO{sub 2} NPs immobilized in nanokaolin (NK) clay, and its individual components. These nanomaterials were analysed by means of FE-SEM and DLS analysis for physicochemical characterization. HepG2 cells were exposed to rutile TiO{sub 2} NPs, NK clay and C-TiO{sub 2} nanocomposite, in the presence and absence of serum for different exposure periods. Possible interferences with the methodological procedures were determined for MTT, neutral red uptake, alamar blue (AB), LDH, and comet assays, for all studied nanomaterials. Results showed that MTT, AB and alkaline comet assay were suitable for toxicity analysis of the present materials after slight modifications to the protocol. Significant decreases in cell viability were observed after exposure to all studied nanomaterials. Furthermore, an increase in HepG2 DNA damage was observed after shorter periods of exposure in the absence of serum proteins and longer periods of exposure in their presence. Although the immobilization of nanoparticles in micron-sized supports could, in theory, decrease the toxicity of single nanoparticles, the selection of a suitable support is essential. The present results suggest that NK clay is not the appropriate substrate to decrease TiO{sub 2} NPs toxicity. Therefore, for future studies, it is critical to select a more appropriate substrate for the immobilization of TiO{sub 2} NPs. - Highlights: • Only the MTT and AB assays were found to be suitable for cytotoxicity assessment. • Alkaline comet assay was also appropriate for genotoxicity evaluation

Clinical significance of combined detection of multiple serum antibodies (AsAb, EmAb, AcAb, AoAb, ToxAb) in infertile women

International Nuclear Information System (INIS)

Chen Jing; Jiang Li; Lu Ya

2005-01-01

Objective: To determine the clinical significance of combined detection of multiple serum antibodies in infertile women. Methods; Serum multiple antibodies were examined in 120 infertile women, including 88 failed to get pregnancy and 32 with repeated spontaneous abortion. The antibodies tested were: (1) anti-sperm antibody (AsAb) (2) endometrial antibody (EmAb) (3) anti-cardiophospholipid antibody (AcAb) (4) Anti-ovarian antibody (AoAb) and Toxoplasmosis antibody (ToxAb). Results: In 48 of the infertile women, none of the five antibodies were positive (40% of 120). The rest were: one antibody positive--38/120 or 31.6%; two antibodies positive--31/120 or 25.83%, three and four antibodies positive--4/120 or 3.33%. None of the women were positive with all five antibodies. Conclusion: Immune factor was the chief cause of infertility in women. (authors)

OPTIMIZATION OF PROCESS PARAMETERS FOR ENHANCED MECHANICAL PROPERTIES OF POLYPROPYLENE TERNARY NANOCOMPOSITES

Directory of Open Access Journals (Sweden)

Oladipupo Olaosebikan Ogunleye

2015-02-01

Full Text Available Preparation of Polypropylene ternary nanocomposites (PPTN was accomplished by blending multiwall carbon nanotube (MWCNT in polypropylene/clay binary system using a melt intercalation method. The effects of MWCNT loadings (A, melting temperature (B and mixing speed (C were investigated and optimized using central composite design. The analysis of the fitted cubic model clearly indicated that A and B were the main factors influencing the tensile properties at a fixed value of C. However, the analysis of variance showed that the interactions between the process parameters, such as; AB, AC, AB2, A2B and ABC, were highly significant on both tensile strength and Young’s modulus enhancement, while no interaction is significant in all models considered for elongation. The established optimal conditions gave 0.17%, 165 °C, and 120 rpm for A, B and C, respectively. These conditions yielded a percentage increase of 57 and 63% for tensile strength and Young’s modulus respectively compared to the virgin Polypropylene used.

MECHANISMS CONTROLLING Ca ION RELEASE FROM SOL-GEL DERIVED IN SITU APATITE-SILICA NANOCOMPOSITE POWDER

Directory of Open Access Journals (Sweden)

Seyed Mohsen Latifi

2015-03-01

Full Text Available Ca ion release from bioactive biomaterials could play an important role in their bioactivity and osteoconductivity properties. In order to improve hydroxyapatite (HA dissolution rate, in situ apatite-silica nanocomposite powders with various silica contents were synthesized via sol-gel method and mechanisms controlling the Ca ion release from them were investigated. Obtained powders were characterized by X-ray diffraction (XRD and transmission electron spectroscopy (TEM techniques, acid dissolution test, and spectroscopy by atomic absorption spectrometer (AAS. Results indicated the possible incorporation of (SiO44- into the HA structure and tendency of amorphous silica to cover the surface of HA particles. However, 20 wt. % silica was the lowest amount that fully covered HA particles. All of the nanocomposite powders showed more Ca ion release compared with pure HA, and HA - 10 wt. % silica had the highest Ca ion release. The crystallinity, the crystallite size, and the content of HA, along with the integrity, thickness, and ion diffusion possibility through the amorphous silica layer on the surface of HA, were factors that varied due to changes in the silica content and were affected the Ca ion release from nanocomposite powders.

Microscopic optical potentials derived from ab initio translationally invariant nonlocal one-body densities

Science.gov (United States)

Gennari, Michael; Vorabbi, Matteo; Calci, Angelo; Navrátil, Petr

2018-03-01

Background: The nuclear optical potential is a successful tool for the study of nucleon-nucleus elastic scattering and its use has been further extended to inelastic scattering and other nuclear reactions. The nuclear density of the target nucleus is a fundamental ingredient in the construction of the optical potential and thus plays an important role in the description of the scattering process. Purpose: In this paper we derive a microscopic optical potential for intermediate energies using ab initio translationally invariant nonlocal one-body nuclear densities computed within the no-core shell model (NCSM) approach utilizing two- and three-nucleon chiral interactions as the only input. Methods: The optical potential is derived at first order within the spectator expansion of the nonrelativistic multiple scattering theory by adopting the impulse approximation. Nonlocal nuclear densities are derived from the NCSM one-body densities calculated in the second quantization. The translational invariance is generated by exactly removing the spurious center-of-mass (COM) component from the NCSM eigenstates. Results: The ground-state local and nonlocal densities of He 4 ,6 ,8 , 12C, and 16O are calculated and applied to optical potential construction. The differential cross sections and the analyzing powers for the elastic proton scattering off these nuclei are then calculated for different values of the incident proton energy. The impact of nonlocality and the COM removal is discussed. Conclusions: The use of nonlocal densities has a substantial impact on the differential cross sections and improves agreement with experiment in comparison to results generated with the local densities especially for light nuclei. For the halo nuclei 6He and 8He, the results for the differential cross section are in a reasonable agreement with the data although a more sophisticated model for the optical potential is required to properly describe the analyzing powers.

A potential photocatalytic, antimicrobial and anticancer activity of chitosan-copper nanocomposite.

Science.gov (United States)

Arjunan, Nithya; Singaravelu, Chandra Mohan; Kulanthaivel, Jeganathan; Kandasamy, Jothivenkatachalam

2017-11-01

In this study, chitosan-copper (CS-Cu) nanocomposite was synthesized without the aid of any external chemical reducing agents. The optical, structural, spectral, thermal and morphological analyses were carried out by several techniques. The prepared nanocomposite acts as a photocatalyst for the removal of Rhodamine B (RhB) and Conge red (CR) dyes under visible light irradiation. The pseudo first order kinetics was derived according to Langmuir-Hinshelwood (L-H) model. The nanocomposite also proved to be an excellent antimicrobial agent against Gram-positive and Gram-negative bacteria; and also show activity against fungus. The advanced material was used for the major research areas which include photocatalytic materials for waste water treatment; biological applications in the development of drug resistant antimicrobials and anticancer agents. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and antitumor activity of some novel thiophene, pyrimidine, coumarin, pyrazole and pyridine derivatives

Directory of Open Access Journals (Sweden)

Albratty Mohammed

2017-03-01

Full Text Available 2-Cyano-N-(thiazol-2-yl acetamide (2a and 2-cyano-N-(oxazol- 2-yl acetamide (2b were obtained via the reaction of ethyl cyanoacetate with either 2-aminothiazole (1a or 2-aminooxazole (1b. The formed products were directed toward the reaction with cyclopentanone and elemental sulfur in the presence of triethylamine to give cyclopenta[b]thiophene derivatives (3a,b. The latter products were reacted with either ethyl cyanoacetate or malononitrile to form compounds 4a,b and 5a,b, respectively. Compounds 4a,b were aimed at synthesizing some heterocyclic compounds; thus internal cyclization reactions were introduced to form compounds 6a,b. Also, compounds 4a,b reacted with salicylaldehyde, hydrazine derivatives and either urea or thiourea to produce coumarin derivatives (7a,b, pyrazole derivatives (8a-d and pyrimidine derivatives (9a-d, respectively. Reaction of either benzaldehyde or benzene diazonium chloride (11 with compounds 4a,b afforded compounds 10a,b and 12a,b, respectively. On the other hand, compounds 5a,b underwent internal cyclization to form pyrimidine derivatives 13a,b. Also, when compounds 5a,b reacted with either ethyl cyanoacetate or malononitrile, they gave pyridine derivatives (15a-d through the formation of intermediates (14a-d. Finally, formation of fused pyrimidine derivatives (17a,b was achieved through the reaction of compounds 5a,b and salicylaldehyde applying two different pathways. The first pathway used a catalytic amount of piperidine to form compounds 16a,b; the latter products underwent cyclization to give compounds 17a,b. The second pathway, using a catalytic amount of sodium ethoxide solution directly in one step, afforded compounds 17a,b. Structures of the newly synthesized compounds were established using IR, 1H NMR, 13C NMR and mass spectrometry and their antitumor activity was investigated. Some of these compounds showed promising inhibitory effects on three different cell lines. However, fused pyrimidine

Magnetic nanocomposite sensor

KAUST Repository

Alfadhel, Ahmed

2016-05-06

A magnetic nanocomposite device is described herein for a wide range of sensing applications. The device utilizes the permanent magnetic behavior of the nanowires to allow operation without the application of an additional magnetic field to magnetize the nanowires, which simplifies miniaturization and integration into microsystems. In5 addition, the nanocomposite benefits from the high elasticity and easy patterning of the polymer-based material, leading to a corrosion-resistant, flexible material that can be used to realize extreme sensitivity. In combination with magnetic sensor elements patterned underneath the nanocomposite, the nanocomposite device realizes highly sensitive and power efficient flexible artificial cilia sensors for flow measurement or tactile sensing.

Biocompatibility and favorable response of mesenchymal stem cells on fibronectin-gold nanocomposites.

Directory of Open Access Journals (Sweden)

Huey-Shan Hung

Full Text Available A simple surface modification method, comprising of a thin coating with gold nanoparticles (AuNPs and fibronectin (FN, was developed to improve the biocompatibility required for cardiovascular devices. The nanocomposites from FN and AuNPs (FN-Au were characterized by the atomic force microscopy (AFM, UV-Vis spectrophotometry (UV-Vis, and Fourier transform infrared spectroscopy (FTIR. The biocompatibility of the nanocomposites was evaluated by the response of monocytes and platelets to the material surface in vitro. FN-Au coated surfaces demonstrated low monocyte activation and platelet activation. The behavior of human umbilical cord-derived mesenchymal stem cells (MSCs on FN-Au was further investigated. MSCs on FN-Au nanocomposites particularly that containing 43.5 ppm of AuNPs (FN-Au 43.5 ppm showed cell proliferation, low ROS generation, as well as increases in the protein expression levels of matrix metalloproteinase-9 (MMP-9 and endothelial nitric oxide synthase (eNOS, which may account for the enhanced MSC migration on the nanocomposites. These results suggest that the FN-Au nanocomposite thin film coating may serve as a potential and simple solution for the surface modification of blood-contacting devices such as vascular grafts.

Facile pyrolysis preparation of rosin-derived biochar for supporting silver nanoparticles with antibacterial activity

DEFF Research Database (Denmark)

Huang, Jian Fei; Shi, Qing Shan; Feng, Jin

2017-01-01

-step preparation process and a low loading capacity of nanoparticles. A facile preparation route for the preparation of antibacterial metallic nanocomposites would be especially beneficial for industrial fabrication. In this study, we provided a facile strategy for the preparation of a rosin-derived biochar matrix...... loaded with silver nanoparticles (Ag NPs) as the fillers. The results demonstrated that the preparation of these rosin-derived biochar silver nanocomposites (Rc/Ag nanocomposites) was achieved by a rapid pyrolysis process and a large amount of Ag NPs were in-situ obtained and homogeneously dispersed...

Nonlinear analysis of piezoelectric nanocomposite energy harvesting plates

International Nuclear Information System (INIS)

Rafiee, M; He, X Q; Liew, K M

2014-01-01

This paper investigates the nonlinear analysis of energy harvesting from piezoelectric functionally graded carbon nanotube reinforced composite plates under combined thermal and mechanical loadings. The excitation, which derives from harmonically varying mechanical in-plane loading, results in parametric excitation. The governing equations of the piezoelectric functionally graded carbon nanotube reinforced composite plates are derived based on classical plate theory and von Kármán geometric nonlinearity. The material properties of the nanocomposite plate are assumed to be graded in the thickness direction. The single-walled carbon nanotubes (SWCNTs) are assumed to be aligned, straight and have a uniform layout. The linear buckling and vibration behavior of the nanocomposite plates is obtained in the first step. Then, Galerkin’s method is employed to derive the nonlinear governing equations of the problem with cubic nonlinearities associated with mid-plane stretching. Periodic solutions are determined by using the Poincaré–Lindstedt perturbation scheme with movable simply supported boundary conditions. The effects of temperature change, the volume fraction and the distribution pattern of the SWCNTs on the parametric resonance, in particular the amplitude of vibration and the average harvested power of the smart functionally graded carbon nanotube reinforced composite plates, are investigated through a detailed parametric study. (paper)

Derivation of Land Surface Albedo at High Resolution by Combining HJ-1A/B Reflectance Observations with MODIS BRDF Products

Directory of Open Access Journals (Sweden)

Bo Gao

2014-09-01

Full Text Available Land surface albedo is an essential parameter for monitoring global/regional climate and land surface energy balance. Although many studies have been conducted on global or regional land surface albedo using various remote sensing data over the past few decades, land surface albedo product with a high spatio–temporal resolution is currently very scarce. This paper proposes a method for deriving land surface albedo with a high spatio–temporal resolution (space: 30 m and time: 2–4 days. The proposed method works by combining the land surface reflectance data at 30 m spatial resolution obtained from the charge-coupled devices in the Huanjing-1A and -1B (HJ-1A/B satellites with the Moderate Resolution Imaging Spectroradiometer (MODIS land surface bidirectional reflectance distribution function (BRDF parameters product (MCD43A1, which is at a spatial resolution of 500 m. First, the land surface BRDF parameters for HJ-1A/B land surface reflectance with a spatial–temporal resolutions of 30 m and 2–4 day are calculated on the basis of the prior knowledge from the MODIS BRDF product; then, the calculated high resolution BRDF parameters are integrated over the illuminating/viewing hemisphere to produce the white- and black-sky albedos at 30 m resolution. These results form the basis for the final land surface albedo derivation by accounting for the proportion of direct and diffuse solar radiation arriving at the ground. The albedo retrieved by this novel method is compared with MODIS land surface albedo products, as well as with ground measurements. The results show that the derived land surface albedo during the growing season of 2012 generally achieved a mean absolute accuracy of ±0.044, and a root mean square error of 0.039, confirming the effectiveness of the newly proposed method.

Volumetric composition of nanocomposites

DEFF Research Database (Denmark)

Madsen, Bo; Lilholt, Hans; Mannila, Juha

2015-01-01

is presented, using cellulose/epoxy and aluminosilicate/polylactate nanocomposites as case materials. The buoyancy method is used for the accurate measurements of materials density. The accuracy of the method is determined to be high, allowing the measured nanocomposite densities to be reported with 5...... significant figures. The plotting of the measured nanocomposite density as a function of the nanofibre weight content is shown to be a first good approach of assessing the porosity content of the materials. The known gravimetric composition of the nanocomposites is converted into a volumetric composition...

Tribology of Nanocomposites

CERN Document Server

2013-01-01

This book provides recent information on nanocomposites tribology. Chapter 1 provides information on tribology of bulk polymer nanocomposites and nanocomposite coatings. Chapter 2 is dedicated to nano and micro PTFE for surface lubrication of carbon fabric reinforced polyethersulphone composites. Chapter 3 describes Tribology of MoS2 -based nanocomposites. Chapter 4 contains information on friction and wear of Al2O2 -based composites with dispersed and agglomerated nanoparticles. Finally, chapter 5 is dedicated to wear of multi-scale phase reinforced composites. It is a useful reference for academics, materials and physics researchers, materials, mechanical and manufacturing engineers, both as final undergraduate and postgraduate levels. It is a useful reference for academics, materials and physics researchers, materials, mechanical and manufacturing engineers, both as final undergraduate and postgraduate levels.

Shear stiffness in nanolaminar Ti3SiC2 challenges ab initio calculations

International Nuclear Information System (INIS)

Kisi, E H; Zhang, J F; Kirstein, O; Riley, D P; Styles, M J; Paradowska, A M

2010-01-01

Nanolaminates such as the M n+1 AX n (MAX) phases are a material class with ab initio derived elasticity tensors published for over 250 compounds. We have for the first time experimentally determined the full elasticity tensor of the archetype MAX phase, Ti 3 SiC 2 , using polycrystalline samples and in situ neutron diffraction. The experimental elastic constants show extreme shear stiffness, with c 44 more than five times greater than expected for an isotropic material. Such shear stiffness is quite rare in hexagonal materials and strongly contradicts the predictions of all published MAX phase elastic constants derived from ab initio calculations. It is concluded that second order properties such as elastic moduli derived from ab initio calculations require careful experimental verification. The diffraction technique used currently provides the only method of verification for the elasticity tensor for the majority of new materials where single crystals are not available. (fast track communication)

Magnetoelectric polymer nanocomposite for flexible electronics

KAUST Repository

Al-Nassar, Mohammed Y.

2015-03-06

This paper reports the fabrication and characterization of a new type of magnetoelectric polymer nanocomposite that exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of high aspect ratio ferromagnetic iron nanowires embedded inside a ferroelectric co-polymer poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE). The nanocomposite has been fabricated via a simple low temperature spin coating technique. Structural, ferromagnetic, ferroelectric, and magnetoelectric properties of the developed nanocomposite have been characterized. The nanocomposite films showed isotropic magnetic properties due to the random orientation of the iron nanowires inside the film. In addition, the embedded nanowires did not hinder the ferroelectric phase development of the nanocomposite. The developed nanocomposite showed a high magnetoelectric coupling response of 156 mV/cmOe measured at 3.1 kOe DC bias field. This value is among the highest reported magnetoelectric coupling in two phase particulate polymer nanocomposites.

Magnetoelectric polymer nanocomposite for flexible electronics

International Nuclear Information System (INIS)

Alnassar, M.; Alfadhel, A.; Ivanov, Yu. P.; Kosel, J.

2015-01-01

This paper reports the fabrication and characterization of a new type of magnetoelectric polymer nanocomposite that exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of high aspect ratio ferromagnetic iron nanowires embedded inside a ferroelectric co-polymer poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE). The nanocomposite has been fabricated via a simple low temperature spin coating technique. Structural, ferromagnetic, ferroelectric, and magnetoelectric properties of the developed nanocomposite have been characterized. The nanocomposite films showed isotropic magnetic properties due to the random orientation of the iron nanowires inside the film. In addition, the embedded nanowires did not hinder the ferroelectric phase development of the nanocomposite. The developed nanocomposite showed a high magnetoelectric coupling response of 156 mV/cmOe measured at 3.1 kOe DC bias field. This value is among the highest reported magnetoelectric coupling in two phase particulate polymer nanocomposites

Magnetoelectric polymer nanocomposite for flexible electronics

KAUST Repository

Al-Nassar, Mohammed Y.; Alfadhel, Ahmed; Ivanov, Yurii P.; Kosel, Jü rgen

2015-01-01

This paper reports the fabrication and characterization of a new type of magnetoelectric polymer nanocomposite that exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of high aspect ratio ferromagnetic iron nanowires embedded inside a ferroelectric co-polymer poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE). The nanocomposite has been fabricated via a simple low temperature spin coating technique. Structural, ferromagnetic, ferroelectric, and magnetoelectric properties of the developed nanocomposite have been characterized. The nanocomposite films showed isotropic magnetic properties due to the random orientation of the iron nanowires inside the film. In addition, the embedded nanowires did not hinder the ferroelectric phase development of the nanocomposite. The developed nanocomposite showed a high magnetoelectric coupling response of 156 mV/cmOe measured at 3.1 kOe DC bias field. This value is among the highest reported magnetoelectric coupling in two phase particulate polymer nanocomposites.

Sol-gel preparation of Ag-silica nanocomposite with high electrical conductivity

Science.gov (United States)

Ma, Zhijun; Jiang, Yuwei; Xiao, Huisi; Jiang, Bofan; Zhang, Hao; Peng, Mingying; Dong, Guoping; Yu, Xiang; Yang, Jian

2018-04-01

Sol-gel derived noble-metal-silica nanocomposites are very useful in many applications. Due to relatively low price, higher conductivity, and higher chemical stability of silver (Ag) compared with copper (Cu), Ag-silica has gained much more research interest. However, it remains a significant challenge to realize high loading of Ag content in sol-gel Ag-silica composite with high structural controllability and nanoparticles' dispersity. Different from previous works by using multifunctional silicon alkoxide to anchor metal ions, here we report the synthesis of Ag-silica nanocomposite with high loading of Ag nanoparticles by employing acetonitrile bi-functionally as solvent and metal ions stabilizer. The electrical conductivity of the Ag-silica nanocomposite reached higher than 6800 S/cm. In addition, the Ag-silica nanocomposite could simultaneously possess high electrical conductivity and positive conductivity-temperature coefficient by properly controlling the loading content of Ag. Such behavior is potentially advantageous for high-temperature devices (like phosphoric acid fuel cells) and inhibiting the thermal-induced increase of devices' internal resistance. The strategy proposed here is also compatible with block-copolymer directed self-assembly of mesoporous material, spin-coating of film and electrospinning of nanofiber, making it more charming in various practical applications.

An introduction to polymer nanocomposites

International Nuclear Information System (INIS)

Armstrong, Gordon

2015-01-01

This review presents an overview of the formulation, characterization and range of applications for polymer nanocomposites. After explaining how material properties at the nanometre scale can vary compared to those observed at longer length scales, typical methods used to formulate and characterize nanocomposites at laboratory and industrial scale will be described. The range of mechanical, electrical and thermal properties obtainable from nanocomposite materials, with examples of current commercial applications, will be outlined. Formulation and characterization of nanoparticle, nanotube and graphene composites will be discussed by reference to nanoclay-based composites, as the latter are presently of most technological relevance. Three brief case studies are presented to demonstrate how structure/property relationships may be controlled in a variety of polymer nanocomposite systems to achieve required performance in a given application. The review will conclude by discussing potential obstacles to commercial uptake of polymer nanocomposites, such as inconsistent protocols to characterize nanocomposites, cost/performance balances, raw material availability, and emerging legislation, and will conclude by discussing the outlook for future development and commercial uptake of polymer nanocomposites. (review)

A curcumin activated carboxymethyl cellulose-montmorillonite clay nanocomposite having enhanced curcumin release in aqueous media.

Science.gov (United States)

Madusanka, Nadeesh; de Silva, K M Nalin; Amaratunga, Gehan

2015-12-10

A novel curcumin activated carboxymethylcellulose-montmorillonite nanocomposite is reported. A superabsorbent biopolymer; carboxymethyl cellulose (CMC) was used as an emulsifier for curcumin which is a turmeric derived water insoluble polyphenolic compound with antibacterial/anti-cancer properties. Montmorillonite (MMT) nanoclay was incorporated in the formulation as a matrix material which also plays a role in release kinetics. It was observed that water solubility of curcumin in the nanocomposite has significantly increased (60% release within 2h and 30 min in distilled water at pH 5.4) compared to pure curcumin. The prepared curcumin activated carboxymethylcellulose-montmorillonite nanocomposite is suitable as a curcumin carrier having enhanced release and structural properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ab interno trabeculectomy: patient selection and perspectives

Science.gov (United States)

Vinod, Kateki; Gedde, Steven J

2016-01-01

Ab interno trabeculectomy is one among several recently introduced minimally invasive glaucoma surgeries that avoid a conjunctival incision and full-thickness sclerostomy involved in traditional glaucoma surgery. Ablation of the trabecular meshwork and inner wall of Schlemm’s canal is performed in an arcuate fashion via a clear corneal incision, alone or in combination with phacoemulsification cataract surgery. Intraocular pressure reduction following ab interno trabeculectomy is limited by resistance in distal outflow pathways and generally stabilizes in the mid-to-high teens. Relief of medication burden has been demonstrated by some studies. A very low rate of complications, most commonly transient hyphema and intraocular pressure elevations in the immediate postoperative period, have been reported. However, available data are derived from small retrospective and prospective case series. Randomized, controlled trials are needed to better elucidate the potential merits of ab interno trabeculectomy in the combined setting versus phacoemulsification cataract surgery alone and to compare it with other minimally invasive glaucoma surgeries. PMID:27574396

Effect of nanocellulose isolation techniques on the formation of reinforced poly(vinyl alcohol nanocomposite films

Directory of Open Access Journals (Sweden)

H. Y. Zhan

2012-10-01

Full Text Available Three techniques including acid hydrolysis (AH, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO-mediated oxidation (TMO and ultrasonication (US were introduced to isolate nanocellulose from microcrystalline cellulose, in order to reinforce poly(vinyl alcohol (PVA films. Important differences were noticed in fiber quality of nanocellulose and film properties of PVA nanocomposite films. The TMO treatment was more efficient in nanocellulose isolation with higher aspect ratio, surface charge (–47 mV and yields (37%. While AH treatment resulted in higher crystallinity index (88.1% and better size dispersion. The fracture surface, thermal behavior and mechanical properties of the PVA nanocomposite films were investigated by means of scanning electron microscopy (SEM, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA and tensile testing. The results showed that both the TMO-derived and AH-derived nanocellulose could be dispersed homogeneously in the PVA matrices. AH/PVA films had higher elongation at break (51.59% at 6 wt% nanocellulose loading as compared with TMO/PVA, while TMO/PVA films shown superior tensile modulus and strength with increments of 21.5% and 10.2% at 6wt% nanocellulose loading. The thermal behavior of the PVA nanocomposite films was higher improved with TMO-derived nanofibrils addition.

Novel Preparation of Nano-Composite CuO-Cr2O3 Using Ctab-Template Method and Efficient for Hydrogenation of Biomass-Derived Furfural

Science.gov (United States)

Yan, Kai; Wu, Xu; An, Xia; Xie, Xianmei

2013-02-01

A simple route to fabricate nano-composite oxides CuO-Cr2O3 using hexadecyltrimethylammonium bromide (CTAB)-templated Cu-Cr hydrotalcite as the precursor is presented. This novel method is based on CTAB-templating effect for mesostructure directing and using the cheap metal nitrate, followed by removal of CTAB. It was indicated that the nano-composite CuO-Cr2O3 was formed during the removal of CTAB. X-ray diffraction (XRD) and transitional electronic microscopy (TEM) revealed nice nano-composite oxides CuO-Cr2O3 were formed with high crystallinity. N2 adsorption and desorption indicated that a high surface area of 170.5 m2/g with a pore size of 2.7 nm of the nano-composite CuO-Cr2O3 was facilely resulted. The as-synthesized nano-composite oxides CuO-Cr2O3 display good catalytic activities for hydrogenation of furfural to furfuryl alcohol, whereas 86% selectivity was achieved at 75% conversion of furfural.

Proposal for novel curcumin derivatives as potent inhibitors against Alzheimer's disease: Ab initio molecular simulations on the specific interactions between amyloid-beta peptide and curcumin

Science.gov (United States)

Ota, Shintaro; Fujimori, Mitsuki; Ishimura, Hiromi; Shulga, Sergiy; Kurita, Noriyuki

2017-10-01

Accumulation of amyloid-β (Aβ) peptides in a brain is closely related with the pathogenesis of Alzheimer's disease. To suppress the production of Aβ peptides, we propose novel curcumin derivatives and investigate their binding properties with the amyloid precursor protein (APP), using protein-ligand docking as well as ab initio molecular simulations. Our proposed derivative (curcumin XIV) is found to have a large binding energy with APP and interacts strongly with the cleavage site Ala19 by secretase. It is thus expected that curcumin XIV can protect APP from the secretase attack and be a potent inhibitor against the production of Aβ peptides.

Multifunctional Polymer/Inorganic Nanocomposites

National Research Council Canada - National Science Library

Manias, E

2003-01-01

... in multifunctional nanocomposite materials. Understanding the structure/property relations in polymer/clay nanocomposites is of great importance in designing materials with desired sets of properties...

Nickel(II) tetra-aminophthalocyanine modified MWCNTs as potential nanocomposite materials for the development of supercapacitors

CSIR Research Space (South Africa)

Chidembo, AT

2010-11-01

Full Text Available -aminophthalocyanine modified MWCNTs as potential nanocomposite materials for the development of supercapacitors? Alfred T. Chidembo,a Kenneth I. Ozoemena,*ab Bolade O. Agboola,b Vinay Gupta,c Gregory G. Wildgoose?d and Richard G. Comptond Received 4th August 2009, Accepted.... Lu, Adv. Funct. Mater., 2009, 19, 1. 13 V. Gupta and N. Miura, J. Power Sources, 2006, 157, 616. 14 J. Liu, A. G. Rinzler, H. Dai, J. H. Hanfer, R. K. Bradley, P. J. Boul, A. Lu, T. Iverson, K. Shelimov, C. B. Huffman, F. R. Macias, Y. S. Shon, T...

Helicase properties of the Escherichia coli UvrAb protein complex

International Nuclear Information System (INIS)

Oh, E.Y.; Grossman, L.

1987-01-01

The Escherichia coli UvrA protein has an associated ATPase activity with a turnover number affected by the presence of UvrB protein as well as by DNA. Specifically, the structure of DNA significantly influences the turnover rate of the UvrAB ATPase activity. Double-stranded DNA maximally activates the turnover rate 10-fold whereas single-stranded DNA maximally activates the turnover rate 20-fold, suggesting that the mode of interaction of UvrAB protein with different DNAs is distinctive. We have previously shown that the UvrAB protein complex, driven by the binding energy of ATP, can locally unwind supercoiled DNA. The nature of the DNA unwinding activity and single-stranded DNA activation of ATPase activity suggest potential helicase activity. In the presence of a number of helicase substrates, the UvrAB complex, indeed, manifests a strand-displacement activity-unwinding short duplexes and D-loop DNA, thereby generating component DNA structures. The energy for the activity is derived from ATP or dATP hydrolysis. Unlike the E. coli DnaB, the UvrAB helicase is sensitive to UV-induced photoproducts

Magnetoelectric Nanocomposites for Flexible Electronics

KAUST Repository

Al-Nassar, Mohammed Y.

2015-09-01

Flexibility, low cost, versatility, miniaturization and multi-functionality are key aspects driving research and innovation in many branches of the electronics industry. With many anticipated emerging applications, like wearable, transparent and biocompatible devices, interest among the research community in pursuit for novel multifunctional miniaturized materials have been amplified. In this context, multiferroic polymer-based nanocomposites, possessing both ferroelectricity and ferromagnetism, are highly appealing. Most importantly, these nanocomposites possess tunable ferroelectric and ferromagnetic properties based on the parameters of their constituent materials as well as the magnetoelectric effect, which is the coupling between electric and magnetic properties. This tunability and interaction is a fascinating fundamental research field promising tremendous potential applications in sensors, actuators, data storage and energy harvesting. This dissertation work is devoted to the investigation of a new class of multiferroic polymer-based flexible nanocomposites, which exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature, with the goal of understanding and optimizing the origin of their magnetoelectric coupling. The nanocomposites consist of high aspect ratio ferromagnetic nanowires (NWs) embedded inside a ferroelectric co-polymer, poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE) matrix. First, electrochemical deposition of ferromagnetic NWs inside anodic aluminum oxide membranes is discussed. Characterization of electrodeposited iron, nickel and highly magnetostrictive iron-gallium alloy NWs was done using XRD, electron and magnetic force microscopy. Second, different nanocomposite films have been fabricated by means of spin coating and drop casting techniques. The effect of incorporation of NWs inside the ferroelectric polymer on its electroactive phase is discussed. The remanent and saturation polarization as well

Single-ion 4f element magnetism: an ab-initio look at Ln(COT)2(-).

Science.gov (United States)

Gendron, Frédéric; Pritchard, Benjamin; Bolvin, Hélène; Autschbach, Jochen

2015-12-14

The electron densities associated with the Ln 4f shell, and spin and orbital magnetizations ('magnetic moment densities'), are investigated for the Ln(COT)2(-) series. The densities are obtained from ab-initio calculations including spin-orbit coupling. For Ln = Ce, Pr the magnetizations are also derived from crystal field models and shown to agree with the ab-initio results. Analysis of magnetizations from ab-initio calculations may be useful in assisting research on single molecule magnets.

C60 and Sc3N@C80(TMB-PPO derivatives as constituents of singlet oxygen generating, thiol-ene polymer nanocomposites

Directory of Open Access Journals (Sweden)

Ashli R. Toles

2016-07-01

Full Text Available Numerous functionalization methods have been employed to increase the solubility, and therefore, the processability of fullerenes in composite structures, and of these radical addition reactions continue to be an important methodology. C60 and Sc3N@C80 derivatives were prepared via radical addition of the photodecomposition products from the commercial photoinitiator TMB-PPO, yielding C60(TMB-PPO5 and Sc3N@C80(TMB-PPO3 as preferred soluble derivatives obtained in high yields. Characterization of the mixture of isomers using standard techniques suggests an overall 1PPO:6TMB ratio of addends, reflecting the increased reactivity of the carbon radical. Although, a higher percentage of PPO is observed in the Sc3N@C80(TMB-PPO3 population, perhaps due to reverse electronic requirements of the substrate. Visually dispersed thiol-ene nanocomposites with low extractables were prepared using two monomer compositions (PETMP:TTT and TMPMP:TMPDE with increasing fullerene derivative loading to probe network structure-property relationships. Thermal stability of the derivatives and the resulting networks decreased with increased functionality and at high fullerene loadings, respectively. TMPMP:TMPDE composite networks show well-dispersed derivatives via TEM imaging, and increasing Tg’s with fullerene loading, as expected for the incorporation of a more rigid network component. PETMP:TTT composites show phase separation in TEM, which is supported by the observed Tg’s. Singlet oxygen generation of the derivatives decreases with increased functionality; however, this is compensated for by the tremendous increase in solubility in organic solvents and miscibility with monomers. Most importantly, singlet oxygen generation from the composites increased with fullerene derivative loading, with good photostability of the networks.

Multiscale Study of Barium Titanate Nanostructures and Nanocomposites

Science.gov (United States)

Louis, Lydie

Advancements in integrated nanoelectronics will continue to require the use of unique materials or systems of materials with diverse functionalities in increasingly confined spaces. Hence, research on finite-dimensional systems strive to unearth and expand the knowledge of fundamental physical properties in certain key materials which exhibit numerous concurrent and exploitable functions. Correspondingly, ferroelectric nanostructures, which particularly display a plethora of complex phenomena, prevalent in countless fields of research, are noteworthy candidates. Presently, however, the assimilation of zero-(0D) and one-dimensional (1D) ferroelectric into micro- or nano-electronics has been lagging, in part due to a lack of applied and fundamental studies but also due to the paucity of synthetic strategies yielding high quality monocrystalline structures. In this work, the problematics of size reduction, which affects many aspects of electronic devices, was addressed. Furthermore, the depolarizing effects associated with finite thickness in ferroelectric nanostructures was investigated in connection with other crucial boundary conditions. The work reported in this dissertation concerned isolated 0D and 1D BaTiO3 nanocrystals and nanocomposites composed of periodic arrays of BaTiO 3 nanowires embedded in a matrix formed by another ferroelectric material. A systematic investigation was conducted for those three types of nanostructures from a quantum mechanical and atomistic perspective using both direct-first-principles and first-principles-derived methods. Using first-principles-based calculations, the structural phase sequences in 0D (cubic-to-tetragonal-to-monoclinic-to-rhombohedral) and 1D (cubic-to-tetragonal-to-orthorhombic-to-monoclinic) BaTiO3 nanoparticles revealed differences from that of the bulk and thin film systems. The monoclinic symmetry found in the 0D compounds, and as for the ground-state of 1D systems, were also affected by size effects and tuned

WxC-β-SiC Nanocomposite Catalysts Used in Aqueous Phase Hydrogenation of Furfural.

Science.gov (United States)

Rogowski, Jacek; Andrzejczuk, Mariusz; Berlowska, Joanna; Binczarski, Michal; Kregiel, Dorota; Kubiak, Andrzej; Modelska, Magdalena; Szubiakiewicz, Elzbieta; Stanishevsky, Andrei; Tomaszewska, Jolanta; Witonska, Izabela Alina

2017-11-22

This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO₂ in the presence of WO₃ at 1550 °C in argon resulted in the formation of W x C-β-SiC nanocomposite powders with significant variations in particle morphology and content of W x C-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA) of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA) and tetrahydrofurfuryl alcohol (THFA). Nanocomposite W x C-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest W x C crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites

Science.gov (United States)

Yoonessi, Mitra; Gaier, James R.

2010-01-01

Graphene nanosheet bisphenol A polycarbonate nanocomposites (0.027 2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 C, exhibited dc electrical percolation threshold of approx.0.14 and approx.0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks.

Effective Optical Properties of Plasmonic Nanocomposites

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Christoph Etrich

2014-01-01

Full Text Available Plasmonic nanocomposites find many applications, such as nanometric coatings in emerging fields, such as optotronics, photovoltaics or integrated optics. To make use of their ability to affect light propagation in an unprecedented manner, plasmonic nanocomposites should consist of densely packed metallic nanoparticles. This causes a major challenge for their theoretical description, since the reliable assignment of effective optical properties with established effective medium theories is no longer possible. Established theories, e.g., the Maxwell-Garnett formalism, are only applicable for strongly diluted nanocomposites. This effective description, however, is a prerequisite to consider plasmonic nanocomposites in the design of optical devices. Here, we mitigate this problem and use full wave optical simulations to assign effective properties to plasmonic nanocomposites with filling fractions close to the percolation threshold. We show that these effective properties can be used to properly predict the optical action of functional devices that contain nanocomposites in their design. With this contribution we pave the way to consider plasmonic nanocomposites comparably to ordinary materials in the design of optical elements.

Preparation of a pure 99mTc-F(ab')2 radioimmunoconjugate by direct labeling methods

International Nuclear Information System (INIS)

Griffiths, G.L.; Jones, A.L.; Hansen, H.J.; Goldenberg, D.M.

1994-01-01

Intact IgG and Fab' can be labeled directly with 99m Tc to give quantitative incorporation of radioactivity into the protein. With F(ab') 2 the reductive conditions yield a mixture of 99m Tc-F(ab') 2 and 99m Tc-Fab'. We now report a direct labeling method to produce only 99m Tc-F(ab') 2 in quantitative yield and contaminated with 99m Tc-Fab'. The properties, stability and biodistribution of the 99m Tc-F(ab') 2 have been compared to 99m Tc-Fab'. This new technology will allow us to compare technetium direct-labeled IgG, F(ab') 2 and Fab' derivatives of the same antibody for radioimmunodetection. (author)

Nanostructured SnO{sub 2} encapsulated guar-gum hybrid nanocomposites for electrocatalytic determination of hydrazine

Energy Technology Data Exchange (ETDEWEB)

Malik, Priya [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Srivastava, Manish [Department of Physics & Astrophysics, University of Delhi, Delhi 110007 (India); Verma, Ranjana [Solar Energy Material Laboratory, Department of Energy, Tezpur University, Tezpur, Assam 784 028 (India); Kumar, Manish [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Kumar, D., E-mail: dkumar@dce.ac.in [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Singh, Jay, E-mail: jay_singh143@yahoo.co.in [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India)

2016-01-01

The present article deals with synthesis of sol–gel derived tin dioxide (SnO{sub 2}) nanoparticles encapsulated in to guar gum (GG) biopolymer as the organic–inorganic hybrid materials for the determination of hydrazine. The organic–inorganic hybrid combines the perfunctory strength offered by the inorganic SnO{sub 2} nanoparticles with flexible binding sites provided by the organic biopolymer (GG) solution by the ultrasonication. The phase identification, crystalline size, surface morphology and optical properties of prepared SnO{sub 2} and SnO{sub 2}-GG nanocomposites has been investigated through FT-IR, XRD, SEM, AFM, TEM, UV–Vis, and PL techniques. The colloidal solution of SnO{sub 2} and GG is electrophoretically deposited (EPD) onto the indium tin-oxide (ITO) glass substrate and studied for the electrooxidation of hydrazine. Under the optimized experimental conditions, the linearity between the current response and the hydrazine concentration has been obtained in the range of 2–22 mM, with a low detection limit of 2.76 mM and a high sensitivity of 5.72 μA cm{sup −2}. Based on the linear increase in amperometric current, a sensitive hydrazine electrochemical sensor is constructed. The proposed SnO{sub 2}-GG/ITO electrode shows a good response time (35 s), reproducibility, and long-term stability. The obtained results suggest that SnO{sub 2}-GG nanocomposites electrode provides a favorable sensing platform for the electrochemical studies. In addition, the cyclic voltammetry (CV) studies are used to evaluate the kinetic parameters. - Graphical abstract: Synthesis of sol–gel derived tin dioxide (SnO{sub 2}) nanoparticles grafted in to gaur gum (GG) organic–inorganic hybrid nanocomposite for determination of hydrazine (HZ). Under optimized experimental conditions, SnO{sub 2}-GG/ITO electrode shows, linearity 2–22 mM, and detection limit 2.769 mM with high sensitivity of 5.72 μA cm{sup −2}. The results clearly suggest that SnO{sub 2}-GG

Fabrication, nanomechanical characterization, and cytocompatibility of gold-reinforced chitosan bio-nanocomposites

International Nuclear Information System (INIS)

Patel, Nimitt G.; Kumar, Ajeet; Jayawardana, Veroni N.; Woodworth, Craig D.; Yuya, Philip A.

2014-01-01

Chitosan, a naturally derived polymer represents one of the most technologically important classes of active materials with applications in a variety of industrial and biomedical fields. Gold nanoparticles (∼ 32 nm) were synthesized via a citrate reduction method from chloroauric acid and incorporated in Chitosan matrix. Bio-nanocomposite films with varying concentrations of gold nanoparticles were prepared through solution casting process. Uniform distribution of gold nanoparticles was achieved throughout the chitosan matrix and was confirmed with SEM. Synthesis outcomes and prepared nanocomposites were characterized using SEM, TEM, EDX, SAED, UV–vis, XRD, DLS, and Zeta potential for their physical, morphological and structural properties. Nanoscale properties of materials under the influence of temperature were characterized through nanoindentation techniques. From quasi-static nanoindentation, it was observed that hardness and reduced modulus of the nanocomposites were increased significantly in direct proportion to the gold nanoparticle concentration. Gold nanoparticle concentration also showed positive impact on storage modulus and thermal stability of the material. The obtained films were confirmed to be biocompatible by their ability to support growth of human cells in vitro. In summary, the results show enhanced mechanical properties with increasing gold nanoparticle concentration, and provide better understanding of the structure–property relationships of such biocompatible materials for potential biomedical applications. - Highlights: • We fabricated gold reinforced chitosan nanocomposite for biomedical applications. • Gold nanoparticles significantly enhanced nanomechanical properties of chitosan. • Nanocomposite films supported growth of human cells in vitro. • Gold nanoparticles significantly improved cell proliferation on chitosan films

Multidimensional Nanocomposites of Epoxy Reinforced with 1D and 2D Carbon Nanostructures for Improve Fracture Resistance

Directory of Open Access Journals (Sweden)

Juventino López-Barroso

2018-03-01

Full Text Available A hybrid nanocomposites based on epoxy reinforced with a combination of 1D and 2D carbon nanomaterials for improving impact resistance are reported. Multi-walled carbon nanotubes and oxidized-multi-walled carbon nanotubes are used as 1D nanoreinforcements, and graphene derivative materials such as graphene oxide and reduced graphene oxide are utilized as 2D nanoreinforcements. In this research, the impact resistance of epoxy matrix reinforced with 1D or 2D and the mixture of both nanomaterials is studied. The research is focused on evaluation of the influence of adding different combinations of nanomaterials into epoxy resin and their Izod impact response. Moreover, fracture surface of nanocomposites is observed by scanning electron microscopy. Images show differences between the surfaces of brittle nature on thermoset epoxy polymer and tough nanocomposites. Synergy created with 1D and 2D nanomaterials produces stable dispersions in the processing, reflected in the interface. The interactions in nanocomposites are evidenced by infrared spectra, principally on the peaks related to oxygenated functional groups present in nanomaterials and absent in polymer matrix. Consequently, an increase of 138% in fracture strength of nanocomposites is exhibited, in comparison to the neat epoxy matrix. In addition, hybrid nanocomposites were synthesized in two different methods to evaluate the influence of manufacturing method on final properties of nanocomposites.

Lithium iron phosphate/carbon nanocomposite film cathodes for high energy lithium ion batteries

International Nuclear Information System (INIS)

Liu, Yanyi; Liu, Dawei; Zhang, Qifeng; Yu, Danmei; Liu, Jun; Cao, Guozhong

2011-01-01

This paper reports sol-gel derived nanostructured LiFePO4/carbon nanocomposite film cathodes exhibiting enhanced electrochemical properties and cyclic stabilities. LiFePO4/carbon films were obtained by spreading sol on Pt coated Si wafer followed by ambient drying overnight and annealing/pyrolysis at elevated temperature in nitrogen. Uniform and crack-free LiFePO4/carbon nanocomposite films were readily obtained and showed olivine phase as determined by means of X-Ray Diffractometry. The electrochemical characterization revealed that, at a current density of 200 mA/g (1.2 C), the nanocomposite film cathodes demonstrated an initial lithium-ion intercalation capacity of 312 mAh/g, and 218 mAh/g after 20 cycles, exceeding the theoretical storage capacity of conventional LiFePO4 electrode. Such enhanced Li-ion intercalation performance could be attributed to the nanocomposite structure with fine crystallite size below 20 nm as well as the poor crystallinity which provides a partially open structure allowing easy mass transport and volume change associated with Li-ion intercalation. Moreover the surface defect introduced by carbon nanocoating could also effectively facilitate the charge transfer and phase transitions.

Experimental analysis of graphene nanocomposite on Kevlar

Science.gov (United States)

Manigandan, S.; Gunasekar, P.; Nithya, S.; Durga Revanth, G.; Anudeep, A. V. S. C.

2017-08-01

Graphene nanocomposite is a two dimensional structure which has intense role in material science. This paper investigates the topological property of the graphene nanocomposite doped in Kevlar fiber by direct mixing process. The Kevlar fiber by direct mixing process. The Kevlar fiber taken as the specimen which is fabricated by vacuum bag moulding process. Epoxy used as resin and HY951 as hardener. Three different specimens are fabricated based on the percentage of graphene nanocomposite 2%, 5%, 10% and 20% respectively. We witnessed the strength of the Kevlar fiber is increased when it is treated with nanocomposite. The percentage of the nanocomposite increase the strength of the fiber is increased. However as the nanocomposite beyond 5% the strength of fiber is dropped. In addition, we also seen the interfacial property of the fiber is dropped when the nanocomposite is added beyond threshold limit.

Crystallization behaviour of nanostructured hybrid SiO2-TiO2 gel glasses to nanocomposites.

Science.gov (United States)

Tsvetelina, Gerganova; Yordanka, Ivanova; Yuliya, Vueva; Miranda, Salvado Isabel M; Helena, Fernandes Maria

2010-04-01

The crystallization behaviour of hybrid SiO2-TiO2 nanocomposites derived from titanosiloxanes by sol-gel method has been investigated depending on the type of siloxane precursor and the pirolysis temperature. The resulting hybrid titanosiloxanes, crosslinked with trimethylsilil isocyanate (nitrogen-modified) or methyltrietoxisilane (carbon-modified), were pirolyzed in an inert atmosphere in the temperature range between 600 to 1100 degrees C in order to form C-(N)-Si-O-TiO2 nanocomposites. By means of XRD, FTIR, 29Si NMR, SEM, TEM and AFM investigations have been established that the transformation of the nanostructured SiO2-TiO2 hybrid materials into nanocomposites as well as the crystalline size depend on the titanium content and the type of cross-linking agents used in the synthesizes.

Ultrahard carbon nanocomposite films

Energy Technology Data Exchange (ETDEWEB)

SIEGAL,MICHAEL P.; TALLANT,DAVID R.; PROVENCIO,PAULA P.; OVERMYER,DONALD L.; SIMPSON,REGINA L.; MARTINEZ-MIRANDA,L.J.

2000-01-27

Modest thermal annealing to 600 C of diamondlike amorphous-carbon (a-C) films grown at room temperature results in the formation of carbon nanocomposites with hardness similar to diamond. These nanocomposite films consist of nanometer-sized regions of high density a-C embedded in an a-C matrix with a reduced density of 5--10%. The authors report on the evolution of density and bonding topologies as a function of annealing temperature. Despite a decrease in density, film hardness actually increases {approximately} 15% due to the development of the nanocomposite structure.

LIGNOCELLULOSE NANOCOMPOSITE CONTAINING COPPER SULFIDE

OpenAIRE

Sanchi Nenkova; Peter Velev; Mirela Dragnevska; Diyana Nikolova; Kiril Dimitrov

2011-01-01

Copper sulfide-containing lignocellulose nanocomposites with improved electroconductivity were obtained. Two methods for preparing the copper sulfide lignocellulose nanocomposites were developed. An optimization of the parameters for obtaining of the nanocomposites with respect to obtaining improved electroconductivity, economy, and lower quantities and concentration of copper and sulfur ions in waste waters was conducted. The mechanisms and schemes of delaying and subsequent connection of co...

Ethylene-Octene Copolymers/Organoclay Nanocomposites: Preparation and Properties

Directory of Open Access Journals (Sweden)

Alice Tesarikova

2016-01-01

Full Text Available Two ethylene-octene copolymers with 17 and 45 wt.% of octene (EOC-17 and EOC-45 were compared in nanocomposites with Cloisite 93A. EOC-45 nanocomposites have a higher elongation at break. Dynamical mechanical analysis (DMA showed a decrease of tan⁡δ with frequency for EOC-17 nanocomposites, but decrease is followed by an increase for EOC-45 nanocomposites; DMA showed also increased modulus for all nanocomposites compared to pure copolymers over a wide temperature range. Barrier properties were improved about 100% by addition of organoclay; they were better for EOC-17 nanocomposites due to higher crystallinity. X-ray diffraction (XRD together with transmission electron microscopy (TEM showed some intercalation for EOC-17 but much better dispersion for EOC-45 nanocomposites. Differential scanning calorimetry (DSC showed increased crystallization temperature Tc for EOC-17 nanocomposite (aggregates acted as nucleation agents but decrease Tc for EOC-45 nanocomposite together with greatly influenced melting peak. Accelerated UV aging showed smaller C=O peak for EOC-45 nanocomposites.

Nanocomposite organomineral hybrid materials. Part 2

Directory of Open Access Journals (Sweden)

KUDRYAVTSEV Pavel Gennadievich

2016-04-01

Full Text Available The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility to change the types of nano-phase which is used for obtaining nanocomposites in different approaches. Various models of packaging spherical, fibrous and layered nanoparticles, introduced into the structure of the nanocomposite, in the preparation thereof were examined.

Nanocomposite organomineral hybrid materials. Part I

Directory of Open Access Journals (Sweden)

KUDRYAVTSEV Pavel Gennadievich

2016-02-01

Full Text Available The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility to change the types of nano-phase which is used for obtaining nanocomposites in different approaches. Various models of packaging spherical, fibrous and layered nanoparticles, introduced into the structure of the nanocomposite, in the preparation thereof were examined.

Nanocomposite organomineral hybrid materials. Part 3

Directory of Open Access Journals (Sweden)

KUDRYAVTSEV Pavel Gennadievich

2016-06-01

Full Text Available The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility to change the types of nano-phase which is used for obtaining nanocomposites in different approaches. Various models of packaging spherical, fibrous and layered nanoparticles, introduced into the structure of the nanocomposite, in the preparation thereof were examined.

nanocomposites chitosan /clay for electrochemical sensors

International Nuclear Information System (INIS)

Braga, Carla R. Costa; Melo, Frank M. Araujo de; Costa, Gilmara M. Silva; Silva, Suedina M. Lima

2009-01-01

This study was performed to obtain films of nanocomposites chitosan/bentonite and chitosan/montmorillonite intercalation by the technique of solution in the proportions of 5:1 and 10:1. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and the nanocomposites Chitosan/montmorillonite also were characterized by thermogravimetric analysis (TG). The results indicated that the feasibility of obtaining films of nanocomposites exfoliate. Among the suggested applications for films developed in this study includes them use for electrochemical sensors. (author)

Effect of Nanocomposite Structures on Fracture Behavior of Epoxy-Clay Nanocomposites Prepared by Different Dispersion Methods

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Mohammad Bashar

2014-01-01

Full Text Available The effects of organic modifier and processing method on morphology and mechanical properties of epoxy-clay nanocomposites were investigated. In this study, the preparation of nanocomposites by exfoliation-adsorption method involved an ultrasonic mixing procedure, and mechanical blending was used for in situ intercalative polymerization. The microstructure study revealed that the organoclay, which was ultrasonically mixed with the epoxy, partially exfoliated and intercalated. In contrast, organoclay remained in phase-separated and flocculated state after the mechanical blending process. Tensile stiffness increased significantly for the nanocomposite prepared by ultrasonic dispersion method through realizing the reinforcing potential of exfoliated silicate layers. Nanocomposites with exfoliated and intercalated nanoclay morphology were ineffective in enhancing the fracture toughness whereas nanocomposites with phase-separated and flocculated morphology have improved crack resistance predominantly by crack deflecting and pinning mechanisms.

Fatigue-free PZT-based nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Hwang, H J; Sando, M [Nat. Ind. Res. Inst., Nagoya (Japan); Tajima, K [Synergy Ceramics Lab., Fine Ceramics Research Association, Nagoya (Japan); Niihara, K [ISIR, Osaka Univ., Mihogaoka, Ibaraki (Japan)

1999-03-01

The goal of this study is to fabricate fatigue-free piezoelectrics-based nanocomposites. Lead zirconate titanate (PZT) and metallic platinum (Pt) were selected as a matrix and secondary phase dispersoid. Fine Pt particles were homogeneously dispersed in the PZT matrix. Fatigue properties of the unpoled PZT-based nanocomposite under electrical cyclic loading were investigated. The electrical-field-induced crack growth was monitored by an optical microscope, and it depended on the number of cycles the sample was subjected to. Resistance to fatigue was significantly enhanced in the nanocomposite. The excellent fatigue behavior of the PZT/Pt nanocomposites may result from the grain boundary strenghtening due to the interaction between the matrix and Pt particles. (orig.) 8 refs.

Ultrahard carbon nanocomposite films

Energy Technology Data Exchange (ETDEWEB)

Siegal, M. P. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Tallant, D. R. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Provencio, P. N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Overmyer, D. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Simpson, R. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Martinez-Miranda, L. J. [Department of Materials and Nuclear Engineering, University of Maryland, College Park, Maryland 20742 (United States)

2000-05-22

Modest thermal annealing to 600 degree sign C of diamondlike amorphous-carbon (a-C) films grown at room temperature results in the formation of carbon nanocomposites with hardness similar to diamond. These nanocomposite films consist of nanometer-sized regions of high density a-C embedded in an a-C matrix with a reduced density of 5%-10%. We report on the evolution of density and bonding topologies as a function of annealing temperature. Despite a decrease in density, film hardness actually increases {approx}15% due to the development of the nanocomposite structure. (c) 2000 American Institute of Physics.

Polyolefin nanocomposites in situ polymerization

Energy Technology Data Exchange (ETDEWEB)

Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine, E-mail: griselda.barrera@ufrgs.br [Universidade Federal do Rio Grande de Sul - UFRGS, Porto Alegre, RS (Brazil); Basso, Nara R.S. [Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil); Quijada, Raul [Universidad de Chile, Santiago (Chile)

2011-07-01

Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

Polyolefin nanocomposites in situ polymerization

International Nuclear Information System (INIS)

Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine; Basso, Nara R.S.; Quijada, Raul

2011-01-01

Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

An analytical model to predict curvature effects of the carbon nanotube on the overall behavior of nanocomposites

International Nuclear Information System (INIS)

Yang, B. J.; Souri, H.; Lee, H. K.; Kim, Sunghwan; Ryu, Seunghwa

2014-01-01

In this study, analytical expressions are introduced to provide a better understanding of carbon nanotubes (CNTs) curvature on the overall behavior of nanocomposites. The curviness of CNT is modeled as the wave geometries, and the transformed physical characteristics are applied to micromechanical framework. Since five independent elastic constants of CNTs are essential to derive the waviness effect, atomistic molecular statics simulations with varying nanotube radii are conducted. Influences of CNT curviness on the effective stiffness of the nanocomposites are analyzed, noting that the curvature effect is significantly influential on the effective stiffness of the nanocomposites, and it may improve or reduce the reinforcing effect depending on the orientation of CNTs. In addition, the predictions are compared with experimental data of the CNT-reinforced nanocomposites to assess the reliability of the proposed method. The developed constitutive model is expected to be used to determine the volume concentration of the reinforcing CNTs and mechanical responses of CNT-reinforced composites under various CNT curvature, radius, and orientation conditions.

Putnam-Fuglede theorem and the range-kernel orthogonality of derivations

Directory of Open Access Journals (Sweden)

B. P. Duggal

2001-01-01

space H into itself. Let d=δ or Δ, where δAB:ℬ(H→ℬ(H is the generalized derivation δAB(S=AS−SB and ΔAB:ℬ(H→ℬ(H is the elementary operator ΔAB(S=ASB−S. Given A,B,S∈ℬ(H, we say that the pair (A,B has the property PF(d(S if dAB(S=0 implies dA∗B∗(S=0. This paper characterizes operators A,B, and S for which the pair (A,B has property PF(d(S, and establishes a relationship between the PF(d(S-property of the pair (A,B and the range-kernel orthogonality of the operator dAB.

Novel nanocomposite coating for dental implant applications in vitro and in vivo evaluation.

Science.gov (United States)

Mehdikhani-Nahrkhalaji, M; Fathi, M H; Mortazavi, V; Mousavi, S B; Hashemi-Beni, B; Razavi, S M

2012-02-01

This study aimed at preparation and in vitro and in vivo evaluation of novel bioactive, biodegradable, and antibacterial nanocomposite coating for the improvement of stem cells attachment and antibacterial activity as a candidate for dental implant applications. Poly (lactide-co-glycolide)/bioactive glass/hydroxyapatite (PBGHA) nanocomposite coating was prepared via solvent casting process. The nanoparticle amounts of 10, 15, and 20 weight percent (wt%) were chosen in order to determine the optimum amount of nanoparticles suitable for preparing an uniform coating. Bioactivity and degradation of the coating with an optimum amount of nanoparticles were evaluated by immersing the prepared samples in simulated body fluid and phosphate buffer saline (PBS), respectively. The effect of nanocomposite coating on the attachment and viability of human adipose-derived stem cells (hASCs) was investigated. Kirschner wires (K-wires) of stainless steel were coated with the PBGHA nanocomposite coating, and mechanical stability of the coating was studied during intramedullary implantation into rabbit tibiae. The results showed that using 10 wt% nanoparticles (5 wt% HA and 5 wt% BG) in the nanocomposite could provide the desired uniform coating. The study of in vitro bioactivity showed rapid formation of bone-like apatite on the PBGHA coating. It was degraded considerably after about 60 days of immersion in PBS. The hASCs showed excellent attachment and viability on the coating. PBGHA coating remained stable on the K-wires with a minimum of 96% of the original coating mass. It was concluded that PBGHA nanocomposite coating provides an ideal surface for the stem cells attachment and viability. In addition, it could induce antibacterial activity, simultaneously.

Parylene nanocomposites using modified magnetic nanoparticles

International Nuclear Information System (INIS)

Garcia, Ignacio; Luzuriaga, A. Ruiz de; Grande, H.; Jeandupeux, L.; Charmet, J.; Laux, E.; Keppner, H.; Mecerreyes, D.; Cabanero, German

2010-01-01

Parylene/Fe 3 O 4 nanocomposites were synthesized and characterized. The nanocomposites were obtained by chemical vapour deposition polymerization of Parylene onto functionalized Fe 3 O 4 nanoparticles. For this purpose, allyltrichlorosilane was used to modify the surface of 7 nm size Fe 3 O 4 nanoparticles obtained by the coprecipitation method. The magnetic nanoparticles and obtained nanocomposite were characterized with X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and magnetic measurements (SQUID). The successful incorporation of different amounts of nanoparticles into Parylene was confirmed by FTIR and TGA. Interestingly, increments in saturation magnetization of the nanocomposites were observed ranging from 0 emu/g of neat Parylene to 16.94 emu/g in the case of nanocomposite films that contained 27.5 wt% of nanoparticles.

WxC-β-SiC Nanocomposite Catalysts Used in Aqueous Phase Hydrogenation of Furfural

Directory of Open Access Journals (Sweden)

Jacek Rogowski

2017-11-01

Full Text Available This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO2 in the presence of WO3 at 1550 °C in argon resulted in the formation of WxC-β-SiC nanocomposite powders with significant variations in particle morphology and content of WxC-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA and tetrahydrofurfuryl alcohol (THFA. Nanocomposite WxC-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest WxC crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

Nano-composite materials

Science.gov (United States)

Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland

2010-05-25

Nano-composite materials are disclosed. An exemplary method of producing a nano-composite material may comprise co-sputtering a transition metal and a refractory metal in a reactive atmosphere. The method may also comprise co-depositing a transition metal and a refractory metal composite structure on a substrate. The method may further comprise thermally annealing the deposited transition metal and refractory metal composite structure in a reactive atmosphere.

Advances in rubber/halloysite nanotubes nanocomposites.

Science.gov (United States)

Jia, Zhixin; Guo, Baochun; Jia, Demin

2014-02-01

The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties.

;Green; carbon with hierarchical three dimensional porous structure derived from - Pongamia pinnata seed oil extract cake and NiCo2O4-Ni(OH)2/Multiwall carbon nanotubes nanocomposite as electrode materials for high performance asymmetric supercapacitor

Science.gov (United States)

Chaitra, K.; Narendra, Reddy; Venkatesh, Krishna; Nagaraju, N.; Kathyayini, Nagaraju

2017-07-01

Herein, we report for the first time synthesis and electrochemical supercapacitance performance of 3-D hierarchical porous "Green" carbon derived from Pongamia pinnata seed oil extract cake and its activation using different amounts of KOH. Also, nanocomposites of multiwalled carbon nanotubes (MWCNT) with various weight percentages of Ni and Co were prepared by hydrothermal method. Physico-chemical properties of "Green" carbon and nanocomposites were analyzed by Powder X-ray Diffraction, Brunner Emmett Teller surface area, Scanning Electron Microscopy-Elemental Dispersive Spectrum, Transmission Electron Microscopy and Raman techniques. KOH activated carbon was found associated with combination of micropores & mesopores while the nanocomposite with mixture of spinel NiCo2O4 and Ni(OH)2. Porous carbon activated with 2:1::KOH:C (KC2) and the nanocomposite with 1:1 Ni & Co (NC1) exhibited excellent electrochemical performance in three electrode system. Further, fabricated asymmetric supercapacitor (AS) device Ni-Co-MWCNT (NC1)//KC2 exhibited specific capacitance (Cs) of 177 F/g as determined by cyclic voltammetry at 10 mV/s and retained 90% even at 3000th cycle in life cycle test conducted at high current density of 50 A/g. In order to evaluate its practical performance, the AS device was charged to 1.8 V at 5 A/g and used successfully to power a calculator for more than 1 h.

BACTERICIDE IMPACT OF POLYMER-STABILIZED MULTI-FUNCTIONAL NANO-COMPOSITES

OpenAIRE

Graskova I.A.; М.А. Zhivet’yev; G.B. Borovskii; B.G. Sukhov

2012-01-01

Synthesis on the basis of natural matrices in order to acquire products with the desired properties is one of the promising trends of modern science. Using polysaccharides as a matrix allowed to generate derivatives with diverse structures and new properties. Growing interest towards anti-microbe effect of selenium-containing nano-composites is induced by the phenomenon of antibiotic-resistance of contemporary pathogenic microorganisms.Clavibacter genus bacteria are the most significant and w...

The MIL-88A-Derived Fe3O4-Carbon Hierarchical Nanocomposites for Electrochemical Sensing

Science.gov (United States)

Wang, Li; Zhang, Yayun; Li, Xia; Xie, Yingzhen; He, Juan; Yu, Jie; Song, Yonghai

2015-01-01

Metal or metal oxides/carbon nanocomposites with hierarchical superstructures have become one of the most promising functional materials in sensor, catalysis, energy conversion, etc. In this work, novel hierarchical Fe3O4/carbon superstructures have been fabricated based on metal-organic frameworks (MOFs)-derived method. Three kinds of Fe-MOFs (MIL-88A) with different morphologies were prepared beforehand as templates, and then pyrolyzed to fabricate the corresponding novel hierarchical Fe3O4/carbon superstructures. The systematic studies on the thermal decomposition process of the three kinds of MIL-88A and the effect of template morphology on the products were carried out in detail. Scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermal analysis were employed to investigate the hierarchical Fe3O4/carbon superstructures. Based on these resulted hierarchical Fe3O4/carbon superstructures, a novel and sensitive nonenzymatic N-acetyl cysteine sensor was developed. The porous and hierarchical superstructures and large surface area of the as-formed Fe3O4/carbon superstructures eventually contributed to the good electrocatalytic activity of the prepared sensor towards the oxidation of N-acetyl cysteine. The proposed preparation method of the hierarchical Fe3O4/carbon superstructures is simple, efficient, cheap and easy to mass production. It might open up a new way for hierarchical superstructures preparation. PMID:26387535

Fracture toughness of epoxy/multi-walled carbon nanotube nano-composites under bending and shear loading conditions

International Nuclear Information System (INIS)

Ayatollahi, M.R.; Shadlou, S.; Shokrieh, M.M.

2011-01-01

Research highlights: → Mode I and mode II fracture tests were conducted on epoxy/MWCNT nano-composites. → Addition of MWCNT to epoxy increased both K Ic and K IIc of nano-composites. → The improvement in K IIc was more pronounced than in K Ic . → Mode I and mode II fracture surfaces were studied by scanning electron microscopy. -- Abstract: The effects of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties of epoxy/MWCNT nano-composites were studied with emphasis on fracture toughness under bending and shear loading conditions. Several finite element (FE) analyses were performed to determine appropriate shear loading boundary conditions for a single-edge notch bend specimen (SENB) and an equation was derived for calculating the shear loading fracture toughness from the fracture load. It was seen that the increase in fracture toughness of nano-composite depends on the type of loading. That is to say, the presence of MWCNTs had a greater effect on fracture toughness of nano-composites under shear loading compared with normal loading. To study the fracture mechanisms, several scanning electron microscopy (SEM) pictures were taken from the fracture surfaces. A correlation was found between the characteristics of fracture surface and the mechanical behaviors observed in the fracture tests.

Development of novel nano-composite membranes as introduction systems for mass spectrometers: Contrasting nano-composite membranes and conventional inlet systems

Science.gov (United States)

Miranda, Luis Diego

This dissertation presents the development of novel nano-composite membranes as introduction systems for mass spectrometers. These nano-composite membranes incorporate anodic aluminum oxide (AAO) membranes as templates that can be used by themselves or modified by a variety of chemical deposition processes. Two types of nano-composite membranes are presented. The first nano-composite membrane has carbon deposited within the pores of an AAO membrane. The second nano-composite membrane is made by coating an AAO membrane with a thin polymer film. The following chapters describe the transmission properties these nano-composite membranes and compare them to conventional mass spectrometry introduction systems. The nano- composite membranes were finally coupled to the inlet system of an underwater mass spectrometer revealing their utility in field deployments.

Formation of Silver and Gold Dendrimer Nanocomposites

International Nuclear Information System (INIS)

Balogh, Lajos; Valluzzi, Regina; Laverdure, Kenneth S.; Gido, Samuel P.; Hagnauer, Gary L.; Tomalia, Donald A.

1999-01-01

Structural types of dendrimer nanocomposites have been studied and the respective formation mechanisms have been described, with illustration of nanocomposites formed from poly(amidoamine) PAMAM dendrimers and zerovalent metals, such as gold and silver. Structure of {(Au(0)) n- PAMAM} and {(Ag(0)) n- PAMAM} gold and silver dendrimer nanocomposites was found to be the function of the dendrimer structure and surface groups as well as the formation mechanism and the chemistry involved. Three different types of single nanocomposite architectures have been identified, such as internal ('I'), external ('E') and mixed ('M') type nanocomposites. Both the organic and inorganic phase could form nanosized pseudo-continuous phases while the other components are dispersed at the molecular or atomic level either in the interior or on the surface of the template/container. Single units of these nanocomposites may be used as building blocks in the synthesis of nanostructured materials

Transparent cellulose/polyhedral oligomeric silsesquioxane nanocomposites with enhanced UV-shielding properties.

Science.gov (United States)

Feng, Ye; Zhang, Jinming; He, Jiasong; Zhang, Jun

2016-08-20

The solubility of eight types of polyhedral oligomeric silsesquioxane (POSS) derivatives in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) and the dispersion of POSS in cellulose matrix were examined. Only a special POSS containing both aminophenyl and nitrophenyl groups (POSS-AN, NH2:NO2=2:6) was selected to prepare nanocomposites, because of its good solubility in AmimCl and high stability during the preparation process. POSS-AN nanoparticles were uniformly dispersed in a cellulose matrix with a size of 30-40nm, and so the resultant cellulose/POSS-AN nanocomposite films were transparent. The mechanical properties of the films achieved a maximum tensile strength of 190MPa after addition of 2wt% POSS-AN. Interestingly, all of the cellulose/POSS-AN films exhibited high UV-absorbing capability. For the 15wt% cellulose/POSS-AN film, the transmittance of UVA (315-400nm) and UVB (280-315nm) was only 9.1% and nearly 0, respectively. The UV aging and shielding experiments showed that the transparent cellulose/POSS-AN nanocomposite films possessed anti-UV aging and UV shielding properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel Nanocomposite Materials for Advanced Li-Ion Rechargeable Batteries

Directory of Open Access Journals (Sweden)

Chuan Cai

2009-09-01

Full Text Available Nanostructured materials lie at the heart of fundamental advances in efficient energy storage and/or conversion, in which surface processes and transport kinetics play determining roles. Nanocomposite materials will have a further enhancement in properties compared to their constituent phases. This Review describes some recent developments of nanocomposite materials for high-performance Li-ion rechargeable batteries, including carbon-oxide nanocomposites, polymer-oxide nanocomposites, metal-oxide nanocomposites, and silicon-based nanocomposites, etc. The major goal of this Review is to highlight some new progress in using these nanocomposite materials as electrodes to develop Li-ion rechargeable batteries with high energy density, high rate capability, and excellent cycling stability.

High-performance polymer/layered silicate nanocomposites

Science.gov (United States)

Heidecker, Matthew J.

High-performance layered-silicate nanocomposites of Polycarbonate (PC), poly(ethylene terephthalate) (PET), and their blends were produced via conventional melt-blending techniques. The focus of this thesis was on the fundamentals of dispersion, control of thermal stability, maintenance of melt-blending processing conditions, and on optimization of the composites' mechanical properties via the design of controlled and thermodynamically favorable nano-filler dispersions within the polymer matrices. PET and PC require high temperatures for melt-processing, rendering impractical the use of conventional/commercial organically-modified layered-silicates, since the thermal degradation temperatures of their ammonium surfactants lies below the typical processing temperatures. Thus, different surfactant chemistries must be employed in order to develop melt-processable nanocomposites, also accounting for polymer matrix degradation due to water (PET) or amine compounds (PC). Novel high thermal-stability surfactants were developed and employed in montmorillonite nanocomposites of PET, PC, and PC/PET blends, and were compared to the respective nanocomposites based on conventional quaternary-ammonium modified montmorillonites. Favorable dispersion was achieved in all cases, however, the overall material behavior -- i.e., the combination of crystallization, mechanical properties, and thermal degradation -- was better for the nanocomposites based on the thermally-stable surfactant fillers. Studies were also done to trace, and ultimately limit, the matrix degradation of Polycarbonate/montmorillonite nanocomposites, through varying the montmorillonite surfactant chemistry, processing conditions, and processing additives. Molecular weight degradation was, maybe surprisingly, better controlled in the conventional quaternary ammonium based nanocomposites -- even though the thermal stability of the organically modified montmorillonites was in most cases the lowest. Dependence of the

Biopolymeric nanocomposites with enhanced interphases.

Science.gov (United States)

Yin, Yi; Hu, Kesong; Grant, Anise M; Zhang, Yuhong; Tsukruk, Vladimir V

2015-10-06

Ultrathin and robust nanocomposite membranes were fabricated by incorporating graphene oxide (GO) sheets into a silk fibroin (SF) matrix by a dynamic spin-assisted layer-by-layer assembly (dSA-LbL). We observed that in contrast to traditional SA-LbL reported earlier fast solution removal during dropping of solution on constantly spinning substrates resulted in largely unfolded biomacromolecules with enhanced surface interactions and suppressed nanofibril formation. The resulting laminated nanocomposites possess outstanding mechanical properties, significantly exceeding those previously reported for conventional LbL films with similar composition. The tensile modulus reached extremely high values of 170 GPa, which have never been reported for graphene oxide-based nanocomposites, the ultimate strength was close to 300 MPa, and the toughness was above 3.4 MJ m(-3). The failure modes observed for these membranes suggested the self-reinforcing mechanism of adjacent graphene oxide sheets with strong 2 nm thick silk interphase composed mostly from individual backbones. This interphase reinforcement leads to the effective load transfer between the graphene oxide components in reinforced laminated nanocomposite materials with excellent mechanical strength that surpasses those known today for conventional flexible laminated carbon nanocomposites from graphene oxide and biopolymer components.

Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

Energy Technology Data Exchange (ETDEWEB)

Silva, Ana Rosa; Unali, Gianfranco, E-mail: ana.rosa.silva@ua.pt [Structured Materials Expertise Group, Unilever Discover Port Sunlight, Quarry Road East, Bebington CH63 3JW (United Kingdom)

2011-08-05

Controlled silver release from cellulosic nanocomposites was achieved by synthesizing silver nanoparticles, under microwave heating for 1-15 min, in a one-pot, versatile and sustainable process in which microcrystalline cellulose simultaneously functions as reducing, stabilizing and supporting agent in water; chitin, starch and other cellulose derivatives could also be used as reducing, stabilizing and supporting agents for silver nanoparticles and the method was also found to be extensible to the preparation of noble metal (Au, Pt) and metal oxide nanoparticle (ZnO, Cu, CuO and Cu{sub 2}O) nanocomposites.

Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

International Nuclear Information System (INIS)

Silva, Ana Rosa; Unali, Gianfranco

2011-01-01

Controlled silver release from cellulosic nanocomposites was achieved by synthesizing silver nanoparticles, under microwave heating for 1-15 min, in a one-pot, versatile and sustainable process in which microcrystalline cellulose simultaneously functions as reducing, stabilizing and supporting agent in water; chitin, starch and other cellulose derivatives could also be used as reducing, stabilizing and supporting agents for silver nanoparticles and the method was also found to be extensible to the preparation of noble metal (Au, Pt) and metal oxide nanoparticle (ZnO, Cu, CuO and Cu 2 O) nanocomposites.

A synthetic cannabinoid FDU-NNEI, two 2H-indazole isomers of synthetic cannabinoids AB-CHMINACA and NNEI indazole analog (MN-18), a phenethylamine derivative N-OH-EDMA, and a cathinone derivative dimethoxy-α-PHP, newly identified in illegal products.

Science.gov (United States)

Uchiyama, Nahoko; Shimokawa, Yoshihiko; Kikura-Hanajiri, Ruri; Demizu, Yosuke; Goda, Yukihiro; Hakamatsuka, Takashi

Six new psychoactive substances were identified together with two other substances (compounds 1 - 8 ) in illegal products by our ongoing survey in Japan between January and July 2014. A new synthetic cannabinoid, FDU-NNEI [1-(4-fluorobenzyl)- N -(naphthalen-1-yl)-1 H -indole-3-carboxamide, 2 ], was detected with the newly distributed synthetic cannabinoid FDU-PB-22 ( 1 ). Two 2 H -indazole isomers of synthetic cannabinoids, AB-CHMINACA 2 H -indazole analog ( 3 ) and NNEI 2 H -indazole analog ( 4 ), were newly identified with 1 H -indazoles [AB-CHMINACA and NNEI indazole analog (MN-18)]. In addition, 2-methylpropyl N -(naphthalen-1-yl) carbamate ( 5 ) and isobutyl 1-pentyl-1 H -indazole-3-carboxylate ( 6 ) were detected in illegal products. Compound 6 is considered to be a by-product of the preparation of NNEI indazole analog from compound 5 and 1-pentyl-1 H -indazole. A phenethylamine derivative, N -OH-EDMA [ N -hydroxy-3,4-ethylenedioxy- N -methylamphetamine, 7 ], and a cathinone derivative, dimethoxy-α-PHP (dimethoxy-α-pyrrolidinohexanophenone, 8 ), were newly identified in illegal products. Among them, compounds 1 and 8 have been controlled as designated substances (Shitei-Yakubutsu) under the Pharmaceutical Affairs Law in Japan since August and November 2014, respectively.

Clinical significance of determination of serum leptin and AsAb, EmAb levels in infertile women

International Nuclear Information System (INIS)

Luo Jian; Zhou Minglian; Sun Gang; He Haoming

2010-01-01

Objective: To study the clinical significance of determination of serum leptin, AsAb, and EmAb levels in infertile women. Methods: Serum leptin (with RIA) and AsAb, EmAb (with ELISA) levels were detected in 32 infertile women and 35 controls. Results: Serum leptin levels in infertile women were significantly lower than those in controls (P<0.01). Serum AsAb and EmAb were both positive in 25 of the 32 infertile women (78.1%) and EmAb (one of two Abs) was positive in the rest 7 women (21.9%). These positive rates were also significantly higher than the respective ones in the controls (both P<0.01). Conclusion: Lower serum leptin level with highly positive AsAb and EmAb might be the chief cause of infertility in women. (authors)

Preparation and properties of biodegradable starch–clay nanocomposites

KAUST Repository

Chung, Yi-Lin; Ansari, Seema; Estevez, Luis; Hayrapetyan, Suren; Giannelis, Emmanuel P.; Lai, Hsi-Mei

2010-01-01

Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The clay didn't significantly influence the type of crystalline structure of starch molecules although the amount of crystallinity appears to be somewhat lower in the nanocomposites. The nanocomposites show improved modulus and strength without a decrease in elongation at break. The increase in modulus and strength is 65% and 30%, respectively for the nanocomposite containing 5 wt.% clay compared to the unfilled starch materials. Further increases in clay result in deterioration in properties most likely due to poorer clay dispersion and lower polymer crystallinity. As the amount of water increases, the modulus of both pure starch and starch nanocomposites decreases, although the change is less pronounced in the nanocomposites suggesting that the addition of clay to form nanocomposites can improve the stability of starch-based products during transportation and storage. © 2009 Elsevier Ltd. All rights reserved.

Preparation and properties of biodegradable starch–clay nanocomposites

KAUST Repository

Chung, Yi-Lin

2010-01-01

Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The clay didn\\'t significantly influence the type of crystalline structure of starch molecules although the amount of crystallinity appears to be somewhat lower in the nanocomposites. The nanocomposites show improved modulus and strength without a decrease in elongation at break. The increase in modulus and strength is 65% and 30%, respectively for the nanocomposite containing 5 wt.% clay compared to the unfilled starch materials. Further increases in clay result in deterioration in properties most likely due to poorer clay dispersion and lower polymer crystallinity. As the amount of water increases, the modulus of both pure starch and starch nanocomposites decreases, although the change is less pronounced in the nanocomposites suggesting that the addition of clay to form nanocomposites can improve the stability of starch-based products during transportation and storage. © 2009 Elsevier Ltd. All rights reserved.

Electrical conduction of a XLPE nanocomposite

Science.gov (United States)

Park, Yong-Jun; Sim, Jae-Yong; Lim, Kee-Joe; Nam, Jin-Ho; Park, Wan-Gi

2014-07-01

The resistivity, breakdown strength, and formation of space charges are very important factors for insulation design of HVDC cable. It is known that a nano-sized metal-oxide inorganic filler reduces the formation of space charges in the polymer nanocomposite. Electrical conduction of cross-linked polyethylene(XLPE) nanocomposite insulating material is investigated in this paper. The conduction currents of two kinds of XLPE nanocomposites and XLPE without nano-filler were measured at temperature of 303 ~ 363 K under the applied electric fields of 10 ~ 50 kV/mm. The current of the nanocomposite specimen is smaller than that of XLPE specimen without nano-filler. The conduction mechanism may be explained in terms of Schottky emission and multi-core model.

Core-satellite Ag@BaTiO3 nanoassemblies for fabrication of polymer nanocomposites with high discharged energy density, high breakdown strength and low dielectric loss.

Science.gov (United States)

Xie, Liyuan; Huang, Xingyi; Li, Bao-Wen; Zhi, Chunyi; Tanaka, Toshikatsu; Jiang, Pingkai

2013-10-28

Dielectric polymer nanocomposites with high dielectric constant have wide applications in high energy density electronic devices. The introduction of high dielectric constant ceramic nanoparticles into a polymer represents an important route to fabricate nanocomposites with high dielectric constant. However, the nanocomposites prepared by this method generally suffer from relatively low breakdown strength and high dielectric loss, which limit the further increase of energy density and energy efficiency of the nanocomposites. In this contribution, by using core-satellite structured ultra-small silver (Ag) decorated barium titanate (BT) nanoassemblies, we successfully fabricated high dielectric constant polymer nanocomposites with enhanced breakdown strength and lower dielectric loss in comparison with conventional polymer-ceramic particulate nanocomposites. The discharged energy density and energy efficiency are derived from the dielectric displacement-electric field loops of the polymer nanocomposites. It is found that, by using the core-satellite structured Ag@BT nanoassemblies as fillers, the polymer nanocomposites can not only have higher discharged energy density but also have high energy efficiency. The mechanism behind the improved electrical properties was attributed to the Coulomb blockade effect and the quantum confinement effect of the introduced ultra-small Ag nanoparticles. This study could serve as an inspiration to enhance the energy storage densities of dielectric polymer nanocomposites.

BACTERICIDE IMPACT OF POLYMER-STABILIZED MULTI-FUNCTIONAL NANO-COMPOSITES

Directory of Open Access Journals (Sweden)

Graskova I.A.

2012-08-01

Full Text Available Synthesis on the basis of natural matrices in order to acquire products with the desired properties is one of the promising trends of modern science. Using polysaccharides as a matrix allowed to generate derivatives with diverse structures and new properties. Growing interest towards anti-microbe effect of selenium-containing nano-composites is induced by the phenomenon of antibiotic-resistance of contemporary pathogenic microorganisms.Clavibacter genus bacteria are the most significant and widely spread among gram-positive bacteria. Bacteria cells are static pleimorphous rods, normally singular, sometimes coupled or joined in short chains, strict anaerobes in need of certain growth factors, non-sporogenous. Clavibacter michiganensis subsp. sepedonicus cause potato ring rot. At the tuber slice the damage is shaped as a ring; growing bacteria are accumulated in the conducting vessels causing their occlusion and therefore gradual withering of leaves and stem. This disease is distributed at all the continents including Australia. Harvest loss through ring rot damage may reach 10-45%.Our work was aimed at the study of complex interaction between microbe cultivar and selenium-based nanocomposites. Bacterial strain Аs1405 was acquired from the All-Russia collection of microorganisms, IMBP RAS. This genus is not included in the classification of pathogenic microorganisms by pathogenic groups of Sanitary-Epidemiological Rules SP 1.3.2322-08. The present study was focused on characteristics of the acquired strain.Fluorescent and electronic-scanning microscope was used to acquire photographs of bacterial cells. Pathogen was identified by PCR-analysis, which confirmed the presence of DNA of desired size. The extracted DNA was sequenced with the sequenced sequence added to Gen Bank under the number HQ394204. Cellulolytic and phytotoxic activity of this strain was determined.Chemistry Institute named A.E. Favorsky provided water-soluble nano-composites

Multiwalled Carbon Nanotube-titania Nanocomposites ...

African Journals Online (AJOL)

NICOLAAS

Physical and chemical characterization of the mesoporous nanocomposites from ... On the other hand, nanocomposites from sol-gel synthetic method had larger surface areas, were more defective ... This highlights the great potential of typical nanomaterials in ... various options available, especially for a developing world.

Chitosan-based nanocomposites

CSIR Research Space (South Africa)

Kesavan Pillai, Sreejarani

2012-08-01

Full Text Available , and hygiene devices. They thus represent a strong and emerging answer for improved and eco-friendly materials. This chapter reviews the recent developments in the area of chitosan-based nanocomposites, with a special emphasis on clay-containing nanocomposites...-sized mineral fillers like silica, talc, and clay are added to reduce the cost and improve chitosan’s performance in some way. However, the mechanical properties such as elongation at break and tensile strength of these composites decrease with the incorporation...

Inorganic-organic nanocomposites for optical coatings

Science.gov (United States)

Schmidt, Helmut K.; Krug, Herbert; Sepeur-Zeitz, Bernhard; Geiter, Elisabeth

1997-10-01

The fabrication of nanoparticles by the sol-gel process and their use in polymeric or sol-gel-derived inorganic-organic composite matrices opens up interesting possibilities for designing new optical materials. Two different routes have been chosen for preparing optical nanocomposites: The first is the so-called 'in situ route,' where the nanoparticles are synthesized in a liquid mixture from Zr-alkoxides in a polymerizable system and diffractive gratings were produced by embossing uncured film. The second is the 'separate' preparation route, where a sterically stabilized dry nanoboehmite powder was completely redispersed in an epoxy group-containing matrix and hard coatings with optical quality on polycarbonate were prepared.

Eco-friendly polymer nanocomposites processing and properties

CERN Document Server

Thakur, Vijay Kumar

2015-01-01

This book contains precisely referenced chapters, emphasizing environment-friendly polymer nanocomposites with basic fundamentals, practicality and alternatives to traditional nanocomposites through detailed reviews of different environmental friendly materials procured from different resources, their synthesis and applications using alternative green approaches. The book aims at explaining basics of eco-friendly polymer nanocomposites from different natural resources and their chemistry along with practical applications which present a future direction in the biomedical, pharmaceutical and automotive industry. The book attempts to present emerging economic and environmentally friendly polymer nanocomposites that are free from side effects studied in the traditional nanocomposites. This book is the outcome of contributions by many experts in the field from different disciplines, with various backgrounds and expertises. This book will appeal to researchers as well as students from different disciplines. The co...

Biodegradable polyurethane nanocomposites containing dexamethasone for ocular route

Energy Technology Data Exchange (ETDEWEB)

Rodrigues da Silva, Gisele [Federal University of Sao Joao Del Rei, School of Pharmacy, Divinopolis, Minas Gerais (Brazil); Silva-Cunha, Armando da [Federal University of Minas Gerais, School of Pharmacy, Belo Horizonte, Minas Gerais (Brazil); Behar-Cohen, Francine [INSERM, Physiopathology of ocular diseases: Therapeutic innovations, Institut des Cordeliers, Paris (France); Laboratoire d' Innovations Therapeutiques, Fondation Rothschild, Paris (France); Universite Rene Descartes, Hotel Dieu University Hospital, Paris (France); Ayres, Eliane [Federal University of Minas Gerais, Department of Metallurgical and Materials Engineering, Belo Horizonte, Minas Gerais (Brazil); Orefice, Rodrigo L., E-mail: rorefice@demet.ufmg.br [Federal University of Minas Gerais, Department of Metallurgical and Materials Engineering, Belo Horizonte, Minas Gerais (Brazil)

2011-03-12

The treatment of posterior segment ocular diseases, such as uveitis, by using eye drops and oral drugs is usually not effective due to the body's natural barriers to drug penetration. In this study, ocular implants to treat uveitis were synthesized by incorporating dexamethasone acetate, an important type of corticoid used in the treatment of some uveitis, into a biodegradable polyurethane containi clay nanoparticles. Biodegradable polyurethane nanocomposites having poly(caprolactone) oligomers as soft segments were obtained by delaminating clay particles within a polyurethane aqueous dispersion. The drug was incorporated into the polymer by dispersing it in the waterborne polyurethane followed by a drying step. Nanoparticles derived from clay were demonstrated to be able to tailor the mechanical properties of polyurethanes to achieve values that can match the properties of ocular soft tissues. Infrared spectra (FTIR) showed that the presence of clay particles was able to change the microphase separation process typical of polyurethanes. X-ray diffraction and small angle x-ray scattering (SAXS) results were explored to show that the incorporation of both dexamethasone acetate and nanocomponents derived from clay led to a less defined two-phase polyurethane. The presence of clay nanoparticles increased the rate of drug release measured in vitro. Human retinal pigment epithelial cells (ARPE-19) were cultured in contact with polyurethanes and polyurethane nanocomposites, and the viability of them (evaluated by using MTT assay after 7 days) showed that no toxic components were released from polyurethanes containing no drugs during the test.

Biodegradable polyurethane nanocomposites containing dexamethasone for ocular route

International Nuclear Information System (INIS)

Rodrigues da Silva, Gisele; Silva-Cunha, Armando da; Behar-Cohen, Francine; Ayres, Eliane; Orefice, Rodrigo L.

2011-01-01

The treatment of posterior segment ocular diseases, such as uveitis, by using eye drops and oral drugs is usually not effective due to the body's natural barriers to drug penetration. In this study, ocular implants to treat uveitis were synthesized by incorporating dexamethasone acetate, an important type of corticoid used in the treatment of some uveitis, into a biodegradable polyurethane containi clay nanoparticles. Biodegradable polyurethane nanocomposites having poly(caprolactone) oligomers as soft segments were obtained by delaminating clay particles within a polyurethane aqueous dispersion. The drug was incorporated into the polymer by dispersing it in the waterborne polyurethane followed by a drying step. Nanoparticles derived from clay were demonstrated to be able to tailor the mechanical properties of polyurethanes to achieve values that can match the properties of ocular soft tissues. Infrared spectra (FTIR) showed that the presence of clay particles was able to change the microphase separation process typical of polyurethanes. X-ray diffraction and small angle x-ray scattering (SAXS) results were explored to show that the incorporation of both dexamethasone acetate and nanocomponents derived from clay led to a less defined two-phase polyurethane. The presence of clay nanoparticles increased the rate of drug release measured in vitro. Human retinal pigment epithelial cells (ARPE-19) were cultured in contact with polyurethanes and polyurethane nanocomposites, and the viability of them (evaluated by using MTT assay after 7 days) showed that no toxic components were released from polyurethanes containing no drugs during the test.

Graphene oxide nanocomposites and their electrorheology

International Nuclear Information System (INIS)

Zhang, Wen Ling; Liu, Ying Dan; Choi, Hyoung Jin

2013-01-01

Graphical abstract: - Highlights: • GO-based PANI, NCOPA and PS nanocomposites are prepared. • The nanocomposites are adopted as novel electrorheological (ER) candidates. • Their critical ER characteristics and dielectric performance are analyzed. • Typical ER behavior widens applications of GO-based nanocomposites. - Abstract: Graphene oxide (GO), a novel one-atom carbon system, has become one of the most interesting materials recently due to its unique physical and chemical properties in addition to graphene. This article briefly reviews a recent progress of the fabrication of GO-based polyaniline, ionic N-substituted copolyaniline and polystyrene nanocomposites. The critical electrorheological characteristics such as flow response and yield stress from rheological measurement, relaxation time and achievable polarizability from dielectric analysis are also analyzed

Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites.

Science.gov (United States)

Deka, Harekrishna; Karak, Niranjan

2009-04-25

The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications. Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 degrees C of melting point, and 111 degrees C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96-99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

Load transfer of nanocomposite film on aluminum substrate.

Science.gov (United States)

Her, Shiuh-Chuan; Chien, Pao-Chu

2018-01-01

Nanocomposite films have attracted much attention in recent years. Depending on the composition of the film and fabrication method, a large range of applications has been employed for nanocomposite films. In this study, nanocomposite films reinforced with multi-walled carbon nanotubes (MWCNTs) were deposited on the aluminum substrate through hot press processing. A shear lag model and Euler beam theory were employed to evaluate the stress distribution and load carrying capability of the nanocomposite film subjected to tensile load and bending moment. The influence of MWCNT on the Young's modulus and load carrying capability of the nanocomposite film was investigated through a parametric study. The theoretical predictions were verified by comparison with experimental tests. A close agreement with difference less than 6% was achieved between the theoretical prediction and experimental measurements. The Young's modulus and load transfer of the nanocomposite film reinforced with MWCNTs increases with the increase of the MWCNT loading. Compared to the neat epoxy film, nanocomposite film with 1 wt % of MWCNT exhibits an increase of 20% in both the Young's modulus and load carrying capability.

Epoxy polyurethane nanocomposites filled with fullerite

International Nuclear Information System (INIS)

Rozhnova, R.A.; Galatenko, N.A.; Lukashevich, S.A.; Shirokov, O.D.; Levenets', Je.G.

2015-01-01

New nanocomposite materials based on epoxy polyurethane (EPU) containing nanoscale fullerite in its composition are produced. The influence of small impurities of fullerite on physical and mechanical properties of the nanocomposites is established. The effect of a nanofiller and its concentration on the structure and properties of the composite and the ability to biodegradation in vitro is studied. The developed nanocomposites exhibit the biodegradability, and the presence of nanofillers in the EPU facilitates the course of the process

Fracture behavior of polypropylene/clay nanocomposites.

Science.gov (United States)

Chen, Ling; Wang, Ke; Kotaki, Masaya; Hu, Charmaine; He, Chaobin

2006-12-01

Polypropylene (PP)/clay nanocomposites have been prepared via a reactive compounding approach with an epoxy based masterbatch. Compared with PP and common PP/organoclay nanocomposites, the PP/clay nanocomposites based on epoxy/clay masterbatch have higher impact strength. The phenomenon can be attributed to the epoxy phase dispersed uniformly in the PP matrix, which may act as impact energy absorber and helps to form a large damage zone, thus a higher impact strength value is achieved.

The impact of core-shell nanotube structures on fracture in ceramic nanocomposites

International Nuclear Information System (INIS)

Liang, Xin; Yang, Yingchao; Lou, Jun; Sheldon, Brian W.

2017-01-01

Multi-wall carbon nanotubes (MWCNTs) can be used to create ceramic nanocomposites with improved fracture toughness. In the present work, atomic layer deposition (ALD) was employed to deposit thin oxide layers on MWCNTs. These core-shell structures were then used to create nanocomposites by using a polymer derived ceramic (PDC) to produce the matrix. Variations in both the initial MWCNT structure and the oxide layers led to substantial differences in fiber-pullout behavior. Single tube pullout tests also showed that the oxide coatings led to stronger bonding with the ceramic matrix. With high defect density MWCNTs, this led to shorter pull-out lengths which is consistent with the conventional understanding of fracture in ceramic matrix composites. However, with low defect density MWCNTs longer pullout lengths were observed with the oxide layers. To interpret the different trends that were observed, we believe that the ALD coatings should not be viewed simply as a means of altering the interfacial properties. Instead, the coated MWCNTs should be viewed as more complex core-shell fibers where both interface and internal properties can be controlled with the ALD layers. - Graphical abstract: Fracture properties of core-shell nanotubes reinforced ceramic nanocomposites.

Cu₂O-Au nanocomposites for enzyme-free glucose sensing with enhanced performances.

Science.gov (United States)

Hu, Qiyan; Wang, Fenyun; Fang, Zhen; Liu, Xiaowang

2012-06-15

A facile method for the synthesis of Cu(2)O-Au nanocomposites has been reported by injecting Cu(2)O nanocubes into Au precursor directly with the assistance of ultrasound radiation at room temperature. The ultrasound radiation is not a necessary requirement but can make the distribution of Au nanoparticles more homogenous. The formation of Cu(2)O-Au nanocomposites is attributed to following two reasons. The first one is the difference in the reduction potential between Cu(2+)/Cu(2)O and AuCl(4)(-)/Au, which can also be considered as the driving force for the redox reaction. The other one is the low lattice mismatch between (200) planes of Cu(2)O and (200) facets of Au, which is favorable for the formation of heterostructure. The electrochemical investigation demonstrates that the performances of Cu(2)O nanocubes in enzyme-free glucose sensing have been improved significantly after the decoration of Au nanoparticles which may be derived from the polarization effect provided by Au nanoparticles. As-prepared Cu(2)O-Au nanocomposites have great potential in enzyme-free glucose sensing. Copyright © 2012 Elsevier B.V. All rights reserved.

Cellulose nanofibrils (CNF) filled boron nitride (BN) nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Sulaiman, Hanisah Syed; Hua, Chia Chin; Zakaria, Sarani [School of Applied Physic, Faculty of Science and Technology, Universiti Kebangsaan Malaysia.43600 Bangi, Selangor (Malaysia)

2015-09-25

In this study, nanocomposite using cellulose nanofibrils filled with different percentage of boron nitride (CNF-BN) were prepared. The objective of this research is to study the effect of different percentage of BN to the thermal conductivity of the nanocomposite produced. The CNF-BN nanocomposite were characterization by FT-IR, SEM and thermal conductivity. The FT-IR analysis of the CNF-BN nanocomposite shows all the characteristic peaks of cellulose and BN present in all samples. The dispersion of BN in CNF were seen through SEM analysis. The effect of different loading percentage of BN to the thermal conductivity of the nanocomposite were also investigated.

Multifunctional Magnetic-fluorescent Nanocomposites for Biomedical Applications

Directory of Open Access Journals (Sweden)

Rakovich Yury

2008-01-01

Full Text Available AbstractNanotechnology is a fast-growing area, involving the fabrication and use of nano-sized materials and devices. Various nanocomposite materials play a number of important roles in modern science and technology. Magnetic and fluorescent inorganic nanoparticles are of particular importance due to their broad range of potential applications. It is expected that the combination of magnetic and fluorescent properties in one nanocomposite would enable the engineering of unique multifunctional nanoscale devices, which could be manipulated using external magnetic fields. The aim of this review is to present an overview of bimodal “two-in-one” magnetic-fluorescent nanocomposite materials which combine both magnetic and fluorescent properties in one entity, in particular those with potential applications in biotechnology and nanomedicine. There is a great necessity for the development of these multifunctional nanocomposites, but there are some difficulties and challenges to overcome in their fabrication such as quenching of the fluorescent entity by the magnetic core. Fluorescent-magnetic nanocomposites include a variety of materials including silica-based, dye-functionalised magnetic nanoparticles and quantum dots-magnetic nanoparticle composites. The classification and main synthesis strategies, along with approaches for the fabrication of fluorescent-magnetic nanocomposites, are considered. The current and potential biomedical uses, including biological imaging, cell tracking, magnetic bioseparation, nanomedicine and bio- and chemo-sensoring, of magnetic-fluorescent nanocomposites are also discussed.

Polypyrrole-silver Nanocomposite: Synthesis and Characterization

Directory of Open Access Journals (Sweden)

D. M. Nerkar

2016-07-01

Full Text Available Polypyrrole-Silver (PPy-Ag nanocomposite has been successfully synthesized by the chemical oxidative polymerization of pyrrole with iron (III chloride as an oxidant, in the presence of a colloidal suspension of silver nanoparticles. Turkevich method (Citrate reduction method was used for the synthesis of silver nanoparticles (Ag NPs. The silver nanoparticles were characterized by UV-Visible spectroscopy which showed an absorption band at 423 nm confirming the formation of nanoparticles. PPy-Ag nanocomposite was characterized by Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM, Fourier Transform Infrared Spectroscopy (FTIR and X-ray diffraction (XRD techniques for morphological and structural confirmations. TEM and SEM images revealed that the silver nanoparticles were well dispersed in the PPy matrix. XRD pattern showed that PPy is amorphous but the presence of the peaks at 2q values of 38.24°, 44.57°, 64.51° and 78.45° corresponding to a cubic phase of silver, revealed the incorporation of silver nanoparticles in the PPy matrix. A possible formation mechanism of PPy-Ag nanocomposite was also proposed. The electrical conductivity of PPy-Ag nanocomposite was studied using two probe method. The electrical conductivity of the PPy-Ag nanocomposite prepared was found to be 4.657´10- 2 S/cm, whereas that of pure PPy was found to be 9.85´10-3 S/cm at room temperature (303 K. The value of activation energy (Ea for pure PPy was 0.045 eV while it decreased to 0.034 eV for PPy-Ag nanocomposite. The synthesized nanocomposite powder can be utilized as a potential material for fabrication of gas sensors operating at room temperature.

Polyaniline-CuO hybrid nanocomposite with enhanced electrical conductivity

Science.gov (United States)

de Souza, Vânia S.; da Frota, Hidembergue O.; Sanches, Edgar A.

2018-02-01

A hybrid nanocomposite based on a polymer matrix constituted of Polyaniline Emeraldine-salt form (PANI-ES) reinforced by copper oxide II (CuO) particles was obtained by in situ polymerization. Structural, morphological and electrical properties of the pure materials and nanocomposite form were investigated. The presence of CuO particles in the nanocomposite material affected the natural alignment of the polymer chains. XRD technique allowed the visualization of the polymer amorphization in the nanocomposite form, suggesting an interaction between both phases. The FTIR spectra confirmed this molecular interaction due to the blue shift of the characteristic absorption peaks of PANI-ES in the nanocomposite form. SEM images revealed that the polymer nanofiber morphology was no longer observed in the nanocomposite. The CuO spherical particles are randomly dispersed in the polymer matrix. The density functional theory plus the Coulomb interaction method revealed a charge transfer from PANI to CuO slab. Moreover, the density of states (DOS) has revealed that the nanocomposite behaves as a metal. In agreement, the electrical conductivity showed an increase of 60% in the nanocomposite material.

Force fields for silicas and aluminophosphates based on ab initio calculations

NARCIS (Netherlands)

Beest, van B.W.H.; Kramer, G.J.; Santen, van R.A.

1990-01-01

Authors address the problem of finding interat. force fields for silicas from ab initio calcns. on small clusters. The force field cannot be detd. from cluster data alone; incorporation of bulk-system information into the force field remains essential. Bearing this in mind, authors derive a force

Large-Strain Transparent Magnetoactive Polymer Nanocomposites

Science.gov (United States)

Meador, Michael A.

2012-01-01

A document discusses polymer nano - composite superparamagnetic actuators that were prepared by the addition of organically modified superparamagnetic nanoparticles to the polymer matrix. The nanocomposite films exhibited large deformations under a magnetostatic field with a low loading level of 0.1 wt% in a thermoplastic polyurethane elastomer (TPU) matrix. The maximum actuation deformation of the nanocomposite films increased exponentially with increasing nanoparticle concentration. The cyclic deformation actuation of a high-loading magnetic nanocomposite film was examined in a low magnetic field, and it exhibited excellent reproducibility and controllability. Low-loading TPU nanocomposite films (0.1-2 wt%) were transparent to semitransparent in the visible wavelength range, owing to good dispersion of the magnetic nanoparticles. Magnetoactuation phenomena were also demonstrated in a high-modulus, high-temperature polyimide resin with less mechanical deformation.

Polymer Nanocomposite Membranes for Antifouling Nanofiltration.

Science.gov (United States)

Kamal, Tahseen; Ali, Nauman; Naseem, Abbas A; Khan, Sher B; Asiri, Abdullah M

2016-01-01

Fouling refers to the unwanted and undesirable attachment of biological macromolecules, inorganic, organic matter, and microorganisms on water contact surfaces. Fouling reduces the performance of devices involving these submerged surfaces and is considered the bottle-neck issue for various applications in the biomedical industry, food processing, and water treatment, especially in reverse osmosis (RO) desalination. Investigations have proven that nanocomposite membranes can exhibit enhanced antifouling performances and can be used for longer life times. The nanocomposite means addition of nanomaterials to main matrix at low loadings, exhibiting better properties compared to virgin matrix. In this review, a summarized description about related methods and their mechanisms for the fabrication of nanocomposite membranes with antifouling properties has been documented. Around 87 manuscripts including 10 patents were used to demonstrate the antifouling applications of of various nanocomposite membranes.

Fabrication and properties of multiferroic nanocomposite films

KAUST Repository

Al-Nassar, Mohammed Y.; Ivanov, Yurii P.; Kosel, Jü rgen

2015-01-01

A new type of multiferroic polymer nanocomposite is presented, which exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of a ferroelectric copolymer poly(vinylindene fluoride-trifluoroethylene) [P(VDF-TrFE)] and high aspect ratio ferromagnetic nickel (Ni) nanowires (NWs), which were grown inside anodic aluminum oxide membranes. The fabrication of nanocomposite films with Ni NWs embedded in P(VDF-TrFE) has been successfully carried out via a simple low-temperature spin-coating technique. Structural, ferromagnetic, and ferroelectric properties of the developed nanocomposite have been investigated. The remanent and saturation polarization as well as the coercive field of the ferroelectric phase are slightly affected by the incorporation of the NWs as well as the thickness of the films. While the former two decrease, the last increases by adding the NWs or increasing the thickness. The ferromagnetic properties of the nanocomposite films are found to be isotropic.

Synthesis, thermal properties and applications of polymer-clay nanocomposites

International Nuclear Information System (INIS)

Meneghetti, Paulo; Qutubuddin, Syed

2006-01-01

Polymer-clay nanocomposites constitute a new class of materials in which the polymer matrix is reinforced by uniformly dispersed inorganic particles (usually 10 wt.% or less) having at least one dimension in the nanometer scale. Nanocomposites exhibit improved properties when compared to pure polymer or conventional composites, such as enhanced mechanical and thermal properties, reduced gas permeability, and improved chemical stability. In this work, the synthesis of poly(methyl methacrylate) (PMMA)/clay nanocomposites is described via two methods: in situ and emulsion polymerization. The in situ technique follows a two-step process: ion-exchange of the clay to make it hydrophobic, and polymerization after dispersing the functionalized clay in the monomer. The emulsion technique combines the two steps of the in situ method into one by conducting ion-exchange and polymerization in an aqueous medium in the same reactor. The clay (montmorillonite, MMT) is functionalized with a zwitterionic surfactant, octadecyl-dimethyl betaine (C18DMB). Partially exfoliated nanocomposite, observed by transmission electron microscopy (TEM), was obtained by emulsion polymerization with 10 wt.% clay. Glass transition temperature (T g ) of this nanocomposite was 18 deg. C higher than pure PMMA. With the same clay content, in situ polymerization produced intercalated nanocomposite with T g 10 deg. C lower than the emulsion nanocomposite. The storage modulus of partially exfoliated nanocomposite was superior to the intercalated structure and to the pure polymer. Using nanocomposite technology, novel PMMA nanocomposite gel electrolytes were synthesized exhibiting improved ionic conductivity and stable lithium interfacial resistance. Nanocomposites can also be used for gas storage and packaging applications as demonstrated by high barrier polymer-clay films

Synthesis, thermal properties and applications of polymer-clay nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Meneghetti, Paulo [Chemical Engineering Department, Case Western Reserve University, 10900 Euclid Ave. Cleveland, OH 44106 (United States); Qutubuddin, Syed [Chemical Engineering Department, Case Western Reserve University, 10900 Euclid Ave. Cleveland, OH 44106 (United States)]. E-mail: sxq@case.edu

2006-03-15

Polymer-clay nanocomposites constitute a new class of materials in which the polymer matrix is reinforced by uniformly dispersed inorganic particles (usually 10 wt.% or less) having at least one dimension in the nanometer scale. Nanocomposites exhibit improved properties when compared to pure polymer or conventional composites, such as enhanced mechanical and thermal properties, reduced gas permeability, and improved chemical stability. In this work, the synthesis of poly(methyl methacrylate) (PMMA)/clay nanocomposites is described via two methods: in situ and emulsion polymerization. The in situ technique follows a two-step process: ion-exchange of the clay to make it hydrophobic, and polymerization after dispersing the functionalized clay in the monomer. The emulsion technique combines the two steps of the in situ method into one by conducting ion-exchange and polymerization in an aqueous medium in the same reactor. The clay (montmorillonite, MMT) is functionalized with a zwitterionic surfactant, octadecyl-dimethyl betaine (C18DMB). Partially exfoliated nanocomposite, observed by transmission electron microscopy (TEM), was obtained by emulsion polymerization with 10 wt.% clay. Glass transition temperature (T {sub g}) of this nanocomposite was 18 deg. C higher than pure PMMA. With the same clay content, in situ polymerization produced intercalated nanocomposite with T {sub g} 10 deg. C lower than the emulsion nanocomposite. The storage modulus of partially exfoliated nanocomposite was superior to the intercalated structure and to the pure polymer. Using nanocomposite technology, novel PMMA nanocomposite gel electrolytes were synthesized exhibiting improved ionic conductivity and stable lithium interfacial resistance. Nanocomposites can also be used for gas storage and packaging applications as demonstrated by high barrier polymer-clay films.

Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

Directory of Open Access Journals (Sweden)

Deka Harekrishna

2009-01-01

Full Text Available Abstract The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications.Mesua ferreaL. seed oil-based hyperbranched polyurethane (HBPU/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96–99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

Multiwalled Carbon Nanotube-TiO2 Nanocomposite for Visible-Light-Induced Photocatalytic Hydrogen Evolution

Directory of Open Access Journals (Sweden)

Ke Dai

2014-01-01

Full Text Available Multiwalled carbon nanotube- (MWCNT- TiO2 nanocomposite was synthesized via hydrothermal process and characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, field emission scanning electron microscope, thermogravimetry analysis, and N2 adsorption-desorption isotherms. Appropriate pretreatment on MWCNTs could generate oxygen-containing groups, which is beneficial for forming intimate contact between MWCNTs and TiO2 and leads to a higher thermal stability of MWCNT-TiO2 nanocomposite. Modification with MWCNTs can extend the visible-light absorption of TiO2. 5 wt% MWCNT-TiO2 derived from hydrothermal treatment at 140°C exhibiting the highest hydrogen generation rate of 15.1 μmol·h−1 under visible-light irradiation and a wide photoresponse range from 350 to 475 nm with moderate quantum efficiency (4.4% at 420 nm and 3.7% at 475 nm. The above experimental results indicate that the MWCNT-TiO2 nanocomposite is a promising photocatalyst with good stability and visible-light-induced photoactivity.

Fine-scale tribological performance of zeolitic imidazolate framework (ZIF-8 based polymer nanocomposite membranes

Directory of Open Access Journals (Sweden)

Nay Win Khun

2014-12-01

Full Text Available We combined zeolitic imidazolate framework nanoparticles (ZIF-8: ˜150 nm diameter with Matrimid® 5218 polymer to form permeable mixed matrix membranes, featuring different weight fractions of nanoparticles (up to 30 wt. % loading. We used ball-on-disc micro-tribological method to measure the frictional coefficient of the nanocomposite membranes, as a function of nanoparticle loading and annealing heat treatment. The tribological results reveal that the friction and wear of the unannealed samples rise steadily with greater nanoparticle loading because ZIF-8 is relatively harder than the matrix, thus promoting abrasive wear mechanism. After annealing, however, we discover that the nanocomposites display an appreciably lower friction and wear damage compared with the unannealed counterparts. Evidence shows that the major improvement in tribological performance is associated with the greater amounts of wear debris derived from the annealed nanocomposite membranes. We propose that detached Matrimid-encapsulated ZIF-8 nanoparticles could function as “spacers,” which are capable of not only reducing direct contact between two rubbing surfaces but also enhancing free-rolling under the action of lateral forces.

Nanocomposites chitosan/montmorillonite for drug delivery system

International Nuclear Information System (INIS)

Braga, Carla R. Costa; Barbosa, Rossemberg C.; Lima, Rosemary S. Cunha; Fook, Marcus V. Lia; Silva, Suedina M. Lima

2009-01-01

In drugs delivery system the incorporation of an inorganic nanophase in polymer matrix, i.e. production of an inorganic-organic nanocomposite is an attractive alternative to obtain a constant release rate for a prolonged time. This study was performed to obtain films of nanocomposites Chitosan/montmorillonite intercalation by the technique of solution in the proportions of 1:1, 5:1 and 10:1. The nanocomposites were characterized by infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The results indicated that the feasibility of obtaining films of nanocomposites exfoliate. Among the suggested applications for films developed in this study includes them use for drugs delivery system. (author)

Nanostructural study of the thermal transformation of diamond-like amorphous carbon into an ultrahard carbon nanocomposite

International Nuclear Information System (INIS)

Martinez-Miranda, L. J.; Siegal, M. P.; Provencio, P. P.

2001-01-01

We studied the structural transformation of diamond-like amorphous carbon (a-C) films into ultrahard carbon nanocomposites via postannealing to 600 C using transmission electron microscopy, x-ray reflectivity, and small-angle scattering. Film density decreases monotonically above 200 C. Film surfaces roughen upon annealing to 300 C; however, a-C recovers its smoothness with higher temperature annealing. Finally, there exists some quasiperiodic nanostructural feature with a lattice spacing that increases with annealing, correlating well with purely a-C nanocomposite structures imaged from samples annealed at 600 C. We propose that these annealing-induced nanostructural changes are a derivative of localized stress fields in as-grown a-C films

Nanostructural study of the thermal transformation of diamond-like amorphous carbon into an ultrahard carbon nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Martinez-Miranda, L. J.; Siegal, M. P.; Provencio, P. P.

2001-07-23

We studied the structural transformation of diamond-like amorphous carbon (a-C) films into ultrahard carbon nanocomposites via postannealing to 600 C using transmission electron microscopy, x-ray reflectivity, and small-angle scattering. Film density decreases monotonically above 200 C. Film surfaces roughen upon annealing to 300 C; however, a-C recovers its smoothness with higher temperature annealing. Finally, there exists some quasiperiodic nanostructural feature with a lattice spacing that increases with annealing, correlating well with purely a-C nanocomposite structures imaged from samples annealed at 600 C. We propose that these annealing-induced nanostructural changes are a derivative of localized stress fields in as-grown a-C films.

The expression analysis of ICOS-L on activated T cells and immature dendritic cells as well as malignant B cells and Grave's-disease-derived thyroid tissues by two novel mAbs against human ICOS-L.

Science.gov (United States)

Wang, F; Zhu, W; Liu, T; Sun, Z; Ju, S; Ju, S; Yu, G; Xie, W; Deng, Z; Lu, B; Zhang, X

2007-01-01

ICOS-L, a newly identified member of B7 superfamily, plays an important role in immune responses. In this article, we report on two novel mouse anti-human ICOS-L monoclonal antibodies (mAbs) named as 11C4 and 12B11, whose specificities were verified by methods of flow cytometry, western blotting, and epitope competition assay. The two mAbs bound to distinct ICOS-L epitopes on B cells. Interestingly, mAb 11C4 could well recognize ICOS-L molecule on activated T cells and Jurkat cell lines, which is different from commercial anti-ICOS-L mAb (clone number MIH12) and the other mAb 12B11. In addition, we found that the expression of ICOS-L molecule was only detected on the surface of immature monocyte-derived dendritic cells (Mo-DCs) and was sharply decreased after induction of mature Mo-DCs activated by tumor necrosis factor-alpha or CD40. Furthermore, we showed that 11C4 could effectively suppress the maturation of Mo-DCs in vitro as evidenced by the low expression of CD80, CD86, CD83, and human leukocyte antigen-DR, which suggested that ICOS-L may be involved in the maturation of Mo-DCs. Using immunohistochemistry staining with mAb 11C4, the expression of ICOS-L was found in B lymphoma tissues and thyroid tissues from the Grave's disease but not in thyroid adenoma and normal thyroid tissues.

Multifunctional Polymer Nanocomposites

Science.gov (United States)

Galaska, Alexandra Maria; Song, Haixiang; Guo, Zhanhu

With more awareness of energy conversion/storage and saving, different strategies have been developed to utilize the sustainable and renewable energy. Introducing nanoscale fillers can make inert polymer matrix possess unique properties to satisfy certain functions. For example, alumina nanoparticles have strengthened the weak thermosetting polymers. A combined mixture of carbon nanofibers and magnetite nanoparticles have made the inert epoxy sensitive for magnetic field for sensing applications. Introducing silica nanoparticles into conductive polymers such as polyaniline has enhanced the giant magnetoresistance behaviors. The introduced nanoparticles have made the transparent polymer have the electromagnetic interference (EMI) shielding function while reduce the density significantly. With the desired miniaturization, the materials combining different functionalities have become importantly interesting. In this talk, methodologies to prepare nanocomposites and their effects on the produced nanocomposites will be discussed. A variety of advanced polymer nanocomposites will be introduced. Unique properties including mechanical, electrical, magnetoresistance etc. and the applications for environmental remediation, energy storage/saving, fire retardancy, electromagnetic interference shielding, and electronic devices will be presented.

Modification of PMMA/graphite nanocomposites through ion beam technique

Science.gov (United States)

Singhal, Prachi; Rattan, Sunita; Avasthi, Devesh Kumar; Tripathi, Ambuj

2013-08-01

Swift heavy ion (SHI) irradiation is a special technique for inducing physical and chemical modifications in bulk materials. In the present work, the SHI hs been used to prepare nanocomposites with homogeneously dispersed nanoparticles. The nanographite was synthesized from graphite using the intercalation-exfoliation method. PMMA Poly(methyl methacrylate)/graphite nanocomposites have been synthesized by in situ polymerization. The prepared PMMA/graphite nanocomposite films were irradiated with SHI irradiation (Ni ion beam, 80 MeV and C ion beam, 50 MeV) at a fluence of 1×1010 to 3×1012 ions/cm2. The nanocomposite films were characterized by scanning electron microscope (SEM) and were evaluated for their electrical and sensor properties. After irradiation, significant changes in surface morphology of nanocomposites were observed as evident from the SEM images, which show the presence of well-distributed nanographite platelets. The irradiated nanocomposites exhibit better electrical and sensor properties for the detection of nitroaromatics with marked improvement in sensitivity as compared with unirradiated nanocomposites.

Tangible nanocomposites with diverse properties for heart valve application

Science.gov (United States)

Vignesh Vellayappan, Muthu; Balaji, Arunpandian; Priyadarshini Subramanian, Aruna; Aruna John, Agnes; Jaganathan, Saravana Kumar; Murugesan, Selvakumar; Mohandas, Hemanth; Supriyanto, Eko; Yusof, Mustafa

2015-06-01

Cardiovascular disease claims millions of lives every year throughout the world. Biomaterials are used widely for the treatment of this fatal disease. With the advent of nanotechnology, the use of nanocomposites has become almost inevitable in the field of biomaterials. The versatile properties of nanocomposites, such as improved durability and biocompatibility, make them an ideal choice for various biomedical applications. Among the various nanocomposites, polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane, bacterial cellulose with polyvinyl alcohol, carbon nanotubes, graphene oxide and nano-hydroxyapatite nanocomposites have gained popularity as putative choices for biomaterials in cardiovascular applications owing to their superior properties. In this review, various studies performed utilizing these nanocomposites for improving the mechanical strength, anti-calcification potential and hemocompatibility of heart valves are reviewed and summarized. The primary motive of this work is to shed light on the emerging nanocomposites for heart valve applications. Furthermore, we aim to promote the prospects of these nanocomposites in the campaign against cardiovascular diseases.

Tangible nanocomposites with diverse properties for heart valve application

International Nuclear Information System (INIS)

Vellayappan, Muthu Vignesh; Balaji, Arunpandian; Subramanian, Aruna Priyadarshini; John, Agnes Aruna; Jaganathan, Saravana Kumar; Supriyanto, Eko; Yusof, Mustafa; Murugesan, Selvakumar; Mohandas, Hemanth

2015-01-01

Cardiovascular disease claims millions of lives every year throughout the world. Biomaterials are used widely for the treatment of this fatal disease. With the advent of nanotechnology, the use of nanocomposites has become almost inevitable in the field of biomaterials. The versatile properties of nanocomposites, such as improved durability and biocompatibility, make them an ideal choice for various biomedical applications. Among the various nanocomposites, polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane, bacterial cellulose with polyvinyl alcohol, carbon nanotubes, graphene oxide and nano-hydroxyapatite nanocomposites have gained popularity as putative choices for biomaterials in cardiovascular applications owing to their superior properties. In this review, various studies performed utilizing these nanocomposites for improving the mechanical strength, anti-calcification potential and hemocompatibility of heart valves are reviewed and summarized. The primary motive of this work is to shed light on the emerging nanocomposites for heart valve applications. Furthermore, we aim to promote the prospects of these nanocomposites in the campaign against cardiovascular diseases. (review)

Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

Science.gov (United States)

Patel, Binay S.

Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

Modifying Silicates for Better Dispersion in Nanocomposites

Science.gov (United States)

Campbell, Sandi

2005-01-01

An improved chemical modification has been developed to enhance the dispersion of layered silicate particles in the formulation of a polymer/silicate nanocomposite material. The modification involves, among other things, the co-exchange of an alkyl ammonium ion and a monoprotonated diamine with interlayer cations of the silicate. The net overall effects of the improved chemical modification are to improve processability of the nanocomposite and maximize the benefits of dispersing the silicate particles into the polymer. Some background discussion is necessary to give meaning to a description of this development. Polymer/silicate nanocomposites are also denoted polymer/clay composites because the silicate particles in them are typically derived from clay particles. Particles of clay comprise layers of silicate platelets separated by gaps called "galleries." The platelet thickness is 1 nm. The length varies from 30 nm to 1 m, depending on the silicate. In order to fully realize the benefits of polymer/silicate nanocomposites, it is necessary to ensure that the platelets become dispersed in the polymer matrices. Proper dispersion can impart physical and chemical properties that make nanocomposites attractive for a variety of applications. In order to achieve nanometer-level dispersion of a layered silicate into a polymer matrix, it is typically necessary to modify the interlayer silicate surfaces by attaching organic functional groups. This modification can be achieved easily by ion exchange between the interlayer metal cations found naturally in the silicate and protonated organic cations - typically protonated amines. Long-chain alkyl ammonium ions are commonly chosen as the ion-exchange materials because they effectively lower the surface energies of the silicates and ease the incorporation of organic monomers or polymers into the silicate galleries. This completes the background discussion. In the present improved modification of the interlayer silicate surfaces

Histopathological, Histomorphometrical, and Radiographical Evaluation of Injectable Glass-Ceramic-Chitosan Nanocomposite in Bone Reconstruction of Rat

Directory of Open Access Journals (Sweden)

Maryam Seyedmajidi

2015-01-01

Full Text Available Background. Bone defects following tumor resection and osteolysis due to bone lesions, periodontal tissue disorders, and bone reconstruction are challenges that surgeons face. Gass-ceramic-chitosan nanocomposite contains chitosan, a derivative of crustaceans’ exoskeleton. Methods. Thirty-two 6–8-week-old male Wistar rats were chosen. One hole on each right and left tibia was made. The right tibia holes were filled with injectable glass-ceramic-chitosan nanocomposite, and the left tibia holes were left empty. After 7, 14, 28, and 60 days, histopathological, histomorphometrical, and radiographical assessments were performed. Results. Radiographic density on days 7 and 14 was significantly higher in the right tibias than in the left tibias. Trabecular bone thickness, which was higher in the right tibias, increased from day 7 to day 60 in both right and left tibias, although not significantly. Conclusions. Glass-ceramic-chitosan nanocomposite is suggested for use in bone repair in cases of bone loss. More histopathological, histomorphometrical, and radiographical assessments are also recommended.

Methanol sensing characteristics of conducting polypyrrole-silver nanocomposites

Science.gov (United States)

Kabir, L.; Mandal, S. K.

2012-05-01

Methanol sensing characteristics of conducting polypyrrole-silver nanocomposites are reported here. The nanocomposites are synthesized by wet chemical technique with different amount of silver loadings (5-15 mol%). The sensitivity of the nanocomposites upon exposure to gas molecules is critically dependent on the silver loadings and the concentration of the exposed gas. This is possibly instigated by the modified metal-polymer interface and the polar nature of the constituent metal and the exposed gas. Interaction of the alcohol gas with the polypyrrole chains in the presence of silver effectively determines the change in resistance and hence the sensitivity of the nanocomposites upon exposure to methanol. The adsorption of methanol molecules within the nanocomposites and the subsequent chemical reactions are studied by Fourier transform infrared (FTIR) spectroscopy.

Nanoscratching of nylon 66-based ternary nanocomposites

International Nuclear Information System (INIS)

Dasari, Aravind; Yu Zhongzhen; Mai Yiuwing

2007-01-01

The nanoscratch behavior of nylon 66/SEBS-g-MA/clay ternary nanocomposites produced by different blending protocols with contrasting microstructures is studied by using atomic force and transmission electron microscopy. A standard diamond Berkovich indenter is used for scratching and a low load of 1 mN, along with a low sliding velocity of 1 μm s -1 , are employed for this purpose. It is shown that in order to resist penetration it is more important to have exfoliated clay in the continuous nylon matrix during nanoscratching than to have the clay in the dispersed soft rubber domains. The results obtained also explain the preferred usage of ternary nanocomposites compared to binary nanocomposites, particularly nylon 66/exfoliated clay nanocomposites. This research extends current basic knowledge and provides new insights on the nature of nanoscale processes that occur during nanoscratching of polymer nanocomposites. Critical questions are raised on the relationships between the penetration depth and material deformation and damage left behind the moving indenter

Controlled fabrication of luminescent and magnetic nanocomposites

Science.gov (United States)

Ma, Yingxin; Zhong, Yucheng; Fan, Jing; Huang, Weiren

2018-03-01

Luminescent and magnetic multifunctional nanocomposite is in high demand and widely used in many scales, such as drug delivery, bioseparation, chemical/biosensors, and so on. Although lots of strategies have been successfully developed for the demand of multifunctional nanocomposites, it is not easy to prepare multifunctional nanocomposites by using a simple method, and satisfy all kinds of demands simultaneously. In this work, via a facile and versatile method, luminescent nanocrystals and magnetic nanoparticles were successfully synthesized through self-assembly under vigorous stirring and ultrasonic treatment. These multifunctional nanocomposites are not only water stable but also find wide application such as magnetic separation and concentration with a series of moderate speed, multicolor fluorescence at different emission wavelength, high efficiency of the excitation and emission, and so on. By changing different kinds of luminescent nanocrystals and controlling the amount of luminescent and magnetic nanoparticles, a train of multifunctional nanocomposites was successfully fabricated via a versatile and robust method.

Fire and Gas Barrier Properties of Poly(styrene-co-acrylonitrile Nanocomposites Using Polycaprolactone/Clay Nanohybrid Based-Masterbatch

Directory of Open Access Journals (Sweden)

S. Benali

2008-01-01

Full Text Available Exfoliated nanocomposites are prepared by dispersion of poly(ε-caprolactone (PCL grafted montmorillonite nanohybrids used as masterbatches in poly(styrene-co-acrylonitrile (SAN. The PCL-grafted clay nanohybrids with high inorganic content are synthesized by in situ intercalative ring-opening polymerization of ε-caprolactone between silicate layers organomodified by alkylammonium cations bearing two hydroxyl functions. The polymerization is initiated by tin alcoholate species derived from the exchange reaction of tin(II bis(2-ethylhexanoate with the hydroxyl groups borne by the ammonium cations that organomodified the clay. These highly filled PCL nanocomposites (25 wt% in inorganics are dispersed as masterbatches in commercial poly(styrene-co-acrylonitrile by melt blending. SAN-based nanocomposites containing 3 wt% of inorganics are accordingly prepared. The direct blend of SAN/organomodified clay is also prepared for sake of comparison. The clay dispersion is characterized by wide-angle X-ray diffraction (WAXD, atomic force microscopy (AFM, and solid state NMR spectroscopy measurements. The thermal properties are studied by thermogravimetric analysis. The flame retardancy and gas barrier resistance properties of nanocomposites are discussed both as a function of the clay dispersion and of the matrix/clay interaction.

Application of cow milk-derived carbon dots/Ag NPs composite as the antibacterial agent

Science.gov (United States)

Han, Shuai; Zhang, He; Xie, Yujie; Liu, Liangliang; Shan, Changfu; Li, Xiangkai; Liu, Weisheng; Tang, Yu

2015-02-01

Cow milk-derived carbon dots (CMCDs) were prepared by hydrothermal treatment of cow milk, and the as-prepared CMCDs were further extracted by ethyl acetate to obtain amphiphilic CMCDs (ACMCDs). Using the ACMCDs both as a reducing agent and a template, the ACMCDs-supported silver nanoparticles (ACMCD-Ag nanocomposites) were prepared, which showed good biocidal effect on both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterias. After that, a novel ACMCD-Ag/polymethylmethacrylate nanocomposite antibacterial film was fabricated by solvent casting method. Due to the excellent antibacterial, light admitting, and flexible properties, the nanocomposite antibacterial film is considered to be of great potential in applications.

Sol–gel derived silica/chitosan/Fe3O4 nanocomposite for direct electrochemistry and hydrogen peroxide biosensing

International Nuclear Information System (INIS)

Satvekar, R K; Rohiwal, S S; Tiwari, A P; Raut, A V; Tiwale, B M; Pawar, S H

2015-01-01

A novel strategy to fabricate hydrogen peroxide third generation biosensor has been developed from sol–gel of silica/chitosan (SC) organic–inorganic hybrid material assimilated with iron oxide magnetic nanoparticles (Fe 3 O 4 ). The large surface area of Fe 3 O 4 and porous morphology of the SC composite facilitates a high loading of horseradish peroxidase (HRP). Moreover, the entrapped enzyme preserves its conformation and biofunctionality. The fabrication of hydrogen peroxide biosensor has been carried out by drop casting of the SC/F/HRP nanocomposite on glassy carbon electrode (GCE) for study of direct electrochemistry. The x-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) confirms the phase purity and particle size of as-synthesized Fe 3 O 4 nanoparticles, respectively. The nanocomposite was characterized by UV–vis spectroscopy, fluorescence spectroscopy and Fourier transform infrared (FTIR) for the characteristic structure and conformation of enzyme. The surface topographies of the nanocomposite thin films were investigated by scanning electron microscopy (SEM). Dynamic light scattering (DLS) was used to determine the particle size distribution. The electrostatic interactions of the SC composite with Fe 3 O 4 nanoparticles were studied by the zeta potential measurement. Electrochemical impedance spectroscopy (EIS) of the SC/F/HRP/GCE electrode displays Fe 3 O 4 nanoparticles as an excellent candidate for electron transfer. The SC/F/HRP/GCE exhibited a pair of well-defined quasi reversible cyclic voltammetry peaks due to the redox couple of HRP-heme Fe (III)/Fe (II) in pH 7.0 potassium phosphate buffer. The biosensor was employed to detect H 2 O 2 with linear range of 5 μM to 40 μM and detection limit of 5 μM. The sensor displays excellent selectivity, sensitivity, good reproducibility and long term stability. (paper)

A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel.

Science.gov (United States)

Rakhshaei, Rasul; Namazi, Hassan

2017-04-01

Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV-vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles solved this problem and the CMC/ZnO-MCM-41 showed a great improvement in tensile strength (12%), swelling (100%), erosion (53%) and gas permeability (500%) properties. Drug delivery and antibacterial properties of the nanocomposite hydrogel films studied using tetracycline (TC) as a broad spectrum antibiotic and showed a sustained TC release. This could efficiently decrease bandage exchange. Cytocompatibility of the nanocomposite hydrogel films has been analyzed in adipose tissue-derived stem cells (ADSCs) and results showed cytocompatibility of CMC/ZnO-MCM-41. Based on these results the prepared CMC nanocomposite hydrogel containing ZnO impregnated MCM-41, could serve as a kind of promising wound dressing with sustained drug delivery properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanocrystal-polymer nanocomposite electrochromic device

Science.gov (United States)

Milliron, Delia; Runnerstrom, Evan; Helms, Brett; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2015-12-08

Described is an electrochromic nanocomposite film comprising a solid matrix of an oxide based material, the solid matrix comprising a plurality of transparent conducting oxide (TCO) nanostructures dispersed in the solid matrix and a lithium salt dispersed in the solid matrix. Also described is a near infrared nanostructured electrochromic device having a functional layer comprising the electrochromic nanocomposite film.

Effect of unlabelled monoclonal antibody (MoAb) on biodistribution of /sup 111/Indium labelled (MoAb)

Energy Technology Data Exchange (ETDEWEB)

Lamki, L M; Murray, J L; Rosenblum, M G; Patt, Y Z; Babaian, Richard; Unger, M W

1988-08-01

We have evaluated immunoscintigraphy in cancer patients using four /sup 111/In-labelled murine monoclonal antibodies (MoAb): 96.5 (anti-P97 of melanoma), ZME-018 (anti-high molecular weight antibody of melanoma), ZCE-025 (anti-CEA for colon cancer) and PAY-276 (anti-prostatic acid phosphatase for prostatic cancer). The effect of increasing the doses of unlabelled MoAb (co-infused with 1 mg labelled MoAb) on the relative body distribution of each labelled MoAb was assessed. Localization in the liver decreased significantly in all cases, with increasing MoAb dose, except for ZME-018. Localization in other organs increased significantly as the liver activity decreased. The spleen activity, however, fell in the case of MoAb ZME-018. Blood-pool activity increased with MoAb dose in all four MoAbs. These findings correlated with the rise in the detection rate of metastases, the plasma half-life, and other pharmacokinetic parameters. However, the dose level at which this correlation occurred varied with each antibody. These data demonstrate the co-infusion of unlabelled MoAb with /sup 111/In-labelled MoAb could alter the organ distribution, pharmacokinetics and tumour uptake in a favourable manner, though the degree to which this occurs depends on the antibody in question.

Effect of the Polyketone Aromatic Pendent Groups on the Electrical Conductivity of the Derived MWCNTs-Based Nanocomposites

Directory of Open Access Journals (Sweden)

Nicola Migliore

2018-06-01

Full Text Available Electrically conductive plastics with a stable electric response within a wide temperature range are promising substitutes of conventional inorganic conductive materials. This study examines the preparation of thermoplastic polyketones (PK30 functionalized by the Paal–Knorr process with phenyl (PEA, thiophene (TMA, and pyrene (PMA pendent groups with the aim of optimizing the non-covalent functionalization of multiwalled carbon nanotubes (MWCNTs through π–π interactions. Among all the aromatic functionalities grafted to the PK30 backbone, the extended aromatic nuclei of PMA were found to be particularly effective in preparing well exfoliated and undamaged MWCNTs dispersions with a well-defined conductive percolative network above the 2 wt % of loading and in freshly prepared nanocomposites as well. The efficient and superior π–π interactions between PK30PMA and MWCNTs consistently supported the formation of nanocomposites with a highly stable electrical response after thermal solicitations such as temperature annealing at the softening point, IR radiation exposure, as well as several heating/cooling cycles from room temperature to 75 °C.

Development of polymer nanocomposites with regional bentonite clay

International Nuclear Information System (INIS)

Araujo, Edcleide M.; Leite, Amanda M.D.; Paz, Rene A. da; Medeiros, Keila M. de; Melo, Tomas J.A.; Barbosa, Josiane D.V.; Barbosa, Renata

2011-01-01

nanocomposites with regional bentonite clay were prepared by melt intercalation technique. The clays were studied without modification and modified with four quaternary ammonium salts. It was evidenced by X-ray diffraction that salts were incorporated into the clay structure thus confirming its organophilization. The nanocomposites were evaluated by means of thermal mechanic and flammability tests where presented properties significantly improved their pure polymers. The process of biodegradation of obtained bio nanocomposites was accelerated by the presence of clay. The produced membranes from nanocomposites have potential in the oil-water separation. (author)

Controllable synthesis of functional nanocomposites: Covalently functionalize graphene sheets with biocompatible L-lysine

International Nuclear Information System (INIS)

Mo, Zunli; Gou, Hao; He, Jingxian; Yang, Peipei; Feng, Chao; Guo, Ruibin

2012-01-01

Highlights: ► The biocompatible L-lysine functionalized graphene sheets (Gs/Lys) were synthesized controllably using a novel method. ► The Gs/Lys nanocomposites are water-soluble, biocompatible and chiral. ► A chiral graphene derivative was proposed. - Abstract: In this paper a novel method to synthesize functionalize graphene sheets (Gs) by biocompatible L-lysine (Gs/Lys) is reported. The method was composed of two steps: (1) we controllably synthesized self-assembly Gs/Lys-Cu-Lys through the terminal amino of copper L-lysine (Lys-Cu-Lys) attaching to graphite oxide (GO) and then reducing. (2) Obtained the Gs/Lys by eliminating the copper ion. This method could also be used to functionalize other nanomaterials by L-lysine. The Gs/Lys nanocomposites are water-soluble, biocompatible, and above all, it is a chiral material of graphene, which is proposed by us. This novel material will be promising for more applications of graphene. The formation of Gs/Lys nanocomposites were confirmed by scanning electron microscopy (SEM), Fourier-transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermal gravimetric (TG) analysis.

Conducting polyamine nanocomposites development

International Nuclear Information System (INIS)

Nascimento, R.C.; Maciel, T.C.G.L.; Guimaraes, M.J.O.C.; Garcia, M.E.F.

2010-01-01

Polymeric nanocomposites are hybrid materials formed by the combination of inorganic nanoparticles dispersed in a polymeric matrix with, at least, one dimension in the nanometer range. It was used as nanoparticles layered and tubular clay minerals, and its insertion and dispersion were conducted through the in situ polymerization technique. As the polymer matrix, it was utilized a polyamine, which, later, will be inserted in a polyacrylamide gel for the development of a compound that aggregates both main characteristics. The nanocomposites were prepared in different polymerization conditions (temperature, concentration and nanoparticle type) and characterized by XRD and FTIR. It was observed that regarding the polymerization conditions, the temperature had influence on the kind of material obtained and on the reaction speed; the type of nanoparticle affected its interaction with the polymer matrix, predominantly providing the formation of nanocomposites by the intercalation mechanism in the layered clay. (author)

Method to produce catalytically active nanocomposite coatings

Science.gov (United States)

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

2016-02-09

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

Method to produce catalytically active nanocomposite coatings

Energy Technology Data Exchange (ETDEWEB)

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

2017-12-19

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

Multilevel structures of Li3V2(PO4)3/phosphorus-doped carbon nanocomposites derived from hybrid V-MOFs for long-life and cheap lithium ion battery cathodes

Science.gov (United States)

Wang, Zhaoyang; He, Wen; Zhang, Xudong; Yue, Yuanzheng; Liu, Jinhua; Zhang, Chuanjiang; Fang, Leyong

2017-10-01

The Li3V2(PO4)3/phosphorus-doped carbon (LVP/P-C) nanocomposites with multilevel structures (such as spheroidal, foam, prism and flower-like structures) are synthesized via one-pot in-situ synthesis using hybrid vanadium metal-organic frameworks (V-MOFs) as precursor. The structure and morphology of the LVP/P-C nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, Raman, X-ray diffraction and element mapping. The results show that the multilevel structures are generated from the assemblies of the hybrid surfactant templates in the glass fiber drawing wastewater (GFDW) and the hybrid V-MOFs. The structure of LVP/P-C nanocomposite is controlled by V-MOFs. The nanocomposites exhibit a long service life, a discharge capacity of 65 mA h g-1 at 10 C with 90% capacity retention after 1100 cycles. The high cycling stability is attributed to the multilevel structures, which is ideal for making rechargeable lithium ion batteries. More importantly, our results have demonstrated that GFDW can be transformed into treasure of multilevel structure nanocomposites for cheap Li ion batteries.

Electrically and Thermally Conducting Nanocomposites for Electronic Applications

Directory of Open Access Journals (Sweden)

Daryl Santos

2010-02-01

Full Text Available Nanocomposites made up of polymer matrices and carbon nanotubes are a class of advanced materials with great application potential in electronics packaging. Nanocomposites with carbon nanotubes as fillers have been designed with the aim of exploiting the high thermal, electrical and mechanical properties characteristic of carbon nanotubes. Heat dissipation in electronic devices requires interface materials with high thermal conductivity. Here, current developments and challenges in the application of nanotubes as fillers in polymer matrices are explored. The blending together of nanotubes and polymers result in what are known as nanocomposites. Among the most pressing current issues related to nanocomposite fabrication are (i dispersion of carbon nanotubes in the polymer host, (ii carbon nanotube-polymer interaction and the nature of the interface, and (iii alignment of carbon nanotubes in a polymer matrix. These issues are believed to be directly related to the electrical and thermal performance of nanocomposites. The recent progress in the fabrication of nanocomposites with carbon nanotubes as fillers and their potential application in electronics packaging as thermal interface materials is also reported.

Rapid microwave processing of epoxy nanocomposites using carbon nanotubes

OpenAIRE

Luhyna, Nataliia; Inam, Fawad; Winnington, Ian

2013-01-01

Microwave processing is one of the rapid processing techniques for manufacturing nanocomposites. There is very little work focussing on the addition of CNTs for shortening the curing time of epoxy nanocomposites. Using microwave energy, the effect of CNT addition on the curing of epoxy nanocomposites was researched in this work. Differential scanning calorimetry (DSC) was used to determine the degree of cure for epoxy and nanocomposite samples. CNT addition significantly reduced the duration ...

High-frequency magnetoimpedance in nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Yurasov, Alexey [Moscow State Institute of Radioengineering, Electronics and Automation (Technical University), Moscow 117454 (Russian Federation)]. E-mail: alexey_yurasov@mail.ru; Granovsky, Alexander [Faculty of Physics, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Tarapov, Sergey [Institute of Radiophysics and Electronics, National Academy of Sciences of Ukraine, Kharkov 61085 (Ukraine); Clerc, Jean-Pierre [Ecole Polytechnique Universitaire de Marseille, Technopole de Chateau-Gombert, Marseille 13453 (France)

2006-05-15

The transmission of millimeter-range electromagnetic waves (30-50 GHz) through a magnetic nanocomposite thin film exhibiting tunnel magnetoresistance (TMR) is calculated. The relative change of transmission coefficient in an applied magnetic field due to the magnetorefractive effect is approximately linear with TMR and strongly depends on nanocomposite resistivity and film thickness. The obtained results are in a good agreement with experiment.

High-frequency magnetoimpedance in nanocomposites

International Nuclear Information System (INIS)

Yurasov, Alexey; Granovsky, Alexander; Tarapov, Sergey; Clerc, Jean-Pierre

2006-01-01

The transmission of millimeter-range electromagnetic waves (30-50 GHz) through a magnetic nanocomposite thin film exhibiting tunnel magnetoresistance (TMR) is calculated. The relative change of transmission coefficient in an applied magnetic field due to the magnetorefractive effect is approximately linear with TMR and strongly depends on nanocomposite resistivity and film thickness. The obtained results are in a good agreement with experiment

Polymer/metal nanocomposites for biomedical applications.

Science.gov (United States)

Zare, Yasser; Shabani, Iman

2016-03-01

Polymer/metal nanocomposites consisting of polymer as matrix and metal nanoparticles as nanofiller commonly show several attractive advantages such as electrical, mechanical and optical characteristics. Accordingly, many scientific and industrial communities have focused on polymer/metal nanocomposites in order to develop some new products or substitute the available materials. In the current paper, characteristics and applications of polymer/metal nanocomposites for biomedical applications are extensively explained in several categories including strong and stable materials, conductive devices, sensors and biomedical products. Moreover, some perspective utilizations are suggested for future studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Homology of ab1 and ab3 monoclonal antibodies that neutralize Semliki Forest virus

NARCIS (Netherlands)

Fernandez, IM; Bos, NA; Harmsen, M; Verheul, AFM; Snippe, H; Kraaijeveld, CA

2001-01-01

A noninternal image monoclonal antiidiotypic antibody (ab2 mAb), designated 1,13A321, that had proved its efficacy as vaccine against infection with Semliki Forest virus (SFV) in BALB/c mice, was used as immunogen to generate a panel of SFV-neutralizing monoclonal anti-anti-idiotypic antibodies (ab3

Polymer Nanocomposites

Indian Academy of Sciences (India)

methods for the synthesis of polymer nanocomposites. In this article we .... ers, raw materials recovery, drug delivery and anticorrosion .... region giving rise to dose-packed absorption bands called an IR ... using quaternary ammonium salts.

Diamond like carbon nanocomposites with embedded metallic nanoparticles

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Tamulevičius, Sigitas; Meškinis, Šarūnas; Tamulevičius, Tomas; Rubahn, Horst-Günter

2018-02-01

In this work we present an overview on structure formation, optical and electrical properties of diamond like carbon (DLC) based metal nanocomposites deposited by reactive magnetron sputtering and treated by plasma and laser ablation methods. The influence of deposition mode and other technological conditions on the properties of the nanosized filler, matrix components and composition were studied systematically in relation to the final properties of the nanocomposites. Applications of the nanocomposites in the development of novel biosensors combining resonance response of wave guiding structures in DLC based nanocomposites as well as plasmonic effects are also presented.

Diode laser surgery. Ab interno and ab externo versus conventional surgery in rabbits.

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Karp, C L; Higginbotham, E J; Edward, D P; Musch, D C

1993-10-01

Fibroblastic proliferation of subconjunctival tissues remains a primary mechanism of failure in filtration surgery. Minimizing the surgical manipulation of episcleral tissues may reduce scarring. Laser sclerostomy surgery involves minimal tissue dissection, and is gaining attention as a method of potentially improving filter duration in high-risk cases. Twenty-five New Zealand rabbits underwent filtration surgery in one eye, and the fellow eye remained as the unoperated control. Ten rabbits underwent ab externo diode laser sclerostomy surgery, ten underwent ab interno diode sclerostomy surgery, and five had posterior sclerostomy procedures. Filtration failure was defined as a less-than-4-mmHg intraocular pressure (IOP) difference between the operative and control eyes. The mean time to failure for the ab externo, ab interno, and conventional posterior sclerostomy techniques measured 17.4 +/- 11.5, 13.1 +/- 6.7, and 6.0 +/- 3.1 days, respectively. In a comparison of the laser-treated groups with the conventional procedure, the time to failure was significantly longer (P = 0.02) for the ab externo filter. The mean ab interno sclerostomy duration was longer than the posterior lip procedure, but this difference was not statistically significant (P = 0.15). The overall level of IOP reduction was similar in the three groups. These data suggest that diode laser sclerostomy is a feasible technique in rabbits, and the ab externo approach resulted in longer filter duration than the conventional posterior lip procedure in this model.

Generalized Effective Medium Theory for Particulate Nanocomposite Materials

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Muhammad Usama Siddiqui

2016-08-01

Full Text Available The thermal conductivity of particulate nanocomposites is strongly dependent on the size, shape, orientation and dispersion uniformity of the inclusions. To correctly estimate the effective thermal conductivity of the nanocomposite, all these factors should be included in the prediction model. In this paper, the formulation of a generalized effective medium theory for the determination of the effective thermal conductivity of particulate nanocomposites with multiple inclusions is presented. The formulated methodology takes into account all the factors mentioned above and can be used to model nanocomposites with multiple inclusions that are randomly oriented or aligned in a particular direction. The effect of inclusion dispersion non-uniformity is modeled using a two-scale approach. The applications of the formulated effective medium theory are demonstrated using previously published experimental and numerical results for several particulate nanocomposites.

Systematic comparison of model polymer nanocomposite mechanics.

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Xiao, Senbo; Peter, Christine; Kremer, Kurt

2016-09-13

Polymer nanocomposites render a range of outstanding materials from natural products such as silk, sea shells and bones, to synthesized nanoclay or carbon nanotube reinforced polymer systems. In contrast to the fast expanding interest in this type of material, the fundamental mechanisms of their mixing, phase behavior and reinforcement, especially for higher nanoparticle content as relevant for bio-inorganic composites, are still not fully understood. Although polymer nanocomposites exhibit diverse morphologies, qualitatively their mechanical properties are believed to be governed by a few parameters, namely their internal polymer network topology, nanoparticle volume fraction, particle surface properties and so on. Relating material mechanics to such elementary parameters is the purpose of this work. By taking a coarse-grained molecular modeling approach, we study an range of different polymer nanocomposites. We vary polymer nanoparticle connectivity, surface geometry and volume fraction to systematically study rheological/mechanical properties. Our models cover different materials, and reproduce key characteristics of real nanocomposites, such as phase separation, mechanical reinforcement. The results shed light on establishing elementary structure, property and function relationship of polymer nanocomposites.

Novel toughened polylactic acid nanocomposite: Mechanical, thermal and morphological properties

International Nuclear Information System (INIS)

Balakrishnan, Harintharavimal; Hassan, Azman; Wahit, Mat Uzir; Yussuf, A.A.; Razak, Shamsul Bahri Abdul

2010-01-01

The objective of the study is to develop a novel toughened polylactic acid (PLA) nanocomposite. The effects of linear low density polyethylene (LLDPE) and organophilic modified montmorillonite (MMT) on mechanical, thermal and morphological properties of PLA were investigated. LLDPE toughened PLA nanocomposites consisting of PLA/LLDPE blends, of composition 100/0 and 90/10 with MMT content of 2 phr and 4 phr were prepared. The Young's and flexural modulus improved with increasing content of MMT indicating that MMT is effective in increasing stiffness of LLDPE toughened PLA nanocomposite even at low content. LLDPE improved the impact strength of PLA nanocomposites with a sacrifice of tensile and flexural strength. The tensile and flexural strength also decreased with increasing content of MMT in PLA/LLDPE nanocomposites. The impact strength and elongation at break of LLDPE toughened PLA nanocomposites also declined steadily with increasing loadings of MMT. The crystallization temperature and glass transition temperature dropped gradually while the thermal stability of PLA improved with addition of MMT in PLA/LLDPE nanocomposites. The storage modulus of PLA/LLDPE nanocomposites below glass transition temperature increased with increasing content of MMT. X-ray diffraction and transmission electron microscope studies revealed that an intercalated LLDPE toughened PLA nanocomposite was successfully prepared at 2 phr MMT content.

Microstructure and Properties of Polypropylene/Carbon Nanotube Nanocomposites

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Dimitrios Bikiaris

2010-04-01

Full Text Available In the last few years, great attention has been paid to the preparation of polypropylene (PP nanocomposites using carbon nanotubes (CNTs due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. This is due to the unique combination of structural, mechanical, electrical, and thermal transport properties of CNTs. However, it is well-known that the properties of polymer-based nanocomposites strongly depend on the dispersion of nanofillers and almost all the discussed properties of PP/CNTs nanocomposites are strongly related to their microstructure. PP/CNTs nanocomposites were, mainly, prepared by melt mixing and in situ polymerization. Young’s modulus, tensile strength and storage modulus of the PP/CNTs nanocomposites can be increased with increasing CNTs content due to the reinforcement effect of CNTs inside the polymer matrix. However, above a certain CNTs content the mechanical properties are reduced due to the CNTs agglomeration. The microstructure of nanocomposites has been studied mainly by SEM and TEM techniques. Furthermore, it was found that CNTs can act as nucleating agents promoting the crystallization rates of PP and the addition of CNTs enhances all other physical properties of PP. The aim of this paper is to provide a comprehensive review of the existing literature related to PP/CNTs nanocomposite preparation methods and properties studies.

Enhancement in performance of polycarbazole-graphene nanocomposite Schottky diode

International Nuclear Information System (INIS)

Pandey, Rajiv K.; Singh, Arun Kumar; Prakash, Rajiv

2013-01-01

We report formation of polycarbazole (PCz)–graphene nanocomposite over indium tin oxide (ITO) coated glass substrate using electrochemical technique for fabrication of high performance Schottky diodes. The synthesized nanocomposite is characterized before fabrication of devices for confirmation of uniform distribution of graphene nanosheets in the polymer matrix. Pure PCz and PCz-graphene nanocomposites based Schottky diodes are fabricated of configuration Al/PCz/ITO and Al/PCz-graphene nanocomposite/ITO, respectively. The current density–voltage (J-V) characteristics and diode performance parameters (such as the ideality factor, barrier height, and reverse saturation current density) are compared under ambient condition. Al/PCz-graphene nanocomposite/ITO device exhibits better ideality factor in comparison to the device formed using pure PCz. It is also observed that the Al/PCz-graphene nanocomposite/ITO device shows large forward current density and low turn on voltage in comparison to Al/PCz/ITO device

Nanostructural study of the thermal transformation of diamond-like amorphous carbon into an ultrahard carbon nanocomposite

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Martínez-Miranda, L. J.; Siegal, M. P.; Provencio, P. P.

2001-07-01

We studied the structural transformation of diamond-like amorphous carbon (a-C) films into ultrahard carbon nanocomposites via postannealing to 600 °C using transmission electron microscopy, x-ray reflectivity, and small-angle scattering. Film density decreases monotonically above 200 °C. Film surfaces roughen upon annealing to 300 °C; however, a-C recovers its smoothness with higher temperature annealing. Finally, there exists some quasiperiodic nanostructural feature with a lattice spacing that increases with annealing, correlating well with purely a-C nanocomposite structures imaged from samples annealed at 600 °C. We propose that these annealing-induced nanostructural changes are a derivative of localized stress fields in as-grown a-C films.

Non-Covalent Supported of l-Proline on Graphene Oxide/Fe3O4 Nanocomposite: A Novel, Highly Efficient and Superparamagnetically Separable Catalyst for the Synthesis of Bis-Pyrazole Derivatives

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Mosadegh Keshavarz

2018-02-01

Full Text Available A superparamagnetic graphene oxide/Fe3O4/l-proline nano hybrid that was obtained from the non-covalent immobilization of l-proline on graphene oxide/Fe3O4 nanocomposite was used as a new magnetically separable catalyst for the efficient synthesis of 4,4′-(arylmethylenebis(1H-pyrazol-5-ol derivatives. The prepared heterogeneous catalyst was characterized using FTIR, TGA, DTG, XRD, TEM, SEM, and elemental analysis techniques. Short reaction times (5–15 min, excellent yields (87–98%, and simple experimental procedure with an easy work-up are some of the advantages of the introduced catalyst.

Conducting polymer nanocomposite-based supercapacitors

OpenAIRE

Liew, Soon Yee; Walsh, Darren A.; Chen, George Z.

2016-01-01

The use of nanocomposites of electronically-conducting polymers for supercapacitors has increased significantly over the past years, due to their high capacitances and abilities to withstand many charge-discharge cycles. We have recently been investigating the use of nanocomposites of electronically-conducting polymers containing conducting and non-conducting nanomaterials such as carbon nanotubes and cellulose nanocrystals, for use in supercapacitors. In this contribution, we provide a summa...

PVC/carbon nanotubes nanocomposites: evaluation of electrical resistivity and the residual solvent effect over the thermal properties of nanocomposites

International Nuclear Information System (INIS)

Araujo, Rogerio Gomes; Pires, Alfredo T.N.

2013-01-01

The procedure for obtaining nanocomposite by dispersing the nanoparticles in matrix polymer in solution with subsequent elimination of the solvent has been widely used, considering better efficiency in obtaining homogeneity of the final product. However, the presence of residual solvent may affect the nanocomposites in micro-and macroscopic properties of the product. The aim of this study was to evaluate the thermal properties of nanocomposites of poly(vinylchloride)/multi-walled carbon nanotube obtained from the polymer solution and dispersion of carbon nanotubes in tetrahydrofuran (THF), as well as the electrical resistivity of nanocomposites and the influence of residual solvent. The presence of residual tetrahydrofuran reduces the glass transition temperature (Tg) up to 26 °C, being independent of the amount of carbon nanotubes. The total elimination of the solvent is an important factor that does not induce changes in the properties of the polymeric matrix. The graft-COOH groups in the structure of the nanotubes leads to a considerable reduction of the electrical resistivity in ten orders of magnitude, from 0.4 %wt of nanotubes in the nanocomposite composition. (author)

A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel

Energy Technology Data Exchange (ETDEWEB)

Rakhshaei, Rasul [Research Laboratory of Dendrimers and Nanopolymers, Faculty of Chemistry, University of Tabriz, P.O. Box 51666, Tabriz (Iran, Islamic Republic of); Namazi, Hassan, E-mail: namazi@tabrizu.ac.ir [Research Laboratory of Dendrimers and Nanopolymers, Faculty of Chemistry, University of Tabriz, P.O. Box 51666, Tabriz (Iran, Islamic Republic of); Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Science, Tabriz (Iran, Islamic Republic of)

2017-04-01

Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV–vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles solved this problem and the CMC/ZnO-MCM-41 showed a great improvement in tensile strength (12%), swelling (100%), erosion (53%) and gas permeability (500%) properties. Drug delivery and antibacterial properties of the nanocomposite hydrogel films studied using tetracycline (TC) as a broad spectrum antibiotic and showed a sustained TC release. This could efficiently decrease bandage exchange. Cytocompatibility of the nanocomposite hydrogel films has been analyzed in adipose tissue-derived stem cells (ADSCs) and results showed cytocompatibility of CMC/ZnO-MCM-41. Based on these results the prepared CMC nanocomposite hydrogel containing ZnO impregnated MCM-41, could serve as a kind of promising wound dressing with sustained drug delivery properties. - Highlights: • CMC nanocomposite hydrogel incorporated with TC loaded ZnO-MCM-41 nanoparticles have been prepared as active wound dressing. • Citric acid was used as cross linker to avoid conventional toxic crosslinkers. • CMC/ZnO-MCM-41

Hydrogen Storage Performance in Pd/Graphene Nanocomposites.

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Zhou, Chunyu; Szpunar, Jerzy A

2016-10-05

We have developed a Pd-graphene nanocomposite for hydrogen storage. The spherically shaped Pd nanoparticles of 5-45 nm in size are homogeneously distributed over the graphene matrix. This new hydrogen storage system has favorable features like desirable hydrogen storage capacity, ambient conditions of hydrogen uptake, and low temperature of hydrogen release. At a hydrogen charging pressure of 50 bar, the material could yield a gravimetric density of 6.7 wt % in the 1% Pd/graphene nanocomposite. As we increased the applied pressure to 60 bar, the hydrogen uptake capacity reached 8.67 wt % in the 1% Pd/graphene nanocomposite and 7.16 wt % in the 5% Pd/graphene nanocomposite. This system allows storage of hydrogen in amounts that exceed the capacity of the gravimetric target announced by the U.S. Department of Energy (DOE).

Intracellular reprogramming of expression, glycosylation, and function of a plant-derived antiviral therapeutic monoclonal antibody.

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Jeong-Hwan Lee

Full Text Available Plant genetic engineering, which has led to the production of plant-derived monoclonal antibodies (mAb(Ps, provides a safe and economically effective alternative to conventional antibody expression methods. In this study, the expression levels and biological properties of the anti-rabies virus mAb(P SO57 with or without an endoplasmic reticulum (ER-retention peptide signal (Lys-Asp-Glu-Leu; KDEL in transgenic tobacco plants (Nicotiana tabacum were analyzed. The expression levels of mAb(P SO57 with KDEL (mAb(PK were significantly higher than those of mAb(P SO57 without KDEL (mAb(P regardless of the transcription level. The Fc domains of both purified mAb(P and mAb(PK and hybridoma-derived mAb (mAb(H had similar levels of binding activity to the FcγRI receptor (CD64. The mAb(PK had glycan profiles of both oligomannose (OM type (91.7% and Golgi type (8.3%, whereas the mAb(P had mainly Golgi type glycans (96.8% similar to those seen with mAb(H. Confocal analysis showed that the mAb(PK was co-localized to ER-tracker signal and cellular areas surrounding the nucleus indicating accumulation of the mAb(P with KDEL in the ER. Both mAb(P and mAb(PK disappeared with similar trends to mAb(H in BALB/c mice. In addition, mAb(PK was as effective as mAb(H at neutralizing the activity of the rabies virus CVS-11. These results suggest that the ER localization of the recombinant mAb(P by KDEL reprograms OM glycosylation and enhances the production of the functional antivirus therapeutic antibody in the plant.

Preparation and fluorescence properties of 6-carboxyfluorescein/hydrotalcite nanocomposites

International Nuclear Information System (INIS)

Li, Chunfang; Qi, Yanhai; Li, Qianru; Li, Dongxiang; Hou, Wanguo

2014-01-01

The nanocomposites of fluorescent dye/hydrotalcite-like compounds (HTlc) synthesized by intercalation and/or surface adsorption methods have exhibited specific photophysical and photochemical property. In this work, 6-carboxyfluorescein (6CF)/HTlc nanocomposites were synthesized by ammonia coprecipitation and reconstruction-induced surface adsorption methods, and they were characterized by powder X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Thermogravimetric differential thermal measurements (TG-DTA) and fluorescence spectra. The results demonstrate that the dye molecules are primarily adsorbed on HTlc surface. The fluorescence emission of 6CF/Mg–Al HTlc composites is related with 6CF dosage due to the self-quenching mechanism. The 6CF/Zn–Al HTlc nanocomposite reconstructed at high temperature have much strong luminescence than that reconstructed at room temperature and the 6CF/Mg–Al HTlc nanocomposites. -- Highlights: • Fluorescent 6-carboxyfluorescein/HTlc nanocomposites were synthesized. • Fluorescent dye molecules are primarily adsorbed on HTlc surface. • Nanocomposite luminescence is related with the cluster structure of fluorescent dyes

Biomimetic magnetic nanocomposite for smart skins

KAUST Repository

Alfadhel, Ahmed; Kosel, Jü rgen

2015-01-01

We report a biomimetic tactile sensor consisting of magnetic nanocomposite artificial cilia and magnetic sensors. The nanocomposite is fashioned from polydimethylsiloxane and iron nanowires and exhibits a permanent magnetic behavior. This enables remote operation without an additional magnetic field to magnetize the nanowires, which simplifies device integration. Moreover, the highly elastic and easy patternable nanocomposite is corrosion resistant and thermally stable. The highly sensitive and power efficient tactile sensors can detect vertical and shear forces from interactions with objects. The sensors can operate in dry and wet environment with the ability to measure different properties such as the texture and the movement or stability of objects, with easily adjustable performance.

Biomimetic magnetic nanocomposite for smart skins

KAUST Repository

Alfadhel, Ahmed

2015-11-01

We report a biomimetic tactile sensor consisting of magnetic nanocomposite artificial cilia and magnetic sensors. The nanocomposite is fashioned from polydimethylsiloxane and iron nanowires and exhibits a permanent magnetic behavior. This enables remote operation without an additional magnetic field to magnetize the nanowires, which simplifies device integration. Moreover, the highly elastic and easy patternable nanocomposite is corrosion resistant and thermally stable. The highly sensitive and power efficient tactile sensors can detect vertical and shear forces from interactions with objects. The sensors can operate in dry and wet environment with the ability to measure different properties such as the texture and the movement or stability of objects, with easily adjustable performance.

New hyperbranched polytriazoles containing isolation chromophore moieties derived from AB4 monomers through click chemistry under copper(I) catalysis: improved optical transparency and enhanced NLO effects.

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Wu, Wenbo; Ye, Cheng; Yu, Gui; Liu, Yunqi; Qin, Jingui; Li, Zhen

2012-04-02

By modifying a synthetic procedure, two new hyperbranched polytriazoles (HP1 and HP2) containing isolation chromophores were synthesized successfully through click chemistry reactions under copper(I) catalysis. For the first time, these two polymers were derived from an AB(4)-type monomer, although they contain different end-capping chromophores. They are soluble in normal polar organic solvents and are well characterized. Thanks to the presence of the isolation chromophore, the two polymers demonstrate good nonlinear optical (NLO) properties and optical transparency, making them promising candidates for practical applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites

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David Florián-Algarín

2018-03-01

Full Text Available This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas welding of aluminum. A206 (Al-4.5Cu-0.25Mg master nanocomposites with 5 wt % γAl2O3 nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl2O3 nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al–γAl2O3 nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires’ electrical conductivity compared with that of pure aluminum and aluminum–copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding.

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites.

Science.gov (United States)

Florián-Algarín, David; Marrero, Raúl; Li, Xiaochun; Choi, Hongseok; Suárez, Oscar Marcelo

2018-03-10

This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl₂O₃ nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl₂O₃ nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al-γAl₂O₃ nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires' electrical conductivity compared with that of pure aluminum and aluminum-copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding.

Preparation, characterization and antimicrobial efficiency of Ag/PDDA-diatomite nanocomposite.

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Panáček, Aleš; Balzerová, Anna; Prucek, Robert; Ranc, Václav; Večeřová, Renata; Husičková, Vendula; Pechoušek, Jiří; Filip, Jan; Zbořil, Radek; Kvítek, Libor

2013-10-01

Nanocomposites consisting of diatomaceous earth particles and silver nanoparticles (silver NPs) with high antimicrobial activity were prepared and characterized. For the purpose of nanocomposite preparation, silver NPs with an average size of 28nm prepared by modified Tollens process were used. Nanocomposites were prepared using poly(diallyldimethylammonium) chloride (PDDA) as an interlayer substance between diatomite and silver NPs which enables to change diatomite original negative surface charge to positive one. Due to strong electrostatic interactions between negatively charged silver NPs and positively charged PDDA-modified diatomite, Ag/PDDA-diatomite nanocomposites with a high content of silver (as high as 46.6mgAg/1g of diatomite) were prepared. Because of minimal release of silver NPs from prepared nanocomposites to aqueous media (<0.3mg Ag/1g of nanocomposite), the developed nanocomposites are regarded as a potential useful antimicrobial material with a long-term efficiency showing no risk to human health or environment. All the prepared nanocomposites exhibit a high bactericidal activity against Gram-negative and Gram-positive bacteria and fungicidal activity against yeasts at very low concentrations as low as 0.11g/L, corresponding to silver concentration of 5mg/L. Hence, the prepared nanocomposites constitute a promising candidate suitable for the microbial water treatment in environmental applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Nanostructure and Volatile Organic Compounds Sensing Properties of α-Fe2O3/Reduced Graphene Oxide Nanocomposite Derived by Spray Method

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Zolghadr, S.; Kimiagar, S.; Khojier, K.

2017-12-01

This paper investigates the α-Fe2O3/reduced graphene oxide (rGO) nanocomposite as a volatile organic compounds (VOCs) sensor. The α-Fe2O3/reduced graphene oxide nanocomposites of about 370 nm thickness were synthesized by a spray method with different rGO contents (3%, 4%, and 5%) on SiO2/Si substrates. The samples were structurally and morphologically characterized by x-ray diffraction, and field emission scanning electron microscopy. These analyses showed that an increase in rGO content decreases the crystallinity of the samples. In order to study the VOCs sensing properties, the sensitivity and selectivity of the samples were tested with different VOCs vapors including ethanol, methanol, toluene, benzene, and formic acid in the temperature range of 200-400°C. The results show that the α-Fe2O3/rGO nanocomposites are more selective to ethanol than the other vapors, while an increase in rGO content decreases the sensitivity of the samples. The α-Fe2O3/rGO (3%)-based ethanol sensor also shows a good stability with respect to relative humidity in the range of 20-50% with a 1-ppm detection limit at the operating temperature of 280°C.

Scattering, absorption and transmittance of experimental graphene dental nanocomposites

Science.gov (United States)

Pérez, María. M.; Salas, Marianne; Moldovan, Marionara; Dudea, Diana; Yebra, Ana; Ghinea, Razvan

2017-08-01

Optical properties of experimental graphene dental nanocomposites were studied. Spectral reflectance was measured and S and K coefficients as well as transmittance of samples were calculated using Kubelka-Munk's equations. The spectral behavior of S, K and T experimental graphene exhibited different trends compared with the commercial nanocomposites and they were statistically different. Experimental nanocomposites show higher scattering and lower transmittance when compared with commercial nanocomposite, probably, due to the shape, type and size of the filler. K for short wavelength of the pre-polymerized experimental nancomposites was very low. According to our results, hidroxypatite with graphene oxide used in dental nanocomposites needs to be improved to reproduce esthetic properties of natural dental tissues and to have potentially clinical applications.

Polyaniline/partially exfoliated multi-walled carbon nanotubes based nanocomposites for supercapacitors

International Nuclear Information System (INIS)

Potphode, Darshna D.; Sivaraman, P.; Mishra, Sarada P.; Patri, Manoranjan

2015-01-01

In the present study, polyaniline (PANI)/partially exfoliated multi-walled carbon nanotubes (Px-MWCNT) nanocomposites were investigated for supercapacitor application. Nanocomposites with varying weight/weight ratio of PANI and Px-MWCNT were prepared by in-situ polymerization of aniline over Px-MWCNT. Transmission and scanning electron microscopic analysis showed that the MWCNT was partial unzipped along the length of tubes. The morphology of PANI/Px-MWCNT nanocomposites exhibited wrapping of PANI over Px-MWCNT. Symmetric supercapacitors containing PANI/Px-MWCNT nanocomposites as the electrode material were fabricated. The electrochemical characterization of the nanocomposites was carried by two electrode method (unit cell configuration). Cyclic voltammetric analysis showed a synergistic increase in specific capacitance of the nanocomposites. Charge-discharge cycle study indicated that nanocomposites have greater charge-discharge rate capability than pure PANI. The observed result is attributed to the shorter diffusion length of ions in the nanocomposites as compared to that of pure PANI. The electrochemical impedance spectra of supercapacitors were resolved into real and losscapacitances. The loss capacitance indicated that the time constant of the nanocomposites decreases with increase in the Px-MWCNT content. The supercapacitors showed enhanced stability during continuous charge-discharge cycling as the PX-MWCNT content in the nanocomposites increased. PANI-50 and PANI-25 nanocomposites based supercapacitors exhibited 91% and 93% capacitive retention after 2000 charge-discharge cycle while pure PANI showed only 67% capacitance retention for the same number of cycles

Transmission electron microscopy of polyhydroxybutyrate-co-valerate (PHBV)/nanocrystalline cellulose (NCC) bio-nanocomposite prepared using cryo-ultramicrotomy

Science.gov (United States)

Ismarul, N. I.; Engku, A. H. E. U.; Siti, N. K.; Tay, K. Y.

2017-12-01

Environmental issues on disposal and end-of-life for product made from synthetic petroleum-derived polymers have gained increasing attention from materials scientist to search for new materials with similar physical and mechanical properties but environmental friendly in a way that they are renewable and biodegradable as well. This work is to study the effect of nanocrystalline cellulose in improving the thermal stability of polyhydroxybutyrate-co-valerate biopolymer for high temperature processing of packaging material. 10 % w/w PHBV-NCC bio-nanocomposite feedstock pellet prepared using RONDOL minilab compounder was used as the sample for the preparation of Transmission Electron Microscopy (TEM) sample. RMC Cryo-Ultramicrotomy equipment was used to prepare the ultra-thin slice of the bio-nanocomposite pellet under liquid nitrogen at - 60 °C. Diamond knife was used to slice off about 80-100 nm ultra-thin bio-nanocomposite films and was transferred into the lacey carbon film coated grid using cooled sugar solution. A few drops of phosphotungstic acid was used as negative stain to improve the contrast during the TEM analysis. HITACHI TEM systems was used to obtain the TEM micrograph of PHBV-NCC bio-nanocomposite using 80kV accelerating voltage. A well dispersed NCC in PHBV matrix, ranging from 5 to 25 nm in width was observed.

Biosorption of Acid Blue 290 (AB 290) and Acid Blue 324 (AB 324) dyes on Spirogyra rhizopus

International Nuclear Information System (INIS)

Ozer, Ayla; Akkaya, Goenuel; Turabik, Meral

2006-01-01

In this study, the biosorption of Acid Blue 290 and Acid Blue 324 on Spirogyra rhizopus, a green algae growing on fresh water, was studied with respect to initial pH, temperature, initial dye concentration and biosorbent concentration. The optimum initial pH and temperature values for AB 290 and AB 324 biosorption were found to be 2.0, 30 deg. C and 3.0, 25 deg. C, respectively. It was observed that the adsorbed AB 290 and AB 324 amounts increased with increasing the initial dye concentration up to 1500 and 750 mg/L, respectively. The Langmuir, Freundlich, Redlich-Peterson and Koble-Corrigan isotherm models were applied to the experimental equilibrium data and the isotherm constants were determined by using Polymath 4.1 software. The monolayer coverage capacities of S. rhizopus for AB 290 and AB 324 dyes were found as 1356.6 mg/g and 367.0 mg/g, respectively. The intraparticle diffusion model and the pseudo-second order kinetic model were applied to the experimental data in order to describe the removal mechanism of these acidic dyes by S. rhizopus. The pseudo-second order kinetic model described very well the biosorption kinetics of AB 290 and AB 324 dyes. Thermodynamic studies showed that the biosorption of AB 290 and AB 324 on S. rhizopus was exothermic in nature

Formation of reflective and conductive silver film on ABS surface via covalent grafting and solution spray

Energy Technology Data Exchange (ETDEWEB)

Chen, Dexin; Zhang, Yan [School of Mechanical and Automotive Engineering, South China University of Technology, 381 Wushan, Guangzhou 510640 (China); Bessho, Takeshi [Higashifuji Technical Center, Toyota Motor Corporation, 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan); Kudo, Takahiro; Sang, Jing; Hirahara, Hidetoshi; Mori, Kunio [Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Kang, Zhixin, E-mail: zxkang@scut.edu.cn [School of Mechanical and Automotive Engineering, South China University of Technology, 381 Wushan, Guangzhou 510640 (China)

2015-09-15

Highlights: • A pure and homogenous silver film was deposited by spray-style plating technique. • The mechanism of covalent bonding between coating and substrate was studied. • The silver coating is highly reflective and conductive. • UV light was used to activate the ABS surface with triazine azide derivative. - Abstract: Conductive and reflective silver layers on acrylonitrile butadiene styrene (ABS) plastics have been prepared by photo grafting of triazine azides upon ultraviolet activation, self-assembling of triazine dithiols and silver electroless plating by solution spray based on silver mirror reaction. The as-prepared silver film exhibited excellent adhesion with ABS owing to covalent bonds between coating and substrate, and the detailed bonding mechanism have been investigated by X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) result revealed that silver film on ABS was pure and with a nanocrystalline structure. Atomic force microscope (AFM) analysis demonstrated that massive silver particles with sizes varying from 80 to 120 nm were deposited on ABS and formed a homogenous and smooth coating, resulting in highly reflective surface. Furthermore, silver maintained its unique conductivity even as film on ABS surface in term of four-point probe method.

Formation of reflective and conductive silver film on ABS surface via covalent grafting and solution spray

International Nuclear Information System (INIS)

Chen, Dexin; Zhang, Yan; Bessho, Takeshi; Kudo, Takahiro; Sang, Jing; Hirahara, Hidetoshi; Mori, Kunio; Kang, Zhixin

2015-01-01

Highlights: • A pure and homogenous silver film was deposited by spray-style plating technique. • The mechanism of covalent bonding between coating and substrate was studied. • The silver coating is highly reflective and conductive. • UV light was used to activate the ABS surface with triazine azide derivative. - Abstract: Conductive and reflective silver layers on acrylonitrile butadiene styrene (ABS) plastics have been prepared by photo grafting of triazine azides upon ultraviolet activation, self-assembling of triazine dithiols and silver electroless plating by solution spray based on silver mirror reaction. The as-prepared silver film exhibited excellent adhesion with ABS owing to covalent bonds between coating and substrate, and the detailed bonding mechanism have been investigated by X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) result revealed that silver film on ABS was pure and with a nanocrystalline structure. Atomic force microscope (AFM) analysis demonstrated that massive silver particles with sizes varying from 80 to 120 nm were deposited on ABS and formed a homogenous and smooth coating, resulting in highly reflective surface. Furthermore, silver maintained its unique conductivity even as film on ABS surface in term of four-point probe method

Polyurethane Nanocomposites Containing Reduced Graphene Oxide, FTIR, Raman, and XRD Studies

Directory of Open Access Journals (Sweden)

Michał Strankowski

2016-01-01

Full Text Available Recently, graphene and other graphene-based materials have become an essential part of composite science and technology. Their unique properties are not only restricted to graphene but also shared with derivative compounds like graphene oxide, reduced graphene oxide, functionalized graphene, and so forth. One of the most structurally important materials, graphene oxide (GO, is prepared by the oxidation of graphite. Though removal of the oxide groups can create vacancies and structural defects, reduced graphene oxide (rGO is used in composites as effective filler similar to GO. Authors developed a new polyurethane nanocomposite using a derivative of grapheme, thermally reduced graphene oxide (rGO, to modify the matrix of polyurethane elastomers, by rGO.

Monkey-derived monoclonal antibodies against Plasmodium falciparum

International Nuclear Information System (INIS)

Stanley, H.A.; Reese, R.T.

1985-01-01

A system has been developed that allows efficient production of monkey monoclonal antibodies from owl monkeys. Splenocytes or peripheral blood lymphocytes from monkeys immune to the human malarial parasite, Plasmodium falciparum, were fused with P3X63 Ag8.653 mouse myelomas. The resulting hybridomas were screened by an indirect fluorescent antibody test for the production of monkey monoclonal antibodies (mAb) reactive with P. falciparum. Most of the mAb reacted with the P. falciparum merozoites and immunoprecipitated a parasite-derived glycoprotein having a relative molecular weight of 185,000. These mAb gave a minimum of five different immunoprecipitation patterns, thus demonstrating that a large number of polypeptides obtained when parasitized erythrocytes are solubilized share epitopes with this large glycoprotein. In addition, mAb were obtained that reacted with antigens associated with the infected erythrocyte membrane. One of these mAb bound a M/sub r/ 95,000 antigen. Radioimmunoprecipitation assays using 125 T-antibodies were done

Nanotechnology : emerging applications of cellulose-based green magnetic nanocomposites

Science.gov (United States)

Tao Wang; Zhiyong Cai; Lei Liu; Ilker S. Bayer; Abhijit Biswas

2010-01-01

In recent years, a new type of nanocomposite – cellulose based hybrid nanocomposites, which adopts cellulose nanofibers as matrices, has been intensively developed. Among these materials, hybrid nanocomposites consisting of cellulosic fibers and magnetic nanoparticles have recently attracted much attention due to their potential novel applications in biomedicine,...

Polymer nanocomposites for high-temperature composite repair

Energy Technology Data Exchange (ETDEWEB)

Sheng, Xia [Iowa State Univ., Ames, IA (United States)

2008-01-01

A novel repair agent for resin-injection repair of advanced high temperature composites was developed and characterized. The repair agent was based on bisphenol E cyanate ester (BECy) and reinforced with alumina nanoparticles. To ensure good dispersion and compatibility with the BECy matrix in nanocomposites, the alumina nanoparticles were functionalized with silanes. The BECy nanocomposites, containing bare and functionalized alumina nanoparticles, were prepared and evaluated for their thermal, mechanical, rheological, and viscoelastic properties. The monomer of BECy has an extremely low viscosity at ambient temperature, which is good for processability. The cured BECy polymer is a highly cross-linked network with excellent thermal mechanical properties, with a high glass transition temperature (T_g) of 270 C and decomposition temperature above 350 C. The incorporation of alumina nanoparticles enhances the mechanical and rheological properties of the BECy nanocomposites. Additionally, the alumina nanoparticles are shown to catalyze the cure of BECy. Characterization of the nanocomposites included dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, rheological and rheokinetic evaluation, and transmission electron microscopy. The experimental results show that the BECy nanocomposite is a good candidate as repair agent for resin-injection repair applications.

Synthesis of PbS/poly (vinyl-pyrrolidone) nanocomposite

International Nuclear Information System (INIS)

Patel, Jayesh D.; Chaudhuri, Tapas K.

2009-01-01

A simple solution growth method for synthesis of nanocomposite of PbS nanoparticles in poly(vinyl-pyrrolidone) (PVP) polymer is described. The nanocomposite is prepared from methanolic solution of lead acetate (PbAc), thiourea (TU) and PVP at room temperature (∼27 deg. C). Optical absorption spectrum of PbS/PVP nanocomposite solution shows strong absorption from 300 to 650 nm with significant bands at 400 and 590 nm which is characteristic of nanoscale PbS. Spin-coated nanocomposite films on glass have an absorption edge at ∼650 nm with band gap of 2.55 eV. Fourier transform infrared (FTIR) spectroscopy of PbS/PVP nanocomposite and PVP shows strong chemical bond between PbS nanoparticles and host PVP polymer. The transmission electron microscope (TEM) images reveal that 5-10 nm PbS particles are evenly embedded in PVP polymer. The formation of PbS is confirmed by selective area electron diffraction (SAED) of a typical nanoparticle.

Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

Science.gov (United States)

Tan, Seng; Zhou, Jian-guo

2013-01-01

Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

Carbon nanotube epoxy nanocomposites: the effects of interfacial modifications on the dynamic mechanical properties of the nanocomposites.

Science.gov (United States)

Yoonessi, Mitra; Lebrón-Colón, Marisabel; Scheiman, Daniel; Meador, Michael A

2014-10-08

Surface functionalization of pretreated carbon nanotubes (CNT) using aromatic, aliphatic, and aliphatic ether diamines was performed. The pretreatment of the CNT consisted of either acid- or photo-oxidation. The acid treated CNT had a higher initial oxygen content compared to the photo-oxidized CNT and this resulted in a higher density of functionalization. X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) were used to verify the presence of the oxygenated and amine moieties on the CNT surfaces. Epoxy/0.1 wt % CNT nanocomposites were prepared using the functionalized CNT and the bulk properties of the nanocomposites were examined. Macroscale correlations between the interfacial modification and bulk dynamic mechanical and thermal properties were observed. The amine modified epoxy/CNT nanocomposites exhibited up to a 1.9-fold improvement in storage modulus (G') below the glass transition (Tg) and up to an almost 4-fold increase above the Tg. They also exhibited a 3-10 °C increase in the glass transition temperature. The aromatic diamine surface modified epoxy/CNT nanocomposites resulted in the largest increase in shear moduli below and above the Tg and the largest increase in the Tg. Surface examination of the nanocomposites with scanning electron microscopy (SEM) revealed indications of a greater adhesion of the epoxy resin matrix to the CNT, most likely due to the covalent bonding.

Derivation of the stress-strain behavior of the constituents of bio-inspired layered TiO2/PE-nanocomposites by inverse modeling based on FE-simulations of nanoindentation test.

Science.gov (United States)

Lasko, G; Schäfer, I; Burghard, Z; Bill, J; Schmauder, S; Weber, U; Galler, D

2013-03-01

Owing to the apparent simple morphology and peculiar properties, nacre, an iridescent layer, coating of the inner part of mollusk shells, has attracted considerable attention of biologists, material scientists and engineers. The basic structural motif in nacre is the assembly of oriented plate-like aragonite crystals with a 'brick' (CaCO3 crystals) and 'mortar' (macromolecular components like proteins) organization. Many scientific researchers recognize that such structures are associated with the excellent mechanical properties of nacre and biomimetic strategies have been proposed to produce new layered nanocomposites. During the past years, increasing efforts have been devoted towards exploiting nacre's structural design principle in the synthesis of novel nanocomposites. However, the direct transfer of nacre's architecture to an artificial inorganic material has not been achieved yet. In the present contribution we report on laminated architecture, composed of the inorganic oxide (TiO2) and organic polyelectrolyte (PE) layers which fulfill this task. To get a better insight and understanding concerning the mechanical behaviour of bio-inspired layered materials consisting of oxide ceramics and organic layers, the elastic-plastic properties of titanium dioxide and organic polyelectrolyte phase are determined via FE-modelling of the nanoindentation process. With the use of inverse modeling and based on numerical models which are applied on the microscopic scale, the material properties of the constituents are derived.

Cellulose nanocrystals reinforced foamed nitrile rubber nanocomposites.

Science.gov (United States)

Chen, Yukun; Zhang, Yuanbing; Xu, Chuanhui; Cao, Xiaodong

2015-10-05

Research on foamed nitrile rubber (NBR)/cellulose nanocrystals (CNs) nanocomposites is rarely found in the literatures. In this paper, CNs suspension and NBR latex was mixed to prepared the foamed NBR/CNs nanocomposites. We found that the CNs mainly located in the cell walls, effectively reinforcing the foamed NBR. The strong interaction between the CNs and NBR matrix restricted the mobility of NBR chains surrounding the CNs, hence increasing the crosslink density of the NBR matrix. CNs exhibited excellent reinforcement on the foamed NBR: a remarkable increase nearly 76% in the tensile strength of the foamed nanocomposites was achieved with a load of only 15 phr CNs. Enhanced mechanical properties make the foamed NBR/CNs nanocomposites a promising damping material for industrial applications with a potential to reduce the petroleum consumption. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photodeposited metal-semiconductor nanocomposites and their applications

Directory of Open Access Journals (Sweden)

Yoonkyung Lee

2018-06-01

Full Text Available While two-dimensional layered nanomaterials including transition metal oxides and transition metal dichalcogenides have been widely researched because of their unique electronic and optical properties, they still have some limitations. To overcome these limitations, transition metal oxides and transition metal dichalcogenides based nanocomposites have been developed using various methods and have exhibited superior properties. In this paper, we introduce the photodeposition method and review the photodeposition of metal nanoparticles on the surface of transition metal oxide and transition metal dichalcogenides. Their current applications are also explained, such as photocatalysis, hydrogen evolution reaction, surface enhanced Ramanscattering, etc. This approach for nanocomposites has potential for future research areas such as photocatalysis, hydrogen evolution reaction, surface enhanced Raman scattering, and other applications. This approach for nanocomposite has the potential for future research areas. Keywords: Photodeposition, Nanocomposite, Transition metal oxide, Transition metal dichalcogenide

Polymer and ceramic nanocomposites for aerospace applications

Science.gov (United States)

Rathod, Vivek T.; Kumar, Jayanth S.; Jain, Anjana

2017-11-01

This paper reviews the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications. Special, unique and multifunctional properties arising due to the dispersion of nanoparticles in ceramic and metal matrix are briefly discussed followed by a classification of resulting aerospace applications. The paper presents polymer matrix composites comprising majority of aerospace applications in structures, coating, tribology, structural health monitoring, electromagnetic shielding and shape memory applications. The capabilities of the ceramic matrix nanocomposites to providing the electromagnetic shielding for aircrafts and better tribological properties to suit space environments are discussed. Structural health monitoring capability of ceramic matrix nanocomposite is also discussed. The properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed. The paper concludes after the discussion of the possible future perspectives and challenges in implementation and further development of polymer and ceramic nanocomposite materials.

Studies of the distribution of intrathecally injected 125I-tetanus antitoxin-F(ab')2

International Nuclear Information System (INIS)

Hanauske, A.R.

1981-01-01

Overall F(ab') 2 and antitetanus-f(ab') 2 - fragments were labelled with 125 I and injected i.th. into normal juvenile cats and adult rats. One group of rats was normal; in the other, unilateral local tetanus had been induced by injection of tetanus toxin into a M. gastrocnemius. The animals were sacrificed 24 h after the i.th. injection, and tissue samples were taken for histoautoradiography. 125 I-antitetanus-F(ab') 2 permeated into the extracellular space of the spinal cord, roots, and ganglia but not into the neuronal intracellular space. 125 I-overall-F(ab') showed identical permeation behaviour. 125 I-antitetanus-F(ab') 2 reacted with tetanus toxin issuing from the motoneurons after i.th. injection, forming an immunocomplex around the motorneurons. The immunocomplex was not formed around pseudo-unipolar ganglian cells in the spinal ganglia even though some of the ganglian cells contained tetanus toxin, and 125 I-antitetanus-F(ab') 2 was present in the extracellular space. As an explanation, it was suggested that tetanus toxin does not permeate into the extracellular space through the membrane of the pseudo-unipolar ganglian cells so that immune reactions will not occur. These findings help to explain the widely divergent results of tetanus therapy by means of i.th. injection of tetanus antitoxin. Recommendations for future therapy measures are derived from the findings. (orig./MG) [de

Exploring the speed and performance of molecular replacement with AMPLE using QUARK ab initio protein models

Energy Technology Data Exchange (ETDEWEB)

Keegan, Ronan M. [STFC Rutherford Appleton Laboratory, Didcot OX11 0FA (United Kingdom); Bibby, Jaclyn; Thomas, Jens [University of Liverpool, Liverpool L69 7ZB (United Kingdom); Xu, Dong [Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037 (United States); Zhang, Yang [University of Michigan, Ann Arbor, MI 48109 (United States); Mayans, Olga [University of Liverpool, Liverpool L69 7ZB (United Kingdom); Winn, Martyn D. [Science and Technology Facilities Council Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Rigden, Daniel J., E-mail: drigden@liv.ac.uk [University of Liverpool, Liverpool L69 7ZB (United Kingdom); STFC Rutherford Appleton Laboratory, Didcot OX11 0FA (United Kingdom)

2015-02-01

Two ab initio modelling programs solve complementary sets of targets, enhancing the success of AMPLE with small proteins. AMPLE clusters and truncates ab initio protein structure predictions, producing search models for molecular replacement. Here, an interesting degree of complementarity is shown between targets solved using the different ab initio modelling programs QUARK and ROSETTA. Search models derived from either program collectively solve almost all of the all-helical targets in the test set. Initial solutions produced by Phaser after only 5 min perform surprisingly well, improving the prospects for in situ structure solution by AMPLE during synchrotron visits. Taken together, the results show the potential for AMPLE to run more quickly and successfully solve more targets than previously suspected.

PCL/MWCNT Nanocomposites as Nanosensors

Science.gov (United States)

Grozdanov, Anita; Buzarovska, Alexandra; Avella, Maurizio; Errico, Maria E.; Gentile, Gennaro

Due to the unique electronic, metallic and structural properties of carbon nanotubes (CNTs) as compared to other materials, researchers focused on utilizing these characteristics for engineering applications such as actuators, hydrogen storage materials, chemical sensors and nanoelectronic devices. Many papers have been published utilizing CNTs as the sensing material in pressure, flow, thermal, gas, optical, mass, strain, stress, chemical and biological sensors. Amongst many of their superior electro-mechanical properties, the piezoresistive effect in CNTs is attractive for designing strain sensors. When CNTs are subjected to a mechanical strain, a change in their chirality leads to modulation of the conductance. In this paper, a novel carbon nanotube/biopolymer nanocomposite was used to develop a piezoresistive strain nano bio-sensor. A biocompatible polymer matrix has been used to provide good interfacial bonding between the carbon nanotubes. Multi-walled carbon nanotubes (MWCNT, diameter d = 30-50 nm, purity >95%) have been used for the preparation of polycaprolactone (PCL)-based nanocomposites (PCL/MWCNT). The nanocomposites were prepared by mixing the MWCNTs and PCL in a tetrahydrofuran solution for 24 h. Characterization of the PCL/MWCNTs nanocomposite films was performed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) and scanning electron microscopy (SEM), as well as by mechanical and electrical measurements.

Revealing strategies of quorum sensing in Azospirillum brasilense strains Ab-V5 and Ab-V6.

Science.gov (United States)

Fukami, Josiane; Abrantes, Julia Laura Fernandes; Del Cerro, Pablo; Nogueira, Marco Antonio; Ollero, Francisco Javier; Megías, Manuel; Hungria, Mariangela

2018-01-01

Azospirillum brasilense is an important plant-growth promoting bacterium (PGPB) that requires several critical steps for root colonization, including biofilm and exopolysaccharide (EPS) synthesis and cell motility. In several bacteria these mechanisms are mediated by quorum sensing (QS) systems that regulate the expression of specific genes mediated by the autoinducers N-acyl-homoserine lactones (AHLs). We investigated QS mechanisms in strains Ab-V5 and Ab-V6 of A. brasilense, which are broadly used in commercial inoculants in Brazil. Neither of these strains carries a luxI gene, but there are several luxR solos that might perceive AHL molecules. By adding external AHLs we verified that biofilm and EPS production and cell motility (swimming and swarming) were regulated via QS in Ab-V5, but not in Ab-V6. Differences were observed not only between strains, but also in the specificity of LuxR-type receptors to AHL molecules. However, Ab-V6 was outstanding in indole acetic acid (IAA) synthesis and this molecule might mimic AHL signals. We also applied the quorum quenching (QQ) strategy, obtaining transconjugants of Ab-V5 and Ab-V6 carrying a plasmid with acyl-homoserine lactonase. When maize (Zea mays L.) was inoculated with the wild-type and transconjugant strains, plant growth was decreased with the transconjugant of Ab-V5-confirming the importance of an AHL-mediated QS system-but did not affect plant growth promotion by Ab-V6.

Gamma irradiation of melt processed biomedical PDLLA/HAP nanocomposites

International Nuclear Information System (INIS)

Dadbin, Susan; Kheirkhah, Yahya

2014-01-01

Poly(D-L lactide) PDLLA/hydroxyapatite (HAP) nanocomposites at various compositions were prepared by melt-compounding process and then subjected to gamma irradiation at a dose of 30 kGy. The morphology of the nanocomposites, characterized by transmission electron microscopy (TEM), displayed HAP nanoparticles at various sizes ranging from 10 to 100 nm distributed almost evenly within the polymer matrix. Differential scanning calorimetric (DSC) analysis of the irradiated nanocomposites showed an increase in the degree of crystallinity along with a melting peak split. The double melting peak suggested formation of different crystalline structures in the radiation exposed nanocomposites. Also the cold crystallization peak shifted to lower temperatures and became much sharper upon irradiation, indicating higher crystallization rate. The irradiated nanocomposites showed lower tensile strength and elongation at break, suggesting occurrence of some chain scission reactions in the PLA. - Highlights: • Biomedical polylactic acid/hydroxyapatite nanocomposites prepared by melt-compounding were gamma irradiated. • Transmission electron microscopy showed hydroxyapatite nanoparticles evenly distributed within polylactic acid ranging from 10 to 100 nm. • A halo appeared around hydroxyapatite particles showing interfacial interactions between polylactic acid and the particles. • Double melting peak appeared for polylactic acid in DSC thermograms upon gamma irradiation of the nanocomposites

Single-walled carbon nanotubes nanocomposite microacoustic organic vapor sensors

Energy Technology Data Exchange (ETDEWEB)

Penza, M. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy)]. E-mail: michele.penza@brindisi.enea.it; Tagliente, M.A. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy); Aversa, P. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy); Cassano, G. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy); Capodieci, L. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy)

2006-07-15

We have developed highly sensitive microacoustic vapor sensors based on surface acoustic waves (SAWs) configured as oscillators using a two-port resonator 315, 433 and 915 MHz device. A nanocomposite film of single-walled carbon nanotubes (SWCNTs) embedded in a cadmium arachidate (CdA) amphiphilic organic matrix was prepared by Langmuir-Blodgett technique with a different SWCNTs weight filler content onto SAW transducers as nanosensing interface for vapor detection, at room temperature. The structural properties and surface morphology of the nanocomposite have been examined by X-ray diffraction, transmission and scanning electron microscopy, respectively. The sensing properties of SWCNTs nanocomposite LB films consisting of tangled nanotubules have been also investigated by using Quartz Crystal Microbalance 10 MHz AT-cut quartz resonators. The measured acoustic sensing characteristics indicate that the room-temperature SAW sensitivity to polar and nonpolar tested organic molecules (ethanol, ethylacetate, toluene) of the SWCNTs-in-CdA nanocomposite increases with the filler content of SWCNTs incorporated in the nanocomposite; also the SWCNTs-in-CdA nanocomposite vapor sensitivity results significantly enhanced with respect to traditional organic molecular cavities materials with a linearity in the frequency change response for a given nanocomposite weight composition and a very low sub-ppm limit of detection.

Designed graphene-peptide nanocomposites for biosensor applications: A review

International Nuclear Information System (INIS)

Wang, Li; Zhang, Yujie; Wu, Aiguo; Wei, Gang

2017-01-01

The modification of graphene with biomacromolecules like DNA, protein, peptide, and others extends the potential applications of graphene materials in various fields. The bound biomacromolecules could improve the biocompatibility and bio-recognition ability of graphene-based nanocomposites, therefore could greatly enhance their biosensing performances on both selectivity and sensitivity. In this review, we presented a comprehensive introduction and discussion on recent advance in the synthesis and biosensor applications of graphene-peptide nanocomposites. The biofunctionalization of graphene with specifically designed peptides, and the synthesis strategies of graphene-peptide (monomer, nanofibrils, and nanotubes) nanocomposites were demonstrated. On the other hand, the fabrication of graphene-peptide nanocomposite based biosensor architectures for electrochemical, fluorescent, electronic, and spectroscopic biosensing were further presented. This review includes nearly all the studies on the fabrication and applications of graphene-peptide based biosensors recently, which will promote the future developments of graphene-based biosensors in biomedical detection and environmental analysis. - Highlights: • A comprehensive review on the fabrication and application of graphene-peptide nanocomposites was presented. • The design of peptide sequences for biofunctionalization of various graphene materials was presented. • Multi-strategies on the fabrication of biosensors with graphene-peptide nanocomposites were discussed. • Designed graphene-peptide nanocomposites showed wide biosensor applications.

Field emission study of MWCNT/conducting polymer nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Alvi, M.A., E-mail: maalvee@yahoo.co.in [Department of Physics, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Al-Ghamdi, A.A. [Department of Physics, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Husain, M. [Department of Physics, Jamia Millia Islamia, New Delhi-110025 (India)

2014-12-01

MWCNTs/Polypyrrole nanocomposites were synthesized by solution mixing method. These synthesized nanocomposites were studied carefully by Raman Spectroscopy and Scanning Electron Microscopy measurements. The field emission study of MWCNTs/Polypyrrole nanocomposites were performed in diode arrangement under vacuum of the order of 10{sup −5} Torr. The emission current under exploration depends on applied voltage. The prepared nanocomposites depict low turn-on field at 1.4 V/μm that reaches to a maximum emission current density 0.020 mA/cm{sup 2} at 2.4 V/µm, which is calculated from the graph of current density (J) against the applied electric field (E) and from Fowler–Nordheim (F–N) plot.

Synthesis of thermoresponsive poly(N-isopropylacrylamide)/clay nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Kim, J.P.; Lyu, S.G. [Yeungnam Univeristy, Kyongsan (Korea); Bae, K.S. [Andong Institute of Information and Technology, Andong (Korea); Sur, G.S. [Yeungnam Univeristy, Kyungsan (Korea)

2001-03-01

MAPTAC-MMT was prepared by exchanging the mineral cation (sodium montmorillonite) with 3-(methacryloyl amino) propyltrimethyl ammonium chloride, thus rendering the mineral organophilic and forming polymerizable moieties directly bonded to the surface of montmorillonite (MMT). Thermoresponsive nanocomposites (PNIPAM-MMT) were synthesized by polymerization of N-isopropyl acrylamide in an aqueous suspension of MAPTAC-MMT at room temperature. Thermoresponsive nanocomposites exhibited a low critical solution temperature (LCST) similar to unmodified poly(N-isopropyl acrylamide) (PNIPAM). The LCST of thermoresponsive nanocomposites decreased in proportion to the amount of MAPTAC-MMT. TGA results showed that the thermal stability of thermoresponsieve nanocomposites was improved compared to PNIPAM itself the thermoresponsive polymer. (author). 25 refs., 9 figs.

Carbon-Nickel oxide nanocomposites: Preparation and charecterisation

CSIR Research Space (South Africa)

Tile, N

2011-07-01

Full Text Available Nanocomposite materials have wide range of applications in solar energy conversion. In this work, C-NiO nanocomposite coatings are prepared using sol-gel synthesis and deposited on aluminium substrates using a spin coater. The coatings are prepared...

Microstructural evolution of alumina-zirconia nanocomposites

International Nuclear Information System (INIS)

Ojaimi, C.L.; Chinelatto, A.S.A.; Chinelatto, A.L.; Pallone, E.M.J.A.

2012-01-01

Ceramic materials have limited use due to their brittleness. The inclusion of nanosized particles in a ceramic matrix, which are called nanocomposites, and ceramic processing control by controlling the grain size and densification can aid in obtaining ceramic products of greater strength and toughness. Studies showed that the zirconia nano inclusions in the matrix of alumina favors an increase in mechanical properties by inhibiting the grain growth of the matrix and not by the mechanism of the transformation toughening phase of zirconia. In this work, the microstructural evolution of alumina nanocomposites containing 15% by volume of nanometric zirconia was studied. From the results it was possible to understand the sintering process of these nanocomposites. (author)

Undoing Gender Through Legislation and Schooling: the Case of AB 537 and AB 394 IN California, USA

Science.gov (United States)

Knotts, Greg

2009-11-01

This article investigates California laws AB 537: The Student Safety and Violence Prevention Act of 2000, and the recently enacted AB 394: Safe Place to Learn Act. Both demand that gender identity and sexual orientation be added to the lexicon of anti-harassment protection in public education. However, despite these progressive measures, schools have an unconscious acceptance of heteronormativity and gendered norms, which undermines both the spirit and language of these laws. This paper examines how California schools can both change standard practices and realise the transformative social change that laws like AB 537 and AB 394 can instigate. I assert that the systemic implementation of these laws, through the adoption, enforcement and evaluation of existing AB 537 Task Force Recommendations, is necessary for their success. My second assertion is that AB 537 and AB 394 have the potential to change and reconstitute gender-based and heteronormative standards at school sites.

Limitations of Ab Initio Predictions of Peptide Binding to MHC Class II Molecules

DEFF Research Database (Denmark)

Zhang, Hao; Lund, Ole; Nielsen, Morten

2010-01-01

potentials derived from the analysis of known protein structures; energetic evaluation of different peptide snapshots in a molecular dynamics simulation; and direct analysis of contacts made in known 3D structures of peptide:MHC complexes. These methods are ab initio in that they require structural data...

Preparation and Characteristics of Biodegradable Polyurethane/Clay Nanocomposite Films

Energy Technology Data Exchange (ETDEWEB)

Kim, Seong Woo [Kyonggi University, Suwon (Korea, Republic of)

2013-06-15

Biodegradable polyurethane (PU)/clay nanocomposite films were prepared via extrusion compounding process followed by casting film process. Organically modified montmorillonite (denoted as C30B) with a large amount of hydroxyl groups on its surface was used for the formation of strong bonding with PU resin. From both XRD analysis and TEM observations, the intercalated and exfoliated structure, and dispersion state of silicate platelets in the compounded nanocomposite films were confirmed. In addition, the rheological and tensile properties, optical transparency, oxygen permeability of the prepared nanocomposites were investigated as a function of added nanoclay content, and moreover based on these results, the correlation between the morphology and the resulting properties of the nanocomposites could be presented. The inclusion of nanoclays at appropriate content resulted in remarkable improvement in the nanocomposite performance including tensile modulus, elongation, transparency, and oxygen barrier property, however at excess amount of nanoclays, reduction or very slight increase was observed due to poor dispersion. The biodegradability of the prepared nanocomposite film was evaluated by examining the deterioration in the barrier and tensile properties during degradation period under compost.

clay nanocomposites

Indian Academy of Sciences (India)

The present work deals with the synthesis of specialty elastomer [fluoroelastomer and poly (styrene--ethylene-co-butylene--styrene (SEBS)]–clay nanocomposites and their structure–property relationship as elucidated from morphology studies by atomic force microscopy, transmission electron microscopy and X-ray ...

Use of MMT and MMT organoclay in production of starch nanocomposites

International Nuclear Information System (INIS)

Schlemmer, D.; Sales, M.J.A.; Macedo, J.L. de; Angelica, R.S.

2010-01-01

Starch can be used to replace petrochemical plastics for short shelf life. However, starch films have poor mechanical strength and sensitivity to moisture. This can be improved through the incorporation of nanoclays, such as montmorillonite, forming nanocomposites. Nanocomposites were prepared with 1, 3, 5 and 10% of montmorillonite, using pequi oil as plasticizer. The clay was also modified with a quaternary ammonium salt. The clays were characterized by XRF, XRD, IR and TG. Results confirmed the organophilization. The nanocomposites diffractograms showed that the addition of small amounts of clay produces delaminated nanocomposites. Already the addition of larger amount of clay does not form nanocomposites, or leads to the formation of intercalated nanocomposites. (author)

Ecoefficiency indicators for development of nano-composites

DEFF Research Database (Denmark)

Olsen, Stig Irving; Laurent, Alexis

nanocomposites (5 wt%-nanofiller) were investigated; PU/CNT (in-situ polymerization), PP/CNT (in-situ polymerization), PU/clay (bulk polymerization), and PP/clay nanocomposites (bulk polymerization). Due to of lack of information, only the material stages (extraction of materials) and the production...

Nanocomposite of graphene and metal oxide materials

Science.gov (United States)

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2012-09-04

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10C.

Nanocomposite of graphene and metal oxide materials

Science.gov (United States)

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2013-10-15

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

Metal–carbon nanocomposites based on pyrolysed polyacrylonitrile

Directory of Open Access Journals (Sweden)

Irina A. Zaporotskova

2015-06-01

Full Text Available The electronic structure and geometry of metal−carbon nanocomposites based on pyrolyzed polyacrylonitrile (PPAN with Cu, Si, Fe, Co and Ni atoms using the DFT method have been theoretically studied. The effect of nitrogen on the stability of PPAN and its conductivity has been determined. The electrophysical properties and structure of metal nanocomposites have been studied using the XFA method. The composites have been produced by IR heating. We suggest that metal−carbon nanocomposites form due to the special processing of the (PAN−MeR samples. Metal nanoparticles are regularly dispersed in the nanocrystalline matrix of PPAN. The conductivity of these metal−carbon nanocomposites has an activation character and varies from 10−1 to 103 Om/cm depending on synthesis temperature (T=600–900 °С. The results of theoretical and experimental research are in a good agreement.

Polymer matrix nanocomposites for automotive structural components

Science.gov (United States)

Naskar, Amit K.; Keum, Jong K.; Boeman, Raymond G.

2016-12-01

Over the past several decades, the automotive industry has expended significant effort to develop lightweight parts from new easy-to-process polymeric nanocomposites. These materials have been particularly attractive because they can increase fuel efficiency and reduce greenhouse gas emissions. However, attempts to reinforce soft matrices by nanoscale reinforcing agents at commercially deployable scales have been only sporadically successful to date. This situation is due primarily to the lack of fundamental understanding of how multiscale interfacial interactions and the resultant structures affect the properties of polymer nanocomposites. In this Perspective, we critically evaluate the state of the art in the field and propose a possible path that may help to overcome these barriers. Only once we achieve a deeper understanding of the structure-properties relationship of polymer matrix nanocomposites will we be able to develop novel structural nanocomposites with enhanced mechanical properties for automotive applications.

Synthesis of polyanthranilic acid–Au nanocomposites by emulsion ...

Indian Academy of Sciences (India)

Administrator

PANA–Au nanocomposites are characterized by SEM, equipped with EDS, TGA, FT–IR, XRD and electrochemical techniques. XRD of ... Polyanthranilic acid; nanocomposite; in situ polymerization; emulsion polymerization; nano- particles. 1.

Characterization of PAN/ATO nanocomposites prepared by solution ...

Indian Academy of Sciences (India)

Wintec

Institute of Materials and Chemical Engineering, Zhongyuan University of Technology, ... The storage modulus of the nanocomposites increased with increasing content of ATO, ... Thermal stability of the nanocomposites was found remarka-.

Graphene oxide - Polyvinyl alcohol nanocomposite based electrode material for supercapacitors

Science.gov (United States)

Pawar, Pranav Bhagwan; Shukla, Shobha; Saxena, Sumit

2016-07-01

Supercapacitors are high capacitive energy storage devices and find applications where rapid bursts of power are required. Thus materials offering high specific capacitance are of fundamental interest in development of these electrochemical devices. Graphene oxide based nanocomposites are mechanically robust and have interesting electronic properties. These form potential electrode materials efficient for charge storage in supercapacitors. In this perspective, we investigate low cost graphene oxide based nanocomposites as electrode material for supercapacitor. Nanocomposites of graphene oxide and polyvinyl alcohol were synthesized in solution phase by integrating graphene oxide as filler in polyvinyl alcohol matrix. Structural and optical characterizations suggest the formation of graphene oxide and polyvinyl alcohol nanocomposites. These nanocomposites were found to have high specific capacitance, were cyclable, ecofriendly and economical. Our studies suggest that nanocomposites prepared by adding 0.5% wt/wt of graphene oxide in polyvinyl alcohol can be used an efficient electrode material for supercapacitors.

Hazy Al2O3-FTO Nanocomposites: A Comparative Study with FTO-Based Nanocomposites Integrating ZnO and S:TiO2 Nanostructures

Directory of Open Access Journals (Sweden)

Shan-Ting Zhang

2018-06-01

Full Text Available In this study, we report the use of Al2O3 nanoparticles in combination with fluorine doped tin oxide (F:SnO2, aka FTO thin films to form hazy Al2O3-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites integrating ZnO and sulfur doped TiO2 (S:TiO2 nanoparticles (i.e., ZnO-FTO and S:TiO2-FTO nanocomposites, the newly developed Al2O3-FTO nanocomposites show medium haze factor HT of about 30%, while they exhibit the least loss in total transmittance Ttot. In addition, Al2O3-FTO nanocomposites present a low fraction of large-sized nanoparticle agglomerates with equivalent radius req > 1 μm; effectively 90% of the nanoparticle agglomerates show req < 750 nm. The smaller feature size in Al2O3-FTO nanocomposites, as compared to ZnO-FTO and S:TiO2-FTO nanocomposites, makes them more suitable for applications that are sensitive to roughness and large-sized features. With the help of a simple optical model developed in this work, we have simulated the optical scattering by a single nanoparticle agglomerate characterized by bottom radius r0, top radius r1, and height h. It is found that r0 is the main factor affecting the HT(λ, which indicates that the haze factor of Al2O3-FTO and related FTO nanocomposites is mainly determined by the total surface coverage of all the nanoparticle agglomerates present.

Mechanical and optical characterization of bio-nanocomposite from pineapple leaf fiber material for food packaging

Science.gov (United States)

Nikmatin, Siti; Rudwiyanti, Jerry R.; Prasetyo, Kurnia W.; Yedi, Dwi A.

2015-01-01

The utilization of Bio-nanocomposite material that was derived from pineapple leaf fiber as filler and tapioca starch with plasticizer glycerol as a matrix for food packaging can reduce the use of plastic that usually was made from petroleum materials. It is important to develop and producethis environmental friendly plastic because of limited availability of petroleum nowadays. The process of synthesize and characterization tapioca starch with the plasticizer glycerol bionanocomposites using print method had been conducted. There were 3 samples with different filler concentration variation; 3%, 4% and 5%.The results of mechanical test from each sample showed that bio-nanocomposite with 5% filler concentration was the optimum sample with 4.6320 MPa for tensile strength test and 24.87% for the elongation test. Based on the result of optical test for each sample was gained that along with the increasing of concentration filler would make the absorbance value of the sample became decreased, bio-nanocomposite with 5% filler concentration had several peaks with low absorbance values. The first peak was in 253 nm of wavelength regionwith absorbance of 0.131%, and the second peak was in 343 nmwavelength region and absorbance was 0.087%.

Synthesis of poly(furfuryl alcohol)/montmorillonite nanocomposites ...

Indian Academy of Sciences (India)

The purpose of this study was to obtain poly(furfuryl alcohol) nanocomposites with Algerian organically modified clay (termed 12-montmorillonite). The formation of poly(furfuryl alcohol) was confirmed by infrared spectroscopy (IR); the prepared nanocomposites were characterized by X-ray diffraction (XRD), transmission ...

What does See the Impulse Acoustic Microscopy inside Nanocomposites?

Science.gov (United States)

Levin, V. M.; Petronyuk, Y. S.; Morokov, E. S.; Celzard, A.; Bellucci, S.; Kuzhir, P. P.

The paper presents results of studying bulk microstructure in carbon nanocomposites by impulse acoustic microscopy technique. Nanocomposite materials are in the focus of interest because of their outstanding properties in minimal nanofiller content. Large surface area and high superficial activity cause strong interaction between nanoparticles that can result in formation of fractal conglomerates. This paper involves results of the first direct observation of nanoparticle conglomerates inside the bulk of epoxy-carbon nanocomposites. Diverse types of carbon nanofiller have been under investigation. The impulse acoustic microscope SIAM-1 (Acoustic Microscopy Lab, IBCP RAS) has been employed for 3D imaging bulk microstructure and measuring elastic properties of the nanocomposite specimens. The range of 50-200 MHz allows observing microstructure inside the entire specimen bulk. Acoustic images are obtained in the ultramicroscopic regime; they are formed by the Rayleigh type scattered radiation. It has been found the high-resolution acoustic vision (impulse acoustic microscopy) is an efficient technique to observe mesostructure formed by fractal cluster inside nanocomposites. The clusterization takes its utmost form in nanocomposites with graphite nanoplatelets as nanofiller. The nanoparticles agglomerate into micron-sized conglomerates distributed randomly over the material. Mesostructure in nanocomposites filled with carbon nanotubes is alternation of regions with diverse density of nanotube packing. Regions with alternative density of CNT packing are clearly seen in acoustical images as neighboring pixels of various brightness.

Carbon nanofiber/polyethylene nanocomposite: Processing behavior, microstructure and electrical properties

International Nuclear Information System (INIS)

Al-Saleh, Mohammed H.; Gelves, Genaro A.; Sundararaj, Uttandaraman

2013-01-01

Highlights: • Electrically conductive CNF/HDPE nanocomposite were prepared by melt compounding. • The effect of processing on the nanocomposites macro and micro structures was analyzed. • 1.4 vol% CNF were required to construct a conductive network within the HDPE matrix. • An EMI SE of 42 dB was reported for 15 vol% CNF/HDPE nanocomposite. • An empirical model was developed to estimate the EMI SE. - Abstract: Electrically conductive polymer nanocomposite of high density polyethylene (HDPE) filled with carbon nanofibers (CNFs) were prepared by melt compounding in a batch mixer. The nanocomposite processing behavior was studied by monitoring the mixing torque vs. time as function of filler content. Scanning electron microscopy and optical microscopy were used to investigate the nanocomposite dispersion of nanofiller and the adhesion between the nanofiller and polymer matrix. The electrical and electromagnetic interference (EMI) shielding behaviors of the nanocomposite were reported as function of nanofibers concentration, and an empirical correlation related the EMI SE to the nanocomposite’s electrical resistivity was developed. Good level of CNF dispersion was evident despite the poor adhesion exhibited between the nanofibers and the HDPE matrix. At 1.5 vol% CNF loading, the nanocomposite exhibited an electrical volume resistivity of 10 5 Ω·cm. EMI shielding effectiveness was found to increase with increase in nanofiller concentration. In the 0.1–1.5 GHz frequency range, 2 mm thick plate made of 5 vol% CNF/HDPE nanocomposite exhibits an EMI shielding effectiveness of 20 dB

Understanding hydration of Zn(2+) in hydrothermal fluids with ab initio molecular dynamics

NARCIS (Netherlands)

Liu, X.; Lu, X.; Wang, R.; Meijer, E.J.

2011-01-01

With ab initio molecular dynamics simulations, the free-energy profiles of hydrated Zn2+ are calculated for both gaseous and aqueous systems from ambient to supercritical conditions, and from the derived free-energy information, the speciation of hydrated Zn2+ has been revealed. It is shown that the

Preparation and Properties of Polyester-Based Nanocomposite Gel Coat System

Directory of Open Access Journals (Sweden)

P. Jawahar

2006-01-01

Full Text Available Nanocomposite gel coat system is prepared using unsaturated polyester resin with aerosil powder, CaCO3, and organoclay. The influence of organoclay addition on mechanical and water barrier properties of gel coat system is studied for different amount (1, 2, and 3 wt % of organoclay. The nanolevel incorporation of organoclay improves the mechanical and water barrier properties of nanocomposite gel coat system. The nanocomposite gel coat system exhibits 55% improvement in tensile modulus and 25% improvement in flexural modulus. There is a 30% improvement in impact property of nanocomposite gel coat system. The dynamic mechanical analysis shows a slight increase in glass transition temperature for nanocomposite gel coat system.

Development of nanocomposites employing high-density polyethylene and organo clay

International Nuclear Information System (INIS)

Lessa, Tathiane C. Rodrigues F.; Tavares, Maria Ines B.; Pita, Vitor J.R.R.

2009-01-01

The purpose of this study was to prepare nanocomposites of high-density polyethylene and montmorillonite organoclay by polymer melt intercalation, employing different processing parameters. Effective clay incorporation into polyethylene matrix was observed. The nanocomposites were structurally characterized. Intercalated nanocomposites were obtained from different process parameters, employing polyethylene resin and montmorillonite organoclays. The XRD results and other analysis showed that the processing parameters affect the organoclay delamination. The polyethylene nanocomposite presented the better performance using twin screw extruder, at 90 rpm. The purpose of characterization of polyethylene/organoclay nanocomposite by low-field NMR showed that this technique was important to understand changes in the molecular mobility of polyethylene when organoclay was incorporated. (author)

Visible-light photocatalytic performances of TiO2 nanoparticles modified by trace derivatives of PVA

Directory of Open Access Journals (Sweden)

Le SHI

2016-10-01

Full Text Available In order to study the visible-light photocatalytic activity and catalysis stability of nanocomposites, a TiO2-based visible-light photocatalyst is prepared by surface-modification of TiO2 nanoparticles using trace conjugated derivatives from polyvinyl alcohol (DPVA via a facile method. The obtained DPVA/TiO2 nanocomposites are characterized by X-ray diffraction (XRD, Fourier transform infrared Spectra (FT-IR, scanning electron microscopy (SEM, UV-vis diffuse reflection spectroscopy (DRS, and X-ray photoelectron spectroscopy (XPS. With Rhodamine B (RhB as a model pollutant, the visible-light photocatalytic activity and stability of DPVA/TiO2 nanocomposites are investigated by evaluating the RhB decomposition under visible light irradiation. The results reveal that the trace conjugated polymers on the TiO2 surface doesn’t change the crystalline and crystal size of TiO2 nanoparticles, but significantly enhances their visible-light absorbance and visible-light photocatalytic activity. The nanocomposite with the PVA and TiO2 mass ratio of 1∶200 exhibits the highest visible-light photocatalytic activity. The investigated nanocomposites exhibit well visible-light photoctatalytic stability. The photogenerated holes are thought as the main active species for the RhB photodegradation in the presence of the DPVA/TiO2 nanocomposites.

Titanium dioxide–cellulose hybrid nanocomposite and its glucose biosensor application

International Nuclear Information System (INIS)

Maniruzzaman, Mohammad; Jang, Sang-Dong; Kim, Jaehwan

2012-01-01

Highlights: ► An organic–inorganic hybrid nanocomposite was fabricated by blending TiO 2 nanoparticles and cellulose solution. ► The hybrid nanocomposite has advantages of biodegradability and bio-compatibility of cellulose and physical properties of TiO 2 . ► Enzyme glucose oxidase (GOx) was immobilized into the hybrid nanocomposite and covalent bonding between TiO 2 and GOx was confirmed by X-ray photoelectron analysis. ► Linear response of the glucose biosensor was obtained in the range of 1–10 mM. - Abstract: This paper investigates the fabrication of titanium dioxide (TiO 2 )–cellulose hybrid nanocomposite and its possibility for a conductometric glucose biosensor. TiO 2 nanoparticles were blended with cellulose solution prepared by dissolving cotton pulp with lithium chloride/N,N-dimethylacetamide solvent to fabricate TiO 2 –cellulose hybrid nanocomposite. The enzyme, glucose oxidase (GOx) was immobilized into this hybrid nanocomposite by physical adsorption method. The successful immobilization of glucose oxidase into TiO 2 –cellulose hybrid nanocomposite via covalent bonding between TiO 2 and GOx was confirmed by X-ray photoelectron analysis. The linear response of the glucose biosensor is obtained in the range of 1–10 mM. This study demonstrates that TiO 2 –cellulose hybrid nanocomposite can be a potential candidate for an inexpensive, flexible and disposable glucose biosensor.

Phenyl hepta cyclopentyl – polyhedral oligomeric silsesquioxane (ph,hcp-POSS/Polystyrene (PS nanocomposites: the influence of substituents in the phenyl group on the thermal stability

Directory of Open Access Journals (Sweden)

I. Blanco

2012-12-01

Full Text Available Some new Polystyrene (PS nanocomposites were prepared by using two Polyhedral Oligomeric Silsesquioxanes (POSSs, namely RR’7(SiO1.58 (where R = 4-methoxyphenyl or 2,4-difluorophenyl and R’ = cyclopentyl, as fillers, and their degradation was studied to investigate the effect of the electron-donor or electron-withdrawing character of the phenyl group substituents on thermal stability. Nanocomposites were synthesized by in situ polymerization of styrene in the presence of various concentrations of POSS. Proton nuclear magnetic resonance (1H NMR spectra indicated that the POSS content in the obtained nanocomposites was higher than that in reactant mixtures. Inherent viscosity (ηinh and glass transition temperature (Tg determinations indicated that the average molar mass of polymer in 4-methoxynanocomposites was the same than neat PS, while it was much lower in 2,4-difluoro derivatives. Degradations were carried out in both flowing nitrogen and static air atmospheres, in the scanning mode, at various heating rates, and temperature at 5% mass loss (T5% and the activation energy (Ea of degradation of various nanocomposites were determined. The values obtained for 4-methoxyderivatives were higher than unfilled PS thus indicating higher thermal stability. Conversely, the values found for 2,4-difluoro derivatives were lower, in some cases even than those of neat PS. The results were discussed and interpreted.

Aromatic-aliphatic polyamide/montmorillonite clay nanocomposite materials: Synthesis, nanostructure and properties

International Nuclear Information System (INIS)

Zulfiqar, Sonia; Ahmad, Zahoor; Ishaq, Muhammad; Sarwar, Muhammad Ilyas

2009-01-01

New type of aromatic-aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T g ) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability.

Aromatic-aliphatic polyamide/montmorillonite clay nanocomposite materials: Synthesis, nanostructure and properties

Energy Technology Data Exchange (ETDEWEB)

Zulfiqar, Sonia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Ahmad, Zahoor [Department of Chemistry, Faculty of Science, Kuwait University, P. O. Box: 5969, Safat 13060 (Kuwait); Ishaq, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Sarwar, Muhammad Ilyas, E-mail: ilyassarwar@hotmail.com [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716 (United States)

2009-11-15

New type of aromatic-aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T{sub g}) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability.

Au Based Nanocomposites Towards Plasmonic Applications

Science.gov (United States)

Panniello, A.; Curri, M. L.; Placido, T.; Reboud, V.; Kehagias, N.; Sotomayor Torres, C. M.; Mecerreyes, D.; Agostiano, A.; Striccoli, M.

2010-06-01

Incorporation of nano-sized metals in polymers can transfer their unique features to the host matrix, providing nanocomposite materials with improved optical, electric, magnetic and mechanical properties. In this work, colloidal Au nanorods have been incorporated into PMMA based random co-polymer, properly functionalized with amino groups and the optical and morphological properties of the resulting nanocomposite have been investigated by spectroscopic and AFM measurements. Au nanorods have demonstrated to preserve the plasmon absorption and to retain morphological features upon the incorporation, thus making the final metal modified polymer composite exploitable for the fabrication of plasmonic devices. The prepared nanocomposites have been then patterned by Nano Imprint Lithography technique in order to demonstrate the viability of the materials towards optical applications.

Poly (Lactic Acid)/Layered Silicate Nanocomposite Films: Effect of Irradiation

Energy Technology Data Exchange (ETDEWEB)

Dadbin, S.; Naimian, F.; Akhavan, A.; Hasanpoor, S., E-mail: sdadbin@yahoo.com, E-mail: sdadbin@aeoi.org.ir [Atomic Energy Organization of Iran (AEOI), Nuclear Science and Technology Research Institute, P.O. Box 11365-8486, Tehran, North Kargar (Iran, Islamic Republic of)

2010-07-01

Poly (Lactic acid) –layered silicate nanocomposite films were prepared by solution casting method. The films were irradiated with Co{sup 60} radiation facility at dose of 30 kGy. The effect of gamma irradiation on mechanical properties of the neat PLA and nanocomposites was evaluated by data obtained from tensile testing measurements. The tensile strength of the irradiated PLA films increased with addition of 1 wt% Triallyl Cyanurate (TAC) indicating crosslink formation. Significant ductile behavior was observed in the PLA nanocomposites containing 4 pph of nanoclay. Incorporation of nanoclay particles in the PLA matrix stimulated crystal growth as it was studied by differential scanning calorimetry (DSC). The morphology of the nanocomposites characterized by transmission electron microscopy (TEM) and X- ray diffraction (XRD) revealed an exfoliated morphology in the PLA nanocomposite films containing 4 pph of nanoclay. Only very small changes were observed in the chemical structure of the irradiated samples as it was investigated by Fourier transform infrared (FTIR) spectroscopy. Enzymatic degradation rate of PLA and its nanocomposite decreased with increasing crystallinity of the samples. The rate of weight loss was also affected by the morphology of the nanocomposites. (author)

Poly (Lactic Acid)/Layered Silicate Nanocomposite Films: Effect of Irradiation

International Nuclear Information System (INIS)

Dadbin, S.; Naimian, F.; Akhavan, A.; Hasanpoor, S.

2010-01-01

Poly (Lactic acid) –layered silicate nanocomposite films were prepared by solution casting method. The films were irradiated with Co 60 radiation facility at dose of 30 kGy. The effect of gamma irradiation on mechanical properties of the neat PLA and nanocomposites was evaluated by data obtained from tensile testing measurements. The tensile strength of the irradiated PLA films increased with addition of 1 wt% Triallyl Cyanurate (TAC) indicating crosslink formation. Significant ductile behavior was observed in the PLA nanocomposites containing 4 pph of nanoclay. Incorporation of nanoclay particles in the PLA matrix stimulated crystal growth as it was studied by differential scanning calorimetry (DSC). The morphology of the nanocomposites characterized by transmission electron microscopy (TEM) and X- ray diffraction (XRD) revealed an exfoliated morphology in the PLA nanocomposite films containing 4 pph of nanoclay. Only very small changes were observed in the chemical structure of the irradiated samples as it was investigated by Fourier transform infrared (FTIR) spectroscopy. Enzymatic degradation rate of PLA and its nanocomposite decreased with increasing crystallinity of the samples. The rate of weight loss was also affected by the morphology of the nanocomposites. (author)

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

International Nuclear Information System (INIS)

Sitompul, Johnner; Setyawan, Daru; Kim, Daniel Young Joon; Lee, Hyung Woo

2016-01-01

This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were then characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.

Preparation and Characterization of Phenolic Resin/Montmorillonite Nanocomposite

Directory of Open Access Journals (Sweden)

Morteza Soltan-Dehghan

2012-12-01

Full Text Available Phenolic resins have been widely used for selective high technology applications due to their excellent ablative properties, structural integrity and thermal stability that make them appropriate for thermal insulation materials, wood products industry, coatings, moulding compounds and composite materials. Polymer layered silicate nanocomposites based on montmorillonite (MMT have attracted a great deal of attention because of enhanced properties in mechanical, thermal, barrier and clarity properties without a significant increase in density, which is not possible with conventional fillers. Phenolic resin/montmorillonite (Cloisite 15A nanocomposite was prepared by a combined route of solution blending and in-situ polymerization. Theoptimized conditions for preparation of nanocomposite were achieved by evaluation of various processing parameters (mechanical mixer, high speed disperser and high energy ultrasonic source, mixing time (0.5, 1, 3, 10, 24, 48, 72, and 96 h and different amounts of montmorillonite (5 and 10 weight percents of montmorillonite relative to resol. X-Ray Diffractometer and thermal gravimetric analyzer were used accordingly to show the degree of nanodispersions of organomontmorillonite in polymeric matrix and the effect of nanofiller on thermal stability of nanocomposite with respect to neatresol. The results of high energy ultrasonic source show that a nanocomposite of phenolic resin with 5 wt% montmorillonite displays the best dispersion of clay layers. Thermal stability of nanocomposite was increased by 27% in comparison with neat resol.

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

Energy Technology Data Exchange (ETDEWEB)

Sitompul, Johnner, E-mail: sitompul@che.itb.ac.id; Setyawan, Daru, E-mail: daru.setyawan@gmail.com; Kim, Daniel Young Joon, E-mail: daniel.kim12321@gmail.com [Department of Chemical Engineering, Faculty of Industrial Technology, Institute of Technology Bandung Jl. Ganesha 10, Bandung, West Java, 40132 (Indonesia); Lee, Hyung Woo, E-mail: leehw@che.itb.ac.id [Department of Chemical Engineering, Faculty of Industrial Technology, Institute of Technology Bandung Jl. Ganesha 10, Bandung, West Java, 40132 (Indonesia); Research and Business Foundation, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi, 440-746 (Korea, Republic of)

2016-04-19

This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were then characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.

Handbook of polymer nanocomposites processing, performance and application

CERN Document Server

Mohanty, Amar; Misra, Manjusri; Kar, Kamal K; Pandey, Jitendra; Rana, Sravendra; Takagi, Hitoshi; Nakagaito, Antonio; Kim, Hyun-Joong

Volume A forms one volume of a Handbook about Polymer Nanocomposites. In some 20 chapters the preparation, architecture, characterisation, properties and application of polymer nanocomposites are discussed by experts in their respective fields.

Laser additive manufacturing bulk graphene-copper nanocomposites.

Science.gov (United States)

Hu, Zengrong; Chen, Feng; Lin, Dong; Nian, Qiong; Parandoush, Pedram; Zhu, Xing; Shao, Zhuqiang; Cheng, Gary J

2017-11-03

The exceptional mechanical properties of graphene make it an ideal nanofiller for reinforcing metal matrix composites (MMCs). In this work, graphene-copper (Gr-Cu) nanocomposites have been fabricated by a laser additive manufacturing process. Transmission electron microscopy (TEM), x-ray diffraction (XRD) and Raman spectroscopy were utilized to characterize the fabricated nanocomposites. The XRD, Raman spectroscopy, energy dispersive spectroscopy and TEM results demonstrated the feasibility of laser additive manufacturing of Gr-Cu nanocomposites. The microstructures were characterized by high resolution TEM and the results further revealed the interface between the copper matrix and graphene. With the addition of graphene, the mechanical properties of the composites were enhanced significantly. Nanoindentation tests showed that the average modulus value and hardness of the composites were 118.9 GPa and 3 GPa respectively; 17.6% and 50% increases were achieved compared with pure copper, respectively. This work demonstrates a new way to manufacture graphene copper nanocomposites with ultra-strong mechanical properties and provides alternatives for applications in electrical and thermal conductors.

Epoxy-silicate nanocomposites: Cure monitoring and characterization

International Nuclear Information System (INIS)

Hussain, Farzana; Chen, Jihua; Hojjati, Mehdi

2007-01-01

Epoxy-clay nanocomposites were prepared with organically modified layered clay with varying clay contents (1-8 wt.%). Neat resin and nanocomposite were characterized using different techniques. At first, the effect of nanoclay concentration on the cure behaviour was investigated using an on-line dielectric cure monitoring technique. Differential scanning calorimetry (DSC) was used to verify the dielectric measurement results. Furthermore, mechanical and thermal properties were studied using tensile test and Dynamic Mechanical Analysis (DMA), respectively. Experimental results showed that properties of the epoxy were changed evidently because of the nanoclay loading. The tensile modulus of the nanocomposites increased by 47%, however, no improvement in tensile strength and glass transition temperature (T g ) was observed. Fracture surface of the tensile samples were analyzed by Scanning Electron Microscope (SEM). The nanocomposites structures were characterized with Wide Angle X-Ray Diffraction (WAXD) and Transmission Electron Microscopy (TEM), which revealed the intercalated morphology of clay layers in the epoxy resin systems

Nafion–clay nanocomposite membranes: Morphology and properties

KAUST Repository

Herrera Alonso, Rafael; Estevez, Luis; Lian, Huiqin; Kelarakis, Antonios; Giannelis, Emmanuel P.

2009-01-01

A series of Nafion-clay nanocomposite membranes were synthesized and characterized. To minimize any adverse effects on ionic conductivity the clay nanoparticles were H+ exchanged prior to mixing with Nafion. Well-dispersed, mechanically robust, free-standing nanocomposite membranes were prepared by casting from a water suspension at 180 °C under pressure. SAXS profiles reveal a preferential orientation of Nafion aggregates parallel to the membrane surface, or normal plane. This preferred orientation is induced by the platy nature of the clay nanoparticles, which tend to align parallel to the surface of the membrane. The nanocomposite membranes show dramatically reduced methanol permeability, while maintaining high levels of proton conductivity. The hybrid films are much stiffer and can withstand much higher temperatures compared to pure Nafion. The superior thermomechanical, electrochemical and barrier properties of the nanocomposite membranes are of significant interest for direct methanol fuel cell applications. © 2009 Elsevier Ltd. All rights reserved.

Nafion–clay nanocomposite membranes: Morphology and properties

KAUST Repository

Herrera Alonso, Rafael

2009-05-01

A series of Nafion-clay nanocomposite membranes were synthesized and characterized. To minimize any adverse effects on ionic conductivity the clay nanoparticles were H+ exchanged prior to mixing with Nafion. Well-dispersed, mechanically robust, free-standing nanocomposite membranes were prepared by casting from a water suspension at 180 °C under pressure. SAXS profiles reveal a preferential orientation of Nafion aggregates parallel to the membrane surface, or normal plane. This preferred orientation is induced by the platy nature of the clay nanoparticles, which tend to align parallel to the surface of the membrane. The nanocomposite membranes show dramatically reduced methanol permeability, while maintaining high levels of proton conductivity. The hybrid films are much stiffer and can withstand much higher temperatures compared to pure Nafion. The superior thermomechanical, electrochemical and barrier properties of the nanocomposite membranes are of significant interest for direct methanol fuel cell applications. © 2009 Elsevier Ltd. All rights reserved.

Molecular structures and vibrational frequencies of xanthine and its methyl derivatives (caffeine and theobromine) by ab initio Hartree-Fock and density functional theory calculations

Science.gov (United States)

Ucun, Fatih; Sağlam, Adnan; Güçlü, Vesile

2007-06-01

The molecular structures, vibrational frequencies and corresponding vibrational assignments of xanthine and its methyl derivatives (caffeine and theobromine) have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with 6-31G(d, p) basis set level. The calculations were utilized to the CS symmetries of the molecules. The obtained vibrational frequencies and optimised geometric parameters (bond lengths and bond angles) were seen to be well agreement with the experimental data. The used scale factors which have been obtained the ratio of the frequency values of the strongest peaks in the calculated and experimental spectra seem to cause the gained vibrations well corresponding to the experimental ones. Theoretical infrared intensities and Raman activities are also reported.

Fracture behavior of α-zirconium phosphate-based epoxy nanocomposites

International Nuclear Information System (INIS)

Sue, H.-J.; Gam, K.T.; Bestaoui, N.; Clearfield, A.; Miyamoto, M.; Miyatake, N.

2004-01-01

The fracture behaviors of α-zirconium phosphate (α-ZrP) based epoxy nanocomposites, with and without core-shell rubber (CSR) toughening, were investigated. The state of exfoliation and dispersion of α-ZrP nanofiller in epoxy were characterized using X-ray scattering and various microscopy tools. The level of enhancement in storage moduli of epoxy nanocomposite against neat epoxy is found to depend on the state of exfoliation of α-ZrP as well as the damping characteristics of the epoxy matrix. The fracture process in epoxy nanocomposite is dominated by preferred crack propagation along the weak intercalated α-ZrP interfaces, and the presence of α-ZrP does not alter the fracture toughness of the epoxy matrix. However, the toughening using CSR can significantly improve the fracture toughness of the nanocomposite. The fracture mechanisms responsible for such a toughening effect in CSR-toughened epoxy nanocomposite are rubber particle cavitation, followed by shear banding of epoxy matrix. The ductility and toughenability of epoxy do not appear to be affected by the incorporation of α-ZrP. Approaches for producing toughened high performance polymer nanocomposites are discussed

Preparation, Characterization, and Modeling of Carbon Nanofiber/Epoxy Nanocomposites

Directory of Open Access Journals (Sweden)

Lan-Hui Sun

2011-01-01

Full Text Available There is a lack of systematic investigations on both mechanical and electrical properties of carbon nanofiber (CNF-reinforced epoxy matrix nanocomposites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nanocomposites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nanocomposites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nanocomposite with a 1.0 wt% CNFs. The alternate-current (AC electrical properties of the CNF/epoxy nanocomposites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt% (0.058 vol% CNFs and by ten orders of magnitude for nanocomposites with CNF volume fractions higher than 1.0 wt% (0.578 vol%. The percolation threshold (i.e., the critical CNF volume fraction is found to be at 0.057 vol%.

PVDF-PZT nanocomposite film based self-charging power cell.

Science.gov (United States)

Zhang, Yan; Zhang, Yujing; Xue, Xinyu; Cui, Chunxiao; He, Bin; Nie, Yuxin; Deng, Ping; Lin Wang, Zhong

2014-03-14

A novel PVDF-PZT nanocomposite film has been proposed and used as a piezoseparator in self-charging power cells (SCPCs). The structure, composed of poly(vinylidene fluoride) (PVDF) and lead zirconate titanate (PZT), provides a high piezoelectric output, because PZT in this nanocomposite film can improve the piezopotential compared to the pure PVDF film. The SCPC based on this nanocomposite film can be efficiently charged up by the mechanical deformation in the absence of an external power source. The charge capacity of the PVDF-PZT nanocomposite film based SCPC in 240 s is ∼0.010 μA h, higher than that of a pure PVDF film based SCPC (∼0.004 μA h). This is the first demonstration of using PVDF-PZT nanocomposite film as a piezoseparator for SCPC, and is an important step for the practical applications of SCPC for harvesting and storing mechanical energy.

In situ SU-8 silver nanocomposites

Directory of Open Access Journals (Sweden)

Søren V. Fischer

2015-07-01

Full Text Available Nanocomposite materials containing metal nanoparticles are of considerable interest in photonics and optoelectronics applications. However, device fabrication of such materials always encounters the challenge of incorporation of preformed nanoparticles into photoresist materials. As a solution to this problem, an easy new method of fabricating silver nanocomposites by an in situ reduction of precursors within the epoxy-based photoresist SU-8 has been developed. AgNO3 dissolved in acetonitrile and mixed with the epoxy-based photoresist SU-8 forms silver nanoparticles primarily during the pre- and post-exposure soft bake steps at 95 °C. A further high-temperature treatment at 300 °C resulted in the formation of densely homogeneously distributed silver nanoparticles in the photoresist matrix. No particle growth or agglomeration of nanoparticles is observed at this point. The reported new in situ silver nanocomposite materials can be spin coated as homogeneous thin films and structured by using UV lithography. A resolution of 5 µm is achieved in the lithographic process. The UV exposure time is found to be independent of the nanoparticle concentration. The fabricated silver nanocomposites exhibit high plasmonic responses suitable for the development of new optoelectronic and optical sensing devices.

Synthesis and utilization of poly (methylmethacrylate) nanocomposites based on modified montmorillonite

OpenAIRE

Youssef, Ahmed M.; Malhat, F.M.; Abdel Hakim, A.A.; Dekany, Imre

2015-01-01

Poly (methylmethacrylate) nanocomposite was prepared via in-situ emulsion polymerization (PMMA/Mt-CTA). The modified montmorillonite (Mt-CTA) is used as hosts for the preparation of poly (methylmethacrylate) nanocomposites with basal distance 1.95 nm. Moreover, exfoliated nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The fashioned nanocomposites exhibited bett...

MWCNT/CdS hybrid nanocomposite for enhanced photocatalytic activity

International Nuclear Information System (INIS)

Chaudhary, Deepti; Khare, Neeraj; Vankar, V. D.

2016-01-01

Multi-walled carbon nanotubes (MWCNT)/CdS hybrid nanocomposite were synthesized by one step hydrothermal method. MWCNTs were used as a substrate for the growth of CdS nanoparticles. MWCNT/CdS nanocomposite and pure CdS were characterized by XRD, TEM, UV-vis and photoluminescence spectroscopy. HRTEM study confirms the intimate contact of CdS with MWCNT. The photocatalytic activity of nanocomposite was studied for the degradation of methylene blue dye under UV irradiation. The enhanced photocatalytic activity of MWCNT/CdS nanocomposite as compared to pure CdS has been attributed to reduced recombination of photogenerated charge carriers due to interfacial electron transfer from CdS to MWCNT.

Rapid synthesis of flexible conductive polymer nanocomposite films

International Nuclear Information System (INIS)

Blattmann, C O; Sotiriou, G A; Pratsinis, S E

2015-01-01

Polymer nanocomposite films with nanoparticle-specific properties are sought out in novel functional materials and miniaturized devices for electronic and biomedical applications. Sensors, capacitors, actuators, displays, circuit boards, solar cells, electromagnetic shields and medical electrodes rely on flexible, electrically conductive layers or films. Scalable synthesis of such nanocomposite films, however, remains a challenge. Here, flame aerosol deposition of metallic nanosliver onto bare or polymer-coated glass substrates followed by polymer spin-coating on them leads to rapid synthesis of flexible, free-standing, electrically conductive nanocomposite films. Their electrical conductivity is determined during their preparation and depends on substrate composition and nanosilver deposition duration. Accordingly, thin (<500 nm) and flexible nanocomposite films are made having conductivity equivalent to metals (e.g. 5  × 10 4 S cm −1 ), even during repetitive bending. (paper)

Evaluation of tumor targeting with radiolabeled F(ab2 fragment of a humanized monoclonal antibody

Directory of Open Access Journals (Sweden)

"Babaei MH

2002-08-01

Full Text Available Humanized monoclonal antibody U36 and its F(ab'2 fragment, radio labeled with 125I, were tested for tumor localization in nude mice bearing a squamous cell carcinoma xenograft line derived from a head and neck carcinoma. Monoclonal antibody IgG or F(ab'2 fragment were injected in parallel and at days 1, 2 and 3, mice were dissected for determination of isotope biodistribution. IgG as well as F(ab'2 showed highly specific localization in tumor tissue. The mean tumor uptake (n=3 is expressed as the percentage of the injected dose per gram of tumor tissue (%ID/g. %ID/g of IgG was 11.7% at day 1 and decreased to 10.9% at day 3 whereas %ID/g of F(ab'2 was 2.9% at day 1 and decreased on following days. Tumor to blood ratios (T/B at day 1 were 0.86 for IgG and 1.32 for F(ab'2 and reached a maximum at day 3 with values of 4.41 and 1.84 respectively. These findings suggest that the superior tumor to non-tumor ratios in the day of 1 render the F(ab'2 fragment more qualified for specific targeting radioisotopes to tumor xenografts in this exprimental setting.

Investigation on VOX/CNTS Nanocomposites Act as Electrode of Supercapacitors

Science.gov (United States)

Zhu, Quanyao; Li, Zhaolong; Zhang, Xiaoyan; Huang, Shengnan; Yu, Yue; Chen, Wen; Zakharova, Galina S.

2013-07-01

The VOx/CNTs nanocomposites were synthesized by the hydrothermal method. The structure and morphologies of the nanocomposites were characteristic by XRD, SEM and TEM. The electrochemical properties of the nanocomposites were explored by cyclic voltammetry, constant current charge/discharge testing and electrochemical impedance spectroscopy in 1M KNO3 aqueous solution. The results showed that the nanocomposites perform characteristics of electrical both double-layer capacitance and pseudocapacitance. The specific capacitances were 136.5F/g, when the current density was 0.15A/g.

LIGNOCELLULOSE NANOCOMPOSITE CONTAINING COPPER SULFIDE

Directory of Open Access Journals (Sweden)

Sanchi Nenkova

2011-04-01

Full Text Available Copper sulfide-containing lignocellulose nanocomposites with improved electroconductivity were obtained. Two methods for preparing the copper sulfide lignocellulose nanocomposites were developed. An optimization of the parameters for obtaining of the nanocomposites with respect to obtaining improved electroconductivity, economy, and lower quantities and concentration of copper and sulfur ions in waste waters was conducted. The mechanisms and schemes of delaying and subsequent connection of copper sulfides in the lignocellulosic matrix were investigated. The modification with a system of 2 components: cupric sulfate pentahydrate (CuSO4. 5H2O and sodium thiosulfate pentahydrate (Na2S2O3.5H2O for wood fibers is preferred. Optimal parameters were established for the process: 40 % of the reduction system; hydromodule M=1:6; and ratio of cupric sulfate pentahydrate:sodium thiosulfate pentahydrate = 1:2. The coordinative connection of copper ions with oxygen atoms of cellulose OH groups and aromatic nucleus in lignin macromolecule was observed.

Nanocomposites Based on Biodegradable Polymers

Directory of Open Access Journals (Sweden)

Ilaria Armentano

2018-05-01

Full Text Available In the present review paper, our main results on nanocomposites based on biodegradable polymers (on a time scale from 2010 to 2018 are reported. We mainly focused our attention on commercial biodegradable polymers, which we mixed with different nanofillers and/or additives with the final aim of developing new materials with tunable specific properties. A wide list of nanofillers have been considered according to their shape, properties, and functionalization routes, and the results have been discussed looking at their roles on the basis of different adopted processing routes (solvent-based or melt-mixing processes. Two main application fields of nanocomposite based on biodegradable polymers have been considered: the specific interaction with stem cells in the regenerative medicine applications or as antimicrobial materials and the active role of selected nanofillers in food packaging applications have been critically revised, with the main aim of providing an overview of the authors’ contribution to the state of the art in the field of biodegradable polymeric nanocomposites.

Nanocomposite polymer electrolyte based on whisker or microfibrils polyoxyethylene nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Alloin, Fannie, E-mail: fannie.alloin@lepmi.grenoble-inp.f [LEPMI, Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, Grenoble-INP-UJF-CNRS, UMR 5631, BP 75, 38041 Grenoble Cedex 9 (France); D' Aprea, Alessandra [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France); LEPMI, Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, Grenoble-INP-UJF-CNRS, UMR 5631, BP 75, 38041 Grenoble Cedex 9 (France); Ecole Internationale du Papier, de la communication imprimee et des Biomateriaux, PAGORA- Grenoble-INP, BP 65, 38402 Saint Martin d' Heres Cedex (France); Kissi, Nadia El [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France); Dufresne, Alain [Ecole Internationale du Papier, de la communication imprimee et des Biomateriaux, PAGORA- Grenoble-INP, BP 65, 38402 Saint Martin d' Heres Cedex (France); Bossard, Frederic [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France)

2010-07-15

Nanocomposite polymer electrolytes composed of high molecular weight poly(oxyethylene) PEO as a matrix, LiTFSI as lithium salt and ramie, cotton and sisal whiskers with high aspect ratio and sisal microfibrils (MF), as reinforcing phase were prepared by casting-evaporation. The morphology of the composite electrolytes was investigated by scanning electron microscopy and their thermal behavior (characteristic temperatures, degradation temperature) were investigated by thermogravimetric analysis and differential scanning calorimetry. Nanocomposite electrolytes based on PEO reinforced by whiskers and MF sisal exhibited very high mechanical performance with a storage modulus of 160 MPa at high temperature. A weak decrease of the ionic conductivity was observed with the incorporation of 6 wt% of whiskers. The addition of microfibrils involved a larger decrease of the conductivity. This difference may be associated to the more restricted PEO mobility due to the addition of entangled nanofibers.

Titanium dioxide-cellulose hybrid nanocomposite and its glucose biosensor application

Energy Technology Data Exchange (ETDEWEB)

Maniruzzaman, Mohammad; Jang, Sang-Dong [Center for EAPap Actuator, Department of Mechanical Engineering, INHA University, Incheon 402-751 (Korea, Republic of); Kim, Jaehwan, E-mail: jaehwan@inha.ac.kr [Center for EAPap Actuator, Department of Mechanical Engineering, INHA University, Incheon 402-751 (Korea, Republic of)

2012-06-25

Highlights: Black-Right-Pointing-Pointer An organic-inorganic hybrid nanocomposite was fabricated by blending TiO{sub 2} nanoparticles and cellulose solution. Black-Right-Pointing-Pointer The hybrid nanocomposite has advantages of biodegradability and bio-compatibility of cellulose and physical properties of TiO{sub 2}. Black-Right-Pointing-Pointer Enzyme glucose oxidase (GOx) was immobilized into the hybrid nanocomposite and covalent bonding between TiO{sub 2} and GOx was confirmed by X-ray photoelectron analysis. Black-Right-Pointing-Pointer Linear response of the glucose biosensor was obtained in the range of 1-10 mM. - Abstract: This paper investigates the fabrication of titanium dioxide (TiO{sub 2})-cellulose hybrid nanocomposite and its possibility for a conductometric glucose biosensor. TiO{sub 2} nanoparticles were blended with cellulose solution prepared by dissolving cotton pulp with lithium chloride/N,N-dimethylacetamide solvent to fabricate TiO{sub 2}-cellulose hybrid nanocomposite. The enzyme, glucose oxidase (GOx) was immobilized into this hybrid nanocomposite by physical adsorption method. The successful immobilization of glucose oxidase into TiO{sub 2}-cellulose hybrid nanocomposite via covalent bonding between TiO{sub 2} and GOx was confirmed by X-ray photoelectron analysis. The linear response of the glucose biosensor is obtained in the range of 1-10 mM. This study demonstrates that TiO{sub 2}-cellulose hybrid nanocomposite can be a potential candidate for an inexpensive, flexible and disposable glucose biosensor.

Graphene-Decorated Nanocomposites for Printable Electrodes in Thin Wafer Devices

Science.gov (United States)

Bakhshizadeh, N.; Sivoththaman, S.

2017-12-01

Printable electrodes that induce less stress and require lower curing temperatures compared to traditional screen-printed metal pastes are needed in thin wafer devices such as future solar cells, and in flexible electronics. The synthesis of nanocomposites by incorporating graphene nanopowders as well as silver nanowires into epoxy-based electrically conductive adhesives (ECA) is examined to improve electrical conductivity and to develop alternate printable electrode materials that induce less stress on the wafer. For the synthesized graphene and Ag nanowire-decorated ECA nanocomposites, the curing kinetics were studied by dynamic and isothermal differential scanning calorimetry measurements. Thermogravimetric analysis on ECA, ECA-AG and ECA/graphene nanopowder nanocomposites showed that the temperatures for onset of decomposition are higher than their corresponding glass transition temperature ( T g) indicating an excellent thermal resistance. Printed ECA/Ag nanowire nanocomposites showed 90% higher electrical conductivity than ECA films, whereas the ECA/graphene nanocomposites increased the conductivity by over two orders of magnitude. Scanning electron microscopy results also revealed the effect of fillers morphology on the conductivity improvement and current transfer mechanisms in nanocomposites. Residual stress analysis performed on Si wafers showed that the ECA and nanocomposite printed wafers are subjected to much lower stress compared to those printed with metallic pastes. The observed parameters of low curing temperature, good thermal resistance, reasonably high conductivity, and low residual stress in the ECA/graphene nanocomposite makes this material a promising alternative in screen-printed electrode formation in thin substrates.

Metal Nanocomposites

DEFF Research Database (Denmark)

Fischer, Søren Vang; Uthuppu, Basil; Jakobsen, Mogens Havsteen

2014-01-01

We have made SU-8 gold nanoparticle composites in two ways, ex situ and in situ, and found that in both methods nanoparticles embedded in the polymer retained their plasmonic properties. The in situ method has also been used to fabricate a silver nanocomposite which is electrically conductive. Th...

Microstructure of polymer-clay nanocomposites studied by positrons

International Nuclear Information System (INIS)

Wang, S.J.; Liu, L.M.; Fang, P.F.; Chen, Z.; Wang, H.M.; Zhang, S.P.

2007-01-01

The epoxy-rectorite nanocomposites with different rectorite contents, epoxide equivalent were prepared and its microstructure was studied by positron annihilation and X-ray diffraction (XRD). At low rectorite content (0-2.0%), the free volume size in nanocomposites is nearly the same, but its concentration decreases with increasing content; the exfoliated structure was observed by XRD and interfacial layer formation between rectorite platelets and epoxy matrix was probed by positrons. Comparing with epoxy-montmorillonite, the exfoliated structure and interfacial layers are easier formed in epoxy-rectorite nanocomposites

Nanocomposites for Machining Tools

Directory of Open Access Journals (Sweden)

Daria Sidorenko

2017-10-01

Full Text Available Machining tools are used in many areas of production. To a considerable extent, the performance characteristics of the tools determine the quality and cost of obtained products. The main materials used for producing machining tools are steel, cemented carbides, ceramics and superhard materials. A promising way to improve the performance characteristics of these materials is to design new nanocomposites based on them. The application of micromechanical modeling during the elaboration of composite materials for machining tools can reduce the financial and time costs for development of new tools, with enhanced performance. This article reviews the main groups of nanocomposites for machining tools and their performance.

Plasmonic, excitonic and exciton-plasmonic photoinduced nanocomposites

Science.gov (United States)

Bityurin, N.; Ermolaev, N.; Smirnov, A. A.; Afanasiev, A.; Agareva, N.; Koryukina, T.; Bredikhin, V.; Kamensky, V.; Pikulin, A.; Sapogova, N.

2016-03-01

UV irradiation of materials consisting of a polymer matrix that possesses precursors of different kinds can result in creation of nanoparticles within the irradiated domains. Such photoinduced nanocomposites are promising for photonic applications due to the strong alteration of their optical properties compared to initial non-irradiated materials. We report our results on the synthesis and investigation of plasmonic, excitonic and exciton-plasmonic photoinduced nanocomposites. Plasmonic nanocomposites contain metal nanoparticles of noble metals with a pronounced plasmon resonance. Excitonic nanocomposites possess semiconductor nanoclusters (quantum dots). We consider the CdS-Au pair because the luminescent band of CdS nanoparticles enters the plasmon resonance band of gold nanoparticles. The obtaining of such particles within the same composite materials is promising for the creation of media with exciton-plasmon resonance. We demonstrate that it is possible to choose appropriate precursor species to obtain the initially transparent poly(methyl methacrylate) (PMMA) films containing both types of these molecules either separately or together. Proper irradiation of these materials by a light-emitting diode operating at the wavelength of 365 nm provides material alteration demonstrating light-induced optical absorption and photoluminescent properties typical for the corresponding nanoparticles. Thus, an exciton-plasmonic photoinduced nanocomposite is obtained. It is important that here we use the precursors that are different from those usually employed.

Polyethylenedioxythiophene and molybdenum disulfide nanocomposite electrodes for supercapacitor applications

International Nuclear Information System (INIS)

Alamro, Turki; Ram, Manoj K.

2017-01-01

Highlights: • MoS_2-PEDOT nanocomposite electrode material was synthesized using polyanion ‘PSS’ and surfactant CTAB in an aqueous media. • The supercapacitor based on composite MoS_2-PEDOT electrode revealed higher energy density than graphene composite electrodes. • The specific capacitance of 361 Farad/gram (F/g) was obtained for 1:2 weight ratio of MoS2 to the EDOT monomer in MoS_2-PEDOT nanocomposite based electrodes. - Abstract: An innovative nanocomposite electrode was chemically synthesized using molybdenum disulphide (MoS_2)- polyethylenedioxythiophene (PEDOT) to understand the charge mechanism in a symmetric supercapacitor. The MoS_2-PEDOT nanocomposite was produced at various ratios of MoS_2 to ethylenedioxythiophene (EDOT) in an aqueous medium of polyanions polystyrene sulfonate (PSS) and cetyltrimethylammonium bromide (CTAB) at controlled conditions. The morphology, crystallinity, and optical properties of MoS_2-PEDOT nanocomposite materials were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, particle size analyzer, Raman spectroscopy, X-ray-diffraction, and transmission electron microscopy (TEM) techniques, respectively. The electrochemical properties of the supercapacitor were investigated using cyclic voltammetry, charging–discharging at constant current and electrochemical impedance spectroscopy (EIS) techniques. The specific capacitance, power and energy densities of the supercapacitor were estimated using cyclic voltammetry (CV), charging–discharging, Nyquist and Bode plots. The specific capacitance was estimated to be 361 Farad/gram (F/g) for the 1:2 weight ratio of MoS_2 to the EDOT monomer in the MoS_2-PEDOT nanocomposite based electrodes. Nevertheless, this study provides a fundamental aspect of synthesis of nanocomposite material for optimum attainment supercapacitive properties based on the MoS_2-PEDOT nanocomposite electrode for practical energy storage applications.

PBAT based nanocomposites for medical and industrial applications

International Nuclear Information System (INIS)

Fukushima, Kikku; Wu, Meng-Hsiu; Bocchini, Sergio; Rasyida, Amaliya; Yang, Ming-Chien

2012-01-01

Poly(butylene adipate-co-terephthalate) (PBAT) based nanocomposites were prepared by melt blending PBAT with 5 and 10 wt.% of clay nanoparticles (unmodified and modified montmorillonites, unmodified and modified fluoro-hectorites, and unmodified sepiolites). All nanocomposites showed a good level of clay distribution and dispersion into PBAT, especially nanocomposites with high clay chemical affinity with the polymer matrix. DSC results showed that addition of layered silicates slightly hindered kinetics and extent of crystallization of PBAT; however, sepiolite particles were able to promote polymer crystallization kinetics and the transformation of the PBAT crystal structure to a more ordered form. Similar increases in the thermal stability of PBAT in nitrogen and air were obtained upon addition of all clays, due to a barrier effect of the clays toward polymer decomposition product ablation. Preliminary biocompatibility tests indicated that PBAT based materials with 10% clay content have good biological safety and display almost no cytotoxicity. The addition of all nanofillers increased the hardness of PBAT matrix. The DMA analysis showed that all nanocomposites presented higher E′ values than neat PBAT, indicating that addition of clays improved the mechanical properties of PBAT. For layered silicate nanocomposites, the main influencing factors on the thermo-mechanical properties appeared to be the aspect ratio and dispersion of clay nanoplatelets, rather than polymer/clay chemical affinity. The highest E′ values of sepiolite based nanocomposites make this nanoparticle the most attractive material for tissue engineering and environmental industrial applications. Highlights: ► PBAT nanocomposites with high thermo-mechanical properties were obtained. ► The effects of clay presence on PBAT crystalline structure were elucidated. ► The presence of the clays used in PBAT showed good biological safety. ► Sepiolites brought the higher improvements in PBAT

New nanocomposites of polystyrene with polyaniline doped with lauryl sulfuric acid

Science.gov (United States)

Pud, A. A.; Nikolayeva, O. A.; Vretik, L. O.; Noskov, Yu. V.; Ogurtsov, N. A.; Kruglyak, O. S.; Fedorenko, E. A.

2017-08-01

This work is concentrated on synthesis and investigation of new core-shell nanocomposites of polystyrene (PS) with doped polyaniline (PANI). The latex containing PS nanoparticles with sizes of 15-30 nm was prepared by microemulsion polymerization of styrene in water media. The PS/PANI nanocomposites were synthesized by chemical oxidative polymerization of aniline in the PS latex media in a presence of lauryl sulfuric acid (LSA), which served as both dopant and plasticizer. The real content of PANI in the synthesized nanocomposites was determined by UV-Vis spectroscopy method. The composition of the nanocomposites and oxidation state of the doped polyaniline were characterized by FTIR spectroscopy. The core-shell morphology of the nanocomposite nanoparticles was proved by transmission and scanning electron microscopy. It was found that conductivity and thermal behavior in air of these nanocomposites not only nonlinearly depended on the doped polyaniline content but also were strongly effected both by plasticizing properties of the acid-dopant and presence of the polyaniline shell. A possibility of application of these nanocomposites as sensor materials has been demonstrated.

Synthesis and utilization of poly (methylmethacrylate nanocomposites based on modified montmorillonite

Directory of Open Access Journals (Sweden)

Ahmed M. Youssef

2017-07-01

Full Text Available Poly (methylmethacrylate nanocomposite was prepared via in-situ emulsion polymerization (PMMA/Mt-CTA. The modified montmorillonite (Mt-CTA is used as hosts for the preparation of poly (methylmethacrylate nanocomposites with basal distance 1.95 nm. Moreover, exfoliated nanocomposite was characterized by X-ray diffraction (XRD, transmission electron microscope (TEM, thermal gravimetric analysis (TGA, and differential scanning calorimetry (DSC. The fashioned nanocomposites exhibited better thermal stability than pristine PMMA which make it suitable for packaging applications. Furthermore, this nanocomposite reveals tremendous affinity for removing pesticides from aquatic solutions. The data obtained from GC/ECD gas liquid chromatography illustrated that the removal efficiency of PMMA/Mt-CTA nanocomposites for organochlorine pesticides (OCPs varied from 73.65% to 99.36% that make it as a new method for water treatment. Also, the antimicrobial activity of the Mt-CTA and PMMA/Mt-CTA nanocomposites was evaluated by the inhibitory zone tests and revealed good activity against Escherichia coli and Staphylococcus aureus, which makes it suitable materials for packaging applications.

Biodegradability and mechanical properties of reinforced starch nanocomposites using cellulose nanofibers.

Science.gov (United States)

Babaee, Mehran; Jonoobi, Mehdi; Hamzeh, Yahya; Ashori, Alireza

2015-11-05

In this study the effects of chemical modification of cellulose nanofibers (CNFs) on the biodegradability and mechanical properties of reinforced thermoplastic starch (TPS) nanocomposites was evaluated. The CNFs were modified using acetic anhydride and the nanocomposites were fabricated by solution casting from corn starch with glycerol/water as the plasticizer and 10 wt% of either CNFs or acetylated CNFs (ACNFs). The morphology, water absorption (WA), water vapor permeability rate (WVP), tensile, dynamic mechanical analysis (DMA), and fungal degradation properties of the obtained nanocomposites were investigated. The results demonstrated that the addition of CNFs and ACNFs significantly enhanced the mechanical properties of the nanocomposites and reduced the WVP and WA of the TPS. The effects were more pronounced for the CNFs than the ACNFs. The DMA showed that the storage modulus was improved, especially for the CNFs/TPS nanocomposite. Compared with the neat TPS, the addition of nanofibers improved the degradation rate of the nanocomposite and particularly ACNFs reduced degradation rate of the nanocomposite toward fungal degradation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis of Cu-CNTs nanocomposites via double pressing double sintering method

Directory of Open Access Journals (Sweden)

Marjan Darabi

2018-01-01

Full Text Available In this research, copper (Cu-carbon nanotubes (CNTs nanocomposites were synthesized with different weight percentages of CNTs by double pressing double sintering (DPDS method as well as conventional sintering method. A planetary ball mill was used to disperse CNTs in Cu matrix. The milled powders were first cold pressed to 450 MPa in a uniaxial stainless-steel die with cylindrical compacts (diameter: 12 mm and height: 5 mm. The effect of CNTs content and the DPDS method on the properties of the nanocomposites were investigated. The microstructure and phase analysis of Cu-CNTs nanocomposite samples were studied by FESEM and X-Ray Diffraction. The electrical conductivity of nanocomposites was measured and compared to both sintering methods. Mechanical properties of Cu-CNTs nanocomposites were characterized using bending strength and micro-hardness measurements. Enhancements of about 32% in bending strength, 31.6% in hardness and 19.5% in electrical conductivity of Cu-1 wt.% CNTs nanocomposite synthesized by DPDS method were observed as compared to Cu-1 wt.% CNTs nanocomposites fabricated under the similar condition by a conventional sintering process.

Magnetic nanocomposite sensor

KAUST Repository

Alfadhel, Ahmed; Li, Bodong; Kosel, Jü rgen

2016-01-01

A magnetic nanocomposite device is described herein for a wide range of sensing applications. The device utilizes the permanent magnetic behavior of the nanowires to allow operation without the application of an additional magnetic field

Temperature-Dependent Dielectric Properties of Al/Epoxy Nanocomposites

Science.gov (United States)

Wang, Zijun; Zhou, Wenying; Sui, Xuezhen; Dong, Lina; Cai, Huiwu; Zuo, Jing; Chen, Qingguo

2016-06-01

Broadband dielectric spectroscopy was carried out to study the transition in electrical properties of Al/epoxy nanocomposites over the frequency range of 1-107 Hz and the temperature range of -20°C to 200°C. The dielectric permittivity, dissipation factor, and electrical conductivity of the nanocomposites increased with temperature and showed an abrupt increase around the glass transition temperature ( T g). The results clearly reveal an interesting transition of the electrical properties with increasing temperature: insulator below 70°C, conductor at about 70°C. The behavior of the transition in electrical properties of the nanocomposites was explored at different temperatures. The presence of relaxation peaks in the loss tangent and electric modulus spectra of the nanocomposites confirms that the chain segmental dynamics of the polymer is accompanied by the absorption of energy given to the system. It is suggested that the temperature-dependent transition of the electric properties in the nanocomposite is closely associated with the α-relaxation. The large increase in the dissipation factor and electric conductivity depends on the direct current conduction of thermally activated charge carriers resulting from the epoxy matrix above T g.

Enhancement of mechanical properties of epoxy/graphene nanocomposite

Science.gov (United States)

Berhanuddin, N. I. C.; Zaman, I.; Rozlan, S. A. M.; Karim, M. A. A.; Manshoor, B.; Khalid, A.; Chan, S. W.; Meng, Q.

2017-10-01

Graphene is a novel class of nanofillers possessing outstanding characteristics including most compatible with most polymers, high absolute strength, high aspect ratio and cost effectiveness. In this study, graphene was used to reinforce epoxy as a matrix, to enhance its mechanical properties. Two types of epoxy composite were developed which are epoxy/graphene nanocomposite and epoxy/modified graphene nanocomposite. The fabrication of graphene was going through thermal expansion and sonication process. Chemical modification was only done for modified graphene where 4,4’-Methylene diphenyl diisocyanate (MDI) is used. The mechanical properties of both nanocomposite, such as Young’s modulus and maximum stress were investigated. Three weight percentage were used for this study which are 0.5 wt%, 1.0 wt% and 1.5 wt%. At 0.5 wt%, modified and unmodified shows the highest value compared to neat epoxy, where the value were 8 GPa, 6 GPa and 0.675 GPa, respectively. For maximum stress, neat epoxy showed the best result compared to both nanocomposite due to the changes of material properties when adding the filler into the matrix. Therefore, both nanocomposite increase the mechanical properties of the epoxy, however modification surface of graphene gives better improvement.

Ab initio study of the isomerism of (LiAB)2 salt dimers with 24 valence electrons (AB- = NO-, PO-, NS-, PS-)

International Nuclear Information System (INIS)

Charkin, O.P.; Klimenko, N.M.; MakKi, M.L.

2000-01-01

The nonempiric calculations of the potential energies surfaces in the vicinity of the key structures of the loose dimer molecules of the (LiNO) 2 , (LiPO) 2 , (LiNS) 2 and (LiPS) 2 lithium salts with 24 valence electrons are accomplished within the frames of the MP2/6-31G * //HF/6-31g * + ZPE(HF/6-31G * and MP4SDTQ/6-31G * //MP2/6-31G * + ZPE(MP2/6-31G * ) approximation. The equilibrium geometrical parameters, relative energies and isomer decay energies, frequencies and IR-intensities of normal vibrations are determined. The geometrical deformations and shifts of vibrational frequencies of the cis- and trans-dianions under the effect of cations by different ways of their coordination as well as tendencies of the molecular properties behaviour in various series of dimers (LiAB) 2 are analyzed. The results obtained are compared with the data of previous calculations of the LiAB salts monomeric molecules, the Li 2 AB + ions with 12 valence electrons and the (LiAB) 2 dimers with 20 valence electrons [ru

Biocompatible epoxy modified bio-based polyurethane nanocomposites: mechanical property, cytotoxicity and biodegradation.

Science.gov (United States)

Dutta, Suvangshu; Karak, Niranjan; Saikia, Jyoti Prasad; Konwar, Bolin Kumar

2009-12-01

Epoxy modified Mesua ferrea L. seed oil (MFLSO) based polyurethane nanocomposites with different weight % of clay loadings (1%, 2.5% and 5%) have been evaluated as biocompatible materials. The nanocomposites were prepared by ex situ solution technique under high mechanical shearing and ultrasonication at room temperature. The partially exfoliated nanocomposites were characterized by Fourier transform infra-red (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The mechanical properties such as tensile strength and scratch hardness were improved 2 and 5 times, respectively by nanocomposites formation. Even the impact resistance improved a little. The thermostability of the nanocomposites was enhanced by about 40 degrees C. Biodegradation study confirmed 5-10 fold increase in biodegradation rate for the nanocomposites compared to the pristine polymers. All the nanocomposites showed non-cytotoxicity as evident from RBC hemolysis inhibition observed in anti-hemolytic assay carried over the sterilized films. The study reveals that the epoxy modified MFLSO based polyurethane nanocomposites deserve the potential to be applicable as biomaterials.

On the dimensional reduction of a gravitational theory containing higher-derivative terms

International Nuclear Information System (INIS)

Pollock, M.D.

1990-02-01

From the higher-dimensional gravitational theory L-circumflex=R-circumflex-2Λ-circumflex-α-circumflex 1 R-circumflex 2 =α-circumflex 2 R-circumflex AB R-circumflex AB -α-circumflex 3 R-circumflex ABCD R-circumflex ABCD , we derive the effective four-dimensional Lagrangian L. (author). 12 refs

Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

Science.gov (United States)

Li, Shanghua; Qin, Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

2009-05-01

PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

International Nuclear Information System (INIS)

Li Shanghua; Qin Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

2009-01-01

PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

Synthesis and biological evaluation of PMMA/MMT nanocomposite as denture base material.

Science.gov (United States)

Zheng, Junping; Su, Qiang; Wang, Chen; Cheng, Gang; Zhu, Ran; Shi, Jin; Yao, Kangde

2011-04-01

Inorganic-polymer nanocomposites are of significant interest for emerging materials due to their improved properties and unique combination of properties. Poly (methylmethacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were prepared by in situ suspension polymerization with dodecylamine used as MMT-modifier. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the structures of the nanocomposites. Cytotoxicity test, hemolysis test, acute systemic toxicity test, oral mucous membrane irritation test, guinea-pig maximization test and mouse bone-marrow micronucleus test were used to evaluate the biocompatibility of PMMA/MMT nanocomposites. The results indicated that an exfoliated nanocomposite was achieved, and the resulting nanocomposites exhibited excellent biocompatibility as denture base material and had potential application in dental materials.

Epoxy based nanocomposites with fully exfoliated unmodified clay: mechanical and thermal properties.

Science.gov (United States)

Li, Binghai; Zhang, Xiaohong; Gao, Jianming; Song, Zhihai; Qi, Guicun; Liu, Yiqun; Qiao, Jinliang

2010-09-01

The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.

Antimicrobial hyperbranched poly(ester amide)/polyaniline nanofiber modified montmorillonite nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Pramanik, Sujata [Advanced Polymer and Nanomaterial Laboratory, Department of Chemical Sciences, Tezpur University, Tezpur 784028 (India); Bharali, Pranjal; Konwar, B.K. [Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784028 (India); Karak, Niranjan, E-mail: karakniranjan@yahoo.com [Advanced Polymer and Nanomaterial Laboratory, Department of Chemical Sciences, Tezpur University, Tezpur 784028 (India)

2014-02-01

There has been growing interest in the use of nanomaterials featuring potent of antimicrobial activity in the biomedical domain. It still remains a challenge for the researchers to develop an efficient nanocomposite possessing antimicrobial efficacy against broad spectrum microbes including bacteria, fungi as well as algal consortium, posing serious challenges for the human survival. In addressing the above problem, we report the fabrication of bio-based hyperbranched poly(ester amide) (HBPEA)/polyaniline nanofiber modified montmorillonite (MMT) nanocomposites by an ex-situ polymerization technique at varied weight percentages (1, 2.5, 5 wt.%) of the modified MMT (nanohybrid). The Fourier transform infrared spectroscopy confirmed the structural changes upon interaction of the nanohybrid with HBPEA. A probable mechanism is proposed for the formation of nanocomposites with partially exfoliated nanoplatelet structure, which was further confirmed from the high resolution transmission electron microscopic analyses. The prepared nanocomposites exhibited potent efficacy against gram positive bacteria like Bacillus subtilis and Staphylococcus aureus as compared to the gram negative ones like Pseudomonas aeruginosa and Escherichia coli. The nanocomposites showed significant antifungal activity against Aspergillus niger, Fusarium oxysporum and Coleotricum capcii and antialgal activity against algal consortium comprising of Chlorella, Hormidium and Cladophorella species. The formation of thermosetting nanocomposites resulted in the acceptable improvement of desired physico-chemical and mechanical properties including thermostability. Thus pronounced antimicrobial activity of the nanocomposites against a spectrum of bacterial and fungal strains as well as a consortium of algal species along with other desired performance vouched them as potent antimicrobial materials in the realm of health and biomedical industry. - Highlights: • A possible approach for fabrication of the

Antimicrobial hyperbranched poly(ester amide)/polyaniline nanofiber modified montmorillonite nanocomposites

International Nuclear Information System (INIS)

Pramanik, Sujata; Bharali, Pranjal; Konwar, B.K.; Karak, Niranjan

2014-01-01

There has been growing interest in the use of nanomaterials featuring potent of antimicrobial activity in the biomedical domain. It still remains a challenge for the researchers to develop an efficient nanocomposite possessing antimicrobial efficacy against broad spectrum microbes including bacteria, fungi as well as algal consortium, posing serious challenges for the human survival. In addressing the above problem, we report the fabrication of bio-based hyperbranched poly(ester amide) (HBPEA)/polyaniline nanofiber modified montmorillonite (MMT) nanocomposites by an ex-situ polymerization technique at varied weight percentages (1, 2.5, 5 wt.%) of the modified MMT (nanohybrid). The Fourier transform infrared spectroscopy confirmed the structural changes upon interaction of the nanohybrid with HBPEA. A probable mechanism is proposed for the formation of nanocomposites with partially exfoliated nanoplatelet structure, which was further confirmed from the high resolution transmission electron microscopic analyses. The prepared nanocomposites exhibited potent efficacy against gram positive bacteria like Bacillus subtilis and Staphylococcus aureus as compared to the gram negative ones like Pseudomonas aeruginosa and Escherichia coli. The nanocomposites showed significant antifungal activity against Aspergillus niger, Fusarium oxysporum and Coleotricum capcii and antialgal activity against algal consortium comprising of Chlorella, Hormidium and Cladophorella species. The formation of thermosetting nanocomposites resulted in the acceptable improvement of desired physico-chemical and mechanical properties including thermostability. Thus pronounced antimicrobial activity of the nanocomposites against a spectrum of bacterial and fungal strains as well as a consortium of algal species along with other desired performance vouched them as potent antimicrobial materials in the realm of health and biomedical industry. - Highlights: • A possible approach for fabrication of the

Effect of irradiation in nanocomposite films of LLDPE

International Nuclear Information System (INIS)

Jagtap, R.N.; Shaikh, J.; Anandakrishnan, R.; Sharma, A.K.; Varier, P.S.

2009-01-01

Melt compounding was used for the preparation of LLDPE/MMT nanocomposite. The films were irradiated with gamma irradiation to study its mechanical, optical, thermal properties, barrier properties. Montmorillonite clay was treated with cationic emulsifier, to modify the surface properties by HCl and functionalizing with acetic acid. These treated clays were then incorporated in LLDPE to prepare nanocomposite films and then it is irradiated with gamma rays for different dosages of irradiation varying from 0 to 30 kGy, which can be used for food packaging applications. These nanocomposites were characterized by XRD and FTIR. (author)

Cyclic viscoelasticity and viscoplasticity of polypropylene/clay nanocomposites

DEFF Research Database (Denmark)

Drozdov, Aleksey; Christiansen, Jesper de Claville; Hog Lejre, Anne-Lise

2012-01-01

Observations are reported in tensile relaxation tests under stretching and retraction on poly-propylene/clay nanocomposites with various contents of filler. A two-phase constitutive model is developed in cyclic viscoelasticity and viscoplasticity of hybrid nanocomposites. Adjustable parameters in...

Investigation of optical properties of Ag: PMMA nanocomposite structures

Science.gov (United States)

Ponelyte, S.; Palevicius, A.; Guobiene, A.; Puiso, J.; Prosycevas, I.

2010-05-01

In the recent years fundamental research involving the nanodimensional materials has received enormous momentum for observing and understanding new types of plasmonic materials and their physical phenomena occurring in the nanoscale. Mechanical and optical properties of these polymer based nanocomposite structures depend not only on type, dimensions and concentration of filler material, but also on a kind of polymer matrix used. By proper selection of polymer matrix and nanofillers, it is possible to engineer nanocomposite materials with certain favorable properties. One of the most striking features of nanocomposite materials is that they can expose unique optical properties that are not intrinsic to natural materials. In these researches, nanocomposite structures were formed using polymer (PMMA) as a matrix, and silver nanoparticles as fillers. By hot embossing procedure a diffraction grating was imprinted on formed layers. The effect of UV exposure time on nanocomposite structures morphology, optical (diffraction effectiveness, absorbance) and mechanical properties was investigated. Results were confirmed by UV-VIS spectrometer, Laser Diffractometer, PMT- 3 and AFM. Investigations proposed new nanocomposite structures as plasmonic materials with improved optical and mechanical properties, which may be applied for a number of technological applications: micro-electro-mechanical devices, optical devices, various plasmonic sensors, or even in DNA nanotechnology.

Polymer-ceramic nanocomposites for applications in the bone surgery

Science.gov (United States)

Stodolak, E.; Gadomska, K.; Lacz, A.; Bogun, M.

2009-01-01

The subject of this work was preparation and investigation of properties of a nanocomposite material based on polymer matrix modified with nanometric silica particles (SiO2). The composite matrix consisted of resorbable P(L/DL)LA polymer with certified biocompatibility. Nanometric silica was introduced into the matrix by means of ultrasonic homogenisation and/or mechanical stirring. The silica was introduced directly e.g. as nanoparticles or inside calcium alginate fibres which contained 3 wt.% of amorphous SiO2. Proper dispersion of nano-filliers was confirmed by means of thermal analysis (TG/DTA, DSC). It was observed, that the presence of inorganic nanoparticles influenced several surface parameters of the nanocomposites i.e. hydrophility (a decrease of surface energy) and topography (both in micro- and nano-scale). Additionally, the nanocomposites exhibited enhanced mechanical properties (Young's modulus, tensile strength) compared to the pure polymer. The nanocomposites were bioactive materials (SBF/3 days/37oC). Biological tests (MTT test) showed a good viability of human osteoblasts (hFOB 1.19) in contact with the nanocomposites surface. Results of preliminary biological tests carried out with the use of mother cells extracted from human bone marrow showed that the nanocomposites may provide differenation of bone cells.

Polymer-ceramic nanocomposites for applications in the bone surgery

International Nuclear Information System (INIS)

Stodolak, E; Gadomska, K; Lacz, A; Bogun, M

2009-01-01

The subject of this work was preparation and investigation of properties of a nanocomposite material based on polymer matrix modified with nanometric silica particles (SiO 2 ). The composite matrix consisted of resorbable P(L/DL)LA polymer with certified biocompatibility. Nanometric silica was introduced into the matrix by means of ultrasonic homogenisation and/or mechanical stirring. The silica was introduced directly e.g. as nanoparticles or inside calcium alginate fibres which contained 3 wt.% of amorphous SiO 2 . Proper dispersion of nano-filliers was confirmed by means of thermal analysis (TG/DTA, DSC). It was observed, that the presence of inorganic nanoparticles influenced several surface parameters of the nanocomposites i.e. hydrophility (a decrease of surface energy) and topography (both in micro- and nano-scale). Additionally, the nanocomposites exhibited enhanced mechanical properties (Young's modulus, tensile strength) compared to the pure polymer. The nanocomposites were bioactive materials (SBF/3 days/37 deg. C). Biological tests (MTT test) showed a good viability of human osteoblasts (hFOB 1.19) in contact with the nanocomposites surface. Results of preliminary biological tests carried out with the use of mother cells extracted from human bone marrow showed that the nanocomposites may provide differenation of bone cells.

Preparation of Organic-Inorganic Multifunctional Nanocomposite Coating via Sol-Gel Routes

International Nuclear Information System (INIS)

Li Haoying; Chen Yunfa; Ruan Chengxiang; Gao Weimin; Xie Yusheng

2001-01-01

The inorganic-organic nanocomposite coatings are prepared on poly(methyl methacrylate) (PMMA) substrate by the spinning technique which involves incorporating homogeneously nanosized ZnO particle into the molecular inorganic-organic hybrid matrices. The hybrid matrices are derived from tetraethoxyasilane (TEOS) and 3-glycidoxypropyltrimethoxyailane (GLYMO). To avoid the destruction of the polymer structure caused by ZnO and modify the interface between nanoparticles and organic groups, ZnO was first surface-coated with SiO 2 from hydrolyzed TEOS using ammonia water as catalyst. The coatings thus obtained are dense, flexible, abrasion resistant and UV absorbent

Graphene nanocomposites as thermal interface materials for cooling energy devices

Science.gov (United States)

Dmitriev, A. S.; Valeev, A. R.

2017-11-01

The paper describes the technology of creating samples of graphene nanocomposites based on graphene flakes obtained by splitting graphite with ultrasound of high power. Graphene nanocomposites in the form of samples are made by the technology of weak sintering at high pressure (200-300 bar) and temperature up to 150 0 C, and also in the form of compositions with polymer matrices. The reflection spectra in the visible range and the near infrared range for the surface of nanocomposite samples are studied, the data of optical and electronic spectroscopy of such samples are givenIn addition, data on the electrophysical and thermal properties of the nanocomposites obtained are presented. Some analytical models of wetting and spreading over graphene nanocomposite surfaces have been constructed and calculated, and their effective thermal conductivity has been calculated and compared with the available experimental data. Possible applications of graphene nanocomposites for use as thermal interface materials for heat removal and cooling for power equipment, as well as microelectronics and optoelectronics devices are described.

Characterization of polyurethane/organophilic montmorillonite nanocomposites by low field NMR

International Nuclear Information System (INIS)

Silva, Marcos Anacleto da; Tavares, Maria I.B.; Nascimento, Suelen A.M.; Rodrigues, Elton J. da R

2012-01-01

Polyurethanes are important and versatile materials, mainly due to some of their properties, such as high resistance to abrasion and tearing, excellent absorption of mechanical shocks and good flexibility and elasticity. However, they have some drawbacks as well, such as low thermal stability and barrier properties. To overcome these disadvantages, various studies have been conducted involving organophilic polyurethane/montmorillonite nanocomposites. The investigation of the structure of polyurethane/clay nanocomposites has mainly been done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this work, PU/clay nanocomposite films obtained by solution intercalation were studied. The nanocomposites were characterized by XRD and low-field nuclear magnetic resonance (LF-NMR). The LF-NMR measurements, with determination of the spin-lattice relaxation time of the hydrogen nucleus, supplied important information about the molecular dynamics of these nanocomposites. The X-ray diffraction measurements validated the results found by NMR. The thermal stability of the material was also determined by thermogravimetric analysis (TGA) under an inert atmosphere. A slight improvement in this stability was observed in the nanocomposite in comparison with polyurethane (author)

Syntheses and characterization of novel P/Si polysilsesquioxanes/epoxy nanocomposites

International Nuclear Information System (INIS)

Chiu Yiechan; Liu Fangyi; Ma, C.-C.M.; Chou, I.-C.; Riang Linawati; Chiang, C.-L.; Yang, J.-C.

2008-01-01

Phosphorus-containing polysilsesquioxane (PSSQ) was introduced into diglycidyl ether of bisphenol A epoxy (DGEBA) to generate a novel P/Si PSSQ nanocomposite. A series of nanocomposites was fabricated by changing the content of the 2-(diphenylphosphino)ethyltriethoxysilane (DPPETES) monomer or P/Si PSSQ cured with DGEBA epoxy and modified epoxy. The structure, thermal properties and flame-retardancy of the P/Si PSSQ nanocomposites were characterized by FT-IR, solid-state 29 Si NMR, thermogravimetric analysis (TGA) and limited oxygen index (LOI) instruments. The nano-sizes of the particles in P/Si PSSQ were approximately 30-50 nm, and the polarity of nanocomposites might generate the nanophase-separated structure from transmission electron microscopy (TEM). The urethane-like side group of the modified epoxy and the fabrication of oligomers in the curing reaction affected the T d5 values of nanocomposites. TGA and LOI results indicated that the char yield (29 wt%) increased and the nanocomposites were not very flammable (LOI = 30). The hybrid materials also exhibited high thermal stability, good flame-retardance and a lack of phase separation

Characterization of PAN/ATO nanocomposites prepared by solution ...

Indian Academy of Sciences (India)

Conducting nanocomposites of polyacrylonitrile (PAN) and antimony-doped tin oxide (ATO) were prepared by solution blending. Electrical properties of the nanocomposites were characterized by means of electrical conductivity measurements and the phase structures were investigated via scanning electron microscopy ...

High pressure synthesis of zeolite/polymer nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Haines, Julien; Thibaud, Jean-Marc; Rouquette, Jerome; Cambon, Olivier; Di Renzo, Francesco, E-mail: julien.haines@univ-montp2.fr [Institut Charles Gerhardt Montpellier (France); Lee, Arie van der [Institut Europeen des Membranes, Montpellier (France); Scelta, Demetrio; Ceppatelli, Matteo; Dziubek, Kamil; Gorelli, Federico; Bini, Roberto; Santoro, Mario [European Laboratory for Non Linear Spectroscopy, Firenze (Italy)

2016-07-01

Full text: Polymerization of simple organic molecules under high pressure in the subnanometric pores of pure SiO{sub 2} zeolites can be used to produce novel nanocomposite materials, which can be recovered at ambient P and have remarkable mechanical, electrical or optical properties. Polymerization of ethylene in silicalite was studied in situ at high pressure by IR and results in a nanocomposite with isolated chains of non-conducting polyethylene strongly confined in the pores based on single crystal x-ray diffraction data. The nanocomposite is much less compressible than silicalite and has a positive rather than a negative thermal expansion coefficient. In order to target novel electrical and optical properties, isolated chains of conducting polymers can also be prepared in the pores of zeolite hosts at high pressure, such as polyacetylene, which was polymerized under pressure in the pores of the 1-D zeolite TON. The structure of this nanocomposite was determined by synchrotron x-ray powder diffraction data with complete pore filling corresponding to one planar polymer chain confined in each pore with a zig-zag configuration in the yz plane. This very strong confinement can be expected to strongly modify the electrical properties of polyacetylene. In this nanocomposite, our theoretical calculations indicate that the electronic density of states of polyacetylene exhibit van Hove singularities related to quantum 1D confinement, which could lead to future technological applications. This new material is susceptible to have applications in nanoelectronics, nanophotonics and energy and light harvesting. Completely novel nanocomposites were prepared by the polymerization of carbon monoxide CO in silicalite and TON. In these materials, isolated, ideal polycarbonyl chains are obtained in contrast to the non-stoichiometric, branched bulk polymers obtained by high pressure polymerization of this simple system. These poly CO/zeolite composites could be interesting energetic

Biopolymer nanocomposite films reinforced with nanocellulose whiskers

Science.gov (United States)

Amit Saxena; Marcus Foston; Mohamad Kassaee; Thomas J. Elder; Arthur J. Ragauskas

2011-01-01

A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating...

Exploring release and recovery of nanomaterials from commercial polymeric nanocomposites

International Nuclear Information System (INIS)

Busquets-Fité, Martí; Puntes, Víctor; Fernandez, Elisabet; Janer, Gemma; Vilar, Gemma; Vázquez-Campos, Socorro; Zanasca, R; Citterio, C; Mercante, L

2013-01-01

Much concern has been raised about the risks associated with the broad use of polymers containing nanomaterials. Much is known about degradation and aging of polymers and nanomaterials independently, but very few studies have been done in order to understand degradation of polymeric nanocomposites containing nanomaterials and the fate of these nanomaterials, which may occur in suffering many processes such as migration, release and physicochemical modifications. Throughout the UE funded FP7 project NANOPOLYTOX, studies on the migration, release and alteration of mechanical properties of commercial nanocomposites due to ageing and weathering have been performed along with studies on the feasibility of recovery and recycling of the nanomaterials. The project includes the use as model nanocomposites of Polyamide-6 (PA), Polypropylene (PP) and Ethyl Vinyl Acetate (EVA) as polymeric matrix filled with a 3% in mass of a set of selected broadly used nanomaterials; from inorganic metal oxides nanoparticles (SiO2, TiO2 and ZnO) to multi-walled carbon nanotubes (MWCNT) and Nanoclays. These model nanocomposites were then treated under accelerated ageing conditions in climatic chamber. To determine the degree of degradation of the whole nanocomposite and possible processes of migration, release and modification of the nanofillers, nanocomposites were characterized by different techniques. Additionally, recovery of the nanomaterials fro m the polymeric matrix was addressed, being successfully achieved for PA and PP based nanocomposites. In the case of PA, dissolution of the polymeric matrix using formic acid and further centrifugation steps was the chosen approach, while for PP based nanocomposites calcination was performed.

APTES Functionalized Iron Oxide-Silver Magnetic Hetero-Nanocomposites for Selective Capture and Rapid Removal of Salmonella enteritidis from Aqueous Solution

Science.gov (United States)

Trang, Vu Thi; Dinh, Ngo Xuan; Lan, Hoang; Tam, Le Thi; Huy, Tran Quang; Tuan, Pham Anh; Phan, Vu Ngoc; Le, Anh-Tuan

2018-02-01

Magnetic nanomaterials, as a promising platform for the fast and sensitive detection of bacterial pathogens, have attracted increasing interest from researchers in recent years. In this work, by utilizing a two-step synthetic technique consisting of co-precipitation and subsequent hydrothermal reaction, followed by functionalization steps with (3-aminopropyl)triethoxysilane (APTES) and the antibody against Salmonella enteritidis, antibody-conjugated Fe3O4-Ag@APTES hetero-nanocomposites were successfully prepared. Due to the specific antibody, the developed Fe3O4-Ag@APTES@SE-Ab conjugates are capable of selectively capturing S. enteritidis at a low concentration of about 101 CFU/mL. Moreover, the prepared magnetic conjugates also revealed that the S. enteritidis could be rapidly removed from water solution in 20 min by using an external magnetic field with a removal efficiency obtained of ˜ 91.36%. These results indicated that the Fe3O4-Ag@APTES@SE-Ab conjugates are promising for the rapid selective capture and removal of bacterial pathogens from aqueous environments, and can be used for improving the detection quality of pathogens in water samples using immunosensor-based diagnostic tests.

Development of nanocomposites based on potato starch

International Nuclear Information System (INIS)

Brito, Luciana Macedo; Tavares, Maria Ines Bruno

2013-01-01

Nanocomposites of potato starch were prepared by the solution intercalation method with the addition of organically modified montmorillonite clay (Viscogel B and unmodified sodic clay (NT25) as well as modified and unmodified silica (R972 and A200, respectively), using water as the solvent. The nanocomposites were characterized by conventional techniques of X-ray diffraction and thermogravimetric analysis. They were also characterized using the non-conventional low-field nuclear magnetic resonance, which is an effective alternative technique for characterizing nanocomposites. This technique allows one to investigate dispersion of nanofillers by the degree of intercalation and/or exfoliation, in addition to determine the distribution of nanoparticles in the polymer matrix and modifications of the molecular mobility of these fillers. The nanostructured materials obtained with the clays presented good dispersion and formation of mixed nanomaterials, with different degrees of intercalation and exfoliation. The mobility of the material decreased upon adding silica in the starch matrix, which applied to both types of silica. From the TGA technique, a slight increase in thermal stability of the nanocomposite was noted in relation to the starch matrix. (author)

X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites.

Science.gov (United States)

Gandhiraman, Ram P; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E; Chen, Bin; Meyyappan, M

2014-08-14

The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties as the graphene oxide transformation to reduced-graphene oxide is a key step in the synthesis of the electrode materials. Polarized behavior of the synchrotron X-rays and the angular dependency of the near-edge X-ray absorption fine structures (NEXAFS) have been utilized to study the orientation of the σ and π bonds of the graphene oxide and graphene oxide-metal oxide nanocomposites. The core-level transitions of individual metal oxides and that of the graphene oxide nanocomposite showed that the interaction of graphene oxide with the metal oxide nanostructures has not altered the electronic structure of either of them. As the restoration of the π network is important for good electrical conductivity, the C K edge NEXAFS spectra of reduced graphene oxide nanocomposites confirms the same through increased intensity of the sp 2 -derived unoccupied states π* band. A pronounced angular dependency of the reduced sample and the formation of excitonic peaks confirmed the formation of extended conjugated network.

Nonlinear optical properties of ZnO/poly (vinyl alcohol) nanocomposite films

International Nuclear Information System (INIS)

Jeeju, P. P.; Jayalekshmi, S.; Chandrasekharan, K.

2014-01-01

Extensive studies have already been reported on the optical characteristics of ZnO/polymer nanocomposite films, using a variety of polymers including transparent polymers such as polystyrene, polymethyl methacrylate etc and many interesting results have been established regarding the non linear optical characteristics of these systems. Poly (vinyl alcohol)(PVA) is a water soluble polymer. Though the structural and optical studies of ZnO/PVA nanocomposite films have already been investigated, there are no detailed reports on the nonlinear optical characteristics of ZnO/PVA nanocomposite films, irrespective of the fact that these nanocomposite films can be synthesized using quite easy and cost effective methods. The present work is an attempt to study in detail the nonlinear optical behaviour of ZnO/PVA nanocomposite films using Z-scan technique. Highly transparent ZnO/PVA nanocomposite films were prepared from the ZnO incorporated PVA solution in water using spin coating technique. The ZnO nanoparticles were synthesized by the simple chemical route at room temperature. High-resolution transmission electron microscopy studies show that the ZnO nanoparticles are of size around 10 nm. The ZnO/PVA nanocomposite films were structurally characterized by X-ray diffraction technique, from which the presence of both PVA and ZnO in the nanocomposite was established. The optical absorptive nonlinearity in the nanocomposite films was investigated using open aperture Z-scan technique. The results indicate optical limiting type nonlinearity in the films due to two photon absorption in ZnO with efficiency more than 50%. These films also show a self defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The present studies indicate that, highly transparent and homogeneous films of ZnO/PVA nanocomposite can be obtained on glass substrates using simple methods, in a highly cost effective way, since PVA is water soluble. These nanocomposite films offer

Ab initio vel ex eventu

Science.gov (United States)

Thiessen, P. A.; Treder, H.-J.

Der gegenwärtige Stand der physikalischen Erkenntnis, in Sonderheit die Atomistik und die Quantentheorie, ermöglicht (in wohldefinierten Energie-Bereichen) eine ab initio-Berechnung aller physikalischen und chemischen Prozesse und Strukturen. Die Schrödinger-Gleichung erlaubt zusammen mit den Prinzipien der Quantenstatistik (Pauli-Prinzip) aus dem Planckschen Wirkungsquantum h und den atomischen Konstanten die Berechnung aller Energieumsätze, Zeitabläufe etc., die insbesondere die chemische Physik bestimmen. Die Rechenresultate gelten auch quantitativ bis auf die unvermeidliche Stochastik.Die ab initio-Berechnungen korrespondieren einerseits und sind andererseits komplementär zu den auf den Methoden der theoretischen Chemie und der klassischen Thermodynamik beruhenden Ergebnissen ex eventu. Die theoretische Behandlung ab initio führt zu mathematischen Experimenten, die die Laboratoriums-Experimente ergänzen oder auch substituieren.Translated AbstractAb initio vel ex eventuThe present state of physical knowledge, in peculiar atomistic and quantum theory, makes an ab initio calculation of all physical and chemical processes and structures possible (in well defined reaches of energy). The Schrödinger equation together with the principles of quantum statistics (Pauli principle) permits from the Planck and atomistic constants to calculate all exchanges of energy, courses of time, etc. which govern chemical physics. The calculated results are valid even quantitatively apart from the unavoidable stochastics.These ab initio calculations on the one hand correspond and are on the other complimentary to results ex eventu based on the methods of theoretical chemistry and classical thermodynamics. Theoretical treatment ab initio leads to mathematical experiments which add to or even substitute experiments in the laboratory.

Mesoporous carbon-zirconium oxide nanocomposite derived from carbonized metal organic framework: A coating for solid-phase microextraction.

Science.gov (United States)

Saraji, Mohammad; Mehrafza, Narges

2016-08-19

In this paper, a mesoporous carbon-ZrO2 nanocomposite was fabricated on a stainless steel wire for the first time and used as the solid-phase microextraction coating. The fiber was synthesized with the direct carbonization of a Zr-based metal organic framework. With the utilization of the metal organic framework as the precursor, no additional carbon source was used for the synthesis of the mesoporous carbon-ZrO2 nanocomposite coating. The fiber was applied for the determination of BTEX compounds (benzene, toluene, ethylbenzene and m, p-xylenes) in different water samples prior to gas chromatography-flame ionization detection. Such important experimental factors as synthesis time and temperature, salt concentration, equilibrium and extraction time, extraction temperature, desorption time and desorption temperature were studied and optimized. Good linearity in the concentration range of 0.2-200μgL(-1) and detection limits in the range of 0.05-0.56μgL(-1) was achieved for BTEX compounds. The intra- and inter-day relative standard deviations were in the range of 3.5-4.8% and 4.9-6.7%, respectively. The prepared fiber showed high capability for the analysis of BTEX compounds in different water and wastewater samples with good relative recoveries in the range of 93-107%. Copyright © 2016 Elsevier B.V. All rights reserved.

Faster response of NO2 sensing in graphene–WO3 nanocomposites

International Nuclear Information System (INIS)

Srivastava, Shubhda; Jain, Kiran; Gupta, Govind; Senguttuvan, T D; Singh, V N; Singh, Sukhvir; Vijayan, N; Dilawar, Nita

2012-01-01

Graphene-based nanocomposites have proven to be very promising materials for gas sensing applications. In this paper, we present a general approach for the preparation of graphene–WO 3 nanocomposites. Graphene–WO 3 nanocomposite thin-layer sensors were prepared by drop coating the dispersed solution onto the alumina substrate. These nanocomposites were used for the detection of NO 2 for the first time. TEM micrographs revealed that WO 3 nanoparticles were well distributed on graphene nanosheets. Three different compositions (0.2, 0.5 and 0.1 wt%) of graphene with WO 3 were used for the gas sensing measurements. It was observed that the sensor response to NO 2 increased nearly three times in the case of graphene–WO 3 nanocomposite layer as compared to a pure WO 3 layer at room temperature. The best response of the graphene–WO 3 nanocomposite was obtained at 250 °C. (paper)

Characterization of synthesized polyurethane/montmorillonite nanocomposites foams

International Nuclear Information System (INIS)

Ansari, Farahnaz; Njuguna, James; Sachse, Sophia; Kavosh, Masoud; Michalowski, S; Pielichowski, Krzysztof

2014-01-01

Nanophased hybrid composites based on polyurethane/montmorillonite (PU/MMT) have been fabricated. The nanocomposite which was formed by the addition of a polyol premix with 4,4'-diphenylmethane diisocyanate to obtain nanophased polyurethane foams which were then used for fabrication of nanocomposite panels has been shown to have raised strength, stiffness and thermal insulation properties. The nanophased polyurethane foam was characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM) measurements and X-ray diffraction (XRD). TEM and SEM analysis indicated that nanophased particles are dispersed homogeneously in the polyurethane matrix on the nanometer scale indicating that PU/MMT is an intercalated nanocomposite with a 2-3 nm nanolayer thickness

Fracture of vacancy-defected carbon nanotubes and their embedded nanocomposites

International Nuclear Information System (INIS)

Xiao Shaoping; Hou Wenyi

2006-01-01

In this paper, we investigate effects of vacancy defects on fracture of carbon nanotubes and carbon nanotube/aluminum composites. Our studies show that even a one-atom vacancy defect can dramatically reduce the failure stresses and strains of carbon nanotubes. Consequently, nanocomposites, in which vacancy-defected nanotubes are embedded, exhibit different characteristics from those in which pristine nanotubes are embedded. It has been found that defected nanotubes with a small volume fraction cannot reinforce but instead weaken nanocomposite materials. Although a large volume fraction of defected nanotubes can slightly increase the failure stresses of nanocomposites, the failure strains of nanocomposites are always decreased

Epoxy Nanocomposites filled with Carbon Nanoparticles.

Science.gov (United States)

Martin-Gallego, M; Yuste-Sanchez, V; Sanchez-Hidalgo, R; Verdejo, R; Lopez-Manchado, M A

2018-01-10

Over the past decades, the development of high performance lightweight polymer nanocomposites and, in particular, of epoxy nanocomposites has become one the greatest challenges in material science. The ultimate goal of epoxy nanocomposites is to extrapolate the exceptional intrinsic properties of the nanoparticles to the bulk matrix. However, in spite of the efforts, this objective is still to be attained at commercially attractive scales. Key aspects to achieve this are ultimately the full understanding of network structure, the dispersion degree of the nanoparticles, the interfacial adhesion at the phase boundaries and the control of the localization and orientation of the nanoparticles in the epoxy system. In this Personal Account, we critically discuss the state of the art and evaluate the strategies to overcome these barriers. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of F(ab')2 versus Fab antivenom for pit viper envenomation: a prospective, blinded, multicenter, randomized clinical trial.

Science.gov (United States)

Bush, Sean P; Ruha, Anne-Michelle; Seifert, Steven A; Morgan, David L; Lewis, Brandon J; Arnold, Thomas C; Clark, Richard F; Meggs, William J; Toschlog, Eric A; Borron, Stephen W; Figge, Gary R; Sollee, Dawn R; Shirazi, Farshad M; Wolk, Robert; de Chazal, Ives; Quan, Dan; García-Ubbelohde, Walter; Alagón, Alejandro; Gerkin, Richard D; Boyer, Leslie V

2015-01-01

Crotalidae Polyvalent Immune Fab (Ovine) has been the only antivenom commercially available in the US since 2007 for treatment of Crotalinae envenomation. Late coagulopathy can occur or recur after clearance of Fab antivenom, often after hospital discharge, lasting in some cases more than 2 weeks. There have been serious, even fatal, bleeding complications associated with recurrence phenomena. Frequent follow-up is required, and additional intervention or hospitalization is often necessary. F(ab')2 immunoglobulin derivatives have longer plasma half life than do Fab. We hypothesized that F(ab')2 antivenom would be superior to Fab in the prevention of late coagulopathy following treatment of patients with Crotalinae envenomation. We conducted a prospective, double-blind, randomized clinical trial, comparing late coagulopathy in snakebitten patients treated with F(ab')2 with maintenance doses [F(ab')2/F(ab')2], or F(ab')2 with placebo maintenance doses [F(ab')2/placebo], versus Fab with maintenance doses [Fab/Fab]. The primary efficacy endpoint was coagulopathy (platelet count Fab/Fab cohort experienced late coagulopathy versus 4/39 (10.3%, p < 0.05) in the F(ab')2/F(ab')2 cohort and 2/38 (5.3%, p < 0.05) in the F(ab')2/placebo cohort. The lowest heterologous protein exposure was with F(ab')2/placebo. No serious adverse events were related to study drug. In each study arm, one patient experienced an acute serum reaction and one experienced serum sickness. In this study, management of coagulopathic Crotalinae envenomation with longer-half-life F(ab')2 antivenom, with or without maintenance dosing, reduced the risk of subacute coagulopathy and bleeding following treatment of envenomation.

Fabrication and characterization of free-standing polypyrrole/graphene oxide nanocomposite paper

International Nuclear Information System (INIS)

Li Lanyan; Xia Keqiang; Li Liang; Shang Songmin; Guo Qingzhong; Yan Guoping

2012-01-01

Flexible polypyrrole/graphene oxide (GO) nanocomposite paper was prepared via a facile and one-step chemical oxidation polymerization method. The morphology and microstructure of the obtained papers were characterized by SEM, FTIR, and XRD. GO was confirmed experimentally to be exfoliated and uniformly dispersed in the resulting nanocomposites. The specific capacitance value of the nanocomposite paper has been determined to be about 330 F/g at a scan rate of 100 mV/s, suggesting the possible application of the nanocomposite as a supercapacitor electrode. After 700 cycles at a scan rate of 100 mV/s, only 9 % decrease in specific capacitance as compared to initial value indicates the superior electrochemical cyclic stability of the nanocomposite paper.

Preparation, Characterization, and Electrochromic Properties of Nanocellulose-Based Polyaniline Nanocomposite Films.

Science.gov (United States)

Zhang, Sihang; Sun, Gang; He, Yongfeng; Fu, Runfang; Gu, Yingchun; Chen, Sheng

2017-05-17

On the basis of nanocellulose obtained by acidic swelling and ultrasonication, rodlike nanocellulose/polyaniline nanocomposites with a core-shell structure have been prepared via in situ polymerization. Compared to pure polyaniline, the nanocomposites show superior film-forming properties, and the prepared nanocomposite films demonstrate excellent electrochemical and electrochromic properties in electrolyte solution. Nanocomposite films, especially the one prepared with 40% polyaniline coated nanocomposite, exhibited faster response time (1.5 s for bleaching and 1.0 s for coloring), higher optical contrast (62.9%), higher coloration efficiency (206.2 cm 2 /C), and more remarkable switching stability (over 500 cycles). These novel nanocellulose-based nanorod network films are promising novel electrochromic materials with excellent properties.

Highly reddened Type Ia supernova SN 2004ab: another case of anomalous extinction

Science.gov (United States)

Chakradhari, N. K.; Sahu, D. K.; Anupama, G. C.; Prabhu, T. P.

2018-02-01

We present optical photometric and spectroscopic data for supernova SN 2004ab, a highly reddened normal Type Ia supernova. The total reddening is estimated as E(B - V) = 1.70 ± 0.05 mag. The intrinsic decline-rate parameter Δm15(B)true is 1.27 ± 0.05, and the B-band absolute magnitude at maximum MB^{max} is -19.31 ± 0.25 mag. The host galaxy NGC 5054 is found to exhibit anomalous extinction with a very low value of RV = 1.41 ± 0.06 in the direction of SN 2004ab. The peak bolometric luminosity is derived as log L_bol^max = 43.10 ± 0.07 erg s-1. The photospheric velocity measured from the absorption minimum of the Si II λ6355 line shows a velocity gradient of \\dot{v} = 90 km s-1 d-1, indicating that SN 2004ab is a member of the high velocity gradient (HVG) subgroup. The ratio of the strengths of the Si II λ5972 and λ6355 absorption lines, R(Si II), is estimated as 0.37, while their pseudo-equivalent widths suggest that SN 2004ab belongs to the broad line (BL) type subgroup.

Ab initio study of electron-ion structure factors in binary liquids with different types of chemical bonding

International Nuclear Information System (INIS)

Klevets, Ivan; Bryk, Taras

2014-01-01

Electron-ion structure factors, calculated in ab initio molecular dynamics simulations, are reported for several binary liquids with different kinds of chemical bonding: metallic liquid alloy Bi–Pb, molten salt RbF, and liquid water. We derive analytical expressions for the long-wavelength asymptotes of the partial electron-ion structure factors of binary systems and show that the analytical results are in good agreement with the ab initio simulation data. The long-wavelength behaviour of the total charge structure factors for the three binary liquids is discussed

Photocatalysis and Bandgap Engineering Using ZnO Nanocomposites

Directory of Open Access Journals (Sweden)

Muhammad Ali Johar

2015-01-01

Full Text Available Nanocomposites have a great potential to work as efficient, multifunctional materials for energy conversion and photoelectrochemical reactions. Nanocomposites may reveal more improved photocatalysis by implying the improvements of their electronic and structural properties than pure photocatalyst. This paper presents the recent work carried out on photoelectrochemical reactions using the composite materials of ZnO with CdS, ZnO with SnO2, ZnO with TiO2, ZnO with Ag2S, and ZnO with graphene and graphene oxide. The photocatalytic efficiency mainly depends upon the light harvesting span of a material, lifetime of photogenerated electron-hole pair, and reactive sites available in the photocatalyst. We reviewed the UV-Vis absorption spectrum of nanocomposite and photodegradation reported by the same material and how photodegradation depends upon the factors described above. Finally the improvement in the absorption band edge of nanocomposite material is discussed.

Graphene-polyethylenedioxythiophene conducting polymer nanocomposite based supercapacitor

International Nuclear Information System (INIS)

Alvi, Farah; Ram, Manoj K.; Basnayaka, Punya A.; Stefanakos, Elias; Goswami, Yogi; Kumar, Ashok

2011-01-01

Graphical abstract: Schematic diagrams of an electrochemical double layer type capacitor showing the charged (left) and discharged (right) states. Highlights: → The Graphene-PEDOT nanocomposite based smart coating has shown the excellent redox properties in acidic, organic electrolytes, which is promising for suprecapcitor application. → The electrochemical impedance studies have also been estimated which clearly indicates the high conductivity and less charge transfer resistance in the synthesized material. → The specific capacitance of 380F/g have been calculated for G-Pedot material, also it shows the columbic efficiency of 95% for 800 cycles, which tells the remarkable stability of synthesized material. - Abstract: We present here the synthesis, characterization and application of graphene (G)-polyethylenedioxythiophene (PEDOT) nanocomposites as electrode material for supercapacitor applications. The G-PEDOT nanocomposite was synthesized using a chemical oxidative polymerization technique, and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, FTIR spectroscopy, X-ray-diffraction, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) techniques. The electrochemical charge/discharge characteristics of G-PEDOT nanocomposites were investigated in different electrolytic media, and the specific discharge capacitance was estimated to be 374 Farad/gram (F/gm). This manuscript presents the capacitance studies on supercapacitor G-PEDOT electrode with respect to stability of material, specific capacitance, electrical conductivity and specific charge/discharge properties of the supercapacitor electrodes. Our study has revealed that the G-PEDOT nanocomposite could be a transformable and viable electrode material for supercapacitor applications.

Performance of epoxy-nanocomposite under corrosive environment

Directory of Open Access Journals (Sweden)

2007-06-01

Full Text Available Nanocomposite materials consisting of polymeric matrix materials and natural or synthetic layered minerals like clay are currently an expanding field of study because these new materials often exhibit a wide range of improved properties over their unmodified starting polymers. Epoxy/organoclay nanocomposites have been prepared by intercalating epoxy into the organoclay via direct mixing process. The clay exfoliation was monitored by X-ray diffraction (XRD and transmission electron microscopy (TEM. Water diffusion and sulfuric acid corrosion resistance of epoxy-based nanocomposites were evaluated. Diffusion was studied through epoxy samples containing up to 6 phr (parts per hundred resin of an organically treated montmorillonite. The diffusion of the environmental solution was measured by noting the increase in weight of the samples as a function of immersion time in these solutions at 80°C. The effect of the degree of exfoliation of the organoclay on water barrier and corrosion resistance was specifically studied. The data have been compared to those obtained from the neat epoxy resin to evaluate the diffusion properties of the nanocomposites. The flexural strength of the epoxy/organoclay nanocomposites samples made was examined to compare their mechanical performance under corrosive conditions as a function of immersion time and temperature. It was found, that the organoclay was mainly intercalated with some exfoliation and that addition of the organoclay yields better flexural strength retention under immersion into sulfuric acid.

Surface properties of UV irradiated PC–TiO{sub 2} nanocomposite film

Energy Technology Data Exchange (ETDEWEB)

Jaleh, B., E-mail: bkjaleh@yahoo.com; Shahbazi, N.

2014-09-15

Highlights: • Production of PC–TiO{sub 2} nanocomposite films. • Fully characterization of PC–TiO{sub 2} nanocomposite films. • Influence of UV irradiation on surface properties and hardness of PC–TiO{sub 2} nanocomposite film. - Abstract: In this work, polycarbonate–TiO{sub 2} nanocomposite films were prepared with two different percentages. The structure of samples were studied by X-ray diffraction. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA). The polycarbonate and polycarbonate–TiO{sub 2} nanocomposite films were exposed by UV light at different irradiation times. The effects of UV irradiation on the surface properties of samples have been studied by different characterization techniques, viz. scanning electron microscopy (SEM), FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurement and Vickers microhardness tester. Hydrophilicity and surface energy of UV treated samples varied depending on UV irradiation time. TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to polycarbonate. XPS analysis shows that surface of samples become more oxidized due to UV irradiation. For nanocomposite film, the smallest contact angle was observed in association with the longest UV irradiation time. The contact angle significantly decreased from 90° to 12° after 15 h of UV irradiation. It is observed that the hardness of the nanocomposite films increases after UV irradiation.

Cellulose nanocrystal-filled poly(acrylic acid) nanocomposite fibrous membranes

International Nuclear Information System (INIS)

Lu Ping; Hsieh, You-Lo

2009-01-01

Nanocomposite fibrous membranes have been fabricated by electrospinning cellulose nanocrystal (CNC)-loaded poly(acrylic acid) (PAA) ethanol mixtures. Incorporating CNC in PAA significantly reduced fiber diameters and improved fiber uniformity. The average diameters of the as-spun nanocomposite fibers were significantly reduced from 349 nm to 162 nm, 141 nm, 90 nm and 69 nm at 5%, 10%, 15% and 20% CNC loading (by weight of a constant 4% PAA solution), respectively. CNC was well dispersed in the fibers as isolated rods oriented along the fiber axis and as spheres in the PAA matrix. The Young modulus and stress of the PAA/CNC nanocomposite fibers were significantly improved with increasing CNC loadings by up to 35-fold and 16-fold, respectively. Heat-induced esterification between the CNC surface hydroxyls and PAA carboxyl groups produced covalent crosslinks at the CNC-PAA interfaces, rendering the nanocomposite fibrous membranes insoluble in water, more thermally stable and far more superior in tensile strength. With 20% CNC, the crosslinked nanocomposite fibrous membrane exhibited a very impressive 77-fold increase in modulus and 58-fold increase in stress.

Ultrasound assisted synthesis of PMMA/clay nanocomposites: Study ...

Indian Academy of Sciences (India)

The Young's modulus, breaking stress, elongation at break, toughness, yield stress and yield strain of the nanocomposites as a function of different clay concentrations and ultrasonic power were measured. Particle diameter of the nanocomposites was measured by laser diffraction technique. Oxygen permeability of the ...

A review on the effect of mechanical drilling on polymer nanocomposites

International Nuclear Information System (INIS)

Starost, Kristof; Njuguna, James

2014-01-01

Over the past decade, polymer nanocomposites have undergone intensive research and development ensued by its increasing implementation within commercial applications. Consequently, the full life-cycle performance and any health risks associated with these materials have become of major interest. Throughout its use, a nanocomposite will undergo industrial machining where drilling can lead to material damage and/or exposure to the potentially toxic nanoparticles. This study assesses the existing and perspective research on nanocomposite drilling. Currently, although considerable amount of studies have investigated machining on conventional composite materials, there is a lack in knowledge on the effect of drilling on nanocomposites. The data underlines the various drilling parameters that will affect and influence the damage to the material and nano-sized particles released. Importantly, previous studies have identified potential mechanical damage caused by drilling and the release-ability of toxic nanoparticles from nanocomposites. It is therefore crucial to develop a full understanding and characterization on the effect of drilling on polymer nanocomposites

Effect of functional groups on thermal conductivity of graphene/paraffin nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Zabihi, Zabiholah; Araghi, Houshang, E-mail: araghi@aut.ac.ir

2016-11-25

In this paper, thermal conductivity of graphene/paraffin nanocomposite using micromechanical model has been studied. The behavior of thermal conductivity of nanocomposite as a function of volume fraction of graphene is studied. Then is shown that as the interfacial thermal resistance at the graphene–paraffin interface decreases, the thermal conductivity of nanocomposite increases. In order to reduce the interfacial thermal resistance, functional groups in the interface between graphene and paraffin are used. It can be observed that using functional groups of hydrogen, methyl and phenyl in the interface of nanocomposite, contributes to the improvement of the thermal conductivity. Moreover, as the rate of coverage of the surface of graphene with functional groups of H, CH{sub 3} and C{sub 6}H{sub 5} increases, the thermal conductivity of nanocomposite improves. - Highlights: • Thermal conductivity nanocomposite exhibit nonlinear behavior with volume faction. • Phenyl is better to form the thermal conductivity network in paraffin. • The thickness of interfacial layer can be obtained 12.75 nm.

Thermomechanical Behavior of High Performance Epoxy/Organoclay Nanocomposites

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Artur Soares Cavalcanti Leal

2014-01-01

Full Text Available Nanocomposites of epoxy resin containing bentonite clay were fabricated to evaluate the thermomechanical behavior during heating. The epoxy resin system studied was prepared using bifunctional diglycidyl ether of bisphenol A (DGEBA, crosslinking agent diaminodiphenylsulfone (DDS, and diethylenetriamine (DETA. The purified bentonite organoclay (APOC was used in all experiments. The formation of nanocomposite was confirmed by X-ray diffraction analysis. Specimens of the fabricated nanocomposites were characterized by dynamic mechanical analysis (DMA. According to the DMA results a significant increase in glass transition temperature and storage modulus was evidenced when 1 phr of clay is added to epoxy resin.

Structural characterisation and antibacterial activity of PP/TiO2 nanocomposites prepared by an in situ sol–gel method

International Nuclear Information System (INIS)

Bahloul, Walid; Mélis, Flavien; Bounor-Legaré, Véronique; Cassagnau, Philippe

2012-01-01

Graphical abstract: TEM micrograph of PP/TiO 2 nanocomposite materials (a) in situ PP/TiO 2 and (b) PP/TiO 2 (anatase). Highlights: ► Titanium alkoxide hydrolysis–condensation reactions during polypropylene processing. ► Inorganic domains diameter of around 10 nm. ► Interesting antibacterial activities compared to a dispersion of anatase TiO 2 . - Abstract: Polypropylene/titanium dioxide (PP/TiO 2 ) nanocomposites can be prepared using a novel method based on the hydrolysis–condensation reactions (sol–gel method) of titanium alkoxide inorganic precursors that have been premixed with polypropylene under molten conditions. The resultant nanocomposites were characterised by transmission electronic microscopy (TEM), X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). These techniques showed the formation of the titanium oxi-hydroxide chemical structure (Ti x O y (OH) z ) with a diameter of approximately 10 nm in the polymer matrix. Furthermore, a condensation degree of around 17% was determined using XPS analysis. The antibacterial activity was tested according to the JIS Z 2801:2000 standard with Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in the absence of light. Correlations between the microstructure and the chemical composition of PP/TiO 2 nanocomposites and the antibacterial properties of these nanocomposites were discussed. The structure of titanium oxi-hydroxide derivative particles (Ti x O y (OH) z ) within the polypropylene matrix has been shown to impact strongly on the antibacterial properties in comparison with the results obtained with a dispersion of anatase titanium dioxide into the PP.

Reduced graphene oxide–silver nanoparticle nanocomposite: a potential anticancer nanotherapy

Directory of Open Access Journals (Sweden)

Gurunathan S

2015-10-01

Full Text Available Sangiliyandi Gurunathan, Jae Woong Han, Jung Hyun Park, Eunsu Kim, Yun-Jung Choi, Deug-Nam Kwon, Jin-Hoi Kim Department of Animal Biotechnology, Konkuk University, Seoul, Republic of Korea Background: Graphene and graphene-based nanocomposites are used in various research areas including sensing, energy storage, and catalysis. The mechanical, thermal, electrical, and biological properties render graphene-based nanocomposites of metallic nanoparticles useful for several biomedical applications. Epithelial ovarian carcinoma is the fifth most deadly cancer in women; most tumors initially respond to chemotherapy, but eventually acquire chemoresistance. Consequently, the development of novel molecules for cancer therapy is essential. This study was designed to develop a simple, non-toxic, environmentally friendly method for the synthesis of reduced graphene oxide–silver (rGO–Ag nanoparticle nanocomposites using Tilia amurensis plant extracts as reducing and stabilizing agents. The anticancer properties of rGO–Ag were evaluated in ovarian cancer cells. Methods: The synthesized rGO–Ag nanocomposite was characterized using various analytical techniques. The anticancer properties of the rGO–Ag nanocomposite were evaluated using a series of assays such as cell viability, lactate dehydrogenase leakage, reactive oxygen species generation, cellular levels of malonaldehyde and glutathione, caspase-3 activity, and DNA fragmentation in ovarian cancer cells (A2780. Results: AgNPs with an average size of 20 nm were uniformly dispersed on graphene sheets. The data obtained from the biochemical assays indicate that the rGO–Ag nanocomposite significantly inhibited cell viability in A2780 ovarian cancer cells and increased lactate dehydrogenase leakage, reactive oxygen species generation, caspase-3 activity, and DNA fragmentation compared with other tested nanomaterials such as graphene oxide, rGO, and AgNPs. Conclusion: T. amurensis plant extract

Poly(vinyl acetate)/clay nanocomposite materials for organic thin film transistor application.

Science.gov (United States)

Park, B J; Sung, J H; Park, J H; Choi, J S; Choi, H J

2008-05-01

Nanocomposite materials of poly(vinyl acetate) (PVAc) and organoclay were fabricated, in order to be utilized as dielectric materials of the organic thin film transistor (OTFT). Spin coating condition of the nanocomposite solution was examined considering shear viscosity of the composite materials dissolved in chloroform. Intercalated structure of the PVAc/clay nanocomposites was characterized using both wide-angle X-ray diffraction and TEM. Fracture morphology of the composite film on silicon wafer was also observed by SEM. Dielectric constant (4.15) of the nanocomposite materials shows that the PVAc/clay nanocomposites are applicable for the gate dielectric materials.

Dosimetry characteristics of HDPE–SWCNT nanocomposite for real time application

Energy Technology Data Exchange (ETDEWEB)

Malekie, Shahryar [Radiation Application Research School, Nuclear Science & Technology Research Institute, P.O. Box 11365-3486, Tehran (Iran, Islamic Republic of); Ziaie, Farhood, E-mail: fziaie@aeoi.org.ir [Radiation Application Research School, Nuclear Science & Technology Research Institute, P.O. Box 11365-3486, Tehran (Iran, Islamic Republic of); Feizi, Shahzad [Radiation Application Research School, Nuclear Science & Technology Research Institute, P.O. Box 11365-3486, Tehran (Iran, Islamic Republic of); Esmaeli, Abdolreza [Plasma and Fusion Research School, Nuclear Science & Technology Research Institute, Tehran (Iran, Islamic Republic of)

2016-10-11

In this experimental work, different dosimetric characteristics of high density polyethylene-single wall carbon nanotube nanocomposite were investigated. The nanocomposite samples were prepared with different nanotube contents of 0.22, 0.25, and 0.39 weight percentages which were before, exactly in, and after percolation region of the nanocomposite, respectively. The samples were exposed to {sup 60}Co gamma radiation source over the dose rate of 65–214 mGy/min, while the applied bias was 100 V. A linear response achieved for the sample contained 0.25 nanotube wt% verified that the percolation threshold is the optimum point for dosimetric purposes. The current–voltage characteristics curve measured for 0.25 CNT wt% nanocomposite showed that the behavior of this sample was bias polarity independent. Also, the results showed that the response of this nanocomposite was energy-independent. The maximum discrepancy of photocurrent due to angular variation within 0–90° with respect to beam incidence and the reproducibility of the response were measured as 5.4% and 0.8%, respectively. The stability study showed that this material may be suitable for protection dose level control. Therefore, this kind of nanocomposite requiring calibration can be used as a real-time dosimeter. - Highlights: • HDPE–SWCNT nanocomposite was used in this experiment. • Achieved linear response in EPT region verifying that is optimum point for dosimetric purposes. • The response of this nanocomposite was energy-independent. • The angular dependence and the reproducibility of the response were measured. • The stability study shows that this material is suitable for protection dose level control.

Carbon Nanotubes-Hydroxyapatite Nanocomposites for an Improved Osteoblast Cell Response

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Sabrina Constanda

2016-01-01

Full Text Available An alternative and simple coprecipitation method was developed to obtain carbon nanotube-hydroxyapatite (CNTs:HAp based nanocomposites. The incorporation of CNTs (in a concentration of 5% and 10% of total weight of the nanocomposite and their impact on both structural and biological properties were studied by using a set of standard complementary biological, microscopic, and spectroscopic techniques. The characteristic peaks of carbon structure in CNTs were not observed in the CNTs-HAp composites by X-ray diffraction analysis. Moreover, FTIR and Raman spectroscopies confirmed the presence of HAp as the main phase of the synthesized CNTs:HAp nanocomposites. The addition of CNTs considerably affected the nanocomposite morphology by increasing the average crystallite size from 18.7 nm (for raw HAp to 28.6 nm (for CNTs:HAp-10, confirming their proper incorporation. The biocompatibility evaluation of CNTs:HAp-5 and CNTs:HAp-10 nanocomposites included the assessment of several parameters, such as cell viability, antioxidant response, and lipid peroxidation, on human G-292 osteoblast cell line. Our findings revealed good biocompatibility properties for CNTs:HAp nanocomposites prepared by the coprecipitation method supporting their potential uses in orthopedics and prosthetics.

Poly(2-aminothiazole)-silica nanocomposite particles: Synthesis and morphology control

Science.gov (United States)

Zou, Hua; Wu, Di; Sun, Hao; Chen, Suwu; Wang, Xia

2018-04-01

Synthesis of conducting polymer-silica colloidal nanocomposites has been recognized as an effective method to overcome the poor processability of heterocyclic conducting polymers prepared by chemical oxidative method. However, the morphology control of such conducting polymer-silica nanocomposites was seldomly reported in the literature. Novel poly(2-aminothiazole)(PAT)-silica nanocomposite particles can be conveniently prepared by chemical oxidative polymerization of 2-aminothiazole using CuCl2 oxidant in the presence of ∼20 nm silica nanoparticles. The effects of varying the oxidant/monomer ratio and silica sol concentration on the morphology and size of the resulting PAT-silica nanocmposites have been studied. Optimization of the oxidant/monomer molar ratio and initial silica sol concentration allows relatively round spherical particles of 150-350 nm in diameter to be achieved. The nanocomposite particles have a well-defined raspberry-like morphology with a silica-rich surface, but a significant fraction of PAT component still exists on the surface and, which is beneficial for its applications. Furthermore, the surface compositions of the colloidal nanocomposites could be regulated to some extent. Based on the above results, a possible formation mechanism of the spherical nanocomposite particles is proposed.

Structure and mechanical properties of polyamide 6/Brazilian clay nanocomposites

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Amanda Melissa Damião Leite

2009-06-01

Full Text Available Recent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility.

Field theoretic approach to dynamical orbital localization in ab initio molecular dynamics

International Nuclear Information System (INIS)

Thomas, Jordan W.; Iftimie, Radu; Tuckerman, Mark E.

2004-01-01

Techniques from gauge-field theory are employed to derive an alternative formulation of the Car-Parrinello ab initio molecular-dynamics method that allows maximally localized Wannier orbitals to be generated dynamically as the calculation proceeds. In particular, the Car-Parrinello Lagrangian is mapped onto an SU(n) non-Abelian gauge-field theory and the fictitious kinetic energy in the Car-Parrinello Lagrangian is modified to yield a fully gauge-invariant form. The Dirac gauge-fixing method is then employed to derive a set of equations of motion that automatically maintain orbital locality by restricting the orbitals to remain in the 'Wannier gauge'. An approximate algorithm for integrating the equations of motion that is stable and maintains orbital locality is then developed based on the exact equations of motion. It is shown in a realistic application (64 water molecules plus one hydrogen-chloride molecule in a periodic box) that orbital locality can be maintained with only a modest increase in CPU time. The ability to keep orbitals localized in an ab initio molecular-dynamics calculation is a crucial ingredient in the development of emerging linear scaling approaches

Study on Exothermic Oxidation of Acrylonitrile-butadiene-styrene (ABS Resin Powder with Application to ABS Processing Safety

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Jenq-Renn Chen

2010-08-01

Full Text Available Oxidative degradation of commercial grade ABS (Acrylonitrile-butadiene-styrene resin powders was studied by thermal analysis. The instabilities of ABS containing different polybutadiene (PB contents with respect to temperature were studied by Differential Scanning Calorimeter (DSC. Thermograms of isothermal test and dynamic scanning were performed. Three exothermic peaks were observed and related to auto-oxidation, degradation and oxidative decomposition, respectively. Onset temperature of the auto-oxidation was determined to be around 193 °C. However, threshold temperature of oxidation was found to be as low as 140 °C by DSC isothermal testing. Another scan of the powder after degeneration in air showed an onset temperature of 127 °C. Reactive hazards of ABS powders were verified to be the exothermic oxidation of unsaturated PB domains, not the SAN (poly(styrene-acrylonitrile matrix. Heat of oxidation was first determined to be 2,800 ± 40 J per gram of ABS or 4,720 ± 20 J per gram of PB. Thermal hazards of processing ABS powder are assessed by adiabatic temperature rise at process conditions. IR spectroscopy associated with heat of oxidation verified the oxidative mechanism, and these evidences excluded the heat source from the degradation of SAN. A specially prepared powder of ABS without adding anti-oxidant was analyzed by DSC for comparing the exothermic behaviors. Exothermic onset temperatures were determined to be 120 °C and 80 °C by dynamic scanning and isothermal test, respectively. The assessment successfully explained fires and explosions in an ABS powder dryer and an ABS extruder.

Separation performance and interfacial properties of nanocomposite reverse osmosis membranes

KAUST Repository

Pendergast, MaryTheresa M.; Ghosh, Asim K.; Hoek, E.M.V.

2013-01-01

Four different types of nanocomposite reverse osmosis (RO) membranes were formed by interfacial polymerization of either polyamide (PA) or zeolite A-polyamide nanocomposite (ZA-PA) thin films over either pure polysulfone (PSf) or zeolite A-polysulfone nanocomposite (ZA-PSf) support membranes cast by wet phase inversion. All three nanocomposite membranes exhibited superior separation performance and interfacial properties relative to hand-cast TFC analogs including: (1) smoother, more hydrophilic surfaces (2) higher water permeability and salt rejection, and (3) improved resistance to physical compaction. Less compaction occurred for membranes with nanoparticles embedded in interfacially polymerized coating films, which adds further proof that flux decline associated with physical compaction is influenced by coating film properties in addition to support membrane properties. The new classes of nanocomposite membrane materials continue to offer promise of further improved RO membranes for use in desalination and advanced water purification. © 2011 Elsevier B.V.

Electrospun nanocomposite fibrous polymer electrolyte for secondary lithium battery applications

International Nuclear Information System (INIS)

Padmaraj, O.; Rao, B. Nageswara; Jena, Paramananda; Satyanarayana, N.; Venkateswarlu, M.

2014-01-01

Hybrid nanocomposite [poly(vinylidene fluoride -co- hexafluoropropylene) (PVdF-co-HFP)/magnesium aluminate (MgAl 2 O 4 )] fibrous polymer membranes were prepared by electrospinning method. The prepared pure and nanocomposite fibrous polymer electrolyte membranes were soaked into the liquid electrolyte 1M LiPF 6 in EC: DEC (1:1,v/v). XRD and SEM are used to study the structural and morphological studies of nanocomposite electrospun fibrous polymer membranes. The nanocomposite fibrous polymer electrolyte membrane with 5 wt.% of MgAl 2 O 4 exhibits high ionic conductivity of 2.80 × 10 −3 S/cm at room temperature. The charge-discharge capacity of Li/LiCoO 2 coin cells composed of the newly prepared nanocomposite [(16 wt.%) PVdF-co-HFP+(5 wt.%) MgAl 2 O 4 ] fibrous polymer electrolyte membrane was also studied and compared with commercial Celgard separator

Polymer-Ag nanocomposites with enhanced antimicrobial activity against bacterial infection.

Science.gov (United States)

Mei, Lin; Lu, Zhentan; Zhang, Xinge; Li, Chaoxing; Jia, Yanxia

2014-09-24

Herein, a nontoxic nanocomposite is synthesized by reduction of silver nitrate in the presence of a cationic polymer displaying strong antimicrobial activity against bacterial infection. These nanocomposites with a large concentration of positive charge promote their adsorption to bacterial membranes through electrostatic interaction. Moreover, the synthesized nanocomposites with polyvalent and synergistic antimicrobial effects can effectively kill both Gram-positive and Gram-negative bacteria without the emergence of bacterial resistance. Morphological changes obtained by transmission electron microscope observation show that these nanocomposites can cause leakage and chaos of intracellular contents. Analysis of the antimicrobial mechanism confirms that the lethal action of nanocomposites against the bacteria started with disruption of the bacterial membrane, subsequent cellular internalization of the nanoparticles, and inhibition of intracellular enzymatic activity. This novel antimicrobial material with good cytocompatibility promotes healing of infected wounds in diabetic rats, and has a promising future in the treatment of other infectious diseases.

Photonic structures based on hybrid nanocomposites

Science.gov (United States)

Husaini, Saima

In this thesis, photonic structures embedded with two types of nanomaterials, (i) quantum dots and (ii) metal nanoparticles are studied. Both of these exhibit optical and electronic properties different from their bulk counterpart due to their nanoscale physical structure. By integrating these nanomaterials into photonic structures, in which the electromagnetic field can be confined and controlled via modification of geometry and composition, we can enhance their linear and nonlinear optical properties to realize functional photonic structures. Before embedding quantum dots into photonic structures, we study the effect of various host matrices and fabrication techniques on the optical properties of the colloidal quantum dots. The two host matrices of interest are SU8 and PMMA. It is shown that the emission properties of the quantum dots are significantly altered in these host matrices (especially SU8) and this is attributed to a high rate of nonradiative quenching of the dots. Furthermore, the effects of fabrication techniques on the optical properties of quantum dots are also investigated. Finally a microdisk resonator embedded with quantum dots is fabricated using soft lithography and luminescence from the quantum dots in the disk is observed. We investigate the absorption and effective index properties of silver nanocomposite films. It is shown that by varying the fill factor of the metal nanoparticles and fabrication parameters such as heating time, we can manipulate the optical properties of the metal nanocomposite. Optimizing these parameters, a silver nanocomposite film with a 7% fill factor is prepared. A one-dimensional photonic crystal consisting of alternating layers of the silver nanocomposite and a polymer (Polymethyl methacrylate) is fabricated using spin coating and its linear and nonlinear optical properties are investigated. Using reflectivity measurements we demonstrate that the one-dimensional silver-nanocomposite-dielectric photonic crystal

Preparation and characterization of sepiolite-based phase change material nanocomposites for thermal energy storage

International Nuclear Information System (INIS)

Konuklu, Yeliz; Ersoy, Orkun

2016-01-01

Highlights: • Sepiolite-based phase change material nanocomposites were prepared. • An easy direct impregnation process was used. • This paper is one of the first study about sepiolite-based phase change material nanocomposites. • Influence of PCM type on thermal properties of nanocomposites was reported. - Abstract: This paper is one of the first study about the preparation and characterization of sepiolite-based phase change material nanocomposites for thermal energy storage applications. Sepiolite is an important natural fibrous raw material. Nanoscale fibrous tubular structure of sepiolite becomes important in nanocomposite preparation. In this study, sepiolite/paraffin and sepiolite/decanoic acid nanocomposites were manufactured by the direct impregnation method. By the preparation of nanocomposites, PCM move in tubular channels of sepiolite, phase changing occurs in these tubes and surface area increases like as in microencapsulation. The structure and properties of nanocomposites PCMs (CPCM) have been characterized via scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The SEM results prove the successful preparation of phase change material/sepiolite nanocomposites and point out that the fibers of sepiolite is modified with phase change materials in the nanocomposite. The phase change enthalpies of melting and freezing were about 62.08 J/g and −62.05 J/g for sepiolite/paraffin nanocomposites and 35.69 J/g and −34.55 J/g for sepiolite/decanoic acid nanocomposites, respectively. The results show that PCM/sepiolite nanocomposites were prepared successfully and their properties are very suitable for thermal energy storage applications.

Evolution of microstructure, strain and physical properties in oxide nanocomposite films.

Science.gov (United States)

Chen, Aiping; Weigand, Marcus; Bi, Zhenxing; Zhang, Wenrui; Lü, Xuejie; Dowden, Paul; MacManus-Driscoll, Judith L; Wang, Haiyan; Jia, Quanxi

2014-06-24

We, using LSMO:ZnO nanocomposite films as a model system, have studied the effect of film thickness on the physical properties of nanocomposites. It shows that strain, microstructure, as well as magnetoresistance strongly rely on film thickness. The magnetotransport properties have been fitted by a modified parallel connection channel model, which is in agreement with the microstructure evolution as a function of film thickness in nanocomposite films on sapphire substrates. The strain analysis indicates that the variation of physical properties in nanocomposite films on LAO is dominated by strain effect. These results confirm the critical role of film thickness on microstructures, strain states, and functionalities. It further shows that one can use film thickness as a key parameter to design nanocomposites with optimum functionalities.

Synthesis of photothermal nanocomposites and their application to antibacterial assays

Science.gov (United States)

Yang, Ning; Wang, Chun; Wang, Xiaoyu; Li, Lidong

2018-04-01

In this work, we report a novel gold nanorod (AuNR)-based nanocomposite that shows strong binding to bacterium and high antibacterial efficiency. The AuNRs were used as a photothermal material to transform near-infrared radiation (NIR) into heat. We selected poly (acrylic acid) to modify the surface of the AuNRs based on a simple self-assembly method. After conjugation of the bacterium-binding molecule vancomycin, the nanocomposites were capable of efficiently gathering on the cell walls of bacteria. The nanocomposites exhibited a high bacterial inhibition capability owing to NIR-induced heat generation in situ. Therefore, the prepared photothermal nanocomposites show great potential for use in antibacterial assays.

Polyacrolein/mesoporous silica nanocomposite: Synthesis, thermal stability and covalent lipase immobilization

Energy Technology Data Exchange (ETDEWEB)

Motevalizadeh, Seyed Farshad; Khoobi, Mehdi; Shabanian, Meisam [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Asadgol, Zahra; Faramarzi, Mohammad Ali [Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran 14176 (Iran, Islamic Republic of); Shafiee, Abbas, E-mail: ashafiee@ams.ac.ir [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Center of Excellence in Biothermodynamics, University of Tehran, Tehran (Iran, Islamic Republic of)

2013-12-16

In this work, new polyacrolein/MCM-41 nanocomposites with good phase mixing behavior were prepared through an emulsion polymerization technique. Mesoporous silica was synthesized by in situ assembly of tetraethyl orthosilicate (TEOS) and cetyl trimethyl ammonium bromide (CTAB). The structure and properties of polyacrolein containing nanosized MCM-41 particle (5 and 10 wt%), were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N{sub 2} adsorption techniques, and thermogravimetric (TGA) analyses. The SEM images from the final powder have revealed good dispersion of the MCM-41 nanoparticles throughout polymeric matrix with no distinct voids between two phases. The results indicated that the thermal properties of the nanocomposite were enhanced by addition of MCM-41. Thermomyces lanuginosa lipase (TLL) was used as a model biocatalyst and successfully immobilized with polyacrolein and the nanocomposite via covalent bonds with the aldehyde groups. The activity between free enzyme, polyacrolein, and MCM-41 nanocomposite (10 wt%)-immobilized TLL was compared. The immobilized lipase with the nanocomposite shows better operational stability such as pH tolerance, thermal and storage stability. In addition, the immobilized lipase with the nanocomposite can be easily recovered and retained at 74% of its initial activity after 15 time reuses. - Graphical abstract: The influence of incorporation of mesoporous MCM-41 nanoparticle with polyacrolein on the thermal properties and enzyme immobilization was investigated. - Highlights: • Polyacrolein/MCM-41 nanocomposites were prepared by emulsion polymerization method. • Thermal stability and char residues in nanocomposites were improved. • Nanocomposites significant effects on immobilization of lipase.

Environmental and Cost Assessment of a Polypropylene Nanocomposite

NARCIS (Netherlands)

Roes, A.L.|info:eu-repo/dai/nl/303022388; Marsili, E.; Nieuwlaar, E.|info:eu-repo/dai/nl/073931373; Patel, M.K.|info:eu-repo/dai/nl/18988097X

2007-01-01

This paper describes a study on the use of a polypropylene (PP)/layered silicate nanocomposite as packaging film, agricultural film, and automotive panels. The study’s main question was “Are the environmental impacts and costs throughout the life cycle of nanocomposite products lower than those of

Dielectric spectroscopy of Ag-starch nanocomposite films

Science.gov (United States)

Meena; Sharma, Annu

2018-04-01

In the present work Ag-starch nanocomposite films were fabricated via chemical reduction route. The formation of Ag nanoparticles was confirmed using transmission electron microscopy (TEM). Further the effect of varying concentration of Ag nanoparticles on the dielectric properties of starch has been studied. The frequency response of dielectric constant (ε‧), dielectric loss (ε″) and dissipation factor tan(δ) has been studied in the frequency range of 100 Hz to 1 MHz. Dielectric data was further analysed using Cole-Cole plots. The dielectric constant of starch was found to be 4.4 which decreased to 2.35 in Ag-starch nanocomposite film containing 0.50 wt% of Ag nanoparticles. Such nanocomposites with low dielectric constant have potential applications in microelectronic technologies.

Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites

OpenAIRE

Ouyang, Zen-Wei; Chen, Erh-Chiang; Wu, Tzong-Ming

2015-01-01

This work describes the thermal stability and magnetic properties of polyvinylidene fluoride (PVDF)/magnetite nanocomposites fabricated using the solution mixing technique. The image of transmission electron microscopy for PVDF/magnetite nanocomposites reveals that the 13 nm magnetite nanoparticles are well distributed in PVDF matrix. The electroactive β-phase and piezoelectric responses of PVDF/magnetite nanocomposites are increased as the loading of magnetite nanoparticles increases. The pi...

Equation of state of U2Mo up-to Mbar pressure range: Ab-initio study

Science.gov (United States)

Mukherjee, D.; Sahoo, B. D.; Joshi, K. D.; Kaushik, T. C.

2018-04-01

Experimentally, U2Mo is known to exist in tetragonal structure at ambient conditions. In contrast to experimental reports, the past theoretical studies carried out in this material do not find this phase to be stable structure at zero pressure. In order to examine this discrepancy between experiment and theory, we have performed ab-initio electronic band structure calculations on this material. In our theoretical study, we have attempted to search for lowest enthalpy structure at ambient as well at high pressure up to 200 GPa, employing evolutionary structure search algorithm in conjunction with ab-inito method. Our investigations suggest that a hexagonal structure with space group symmetry P6/mmm is the lowest enthalpy structure not only at ambient pressure but also up to pressure range of ˜200 GPa. To further, substantiate the results of these static lattice calculations the elastic and lattice dynamical stability has also been analysed. The theoretical isotherm derived from these calculations has been utilized to determine the Hugoniot of this material. Various physical properties such as zero pressure equilibrium volume, bulk modulus and its pressure derivative has also been derived from theoretical isotherm.

PBAT based nanocomposites for medical and industrial applications

Energy Technology Data Exchange (ETDEWEB)

Fukushima, Kikku, E-mail: kikku81@gmail.com [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei 10607, Taiwan (China); Wu, Meng-Hsiu [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei 10607, Taiwan (China); Bocchini, Sergio [Dipartimento di Scienze dei Materiali ed Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Rasyida, Amaliya; Yang, Ming-Chien [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei 10607, Taiwan (China)

2012-08-01

Poly(butylene adipate-co-terephthalate) (PBAT) based nanocomposites were prepared by melt blending PBAT with 5 and 10 wt.% of clay nanoparticles (unmodified and modified montmorillonites, unmodified and modified fluoro-hectorites, and unmodified sepiolites). All nanocomposites showed a good level of clay distribution and dispersion into PBAT, especially nanocomposites with high clay chemical affinity with the polymer matrix. DSC results showed that addition of layered silicates slightly hindered kinetics and extent of crystallization of PBAT; however, sepiolite particles were able to promote polymer crystallization kinetics and the transformation of the PBAT crystal structure to a more ordered form. Similar increases in the thermal stability of PBAT in nitrogen and air were obtained upon addition of all clays, due to a barrier effect of the clays toward polymer decomposition product ablation. Preliminary biocompatibility tests indicated that PBAT based materials with 10% clay content have good biological safety and display almost no cytotoxicity. The addition of all nanofillers increased the hardness of PBAT matrix. The DMA analysis showed that all nanocomposites presented higher E Prime values than neat PBAT, indicating that addition of clays improved the mechanical properties of PBAT. For layered silicate nanocomposites, the main influencing factors on the thermo-mechanical properties appeared to be the aspect ratio and dispersion of clay nanoplatelets, rather than polymer/clay chemical affinity. The highest E Prime values of sepiolite based nanocomposites make this nanoparticle the most attractive material for tissue engineering and environmental industrial applications. Highlights: Black-Right-Pointing-Pointer PBAT nanocomposites with high thermo-mechanical properties were obtained. Black-Right-Pointing-Pointer The effects of clay presence on PBAT crystalline structure were elucidated. Black-Right-Pointing-Pointer The presence of the clays used in PBAT showed

Solvent (acetone-butanol: ab) production

Science.gov (United States)

This article describes production of butanol [acetone-butanol-ethanol, (also called AB or ABE or solvent)] by fermentation using both traditional and current technologies. AB production from agricultural commodities, such as corn and molasses, was an important historical fermentation. Unfortunately,...

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites

Directory of Open Access Journals (Sweden)

Lik-ho Tam

2017-10-01

Full Text Available The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications across multiple scales. In this research, a molecular dynamics model of the epoxy/single-walled carbon nanotube (SWCNT nanocomposite is constructed to explore the mechanism of the moisture effect, and an analysis of the molecular interactions is provided by focusing on the hydrogen bond (H-bond network inside the nanocomposite structure. The simulations show that at low moisture concentration, the water molecules affect the molecular interactions by favorably forming the water-nanocomposite H-bonds and the small cluster, while at high concentration the water molecules predominantly form the water-water H-bonds and the large cluster. The water molecules in the epoxy matrix and the epoxy-SWCNT interface disrupt the molecular interactions and deteriorate the mechanical properties. Through identifying the link between the water molecules and the nanocomposite structure and properties, it is shown that the free volume in the nanocomposite is crucial for its structural integrity, which facilitates the moisture accumulation and the distinct material deteriorations. This study provides insights into the moisture-affected structure and properties of the nanocomposite from the nanoscale perspective, which contributes to the understanding of the nanocomposite long-term performance under the moisture effect.

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites.

Science.gov (United States)

Tam, Lik-Ho; Wu, Chao

2017-10-13

The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications across multiple scales. In this research, a molecular dynamics model of the epoxy/single-walled carbon nanotube (SWCNT) nanocomposite is constructed to explore the mechanism of the moisture effect, and an analysis of the molecular interactions is provided by focusing on the hydrogen bond (H-bond) network inside the nanocomposite structure. The simulations show that at low moisture concentration, the water molecules affect the molecular interactions by favorably forming the water-nanocomposite H-bonds and the small cluster, while at high concentration the water molecules predominantly form the water-water H-bonds and the large cluster. The water molecules in the epoxy matrix and the epoxy-SWCNT interface disrupt the molecular interactions and deteriorate the mechanical properties. Through identifying the link between the water molecules and the nanocomposite structure and properties, it is shown that the free volume in the nanocomposite is crucial for its structural integrity, which facilitates the moisture accumulation and the distinct material deteriorations. This study provides insights into the moisture-affected structure and properties of the nanocomposite from the nanoscale perspective, which contributes to the understanding of the nanocomposite long-term performance under the moisture effect.

Ab initio quantum chemistry in parallel-portable tools and applications

International Nuclear Information System (INIS)

Harrison, R.J.; Shepard, R.; Kendall, R.A.

1991-01-01

In common with many of the computational sciences, ab initio chemistry faces computational constraints to which a partial solution is offered by the prospect of highly parallel computers. Ab initio codes are large and complex (O(10 5 ) lines of FORTRAN), representing a significant investment of communal effort. The often conflicting requirements of portability and efficiency have been successfully resolved on vector computers by reliance on matrix oriented kernels. This proves inadequate even upon closely-coupled shared-memory parallel machines. We examine the algorithms employed during a typical sequence of calculations. Then we investigate how efficient portable parallel implementations may be derived, including the complex multi-reference singles and doubles configuration interaction algorithm. A portable toolkit, modeled after the Intel iPSC and the ANL-ACRF PARMACS, is developed, using shared memory and TCP/IP sockets. The toolkit is used as an initial platform for programs portable between LANS, Crays and true distributed-memory MIMD machines. Timings are presented. 53 refs., 4 tabs

Recyclable Escherichia coli-Specific-Killing AuNP-Polymer (ESKAP) Nanocomposites.

Science.gov (United States)

Yuan, Yuqi; Liu, Feng; Xue, Lulu; Wang, Hongwei; Pan, Jingjing; Cui, Yuecheng; Chen, Hong; Yuan, Lin

2016-05-11

Escherichia coli plays a crucial role in various inflammatory diseases and infections that pose significant threats to both human health and the global environment. Specifically inhibiting the growth of pathogenic E. coli is of great and urgent concern. By modifying gold nanoparticles (AuNPs) with both poly[2-(methacrylamido)glucopyranose] (pMAG) and poly[2-(methacryloyloxy)ethyl trimethylammonium iodide] (pMETAI), a novel recyclable E. coli-specific-killing AuNP-polymer (ESKAP) nanocomposite is proposed in this study, which based on both the high affinity of glycopolymers toward E. coli pili and the merits of antibacterial quaternized polymers attached to gold nanoparticles. The properties of nanocomposites with different ratios of pMAG to pMETAI grafted onto AuNPs are studied. With a pMAG:pMETAI feed ratio of 1:3, the nanocomposite appeared to specifically adhere to E. coli and highly inhibit the bacterial cells. After addition of mannose, which possesses higher affinity for the lectin on bacterial pili and has a competitive advantage over pMAG for adhesion to pili, the nanocomposite was able to escape from dead E. coli cells, becoming available for repeat use. The recycled nanocomposite retained good antibacterial activity for at least three cycles. Thus, this novel ESKAP nanocomposite is a promising, highly effective, and readily recyclable antibacterial agent that specifically kills E. coli. This nanocomposite has potential applications in biological sensing, biomedical diagnostics, biomedical imaging, drug delivery, and therapeutics.

Elaboration, structural and optical investigations of ZnO/epoxy nanocomposites

Science.gov (United States)

Moussa, S.; Namouchi, F.; Guermazi, H.

2015-07-01

Hybrid nanocomposites were elaborated by incorporating ZnO nanoparticles into a transparent epoxy polymer matrix, using the direct dispersion method. The effect of the nanoparticles on the structural and optical properties of the polymer matrix was investigated using Fourier transform infrared (FTIR), Raman and UV-Visible spectroscopies. Nanocomposites FTIR spectra showed a variation of band intensities attributed to nanoparticles agglomeration within the polymer. The UV-Visible measurements showed a redshift on the band gap energy of the nanocomposites differently from neat epoxy resin, caused by interactions between ZnO NPs and polymer chains. Raman spectra confirm these interactions and the formation of hydrogen bonds in the nanocomposites. The UV-Visible transmittance spectra revealed that addition of a very low concentration (0.2wt%) of ZnO nanoparticles to a transparent epoxy matrix would maintain high visible-light transparency. The decrease of transmittance with increasing ZnO percentage is due to light scattering which originates from the agglomeration of nanoparticles in the matrix, the mismatch between the refractive index of ZnO and that of the epoxy matrix, and the increase of the surface roughness of the nanocomposite with increasing ZnO addition. Moreover, the UV-vis absorption spectra revealed that adding more than 1wt% ZnO leads to the improvement of the UV shielding properties of the nanocomposites. These results prove that the elaborated ZnO/epoxy nanocomposites can be used as UV shielding materials.

Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites

International Nuclear Information System (INIS)

Sarathi, R.; Sahu, R.K.; Rajeshkumar, P.

2007-01-01

In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5 wt%, under AC and DC voltages. The volume resistivity, permittivity and tan(δ) of the epoxy nanocomposites were measured. The Weibull studies indicate that addition of nanoclay upto 5 wt% enhances the characteristic life of epoxy nanocomposite insulation material. The tracking test results indicate that the tracking time is high with epoxy nanocomposites as compared to pure epoxy. Ageing studies were carried out to understand the surface characteristic variation through contact angle measurement. The hydrophobicity of the insulating material was analysed through contact angle measurement. The diffusion coefficients of the material with different percentage of clay in epoxy nanocomposites were calculated. The exfoliation characteristics in epoxy nanocomposites were analyzed through wide angle X-ray diffraction (WAXD) studies. The thermal behaviour of the epoxy nanocomposites was analyzed by carrying out thermo gravimetric-differential thermal analysis (TG-DTA) studies. Heat deflection temperature of the material was measured to understand the stability of the material for intermittent temperature variation. The dynamic mechanical analysis (DMA) results indicated that storage modulus of the material increases with small amount of clay in epoxy resin. The activation energy of the material was calculated from the DMA results

Detection of adult T-cell leukemia virus (ATLV) bearing lymphocytes in concentrated red blood cells derived from ATL associated antibody (ATLA-Ab) positive donors.

Science.gov (United States)

Morishima, Y; Ohya, K; Ueda, R; Fukuda, T

1986-01-01

Adult T cell leukemia associated antibody (ATLA-Ab) positive persons were screened by indirect immunofluorescence (IF) testing. Their lymphocytes were collected from concentrated red blood cells (CRC), and cultured in vitro with and without phytohemagglutinin (PHA) for 10 days. The expression of ATL virus (ATLV) positive lymphocytes during the in vitro culture was then analyzed by IF assay using mouse monoclonal antibody ATL-19 reactive to p19 core protein of ATLV. 97% of ATLA-Ab positive CRC (36 cases) demonstrated ATLV positive lymphocytes after being cultured for more than 10 days with PHA, whereas, none of ATLA-Ab negative CRC (22 cases) demonstrated ATLV positive lymphocytes. All of the 10 ATLA-Ab positive CRC that were stored for 2, 4, and 7 days contained lymphocytes which expressed ATLV after in vitro culture, while 7 of 10 CRC stored for 14 days and only 1 of 10 CRCs stored for 20 days, expressed ATLV positive lymphocytes. This data indicates that almost all of the ATLA-Ab positive blood contained ATLV positive lymphocytes, and that the in vitro appearance of these ATLV positive lymphocytes was reduced by storing the CRC for more than 14 days.

Ab-initio calculation of electronic structure and optical properties of AB-stacked bilayer α-graphyne

Science.gov (United States)

Behzad, Somayeh

2016-09-01

Monolayer α-graphyne is a new two-dimensional carbon allotrope with many special features. In this work the electronic properties of AA- and AB-stacked bilayers of this material and then the optical properties are studied, using first principle plane wave method. The electronic spectrum has two Dirac cones for AA stacked bilayer α-graphyne. For AB-stacked bilayer, the interlayer interaction changes the linear bands into parabolic bands. The optical spectra of the most stable AB-stacked bilayer closely resemble to that of the monolayer, except for small shifts of peak positions and increasing of their intensity. For AB-stacked bilayer, a pronounced peak has been found at low energies under the perpendicular polarization. This peak can be clearly ascribed to the transitions at the Dirac point as a result of the small degeneracy lift in the band structure.

Field Trial Performance of Herculex XTRA (Cry34Ab1/Cry35Ab1) and SmartStax (Cry34Ab1/Cry35Ab1 + Cry3Bb1) Hybrids and Soil Insecticides Against Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae).

Science.gov (United States)

Johnson, K D; Campbell, L A; Lepping, M D; Rule, D M

2017-06-01

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae), are important insect pests in corn, Zea mays L. For more than a decade, growers have been using transgenic plants expressing proteins from the bacterium Bacillus thuringiensis (Bt) to protect corn roots from feeding. In 2011, western corn rootworm populations were reported to have developed resistance to Bt hybrids expressing Cry3Bb1 and later found to be cross-resistant to hybrids expressing mCry3A and eCry3.1Ab. The identification of resistance to Cry3 (Cry3Bb1, mCry3A, and eCry3.1Ab) hybrids led to concerns about durability and efficacy of products with single traits and of products containing a pyramid of a Cry3 protein and the binary Bt proteins Cry34Ab1 and Cry35Ab1. From 2012 to 2014, 43 field trials were conducted across the central United States to estimate root protection provided by plants expressing Cry34Ab1/Cry35Ab1 alone (Herculex RW) or pyramided with Cry3Bb1 (SmartStax). These technologies were evaluated with and without soil-applied insecticides to determine if additional management measures provided benefit where Cry3 performance was reduced. Trials were categorized for analysis based on rootworm damage levels on Cry3-expressing hybrids and rootworm feeding pressure within each trial. Across scenarios, Cry34Ab1/Cry35Ab1 hybrids provided excellent root protection. Pyramided traits provided greater root and yield protection than non-Bt plus a soil-applied insecticide, and only in trials where larval feeding pressure exceeded two nodes of damage did Cry34Ab1/Cry35Ab1 single-trait hybrids and pyramided hybrids show greater root protection from the addition of soil-applied insecticides. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Microwave absorbing property and complex permittivity and permeability of graphene–CdS nanocomposite

International Nuclear Information System (INIS)

Zhang, Dong-Dong; Zhao, Dong-Lin; Zhang, Ji-Ming; Bai, Li-Zhong

2014-01-01

Graphical abstract: Graphene–CdS (G–CdS) nanocomposite with a good structural interface and enhanced microwave absorption has been successfully and directly synthesized from graphene oxide via a facile hydrothermal approach. The permittivity of G–CdS nanocomposite presents triple dielectric relaxations by constructing a good structural G–CdS interface. The triple dielectric relaxations are critical to improve the microwave absorption of the G–CdS nanocomposite. Highlights: • Graphene–CdS (G–CdS) nanocomposite was directly synthesized from graphene oxide. • The G–CdS nanocomposite exhibits enhanced microwave absorption. • The permittivity of G–CdS nanocomposite presents triple dielectric relaxations. -- Abstract: The graphene–CdS (G–CdS) nanocomposite with enhanced microwave absorption was directly synthesized from graphene oxide (GO) via a facile hydrothermal approach, during which the formation of CdS nanoparticles and the reduction of GO occured simultaneously. The morphology, structure, microwave absorbing property, complex permittivity and permeability of G–CdS nanocomposite were systematically investigated by transmission electron microscope, X-ray diffraction and the coaxial line method. The complex permittivity of G–CdS nanocomposite presents triple dielectric relaxations with constructing a good structural graphene–CdS interface. The triple dielectric relaxations were critical to improve the microwave absorption of G–CdS nanocomposite. The G–CdS nanocomposite achieved a reflection loss below –10 dB in the frequency range of 5.2–18 GHz when adjusting the thicknesses from 2 to 5 mm, which was mainly ascribed to the proper electromagnetic matching of the CdS nanoparticles and graphene sheets, and the triple dielectric relaxations. The G–CdS nanocomposite is promising as a lightweight and wide-frequency microwave absorber

Investigation on Electrochemical Properties of Polythiophene Nanocomposite with Graphite Derivatives as Supercapacitor Material on Breath Figure-Decorated PMMA Electrode

Science.gov (United States)

Azimi, Mona; Abbaspour, Mohsen; Fazli, Ali; Setoodeh, Hamideh; Pourabbas, Behzad

2018-03-01

Breath figures have been formed by the direct breath figure method on polymethyl methacrylate electrode sand hexagonal oriented holes with 0.5- to 10- μm2 surface area have been created. Deposition of materials on the electrodes has been performed by the spray-coating method. polythiophene (PTh) nanoparticles, polythiophene-graphene oxide (PTh-GO) and polythiophene-reduced graphene oxide (PTh-G) nanocomposites were synthesized by emulsion polymerization, while characterization of synthetic materials have been carried out by Fourier transform infrared, Χ-ray diffraction, transmission electron microscopy, UV-Vis spectroscopy and field emission scanning electron microscopy techniques. Also, the electrochemical properties of the designed electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. Specific capacitance of porous electrodes coated by PTh nanoparticles, PTh-GO and PTh-G nanocomposites were calculated from cyclic voltammetry curves at 5 mV/s scan rate, andthe values are 3.5 F/g, 16.39 F/g, and 28.68 F/g, respectively. Also, the energy density of each electrode at 5 mV/s scan rate has been calculated and the results show that incorporation of GO and G nanolayers with PTh nanoparticles enhances the electrochemical properties of electrodes.

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures.

Science.gov (United States)

Zhao, Ziguang; Fang, Ruochen; Rong, Qinfeng; Liu, Mingjie

2017-12-01

In the human body, many soft tissues with hierarchically ordered composite structures, such as cartilage, skeletal muscle, the corneas, and blood vessels, exhibit highly anisotropic mechanical strength and functionality to adapt to complex environments. In artificial soft materials, hydrogels are analogous to these biological soft tissues due to their "soft and wet" properties, their biocompatibility, and their elastic performance. However, conventional hydrogel materials with unordered homogeneous structures inevitably lack high mechanical properties and anisotropic functional performances; thus, their further application is limited. Inspired by biological soft tissues with well-ordered structures, researchers have increasingly investigated highly ordered nanocomposite hydrogels as functional biological engineering soft materials with unique mechanical, optical, and biological properties. These hydrogels incorporate long-range ordered nanocomposite structures within hydrogel network matrixes. Here, the critical design criteria and the state-of-the-art fabrication strategies of nanocomposite hydrogels with highly ordered structures are systemically reviewed. Then, recent progress in applications in the fields of soft actuators, tissue engineering, and sensors is highlighted. The future development and prospective application of highly ordered nanocomposite hydrogels are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer nanocomposite patterning by dip-pen nanolithography

International Nuclear Information System (INIS)

Kandemir, Ayse Cagil; Ma, Huan; Reiser, Alain; Spolenak, Ralph; Erdem, Derya

2016-01-01

The ultimate aim of this study is to construct polymer nanocomposite patterns by dip-pen nanolithography (DPN). Recent investigations have revealed the effect of the amount of ink (Laplace pressure) on the mechanism of liquid ink writing. In this study it is shown that not only the amount of ink, but also physisorption and surface diffusion are relevant. After a few writing steps, physisorption and surface diffusion outweigh the influence of the amount of ink, allowing consistent patterning governed by dwell times and writing speeds. Polymer matrices can be utilized as a delivery medium to deposit functional particles. DPN patterning of polymer nanocomposites allows for local tuning of the functionality and mechanical strength of the written patterns in high resolution, with the benefit of pattern flexibility. Typically polymer matrices with volatile components are used as a delivery medium for nanoparticle deposition, with subsequent removal of loosely bound matrix material by heating or oxygen plasma. In our study, nanocomposite patterns were constructed, and the differences between polymer and nanocomposite patterning were investigated. Cross-sectional SEM and TEM analysis confirmed that nanoparticles can be deposited with the liquid-polymer ink and are evenly distributed in the polymer matrix. (paper)

Role of polymer matrix on photo-sensitivity of CdSe polymer nanocomposites

Science.gov (United States)

Kaur, Ramneek; Tripathi, S. K.

2018-04-01

This paper reports the effect of three different polymer matrices (PVP, PMMA and PVK) and Ag doping on the photo-sensitivity of CdSe polymer nanocomposites. The results reveal that the photoconductivity is high for linear chain polymer nanocomposites as compared to aromatic ones with decreasing trend as: CdSe-PMMA > CdSe-PVP > CdSe-PVK. The large substituents or branches along the polymer backbone hinder the stacking sequences in CdSe-PVK nanocomposites resulting in lowest photoconductivity. On contrary, CdSe-PVK nanocomposite exhibit highest photosensitivity. The reason behind it is the low value of dark conductivity in CdSe-PVK nanocomposite and photoconductive PVK matrix. With Ag doping, no considerable effect on the value of photosensitivity has been observed. The obtained results indicate that the photo-conducting properties of these polymer nanocomposites can be tuned by using different polymer matrices.

Regenerated cellulose/halloysite nanotube nanocomposite films prepared with an ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Soheilmoghaddam, Mohammad [Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia (UTM), Johor (Malaysia); Wahit, Mat Uzir, E-mail: mat.uzir@cheme.utm.my [Center for Composites, Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor (Malaysia); Mahmoudian, Shaya [Department of Textile Engineering, Kashan Branch, Islamic Azad University, Kashan (Iran, Islamic Republic of); Hanid, Nurbaiti Abdul [Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia (UTM), Johor (Malaysia)

2013-09-16

Regenerated cellulose/halloysite nanotube (RC/HNT) nanocomposite films were successfully prepared in ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl) using solution casting method. The structural, morphological, thermal and mechanical properties of RC/HNT nanocomposites were investigated. X-ray diffraction analysis revealed a cellulose II crystalline structure and well dispersed HNT in RC/HNT nanocomposite films. At 6 wt.% HNT film, tensile strength and Young's modulus of RC films improved by 55.3% and 100%, respectively. Moisture absorption by the nanocomposites in an environment with 75% constant relative humidity was reduced by the addition of HNT to the RC. The presence of HNT enhanced the thermal stability and char yield of RC. The significant reinforcing effects of HNTs demonstrated that there is a possible interface interaction between cellulose and HNT which yielded better thermal and mechanical properties of the nanocomposite films as compared to pure RC. - Highlights: • The RC/HNT nanocomposite films were prepared via ionic liquid, BMIMCl. • XRD diffraction patterns and FESEM revealed well dispersed HNT in cellulose matrix. • The nanocomposite films exhibited excellent mechanical properties. • Moisture absorption and diffusion coefficient of RC reduced by HNT incorporation. • Addition of HNT enhanced thermal stability and activation energy of the RC.

Regenerated cellulose/halloysite nanotube nanocomposite films prepared with an ionic liquid

International Nuclear Information System (INIS)

Soheilmoghaddam, Mohammad; Wahit, Mat Uzir; Mahmoudian, Shaya; Hanid, Nurbaiti Abdul

2013-01-01

Regenerated cellulose/halloysite nanotube (RC/HNT) nanocomposite films were successfully prepared in ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl) using solution casting method. The structural, morphological, thermal and mechanical properties of RC/HNT nanocomposites were investigated. X-ray diffraction analysis revealed a cellulose II crystalline structure and well dispersed HNT in RC/HNT nanocomposite films. At 6 wt.% HNT film, tensile strength and Young's modulus of RC films improved by 55.3% and 100%, respectively. Moisture absorption by the nanocomposites in an environment with 75% constant relative humidity was reduced by the addition of HNT to the RC. The presence of HNT enhanced the thermal stability and char yield of RC. The significant reinforcing effects of HNTs demonstrated that there is a possible interface interaction between cellulose and HNT which yielded better thermal and mechanical properties of the nanocomposite films as compared to pure RC. - Highlights: • The RC/HNT nanocomposite films were prepared via ionic liquid, BMIMCl. • XRD diffraction patterns and FESEM revealed well dispersed HNT in cellulose matrix. • The nanocomposite films exhibited excellent mechanical properties. • Moisture absorption and diffusion coefficient of RC reduced by HNT incorporation. • Addition of HNT enhanced thermal stability and activation energy of the RC

Preparation of new conductive polymer nanocomposites for cadmium removal from industrial wastewaters

International Nuclear Information System (INIS)

Zoleikani, Leila; Issazadeh, Hossein; ZareNezhad, Bahman

2015-01-01

Different conductive polymer nanocomposites have been synthesized, characterized and tested, regarding the removal of cadmium from industrial wastewaters. The chemical structure and morphology are studied by FTIR spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The cadmium removal performance, using the produced polypyrrole, polyaniline and polythiophene nanocomposites, are about 40.2 %, 59 % and 99.94 %, respectively, suggesting the superior performance of synthesized polythiophene conductive nanocomposite for cadmium removal from industrial wastewaters. It is shown that the Langmuir adsorption model can be used for accurate description of cadmium removal mechanism using different synthesized conductive nanocomposites. Keywords : wastewater, nanocomposite, polythiophene, cadmium removal, conductive polymer.

STUDY ON BIODEGRADABILITY OF POLY (3-HYDROXYBUTYRATE-co-3-HYDROXYVALERATE)/ORGANOPHILIC MONTMORILLONITE NANOCOMPOSITES

Institute of Scientific and Technical Information of China (English)

WANG Shufang; SONG Cunjiang; CHEN Guangxin; LIU Jing; YANG Chao; ZHANG Xihui; GUO Tianying; ZHANG Banghua

2004-01-01

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/Organophilic montmorillonite (PHBV/OMMT) nanocomposites were prepared and the biodegradability of the PHBV/OMMT nanocomposites was studied by a cultivation degrading method in soil suspension. The relationship between structure and biodegradability of PHBV/OMMT nanocomposites was investigated. The results showed that the biodegradability of PHBV/OMMT nanocomposites decreased with increasing amount of OMMT and it was related to the number of PHBV degrading microorganisms in degradation environment, the anti-microbial property of OMMT and the degree of crystallinity of the nanocomposites.

Preparation of superhydrophobic poly(methyl methacrylate)-silicon dioxide nanocomposite films

International Nuclear Information System (INIS)

Wang Jinyan; Chen Xinhua; Kang Yingke; Yang Guangbin; Yu Laigui; Zhang Pingyu

2010-01-01

Superhydrophobic poly(methyl methacrylate)-SiO 2 (coded as PMMA-SiO 2 ) nanocomposite films with micro-nanohierarchical structure were prepared via a simple approach in the absence of low surface-energy compounds. By spin-coating the suspension of hydrophobic silica (SiO 2 ) nanoparticles dispersed in PMMA solution, target nanocomposite films were obtained on glass slides. The wetting behavior of PMMA-SiO 2 nanocomposite films was investigated in relation to the dosage of SiO 2 nanoparticles dispersed in PMMA solution. It was found that hydrophilic PMMA film was transferred to superhydrophobic PMMA-SiO 2 nanocomposite films when hydrophobic SiO 2 nanoparticles were introduced into the PMMA solution at a high enough dosage (0.2 g and above). Resultant PMMA-SiO 2 nanocomposite films had a static water contact angle of above 162 o , showing promising applications in selfcleaning and waterproof for outer wall of building, outer covering for automobile, sanitary wares, and so forth.

New tool for spreading proteins to the environment: Cry1Ab toxin immobilized to bioplastics.

Science.gov (United States)

Moldes, Cristina; Farinós, Gema P; de Eugenio, Laura I; García, Pedro; García, José L; Ortego, Félix; Hernández-Crespo, Pedro; Castañera, Pedro; Prieto, María A

2006-08-01

A new tool to provide an environmentally friendly way to deliver active proteins to the environment has been developed, based on the use of polyhydroxyalkanoate (PHA, bioplastic) granules. To illustrate this novel approach, a derived Cry1Ab insect-specific toxin protein was in vivo immobilized into PHA granules through the polypeptide tag BioF. The new toxin, named Fk-Bt1, was shown to be active against Sesamia nonagrioides (Lepidoptera: Noctuidae). The dose-mortality responses of the new toxin granule formulation (PFk-Bt1) and purified Cry1Ab have been compared, demonstrating the effectiveness of PFk-Bt1 and suggesting a common mode of action.

Morphology study of polyamide 6/bentonite clay nanocomposites

International Nuclear Information System (INIS)

Paz, Rene A.; Araujo, Edcleide M.; Melo, Tomas J.A.; Leite, Amanda M.D.; Medeiros, Vanessa Nobrega; Pessan, Luiz A.; Passador, Fabio R.

2011-01-01

Polymer/clay nanocomposites have had much attention in recent years, especially those developed with layered silicates, due to the need for engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in the crystalline structure of polymer matrices has been studied and it has been observed that it affects the behavior of crystalline and therefore the mechanical and physical properties. In this study, polyamide 6 nanocomposites were obtained by the melt intercalation technique, using regional bentonite clay modified with a quaternary ammonium salt in an amount of 3% by weight. XRD and TEM tests showed obtaining nanocomposites with exfoliated structures (author)

Halloysite and chitosan oligosaccharide nanocomposite for wound healing.

Science.gov (United States)

Sandri, Giuseppina; Aguzzi, Carola; Rossi, Silvia; Bonferoni, Maria Cristina; Bruni, Giovanna; Boselli, Cinzia; Cornaglia, Antonia Icaro; Riva, Federica; Viseras, Cesar; Caramella, Carla; Ferrari, Franca

2017-07-15

Halloysite is a natural nanotubular clay mineral (HNTs, Halloysite Nano Tubes) chemically identical to kaolinite and, due to its good biocompatibility, is an attractive nanomaterial for a vast range of biological applications. Chitosan oligosaccharides are homo- or heterooligomers of N-acetylglucosamine and D-glucosamine, that accelerate wound healing by enhancing the functions of inflammatory and repairing cells. The aim of the work was the development of a nanocomposite based on HNTs and chitosan oligosaccharides, to be used as pour powder to enhance healing in the treatment of chronic wounds. A 1:0.05 wt ratio HTNs/chitosan oligosaccharide nanocomposite was obtained by simply stirring the HTNs powder in a 1% w/w aqueous chitosan oligosaccharide solution and was formed by spontaneous ionic interaction resulting in 98.6% w/w HTNs and 1.4% w/w chitosan oligosaccharide composition. Advanced electron microscopy techniques were considered to confirm the structure of the hybrid nanotubes. Both HTNs and HTNs/chitosan oligosaccharide nanocomposite showed good in vitro biocompatibility with normal human dermal fibroblasts up to 300μg/ml concentration and enhanced in vitro fibroblast motility, promoting both proliferation and migration. The HTNs/chitosan oligosaccharide nanocomposite and the two components separately were tested for healing capacity in a murine (rat) model. HTNs/chitosan oligosaccharide allowed better skin reepithelization and reorganization than HNTs or chitosan oligosaccharide separately. The results suggest to develop the nanocomposite as a medical device for wound healing. The present work is focused on the development of halloysite and chitosan oligosaccharide nanocomposite for wound healing. It considers a therapeutic option for difficult to heal skin lesions and burns. The significance of the research considers two fundamental aspects: the first one is related to the development of a self-assembled nanocomposite, formed by spontaneous ionic

Metallic Nanocomposites as Next-Generation Thermal Interface Materials

Energy Technology Data Exchange (ETDEWEB)

Feng, Xuhui [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); King, Charles C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nagabandi, Nirup [Texas A& M University; Oh, Jun Kyun [Texas A& M University; Akbulut, Mustafa [Texas A& M University; Yegin, Cengiz [Texas A& M University

2017-07-27

Thermal interface materials (TIMs) are an integral and important part of thermal management in electronic devices. The electronic devices are becoming more compact and powerful. This increase in power processed or passing through the devices leads to higher heat fluxes and makes it a challenge to maintain temperatures at the optimal level during operation. Herein, we report a free standing nanocomposite TIM in which boron nitride nanosheets (BNNS) are uniformly dispersed in copper matrices via an organic linker, thiosemicarbazide. Integration of these metal-organic-inorganic nanocomposites was made possible by a novel electrodeposition technique where the functionalized BNNS (f-BNNS) experience the Brownian motion and reach the cathode through diffusion, while the nucleation and growth of the copper on the cathode occurs via the electrochemical reduction. Once the f-BNNS bearing carbonothioyl/thiol groups on the terminal edges come into the contact with copper crystals, the chemisorption reaction takes place. We performed thermal, mechanical, and structural characterization of these nanocomposites using scanning electron microcopy (SEM), diffusive laser flash (DLF) analysis, phase-sensitive transient thermoreflectence (PSTTR), and nanoindentation. The nanocomposites exhibited a thermal conductivity ranging from 211 W/mK to 277 W/mK at a filler mass loading of 0-12 wt.percent. The nanocomposites also have about 4 times lower hardness as compared to copper, with values ranging from 0.27 GPa to 0.41 GPa. The structural characterization studies showed that most of the BNNS are localized at grain boundaries - which enable efficient thermal transport while making the material soft. PSTTR measurements revealed that the synergistic combinations of these properties yielded contact resistances on the order of 0.10 to 0.13 mm2K/W, and the total thermal resistance of 0.38 to 0.56 mm2K/W at bondline thicknesses of 30-50 um. The coefficient of thermal expansion (CTE) of the

Structure and properties of carbon nanotubes/sol-gel nanocomposites

International Nuclear Information System (INIS)

Pokrass, Mariana

2013-08-01

Carbon Nanotubes (CNTs) are promising filler materials owing to their exceptional mechanical, electrical, thermal and optical properties. Since their discovery in 1991, a major effort has been made in developing CNT-polymer nanocomposites, whereas CNT/ceramic based nanocomposites, in particularly, CNT/silica nanocomposites, have been very little studied. This thesis focuses on preparation and characterization of novel CNT/silica nanocomposite glasses synthesized by the Sol-Gel technology. A comprehensive analysis of their morphological, optical, and electrical properties was conducted, and analyzed according to existing theoretical models. The nanocomposites hosting matrix is a hybrid organic/inorganic glass prepared by the Fast-Sol-Gel (FSG) route. Using specific conditions in the FSG procedure, the resultant glasses are nonporous, exhibiting no contraction upon drying. Their analogous Classical-Sol-Gel (CSG) glasses, however, are porous, and do exhibit contraction upon drying. The FSG glasses are relatively new materials, and their physical and optical properties were only meagerly studied. In our present work we have conducted a comprehensive experimental research on some previously ignored characteristics such as: UV-vis-IR optical absorption and transmission, and the organic content effect on the refraction index n, density ρ, thermal expansion coefficient β, and thermo-optic coefficient dn/dT. We found that organic residues within the glass decrease the refractive index, density, and thermo-optic coefficient. The thermal expansion coefficient, however, increases with the organic content. A negative linear dependence of the thermo-optic coefficient on the thermal expansion coefficient was obtained. CNT/FSG nanocomposites were prepared by using a solution mixing method, while CNT/CSG nanocomposites were prepared by means of an in situ polymerization technique. Nanocomposites based on FSG hybrid glasses were characterized for their nonlinear optical and

Development of Poly (Lactic Acid) Nanocomposite Films by Ionizing Radiation

Energy Technology Data Exchange (ETDEWEB)

Dadbin, Susan; Naimian, Faranak; Akhavan, Azam; Hasanpoor, Sorour [Radiation Application Research School, Nuclear Science and Research Institute, North Kargar Ave., Tehran (Iran, Islamic Republic of)

2009-07-01

Poly (lactic acid) and poly (lactic acid) -montmorillonite (MMT) nanocomposite films have been prepared by solvent casting method. Films were irradiated with 60Co radiation facility at various doses in the range of 5 to30 kGy. The effect of gamma irradiation on mechanical properties of neat PLA and nanocomposites is evaluated by the data obtained from tensile testing measurements. The degree of crosslinking is measured by gel content method. Thermal behavior of nanocomposites is studied by differential scanning calorimetry (DSC) and thermal gravimetry analysis (TGA). The morphology of the nanocomposites is characterized by transmission electron microscopy (TEM) and X ray diffraction. Structural changes in poly (lactic acid) are studied by Fourier transform infrared (FTIR). (author)

Development of Poly (Lactic Acid) Nanocomposite Films by Ionizing Radiation

International Nuclear Information System (INIS)

Dadbin, Susan; Naimian, Faranak; Akhavan, Azam; Hasanpoor, Sorour

2009-01-01

Poly (lactic acid) and poly (lactic acid) -montmorillonite (MMT) nanocomposite films have been prepared by solvent casting method. Films were irradiated with 60Co radiation facility at various doses in the range of 5 to30 kGy. The effect of gamma irradiation on mechanical properties of neat PLA and nanocomposites is evaluated by the data obtained from tensile testing measurements. The degree of crosslinking is measured by gel content method. Thermal behavior of nanocomposites is studied by differential scanning calorimetry (DSC) and thermal gravimetry analysis (TGA). The morphology of the nanocomposites is characterized by transmission electron microscopy (TEM) and X ray diffraction. Structural changes in poly (lactic acid) are studied by Fourier transform infrared (FTIR). (author)

Effect of Saline Solution on the Electrical Response of Single Wall Carbon Nanotubes-Epoxy Nanocomposites

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Hammad Younes

2017-01-01

Full Text Available The effects of saline solution on the electrical resistance of single wall carbon nanotubes-epoxy nanocomposites have been investigated experimentally. Ultrasonic assisted fabricated 1.0% and 0.5 W/W% SWCNTs epoxy nanocomposites are integrated into a Kelvin structure by smear cast the nanocomposites on a glass wafer. Four metal pads are deposited on the nanocomposites using the beam evaporator and wires are tethered using soldering. The effect of saline solution on the electrical resistance of the nanocomposites is studied by adding drop of saline solution to the surface of the fabricated nanocomposites and measuring electrical resistance. Moreover, the nanocomposites are soaked completely into 3 wt.% saline solution and real-time measurement of the electrical resistance is conducted. It is found that a drop of saline solution on the surface of the nanocomposites film increases the resistance by 50%. Furthermore, the real-time measurement reveals a 40% increase in the resistance of the nanocomposites film. More importantly, the nanocomposites are successfully reset by soaking in DI water for four hours. This study may open the door for using SWCNTs epoxy nanocomposites as scale sensors in oil and gas industry.

Effect of cellulose nanocrystals (CNCs) on crystallinity, mechanical and rheological properties of polypropylene/CNCs nanocomposites

Science.gov (United States)

Bagheriasl, D.; Carreau, P. J.; Dubois, C.; Riedl, B.

2015-05-01

Rheological and mechanical properties of polypropylene (PP)/CNCs nanocomposites were compared with those of nanocomposites containing poly(ethylene-co-vinyl alcohol) as a compatibilizer. The nanocomposites were prepared by a Brabender internal mixer at CNC contents of 5 wt%. The compression molded nanocomposite dog-bones and disks were characterized regarding their tensile and dynamic rheological behavior, respectively. The complex viscosity of the nanocomposites samples containing the compatibilizer were increased, slightly, compared to the non-compatibilized nanocomposite samples. Moreover, an overshoot in the transient start-up viscosity of the compatibilized nanocomposite was observed. The Young modulus of the nanocomposite samples containing the compatibilizer were increased up to ca. 37% compared to the neat PP. The elongation at break was decreased in all PP/CNC nanocomposite samples, but less for the nanocomposite samples containing the compatibilizer. The crystalline content of the PP in the nanocomposites and also the crystallization temperature were increased after compatibilization. These results could be ascribed to the efficiency of the poly(ethylene-co-vinyl alcohol) as a compatibilizer that favors a better dispersion and wetting of the hydrophilic CNCs within the hydrophobic PP.

Preparation, structure and thermal stability of Cu/LDPE nanocomposites

International Nuclear Information System (INIS)

Xia Xianping; Cai Shuizhou; Xie Changsheng

2006-01-01

Copper/low-density-polyethylene (Cu/LDPE) nanocomposites have been prepared using a melt-blending technique in a single-screw extruder. Their structure and thermal characteristics are characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results of XRD, SEM and SEM-EDS Cu-mapping show that the nanocomposites are a hybrid of the polymer and the copper nanoparticles, and the copper nanoparticles aggregates were distributed uniformly in general. The results also show that the nanocomposites and the base resin, the pure LDPE, have a different crystalline structure and the same oriented characteristics owing to the presence of copper nanoparticles and the same cooling condition. The results of DSC show that the incorporation of copper nanoparticles can decrease the melting temperatures but increase the crystallization temperatures, and can lower the crystallinity degree of the matrix of the composites. The results of TGA show that the presence of copper nanoparticles can improve the thermal stability of the nanocomposites, a maximum increment of 18 deg. C is obtained comparing with the pure LDPE in this experiment. The results of TGA also show that the influence of the incorporation of the copper nanoparticles on the thermal stability of the Cu/LDPE nanocomposites is different from that of the non-metal nanoparticles on the polymer/non-metal nanocomposites and the copper microparticles on the Cu/LDPE microcomposites. The increase of the thermal stability of the Cu/LDPE nanocomposites will decrease when the content of the copper nanoparticles is more than 2 wt.%. The difference might be caused by the fact that the activity of the metal nanoparticles is much more higher than that of the non-metal nanoparticles, and the different size effect the different copper particles has

Bioinspired Graphene-Based Nanocomposites and Their Application in Flexible Energy Devices.

Science.gov (United States)

Wan, Sijie; Peng, Jingsong; Jiang, Lei; Cheng, Qunfeng

2016-09-01

Graphene is the strongest and stiffest material ever identified and the best electrical conductor known to date, making it an ideal candidate for constructing nanocomposites used in flexible energy devices. However, it remains a great challenge to assemble graphene nanosheets into macro-sized high-performance nanocomposites in practical applications of flexible energy devices using traditional approaches. Nacre, the gold standard for biomimicry, provides an excellent example and guideline for assembling two-dimensional nanosheets into high-performance nanocomposites. This review summarizes recent research on the bioinspired graphene-based nanocomposites (BGBNs), and discusses different bioinspired assembly strategies for constructing integrated high-strength and -toughness graphene-based nanocomposites through various synergistic effects. Fundamental properties of graphene-based nanocomposites, such as strength, toughness, and electrical conductivities, are highlighted. Applications of the BGBNs in flexible energy devices, as well as potential challenges, are addressed. Inspired from the past work done by the community a roadmap for the future of the BGBNs in flexible energy device applications is depicted. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermoset nanocomposites from waterborne bio-based epoxy resin and cellulose nanowhiskers.

Science.gov (United States)

Wu, Guo-min; Liu, Di; Liu, Gui-feng; Chen, Jian; Huo, Shu-ping; Kong, Zhen-wu

2015-01-01

Thermoset nanocomposites were prepared from a waterborne terpene-maleic ester type epoxy resin (WTME) and cellulose nanowhiskers (CNWs). The curing behaviors of WTME/CNWs nanocomposites were measured with rotational rheometer. The results show that the storage modulus (G') of WTME/CNWs nanocomposites increased with the increase of CNWs content. Observations by scanning electron microscopy (SEM) demonstrate that the incorporation of CNWs in WTME matrix caused microphase separation and destroyed the compactness of the matrix. This effect leads to the glass transition temperatures (Tg) of WTME/CNWs nanocomposites slightly decrease with the increase of CNWs content, which were confirmed by both DSC and DMA tests. The mechanical properties of WTME/CNWs nanocomposites were investigated by tensile testing. The Yong's modulus (E) and tensile strength (σb) of the nanocomposites were significantly reinforced by the addition of CNWs. These results indicate that CNWs exhibit excellent reinforcement effect on WTME matrix, due to the formation and increase of interfacial interaction by hydrogen bonds between CNWs nano-filler and the WTME matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterization of Nanoreinforcement Dispersion in Inorganic Nanocomposites: A Review

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Nouari Saheb

2014-05-01

Full Text Available Metal and ceramic matrix composites have been developed to enhance the stiffness and strength of metals and alloys, and improve the toughness of monolithic ceramics, respectively. It is possible to further improve their properties by using nanoreinforcement, which led to the development of metal and ceramic matrix nanocomposites, in which case, the dimension of the reinforcement is on the order of nanometer, typically less than 100 nm. However, in many cases, the properties measured experimentally remain far from those estimated theoretically. This is mainly due to the fact that the properties of nanocomposites depend not only on the properties of the individual constituents, i.e., the matrix and reinforcement as well as the interface between them, but also on the extent of nanoreinforcement dispersion. Therefore, obtaining a uniform dispersion of the nanoreinforcement in the matrix remains a key issue in the development of nanocomposites with the desired properties. The issue of nanoreinforcement dispersion was not fully addressed in review papers dedicated to processing, characterization, and properties of inorganic nanocomposites. In addition, characterization of nanoparticles dispersion, reported in literature, remains largely qualitative. The objective of this review is to provide a comprehensive description of characterization techniques used to evaluate the extent of nanoreinforcement dispersion in inorganic nanocomposites and critically review published work. Moreover, methodologies and techniques used to characterize reinforcement dispersion in conventional composites, which may be used for quantitative characterization of nanoreinforcement dispersion in nanocomposites, is also presented.

Ziegler-Natta catalyst for polypropylene and polyethylene nanocomposites preparation

International Nuclear Information System (INIS)

Silvino, Alexandre C.; Dias, Marcos L.; Bezerra, Ana Beatriz F.

2009-01-01

Polypropylene and polyethylene nanocomposites are well known for their improved properties when compared with the neat polymers. In this work we report the preparation, characterization and the activity studies of a fourth generation Ziegler-Natta catalyst for the preparation of polyolefin/clay nanocomposites. The catalyst was prepared treating an organo-modified silicate with magnesium and titanium compounds. The content of titanium and that of the magnesium of the catalyst were determined by UV-vis spectroscopy and atomic absorption respectively. The first results show that the catalyst is active for propylene polymerization being suitable for polypropylene/clay nanocomposite preparation. The catalyst activity for ethylene polymerization was also investigated. The X-ray diffraction patterns of the polyethylene samples suggest the clay exfoliation occurs in the in situ polymerization, even with high clay loading (about 9 %) indicating that a nanocomposite was formed. (author)

Synthesis, characterization and thermal analysis of polyimide-cobalt ferrite nanocomposites

International Nuclear Information System (INIS)

Mazuera, David; Perales, Oscar; Suarez, Marcelo; Singh, Surinder

2010-01-01

Research highlights: · Polyimide-cobalt ferrite nanocomposites were successfully produced. · Produced nanocomposites are suitable for use at temperatures below 80 deg. C. · Magnetic properties of nanocomposites were no sensitive to particle agglomeration. · Good distribution of clustered nanoparticles was achieved in produced composites. - Abstract: Cobalt ferrite nanocrystals were synthesized under size-controlled conditions in aqueous phase and incorporated into a polyimide matrix at various volumetric loads. Synthesized 20 nm cobalt ferrite single crystals, which exhibited a room-temperature coercivity of 2.9 kOe, were dispersed in polyimide precursor using two techniques: homogenizer and ball milling. These suspensions were then cured to develop the polyimide structure in the resulting nanocomposites. Produced films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometry, which confirmed the formation of the desired phases. As expected, the saturation magnetization in the nanocomposites varied according to the polyimide/ferrite weight ratio, while coercivity remained at the value corresponding to pure cobalt ferrite nanocrystals. Thermal degradation, thermal stability and dynamic mechanical analyses tests were also carried out to assess the effect of the concentration of the ferrite disperse phase on the thermo-mechanical behavior of the corresponding nanocomposites as well as the used dispersion techniques.

Photo-degradation of basic green 1 and basic red 46 dyes in their binary solution by La2O3-Al2O3nanocomposite using first-order derivative spectra and experimental design methodology

Science.gov (United States)

Fahimirad, Bahareh; Asghari, Alireza; Rajabi, Maryam

2017-05-01

In this work, the lanthanum oxide-aluminum oxide (La2O3-Al2O3) nanocomposite is introduced as an efficient photocatalyst for the photo-degradation of the dyes basic green 1 (BG1) and basic red 46 (BR46) in their binary aqueous solution under the UV light irradiation. The properties of this catalyst are determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and UV-visible spectrophotometry. The first-order derivative spectra are used for the simultaneous analysis of the dyes in their binary solution. The screening investigations indicate that five parameters including the catalyst dosage, concentration of the dyes, irradiation time, and solution pH have significant effects on the photo-degradation of the dyes. The effects of these variables together with their interactions in the photo-degradation of the dyes are studied using the Box-Behnken design (BBD). Under the optimum experimental conditions, obtained via the desirability function, the photo-catalytic activities of La2O3-Al2O3 and pure Al2O3 are also investigated. The results obtained show an enhancement in the photo-catalytic activity when La2O3 nanoparticles are loaded on the surface of Al2O3 nanoparticles. The La2O3-Al2O3nanocomposite was synthesized as new photo-catalyst for the degradation of binary dyes. The photo-catalytic effect on the binary dyes solution was followed by the first-order derivative spectrophotometric method. Simultaneous dyes photodegradation methodology was presented by using experimental design.

Nanocomposites with High Thermoelectric Figures of Merit

Science.gov (United States)

Chen, Gang (Inventor); Dresselhaus, Mildred (Inventor); Ren, Zhifeng (Inventor)

2015-01-01

The present invention is generally directed to nanocomposite thermoelectric materials that exhibit enhanced thermoelectric properties. The nanocomposite materials include two or more components, with at least one of the components forming nano-sized structures within the composite material. The components are chosen such that thermal conductivity of the composite is decreased without substantially diminishing the composite's electrical conductivity. Suitable component materials exhibit similar electronic band structures. For example, a band-edge gap between at least one of a conduction band or a valence band of one component material and a corresponding band of the other component material at interfaces between the components can be less than about 5k(sub B)T, wherein k(sub B) is the Boltzman constant and T is an average temperature of said nanocomposite composition.

Tribology of polymeric nanocomposites friction and wear of bulk materials and coatings

CERN Document Server

Friedrich, Klaus

2013-01-01

Tribology of Polymeric Nanocomposites provides a comprehensive description of polymeric nanocomposites, both as bulk materials and as thin surface coatings, and provides rare, focused coverage of their tribological behavior and potential use in tribological applications. Providing engineers and designers with the preparation techniques, friction and wear mechanisms, property information and evaluation methodology needed to select the right polymeric nanocomposites for the job, this unique book also includes valuable real-world examples of polymeric nanocomposites in a

Polymer nanocomposite of laponite RD prepared by gamma irradiation

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Maria J.A.; Silva, Estefania O.; Lugao, Ademar Benevolo; Parra, Duclerc Fernandes, E-mail: mariajhho@yahoo.com.br, E-mail: dfparra@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Amato, Valdir S. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Hospital de Clinicas. Divisao de Doencas Infecciosas e Parasitarias

2012-07-01

Nanocomposite hydrogels based on polyvinyl alcohol (PVAl) and polyvinylpyrrolidone (PVP) containing 0-5 wt % of the synthetic laponite RD clay were prepared by gamma irradiation process. The morphology of the nanocomposite hydrogel was observed by characterizations techniques using: scanning electron microscopy (SEM) and atomic force microscopy (AFM). The structural properties crosslinking was determined by measuring the crosslink gel content extraction on mesh 500 sizes and swelling kinetics at 22 °C. The results showed that crosslinks have inverse dependence on the clay level in the nanocomposite hydrogels, while swelling shows direct dependence. (author)

Polymer nanocomposite of laponite RD prepared by gamma irradiation

International Nuclear Information System (INIS)

Oliveira, Maria J.A.; Silva, Estefania O.; Lugao, Ademar Benevolo; Parra, Duclerc Fernandes; Amato, Valdir S.

2012-01-01

Nanocomposite hydrogels based on polyvinyl alcohol (PVAl) and polyvinylpyrrolidone (PVP) containing 0-5 wt % of the synthetic laponite RD clay were prepared by gamma irradiation process. The morphology of the nanocomposite hydrogel was observed by characterizations techniques using: scanning electron microscopy (SEM) and atomic force microscopy (AFM). The structural properties crosslinking was determined by measuring the crosslink gel content extraction on mesh 500 sizes and swelling kinetics at 22 °C. The results showed that crosslinks have inverse dependence on the clay level in the nanocomposite hydrogels, while swelling shows direct dependence. (author)

Mechanical properties and thermal behaviour of LLDPE/MWNTs nanocomposites

Directory of Open Access Journals (Sweden)

Tai Jin-hua

2012-12-01

Full Text Available Multi-walled carbon nanotubes (MWNTs were incorporated into a linear low-density polyethylene (LLDPE matrix through using screw extrusion and injection technique. The effect of different weight percent loadings of MWNTs on the morphology, mechanical, and thermal of LLDPE/MWNTs nanocomposite had been investigated. It was found that, at low concentration of MWNTs, it could uniformly disperse into a linear low-density polyethylene matrix and provide LLDPE/MWNTs nanocomposites much improved mechanical properties. Thermal analysis showed that a clear improvement of thermal stability for LLDPE/MWNTs nanocomposites increased with increasing MWNTs content.

Comparison of dust release from epoxy and paint nanocomposites and conventional products during sanding and sawing.

Science.gov (United States)

Gomez, Virginia; Levin, Marcus; Saber, Anne T; Irusta, Silvia; Dal Maso, Miikka; Hanoi, Roberto; Santamaria, Jesus; Jensen, Keld A; Wallin, Håkan; Koponen, Ismo K

2014-10-01

The release of dust generated during sanding or sawing of nanocomposites was compared with conventional products without nanomaterials. Epoxy-based polymers with and without carbon nanotubes, and paints with different amounts of nano-sized titanium dioxide, were machined in a closed aerosol chamber. The temporal evolution of the aerosol concentration and size distribution were measured simultaneously. The morphology of collected dust by scanning electron microscopy was different depending on the type of nanocomposites: particles from carbon nanotubes (CNTs) nanocomposites had protrusions on their surfaces and aggregates and agglomerates are attached to the paint matrix in particles emitted from alkyd paints. We observed no significant differences in the particle size distributions when comparing sanding dust from nanofiller containing products with dust from conventional products. Neither did we observe release of free nanomaterials. Instead, the nanomaterials were enclosed or partly enclosed in the matrix. A source strength term Si (cm(-3) s(-1)) that describes particle emission rates from continuous sources was introduced. Comparison between the Si parameters derived from sanding different materials allows identification of potential effects of addition of engineered nanoparticles to a composite. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Research Progress on Visible-light Responding ZnO-based Nanocomposite Photocatalyst

Directory of Open Access Journals (Sweden)

ZHAO Yan-ru

2017-06-01

Full Text Available In this review, different types and properties, photocatalysis and functional mechanism of ZnO-based nanocomposite were summarized. Besides, the research advances were discussed in applications of visible-light responding ZnO-based nanocomposite in fields of degradation of organic pollutants,photocatalytic hydrogen production and antibacterial agents, and the way of thinking and suggestions for further research on ZnO-based nanocomposite photocatalyst were put forward. With the developing of basic research and application, ZnO-based nanocomposite photocatalyst will be widely used in the fields of high efficiency catalyst, environmental purification, solar energy conversion and so on.

Synthesis of polypropylene/graphite nanocomposites by means of in situ polymerization

International Nuclear Information System (INIS)

Montagna, Larissa S.; Basso, Nara R.S.

2009-01-01

The nanotechnology presents a large field for research and development of new polymeric materials based in nanocomposites. This work is related to the synthesis of nanocomposites of polypropylene with graphite as filler. The sheets of graphite in nanometer dimensions were made by means of the chemical exfoliation and thermal treatment. The synthesis of the nanocomposites was carried through by means of the in situ polymerization using a metallocene catalyst and with different amounts of inorganic load (0,5; 1 and 2%). The synthesized nanocomposites were characterized by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). (author)

Multilayer graphene rubber nanocomposites

Science.gov (United States)

Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas

2016-05-01

Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

HHV-6A/B Integration and the Pathogenesis Associated with the Reactivation of Chromosomally Integrated HHV-6A/B.

Science.gov (United States)

Collin, Vanessa; Flamand, Louis

2017-06-26

Unlike other human herpesviruses, human herpesvirus 6A and 6B (HHV-6A/B) infection can lead to integration of the viral genome in human chromosomes. When integration occurs in germinal cells, the integrated HHV-6A/B genome can be transmitted to 50% of descendants. Such individuals, carrying one copy of the HHV-6A/B genome in every cell, are referred to as having inherited chromosomally-integrated HHV-6A/B (iciHHV-6) and represent approximately 1% of the world's population. Interestingly, HHV-6A/B integrate their genomes in a specific region of the chromosomes known as telomeres. Telomeres are located at chromosomes' ends and play essential roles in chromosomal stability and the long-term proliferative potential of cells. Considering that the integrated HHV-6A/B genome is mostly intact without any gross rearrangements or deletions, integration is likely used for viral maintenance into host cells. Knowing the roles played by telomeres in cellular homeostasis, viral integration in such structure is not likely to be without consequences. At present, the mechanisms and factors involved in HHV-6A/B integration remain poorly defined. In this review, we detail the potential biological and medical impacts of HHV-6A/B integration as well as the possible chromosomal integration and viral excision processes.

Highly Active PdNi/RGO/Polyoxometalate Nanocomposite Electrocatalyst for Alcohol Oxidation.

Science.gov (United States)

Hu, Jing; Wu, Xiaofeng; Zhang, Qingfan; Gao, Mingyan; Qiu, Haifang; Huang, Keke; Feng, Shouhua; Wang, Tingting; Yang, Ying; Liu, Zhelin; Zhao, Bo

2018-02-27

A PdNi/RGO/polyoxometalate nanocomposite has been successfully synthesized by a simple wet-chemical method. Characterizations such as transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy are employed to verify the morphology, structure, and elemental composition of the as-prepared nanocomposite. Inspired by the fast-developing fuel cells, the electrochemical catalytic performance of the nanocomposite toward methanol and ethanol oxidation in alkaline media is further tested. Notably, the nanocomposite exhibits excellent catalytic activity and long-term stability toward alcohol electrooxidation compared with the PdNi/RGO and commercial Pd/C catalyst. Furthermore, the electrochemical results reveal that the prepared nanocomposite is attractive as a promising electrocatalyst for direct alcohol fuel cells, in which the phosphotungstic acid plays a crucial role in enhancing the electrocatalytic activities of the catalyst.

Functionalized nanocomposites with the optimal graphene oxide/Au ratio for amplified immunoassay of E. coli to estimate quality deterioration in dairy product.

Science.gov (United States)

Zhang, Xinai; Jiang, Yuxiang; Huang, Chenyong; Shen, Jianzhong; Dong, Xiaoya; Chen, Guangwei; Zhang, Wen

2017-03-15

An amplified electrochemical immunosensor was developed by exploiting poly(diallyldimethylammonium chloride)-functionalized graphene oxide and gold nanoparticles (GO-PDDA@AuNP) as sensing platform. Highlight of this work was to investigate and optimize the ratio of GO-PDDA to AuNP for sensitivity enhancement. The suitable GO-PDDA@AuNP nanocomposites were proven to not only provide an excellent biocompatible microenvironment for the immobilized antibody, but also accelerate electron transfer to enhance electrochemical signal. Moreover, the { d Ab-Au-THi} nanoprobes as biorecognition elements were designed by utilizing the amplification effect of AuNPs to load detection antibody ( d Ab) and enormous thionine (THi), in which d Ab was used for specific recognition of E. coli and THi served as electroactive species. Under optimal conditions, experimental results demonstrated that the variations (ΔI) in the peak current linearly depended on the logarithmic value of E. coli concentration from 50 to 5.0×10 6 cfumL - 1 with the detection limit of 35cfumL -1 . Recovery experiments were also performed for E. coli assay in dairy product (pure fresh milk, yogurt in shelf-life and expired yogurt), and the recoveries of standard additions were in the range of 89.7-112.6%. The excellent performance of the proposed strategy indicated its promising prospect as a valuable tool to estimate the quality deterioration in dairy product. Copyright © 2016 Elsevier B.V. All rights reserved.

Study on antibacterial activity of chemically synthesized PANI-Ag-Au nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Boomi, Pandi [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Prabu, Halliah Gurumallesh, E-mail: hgprabu2010@gmail.com [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Manisankar, Paramasivam [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Ravikumar, Sundaram [Department of Oceanography and Coastal Area Studies, School of Marine Sciences, Alagappa University, Thondi Campus 623 409, Tamil Nadu (India)

2014-05-01

Graphical abstract: - Highlights: • New method of synthesizing PANI-Ag-Au nanocomposite. • Surface Plasmon resonance and formation of composite at nano level were analyzed. • HR-TEM study revealed uniform distribution of nanoparticles. • PANI-Ag-Au nanocomposite exhibited good antibacterial activity. - Abstract: Pristine polyaniline (PANI), PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites have been successfully synthesized by chemical oxidative polymerization method using aniline as monomer, ammonium persulphate as oxidant and metal (Ag, Au and Ag-Au) colloids. UV-Vis analysis exhibited surface Plasmon resonances of Ag, Au, Ag-Au nanoparticles. FT-IR spectra revealed the shift in peak position of N-H stretching. X-ray diffraction (XRD) results confirm the presence of Ag, Au and Au-Ag nanoparticles. HR-TEM images show nanosizes of Ag, Au, Ag-Au and the incorporation of such nanoparticles into the PANI matrix. Pristine PANI, PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites were tested for antibacterial activity by agar well diffusion method. PANI-Ag-Au nanocomposite exhibited higher antibacterial activity against both gram-positive [Streptococcus sp. (MTCC 890), Staphylococcus sp. (MTCC 96)] and gram-negative bacteria [Escherichia coli (MTCC 1671) and Klebsiella sp. (MTCC 7407)] when compared with PANI-Ag nanocomposite, PANI-Au nanocomposite and pristine PANI. The novelty of this study is the polymer-bimetal synthesis and its antibacterial potential.

Preparation, characterization, and antibacterial activity of silver nanoparticle-decorated graphene oxide nanocomposite.

Science.gov (United States)

Shao, Wei; Liu, Xiufeng; Min, Huihua; Dong, Guanghui; Feng, Qingyuan; Zuo, Songlin

2015-04-01

In this work, we report a facile and green approach to prepare a uniform silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite (GO-Ag). The nanocomposite was fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, and X-ray photoelectron spectroscopy (XPS), which demonstrated that AgNPs with a diameter of approximately 22 nm were uniformly and compactly deposited on GO. To investigate the silver ion release behaviors, HEPES buffers with different pH (5.5, 7, and 8.5) were selected and the mechanism of release actions was discussed in detail. The cytotoxicity of GO-Ag nanocomposite was also studied using HEK 293 cells. GO-Ag nanocomposite displayed good cytocompatibility. Furthermore, the antibacterial properties of GO-Ag nanocomposite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 by both the plate count method and disk diffusion method. The nanocomposite showed excellent antibacterial activity. These results demonstrated that GO-Ag nanocomposite, as a kind of antibacterial material, had a great promise for application in a wide range of biomedical applications.

Structural mechanical and antibacterial properties of HPMC/SF-AgNPs nanocomposite films

Science.gov (United States)

Harish, K. V.; Rao, B. Lakshmeesha; Asha, S.; Vipin, C.; Sangappa, Y.

2018-04-01

In the present study, Hydroxypropyl Methylcellulose (HPMC) pure and HPMC/SF-AgNPs biopolymer nanocomposite films were prepared by simple solution casting method. The prepared nanocomposite films were characterized using UV-Visible spectroscopy(UV-Vis), X-ray diffraction (XRD) measurements. The mechanical properties of HPMC/SF-AgNPs nanocomposites were found to be decrease with increase in the AgNP's concentrations. The HPMC/SF-AgNPs nanocomposites showed very good antibacterial activity against human pathogens P. aeruginosa, E.coli, and S.aureus.

Self-Assembly of Block Copolymer Chains To Promote the Dispersion of Nanoparticles in Polymer Nanocomposites

Science.gov (United States)

2017-01-01

In this paper we adopt molecular dynamics simulations to study the amphiphilic AB block copolymer (BCP) mediated nanoparticle (NP) dispersion in polymer nanocomposites (PNCs), with the A-block being compatible with the NPs and the B-block being miscible with the polymer matrix. The effects of the number and components of BCP, as well as the interaction strength between A-block and NPs on the spatial organization of NPs, are explored. We find that the increase of the fraction of the A-block brings different dispersion effect to NPs than that of B-block. We also find that the best dispersion state of the NPs occurs in the case of a moderate interaction strength between the A-block and the NPs. Meanwhile, the stress–strain behavior is probed. Our simulation results verify that adopting BCP is an effective way to adjust the dispersion of NPs in the polymer matrix, further to manipulate the mechanical properties. PMID:28892620

Simulation and Robust Contol of Antilock Braking System ABS

Directory of Open Access Journals (Sweden)

David Jordan DELICHRISTOV

2009-06-01

Full Text Available This paper deals with simulation and robust control of Antilock Braking System ABS. The briefly are described the main parts of ABS hydraulic system and control algorithm of ABS. Hydraulic system described here is BOSCH ABS 5.x series. The goal of ABS system is vehicle stability and vehicle steering response when braking. If during the braking occurred slip at one or more wheels from any reason, ABS evaluates this by “brake slip” controller. At this moment ABS is trying to use maximal limits of adhesion between tire and road. It means that is necessary control the differences between braking torque and friction torque , which reacts to the wheel via friction reaction tire-road surface. This is realized through the solenoid valves, which are controls (triggered by on the base of PID controller described further in chapter 4. Presented concept is more or less standard for most of the existing ABS systems. The issue should be applied concept of robust ABS control algorithm, which is specific for every type of ABS.

Properties and applications of polymer nanocomposites clay and carbon based polymer nanocomposites

CERN Document Server

Prasad Sahoo, Bibhu

2017-01-01

The aim of the present edited book is to furnish scientific information about manufacturing, properties, and application of clay and carbon based polymer nanocomposites. It can be used as handbook for undergraduate and post graduate courses (for example material science and engineering, polymer science and engineering, rubber technology, manufacturing engineering, etc.) as well as as reference book for research fellows and professionals. Polymer nanocomposites have received outstanding importance in the present decade because of their broad range of high-performance applications in various areas of engineering and technology due to their special material properties. A great interest is dedicated to nanofiller based polymeric materials, which exhibit excellent enhancement in macroscopic material properties (mechanical, thermal, dynamic mechanical, electrical and many more) at very low filler contents and can therefore be used for the development of next-generation composite materials.

Hierarchical cellulose-derived carbon nanocomposites for electrostatic energy storage

International Nuclear Information System (INIS)

Kuzmenko, V; Saleem, A M; Bhaskar, A; Staaf, H; Desmaris, V; Enoksson, P

2015-01-01

The problem of energy storage and its continuous delivery on demand needs new effective solutions. Supercapacitors are viewed as essential devices for solving this problem since they can quickly provide high power basically countless number of times. The performance of supercapacitors is mostly dependent on the properties of electrode materials used for electrostatic charge accumulation, i.e. energy storage. This study presents new sustainable cellulose-derived materials that can be used as electrodes for supercapacitors. Nanofibrous carbon nanofiber (CNF) mats were covered with vapor-grown carbon nanotubes (CNTs) in order to get composite CNF/CNT electrode material. The resulting composite material had significantly higher surface area and was much more conductive than pure CNF material. The performance of the CNF/CNT electrodes was evaluated by various analysis methods such as cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy and cyclic stability. The results showed that the cellulose-derived composite electrodes have fairly high values of specific capacitance and power density and can retain excellent performance over at least 2 000 cycles. Therefore it can be stated that sustainable cellulose-derived CNF/CNT composites are prospective materials for supercapacitor electrodes. (paper)

A quantum dot-spore nanocomposite pH sensor.

Science.gov (United States)

Zhang, Xingya; Li, Zheng; Zhou, Tao; Zhou, Qian; Zeng, Zhiming; Xu, Xiangdong; Hu, Yonggang

2016-04-01

A new quantum dot (QD)-based pH sensor design is investigated. The sensor is synthesized based on the self-assembly of green QDs onto treated spores to form QD@spore nanocomposites. The nanocomposites are characterized using laser scanning confocal microscopy, transmission electron microscope, and fluorescence spectroscopy, among others. Fluorescence measurements showed that these nanocomposites are sensitive to pH in a broad pH range of 5.0-10.0. The developed pH sensors have been satisfactorily applied for pH estimation of real samples and are comparable with those of the commercial assay method, indicating the potential practical application of the pH sensors. Copyright © 2015 Elsevier B.V. All rights reserved.

Li2S/Carbon Nanocomposite Strips from a Low-Temperature Conversion of Li2SO4 as High-Performance Lithium-Sulfur Cathodes

Energy Technology Data Exchange (ETDEWEB)

Ye, Fangmin; Noh, Hyungjun; Lee, Jin Hong; Lee, Hongkyung; Kim, Hee-Tak

2018-03-12

Carbothermal conversion of Li2SO4 provides a cost-effective strategy to fabricate high-capacity Li2S cathodes, however, Li2S cathodes derived from Li2SO4 at high temperatures (> 800 oC), having high crystallinity and large crystal size, result in a low utilization of Li2S. Here, we report a Li2SO4/poly(vinyl alcohol)-derived Li2S/Carbon nanocomposite (Li2S@C) strips at a record low temperature of 635 oC. These Li2S@C nanocomposite strips as a cathode shows a low initial activation potential (2.63 V), a high initial discharge capacity (805 mAh g-1 Li2S) and a high cycling stability (0.2 C and 1 C). These improvedresults could be ascribed to the nano-sized Li2S particles as well as their low crystallinity due to the PVA-induced carbon network and the low conversion temperature, respectively. An XPS analysis reveals that the C=C and C=O bonds derived from the carbonization of PVA can promote the conversion of Li2SO4 at the low temperature.

Polymer-Layer Silicate Nanocomposites

DEFF Research Database (Denmark)

Potarniche, Catalina-Gabriela

Nowadays, some of the material challenges arise from a performance point of view as well as from recycling and biodegradability. Concerning these aspects, the development of polymer layered silicate nanocomposites can provide possible solutions. This study investigates how to obtain polymer layered...... with a spectacular improvement up to 300 % in impact strength were obtained. In the second part of this study, layered silicate bio-nanomaterials were obtained starting from natural compounds and taking into consideration their biocompatibility properties. These new materials may be used for drug delivery systems...... and as biomaterials due to their high biocompatible properties, and because they have the advantage of being biodegradable. The intercalation process of natural compounds within silicate platelets was investigated. By uniform dispersing of binary nanohybrids in a collagen matrix, nanocomposites with intercalated...

Holographic patterning of organic-inorganic photopolymerizable nanocomposites

Science.gov (United States)

Sakhno, Oksana V.; Goldenberg, Leonid M.; Smirnova, Tatiana N.; Stumpe, J.

2009-09-01

We present here novel easily processible organic-inorganic nanocomposites suitable for holographic fabrication of diffraction optical elements (DOE). The nanocomposites are based on photocurable acrylate monomers and inorganic nanoparticles (NP). The compatibility of inorganic NP with monomers was achieved by capping the NP surface with proper organic shells. Surface modification allows to introduce up to 50wt.% of inorganic NP in organic media. Depending on the NP nature (metal oxides, phosphates, semiconductors, noble metals) and their properties, the materials for both efficient DOE and multifunctional elements can be designed. Organic-inorganic composites prepared have been successfully used for the effective inscription of periodic volume refractive index structures using the holographic photopolymerization method. The nanocomposite preparation procedure, their properties and optical performance of holographic gratings are reported. The use of functional NP makes it possible to obtain effective holographic gratings having additional physical properties such as light-emission or NLO. Some examples of such functional polymer-NP structures and their possible application fields are presented. The combination of easy photo-patterning of soft organic compounds with physical properties of inorganic materials in new nanocomposites and the flexibility of the holographic patterning method allow the fabrication of mono- and multifunctional one- and multi-dimensional passive or active optical and photonic elements.

Biodegradation behaviors of cellulose nanocrystals -PVA nanocomposites

Directory of Open Access Journals (Sweden)

Mahdi Rohani

2014-11-01

Full Text Available In this research, biodegradation behaviors of cellulose nanocrystals-poly vinyl alcohol nanocomposites were investigated. Nanocomposite films with different filler loading levels (3, 6, 9 and 12% by wt were developed by solvent casting method. The effect of cellulose nanocrystals on the biodegradation behaviors of nanocomposite films was studied. Water absorption and water solubility tests were performed by immersing specimens into distilled water. The characteristic parameter of diffusion coefficient and maximum moisture content were determined from the obtained water absorption curves. The water absorption behavior of the nanocomposites was found to follow a Fickian behavior. The maximum water absorption and diffusion coefficients were decreased by increasing the cellulose nanocrystals contents, however the water solubility decrease. The biodegradability of the films was investigated by immersing specimens into cellulase enzymatic solution as well as by burial in soil. The results showed that adding cellulose nanocrystals increase the weight loss of specimens in enzymatic solution but decrease it in soil media. The limited biodegradability of specimens in soil media attributed to development of strong interactions with solid substrates that inhibit the accessibility of functional groups. Specimens with the low degree of hydrolysis underwent extensive biodegradation in both enzymatic and soil media, whilst specimens with the high degree of hydrolysis showed recalcitrance to biodegradation under those conditions.

Dielectric Properties of PANI/CuO Nanocomposites

Science.gov (United States)

Ambalagi, Sharanabasamma M.; Devendrappa, Mahalesh; Nagaraja, Sannakki; Sannakki, Basavaraja

2018-02-01

The combustion method is used to prepare the Copper Oxide (CuO) nanoparticles. The nanocomposites of Polyaniline (PANI) by doping with copper oxide nanoparticles have synthesized at 10, 20, 30, 40 and 50 different weight percentages during the in-situ polymerization. The samples of nanocomposite of PANI-CuO were characterized by using X-Ray diffraction (XRD) technique. The physical properties such as dielectric constant, dielectric loss and A C conductivity of the nanocomposites are studied as a function of frequency in the range 5Hz-35MHz at room temperature. It is found that the dielectric constant decreases as the frequency increases. The dielectric constant it remains constant at higher frequencies and it is also observed that in particular frequency both the dielectric constant and dielectric loss are decreased as a weight percentage of CuO increased. In case of AC conductivity it is found that as the frequency increases the AC conductivity remains constant up to 3.56MHz and afterwards it increases as frequency increases. This is due to the increase in charge carriers through the hopping mechanism in the polymer nanocomposites. It is also observed that as a weight percentage of CuO increased the AC conductivity is also increasing at a particular frequency.

Magnetic graphene based nanocomposite for uranium scavenging

Energy Technology Data Exchange (ETDEWEB)

El-Maghrabi, Heba H. [Egyptian Petroleum Research Institute, 11727, Cairo (Egypt); Abdelmaged, Shaimaa M. [Nuclear Materials Authority, 6530 P.O. Box Maadi, Cairo (Egypt); Nada, Amr A. [Egyptian Petroleum Research Institute, 11727, Cairo (Egypt); Zahran, Fouad, E-mail: f.zahran@quim.ucm.es [Faculty of Science, Helwan University, 11795, Cairo (Egypt); El-Wahab, Saad Abd; Yahea, Dena [Faculty of Science, Ain shams University, Cairo (Egypt); Hussein, G.M.; Atrees, M.S. [Nuclear Materials Authority, 6530 P.O. Box Maadi, Cairo (Egypt)

2017-01-15

Graphical abstract: Graphical representation of U{sup 6+} adsorption on Magnetic Ferberite-Graphene Nanocomposite. - Highlights: • Synthesis of new magnetic wolframite bimetallic nanostructure on graphene. • A promising adsorption capacity of 455 mg/g was recorded for FG-20 within 60 min at room temperature. • The uranium removal was followed pseudo-second order kinetics and Langmuir isotherm. - Abstract: Magnetic graphene based ferberite nanocomposite was tailored by simple, green, low cost and industrial effective method. The microstructure and morphology of the designed nanomaterials were examined via XRD, Raman, FTIR, TEM, EDX and VSM. The prepared nanocomposites were introduced as a novel adsorbent for uranium ions scavenging from aqueous solution. Different operating conditions of time, pH, initial uranium concentration, adsorbent amount and temperature were investigated. The experimental data shows a promising adsorption capacity. In particular, a maximum value of 455 mg/g was obtained within 60 min at room temperature with adsorption efficiency of 90.5%. The kinetics and isotherms adsorption data were fitted with the pseudo-second order model and Langmuir equation, respectively. Finally, the designed nanocomposites were found to have a great degree of sustainability (above 5 times of profiteering) with a complete maintenance of their parental morphology and adsorption capacity.

Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

International Nuclear Information System (INIS)

Erçarıkcı, Elif; Dağcı, Kader; Topçu, Ezgi; Alanyalıoğlu, Murat

2014-01-01

Highlights: • Poly(MB)/graphene thin films are prepared by a simple electrochemical approach. • Graphene layers in the film show a broad band in visible region of absorbance spectra. • Morphology of composite films indicates both disordered and ordered regions. • XRD reveals that nanocomposite films include rGO layers after electropolymerization process. • Chemically prepared graphene is better than electrochemically prepared graphene for electrooxidation of nitrite. - Abstract: Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemical approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene

Polyetherimide/bucky gels nanocomposites with superior conductivity and thermal stability

KAUST Repository

Chen, Ye

2013-08-14

Polyetherimide (PEI) nanocomposites comprising bucky gels of industrial-grade multiwalled carbon nanotubes (MWCNTs) and ionic liquid (IL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6])) were prepared. The processing framework for this nanocomposite is simple, reproducible, and easily scalable. The strong interaction between IL and MWCNTs caused the latter to uniformly disperse in the PEI matrix while IL flowed into the gaps between the nanotubes\\' walls. The nanocomposite exhibited an enhanced conductivity of 2.01 × 104 Ω·cm volume resistivity at room temperature; the value decreased dramatically by 12 orders of magnitude, compared to pristine PEI. The IL free ions and MWCNTs networks provided excellent channels for electron transfer. PEI/bucky gels nanocomposites also showed improved thermal stability and high tensile strength. Other than having antiwear properties, this material can have numerous applications in the aerospace and electronics industries. Moreover, our work presents a "green" method toward modified nanocomposites industrial production as IL is environmentally safe and is easily recyclable. © 2013 American Chemical Society.

Polyetherimide/bucky gels nanocomposites with superior conductivity and thermal stability

KAUST Repository

Chen, Ye; Tao, Jing; Deng, Lin; LI, LIANG; Li., Jun; Yang, Yang; Khashab, Niveen M.

2013-01-01

Polyetherimide (PEI) nanocomposites comprising bucky gels of industrial-grade multiwalled carbon nanotubes (MWCNTs) and ionic liquid (IL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6])) were prepared. The processing framework for this nanocomposite is simple, reproducible, and easily scalable. The strong interaction between IL and MWCNTs caused the latter to uniformly disperse in the PEI matrix while IL flowed into the gaps between the nanotubes' walls. The nanocomposite exhibited an enhanced conductivity of 2.01 × 104 Ω·cm volume resistivity at room temperature; the value decreased dramatically by 12 orders of magnitude, compared to pristine PEI. The IL free ions and MWCNTs networks provided excellent channels for electron transfer. PEI/bucky gels nanocomposites also showed improved thermal stability and high tensile strength. Other than having antiwear properties, this material can have numerous applications in the aerospace and electronics industries. Moreover, our work presents a "green" method toward modified nanocomposites industrial production as IL is environmentally safe and is easily recyclable. © 2013 American Chemical Society.

Green aqueous surface modification of polypropylene for novel polymer nanocomposites.

Science.gov (United States)

Thakur, Vijay Kumar; Vennerberg, Danny; Kessler, Michael R

2014-06-25

Polypropylene is one of the most widely used commercial commodity polymers; among many other applications, it is used for electronic and structural applications. Despite its commercial importance, the hydrophobic nature of polypropylene limits its successful application in some fields, in particular for the preparation of polymer nanocomposites. Here, a facile, plasma-assisted, biomimetic, environmentally friendly method was developed to enhance the interfacial interactions in polymer nanocomposites by modifying the surface of polypropylene. Plasma treated polypropylene was surface-modified with polydopamine (PDA) in an aqueous medium without employing other chemicals. The surface modification strategy used here was based on the easy self-polymerization and strong adhesion characteristics of dopamine (DA) under ambient laboratory conditions. The changes in surface characteristics of polypropylene were investigated using FTIR, TGA, and Raman spectroscopy. Subsequently, the surface modified polypropylene was used as the matrix to prepare SiO2-reinforced polymer nanocomposites. These nanocomposites demonstrated superior properties compared to nanocomposites prepared using pristine polypropylene. This simple, environmentally friendly, green method of modifying polypropylene indicated that polydopamine-functionalized polypropylene is a promising material for various high-performance applications.

Preparation of superhydrophobic poly(methyl methacrylate)-silicon dioxide nanocomposite films

Energy Technology Data Exchange (ETDEWEB)

Wang Jinyan [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China); Chen Xinhua [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China); College of Chemistry and Chemical Engineering, Xuchang University, Xuchang 461000 (China); Kang Yingke; Yang Guangbin; Yu Laigui [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China); Zhang Pingyu, E-mail: pingyu@henu.edu.cn [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Jinming Road, Kaifeng, Henan Province 475004 (China)

2010-12-15

Superhydrophobic poly(methyl methacrylate)-SiO{sub 2} (coded as PMMA-SiO{sub 2}) nanocomposite films with micro-nanohierarchical structure were prepared via a simple approach in the absence of low surface-energy compounds. By spin-coating the suspension of hydrophobic silica (SiO{sub 2}) nanoparticles dispersed in PMMA solution, target nanocomposite films were obtained on glass slides. The wetting behavior of PMMA-SiO{sub 2} nanocomposite films was investigated in relation to the dosage of SiO{sub 2} nanoparticles dispersed in PMMA solution. It was found that hydrophilic PMMA film was transferred to superhydrophobic PMMA-SiO{sub 2} nanocomposite films when hydrophobic SiO{sub 2} nanoparticles were introduced into the PMMA solution at a high enough dosage (0.2 g and above). Resultant PMMA-SiO{sub 2} nanocomposite films had a static water contact angle of above 162{sup o}, showing promising applications in selfcleaning and waterproof for outer wall of building, outer covering for automobile, sanitary wares, and so forth.

Novel ZnWO4/RGO nanocomposite as high performance photocatalyst

Directory of Open Access Journals (Sweden)

Mohamed Jaffer Sadiq Mohamed

2017-01-01

Full Text Available In this study, we report the synthesis of nanocomposite material composed of zinc tungstate (ZnWO4 and reduced graphene oxide (RGO as photocatalyst by a simple microwave irradiation technique. The prepared nanocomposites have been characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, energy dispersive X-ray (EDX analysis, X-ray photoelectron spectroscopy (XPS, Fourier transform infrared spectrometer (FTIR, photoluminescence spectroscopy (PL and UV-Visible spectroscopy. The photocatalytic activities of the prepared nanocomposites are evaluated in terms of the efficiencies of photodegradation of methylene blue (MB dye in aqueous solution under visible light irradiation. The prepared nanocomposites showed excellent photodegradation efficiency compared to the commercial TiO2 under visible light irradiation. The activity of the catalyst towards methyl orange (MO and rhodamine B (RB was also good. Further, in view of the low cost, simple preparation method and high catalytic activity of the material, it is expected that the prepared nanocomposite can serve as an environment friendly photocatalyst for treating the large scale industrial waste waters.

Epoxy/α-alumina nanocomposite with high electrical insulation performance

Directory of Open Access Journals (Sweden)

Yun Chen

2017-10-01

Full Text Available An experimental study was conducted to improve the electrical insulation of epoxy resin. The effects of boehmite, γ-alumina and α-alumina nanoparticles on the volume resistivity, dielectric strength and glass transition temperature of epoxy nanocomposites were investigated. The results showed that α-alumina nanoparticles displayed obvious advantages in enhancing electrical insulation performance of epoxy nanocomposites, compared to boehmite and γ-alumina nanoparticles. The direct current volume resistivity and breakdown strength of epoxy nanocomposite with 2.0 wt% α-alumina nanoparticles was improved to 2.2 × 1018 Ω cm and 76.1 kV mm−1 respectively. And these improved values of electrical insulation properties are much higher than these of epoxy nanocomposites reported in previous studies. The main reason of these improvements may be that the epoxy/α-alumina interaction zone was enhanced by crosslink. Keywords: Nanocomposite, Epoxy resin, Insulation, α-alumina