scholarly journals Magnetic studies of 0.7(Fe2O3)/0.3(ZnO) nanocomposites in nanopowder form and dispersed in polymer matrix

2016 ◽  
Vol 34 (2) ◽  
pp. 286-296 ◽  
Author(s):  
Janusz Typek ◽  
Kamil Wardal ◽  
Grzegorz Zolnierkiewicz ◽  
Anna Szymczyk ◽  
Nikos Guskos ◽  
...  
Keyword(s):  
Polymer Matrix ◽  
Magnetic Behavior ◽  
Magnetic Studies ◽  
Static Magnetization ◽  
Interparticle Interactions ◽  
Neat Polymer ◽  
Two Samples ◽  
Poly Ethylene ◽  
Two Phases ◽  
Average Size

AbstractMagnetic properties of 0.7(Fe2O3)/0.3(ZnO) nanocomposite synthesized by traditional wet chemistry method and containing only two phases: ZnO (nonmagnetic) and ZnFe2O4 (magnetic, with nanocrystallites of average size 12 nm, but forming large agglomerates, up to 100 nm in size) were studied by DC magnetization and ferromagnetic resonance (FMR). The investigated nanocomposite was either in a form of nanopowder or dispersed at concentration of 0.1 wt.% in poly(ethylene naphthalate-block-tetramethylene oxide) PTMO-b-PEN polymer matrix. Similarities and differences in magnetic behavior of these two samples revealed by the study of static magnetization and FMR spectra have been discussed relative to different morphologies and the associated variation of interparticle interactions. Moreover, thermal and thermo-oxidative stability of the nanocomposite and the neat polymer have been studied by thermogravimetric method.

Magnetoelasticity of gels

2018 ◽  
Vol 29 (9) ◽  
pp. 1913-1927 ◽  
Author(s):  
Sakthivel T Kasinathan ◽  
Sivakumar M Srinivasan
Keyword(s):  
Polymer Matrix ◽  
Energy Minimization ◽  
Magnetic Particles ◽  
Structural Integrity ◽  
Mechanical Strain ◽  
Active Material ◽  
Magnetic Behavior ◽  
Interparticle Interactions ◽  
Multiple Length Scales ◽  
Equilibrium Magnetization

Magnetoelastic gel is an active material that is used widely these days. The behavior of these multifunctional gels is derived from a polymer matrix and magnetoresponsive inclusions. The polymer matrix provides structural integrity as well as load bearing capacity to the magnetoelastic gel. The magnetic behavior of the magnetoelastic gel is attributed to a large number of nano-to-micron-sized magnetic particles disbursed in the polymer matrix. The magnetoelastic gel is said to be diluted if the interparticle interactions are negligible/small or concentrated if there are strong interparticle interactions. We consider strong interparticle interactions in the magnetoelastic gel. When the magnetic field is applied to the magnetoelastic gel, the disbursed magnetic particles tend to translate and rotate to a new deformed configuration. Due to these translations and rotations of the many magnetoelastic particles, the polymer matrix around each particle deforms. These micro-deformations then coalesce and lead to the overall macroscopic deformation of the magnetoelastic gel. Both magnetization and mechanical strain characterize the magnetoelastic behavior of the magnetoelastic gel. In this article, an energy minimization approach is followed to find the equilibrium magnetization and strain. We formulate the total energy of the magnetoelastic gel on multiple-length scales and minimize it to obtain these equilibrium magnetization and mechanical strain. We also investigate the effect of particle size and polarization under the framework of energy minimization.

scholarly journals Peculiar Magnetic Features and Superconductivity in Sulfur Doped Amorphous Carbon

2016 ◽  
Author(s):  
Israel Felner
Keyword(s):  
Amorphous Carbon ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Magnetic Behavior ◽  
Protective Atmosphere ◽  
Zero Field ◽  
Magnetic Studies ◽  
High Tc ◽  
Two Phases ◽  
Magnetic States

We report on magnetic studies of inhomogeneous commercial and synthesized amorphous carbon (a-C) and a-C doped with sulfur (a-CS) powders which exhibit (i) peculiar magnetic behavior and (ii) traces of two superconducting (SC) phase ~ Tc=33 and at 65 K. (i) The temperature dependence of zero-field-cooled (ZFC) curves measured up to room temperature show a well distinguish elusive peaks around 50-80 K, their origin is not yet known. These peaks are totally washed-out in the second ZFC sweeps and in the FC branches as well. As a result, in the vicinity of the peaks, the FC curves lie below the ZFC peaks (FC<ZFC), a phenomenon which is rarely observed. These magnetic anomalies are intrinsic properties of a-C and a-CS materials (ii) SC was observed in three different a-C sources: (a) The commercial a-C powder contains 0.21% of sulfur and it is suggested that two different a-CS phases (at 33 and 65 K) are the origin of the two SC states observed. The compositions of these two phases are not yet unknown. The small SC volume fractions of the 33 K phase can be enhanced by a solid reaction with additional sulfur at 250 ºC. (b) The synthesized a-C powder (obtained from decomposition of sucrose) is not SC. However, when mixed with sulfur and heated at 400 ºC under a protective atmosphere, the a-CS powder obtained also show traces of a SC phase at TC= 42 K. (c)The same occurs in a-C thin films. The as-grown films are not SC but a SC phase at Tc = 34 K emerges after the films were reacted with sulfur at elevated temperatures. It is concluded therefore, that all SC phases observed are due to different unknown a-CS phases. Since the a-C and a-CS powders possess SC and magnetic states, we believe that these powders resemble the high TC curates and Fe-As based systems in which the SC and the magnetic states are closed related to each other.

Plant Oil-Based Nanoemulsions: Preparation and Efficacy for Hair Treatment

2020 ◽  
Vol 04 ◽  
Author(s):  
Lívia Gonçalves Ferreira Rodrigues ◽  
Juliana Falcão Alves de Carvalho ◽  
Cristal dos Santos Cerqueira Pinto ◽  
Elisabete Pereira Santos ◽  
Claudia Regina Elias Mansur
Keyword(s):  
Human Hair ◽  
Mechanical Tests ◽  
Plant Oils ◽  
Plant Oil ◽  
Oil In Water ◽  
Hair Samples ◽  
Poly Ethylene Oxide ◽  
Treatment Objective ◽  
Poly Ethylene ◽  
Average Size

Background:: The use of polymers in hair care products is widespread, and silicones in particular are extensively used in cosmetic formulations. In addition, plant oils can also be used for hair treatment. Objective: In the present work, oil-in-water (O/W) nanoemulsions were prepared to repair chemical damage to human hair samples, to investigate the combined use of a silicone polyether copolymer (surfactant) that has a branch composed of poly(ethylene oxide) in its chains, and two types of plant oils: coconut and ojon oil. Materials and Methods:: Surfactant-oil-water formulations were obtained by ultrasonic processing. The nanoemulsions were then applied to human hair strands previously damaged with sodium hydroxide, to compare the treated strands with untreated ones. The efficacy of the formulations was investigated by scanning electron microscopy, thermogravimetric analysis and mechanical tests. Results and Discussion:: Stables nanoemulsions were obtained with average size of the dispersed droplets up to 400 nm. The micrographs suggest that the action mechanism of the nanoemulsions depends not only on the type of plant oil used and size of the droplets dispersed in the system, but also on the type of hair that receives the treatment. The thermal analysis showed that the use of nanoemulsion changed the temperature of keratin interconversion to higher values, which can make hair fibers more resistant to heat. Hair resistance was improved when comparing virgin samples to the damaged ones. Conclusion:: The nanoemulsions were efficient in the treatment of the hair samples, which showed a significant improvement of their mechanical properties.

scholarly journals Study Structure and Properties of Nanocomposite Material Based on Unsaturated Polyester with Clay Modified by Poly(ethylene oxide)

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Tran Duy Thanh ◽  
Nguyen Dang Mao ◽  
Nguyen Thi Kim Ngan ◽  
Ha Thuc Chi Nhan ◽  
Ha Thuc Huy ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Polymer Matrix ◽  
Unsaturated Polyester ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Poly Ethylene Oxide ◽  
Hydrophobic Nature ◽  
Poly Ethylene ◽  
Alkyl Ammonium

In recent years, polymer clay nanocomposites have been attracting considerable interests in polymers science because of their advantages. There are many scientists who researched about this kind of material and demonstrated that when polymer matrix was added to little weight of clay, properties were enhanced considerably. Because clay is a hydrophilic substance so it is difficult to use as filler in polymer matrix having hydrophobic nature, so clay needs to be modified to become compatible with polymer. In this study, poly(ethylene oxide) was used as a new modifier for clay to replace some traditional ionic surfactants such as primary, secondary, tertiary, and quaternary alkyl ammonium or alkylphosphonium cations having the following disadvantages: disintegrate at high temperature, catalyze polymer degradation, and make nanoproducts colorific, and so forth. In order to evaluate modifying effect of poly(ethylene oxide), modified clay products were characterize d by X-ray spectrum. Then organoclay was used to prepare nanocomposite based on unsaturated polyester. Morphology and properties of nanocomposites were measure d by X-ray diffraction, transmission electron microscopy, tensile strength, and thermal stability. The results showed that clay galleries changed to intercalated state in the nanocomposites. Properties of nanocomposites were improved a lot when the loading of the organoclay was used at 1 phr.

scholarly journals Titanate nanotubes for reinforcement of a poly(ethylene oxide)/chitosan polymer matrix

2016 ◽  
Vol 27 (19) ◽  
pp. 195706 ◽  
Author(s):  
R Porras ◽  
D V Bavykin ◽  
J Zekonyte ◽  
F C Walsh ◽  
R J Wood
Keyword(s):  
Ethylene Oxide ◽  
Polymer Matrix ◽  
Titanate Nanotubes ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

scholarly journals Influence of nanoparticles on the morphology, thermal stability and air permeability of electrospun polylactic-acid fibres

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Jenny Alongi ◽  
Merima Pošković
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Polylactic Acid ◽  
Polymer Matrix ◽  
Fibre Diameter ◽  
Air Permeability ◽  
Solution Viscosity ◽  
Polymer Molecular Weight ◽  
Neat Polymer ◽  
Lower Permeability

AbstractPolylactic-acid (PLA) and PLA-clay fibres have been produced from solution of 1,1,1,3,3,3-hexafluoro-2-propanol by electrospinning. Nanoclays having different aspect ratio, namely a montmorillonite and a sepiolite, have been added and dispersed within the polymer matrix in order to enhance the thermal stability and air permeability of PLA. The influence of the polymer molecular weight, the solution viscosity and conductivity on the morphology of the fibres has been investigated. Electron microscopy has shown that fibre diameter and the presence of beads defects in the fibres depend on the type of clay added to the polymer matrix. The thermal stability in nitrogen and in air has been drastically enhanced for the presence of the clays as compared with neat polymer. Finally, permeability tests performed on the electrospun condensed fibres pointed out that PLA-clay fibres exhibit a lower permeability to air (up to 90%) with respect to neat PLA fibres.

scholarly journals Glassy Magnetic Behavior and Correlation Length in Nanogranular Fe-Oxide and Au/Fe-Oxide Samples

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3958 ◽  
Author(s):  
L. Del Bianco ◽  
F. Spizzo ◽  
G. Barucca ◽  
G. Marangoni ◽  
P. Sgarbossa
Keyword(s):  
Au Nanoparticles ◽  
Magnetic Behavior ◽  
Oxide Phase ◽  
Magnetic Interactions ◽  
Basic Knowledge ◽  
Freezing Process ◽  
Collective State ◽  
Magnetic Systems ◽  
Fe Oxide ◽  
Two Samples

In nanoscale magnetic systems, the possible coexistence of structural disorder and competing magnetic interactions may determine the appearance of a glassy magnetic behavior, implying the onset of a low-temperature disordered collective state of frozen magnetic moments. This phenomenology is the object of an intense research activity, stimulated by a fundamental scientific interest and by the need to clarify how disordered magnetism effects may affect the performance of magnetic devices (e.g., sensors and data storage media). We report the results of a magnetic study that aims to broaden the basic knowledge of glassy magnetic systems and concerns the comparison between two samples, prepared by a polyol method. The first can be described as a nanogranular spinel Fe-oxide phase composed of ultrafine nanocrystallites (size of the order of 1 nm); in the second, the Fe-oxide phase incorporated non-magnetic Au nanoparticles (10–20 nm in size). In both samples, the Fe-oxide phase exhibits a glassy magnetic behavior and the nanocrystallite moments undergo a very similar freezing process. However, in the frozen regime, the Au/Fe-oxide composite sample is magnetically softer. This effect is explained by considering that the Au nanoparticles constitute physical constraints that limit the length of magnetic correlation between the frozen Fe-oxide moments.

Effects of altering streambed material size on a specific measure of biological diversity

1976 ◽  
Vol 3 (4) ◽  
pp. 563-570 ◽  
Author(s):  
P. S. Chisholm ◽  
H. D. Ayers ◽  
W. T. Dickinson ◽  
I. D. Macnab
Keyword(s):  
Biological Diversity ◽  
Diversity Index ◽  
Study Data ◽  
Second Phase ◽  
Aquatic Animal ◽  
Hydraulic Characteristics ◽  
Animal Populations ◽  
Sampling Locations ◽  
Two Phases ◽  
Average Size

A study of the relationship between hydraulic characteristics of streams and selected aquatic animal populations was undertaken in the Blue Springs Creek. The Blue Springs Creek is unregulated, free of evidence of pollution, and is an International Hydrologic Decade Representative Basin.The study included two phases of investigation. The preliminary phase involved the collection of field data on aquatic animal populations and hydraulic characteristics at selected stream sampling locations. These data were analyzed to determine the influence of specific hydraulic characteristics upon the animal populations sampled. It was found that the average size (D50) of streambed material has an important influence on the animal populations studied. It was also concluded that the animal populations sampled were not significantly dependent upon values of Reynolds Number, Froude Number, temperature, relative roughness, and average velocity of flow determined from study data.These preliminary results were tested during the second phase of the study. Data for the tests were obtained by altering streambed material size at selected sampling locations. The tests showed that an increase in average size of streambed material resulted in an increase in biological diversity index at a point. Conversely a decrease in the biological diversity index at a point resulted from a decrease in the average size of streambed material.

scholarly journals Poly(3-Hydroxybutyrate)-Based Nanoparticles for Sorafenib and Doxorubicin Anticancer Drug Delivery

2020 ◽  
Vol 21 (19) ◽  
pp. 7312 ◽  
Author(s):  
György Babos ◽  
Joanna Rydz ◽  
Michal Kawalec ◽  
Magdalena Klim ◽  
Andrea Fodor-Kardos ◽  
...  
Keyword(s):  
Drug Release ◽  
Glycolic Acid ◽  
Release Kinetics ◽  
Solvent Evaporation Method ◽  
Poly Ethylene Glycol ◽  
Anticancer Drug Delivery ◽  
Poly Ethylene ◽  
Average Size ◽  
Dual Drug

Dual drug-loaded nanotherapeutics can play an important role against the drug resistance and side effects of the single drugs. Doxorubicin and sorafenib were efficiently co-encapsulated by tailor-made poly([R,S]-3-hydroxybutyrate) (PHB) using an emulsion–solvent evaporation method. Subsequent poly(ethylene glycol) (PEG) conjugation onto nanoparticles was applied to make the nanocarriers stealth and to improve their drug release characteristics. Monodisperse PHB–sorafenib–doxorubicin nanoparticles had an average size of 199.3 nm, which was increased to 250.5 nm after PEGylation. The nanoparticle yield and encapsulation efficiencies of drugs decreased slightly in consequence of PEG conjugation. The drug release of the doxorubicin was beneficial, since it was liberated faster in a tumor-specific acidic environment than in blood plasma. The PEG attachment decelerated the release of both the doxorubicin and the sorafenib, however, the release of the latter drug remained still significantly faster with increased initial burst compared to doxorubicin. Nevertheless, the PEG–PHB copolymer showed more beneficial drug release kinetics in vitro in comparison with our recently developed PEGylated poly(lactic-co-glycolic acid) nanoparticles loaded with the same drugs.

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