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Nanocomposite Formation (nanocomposite + formation)

Distribution by Scientific Domains

Polymers and Materials Science	71%

Selected Abstracts

Nanocomposite Formation Through Thermal Decomposition of Mixed Samarium and Magnesium Citrate-Derived Gels Formed by Spray Pyrolysis

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2008
Thorsten Enz
Metal citrate gels of samarium and magnesium were used as precursors for the generation of hollow sphere particles by spray pyrolysis under mild thermal conditions. Six mixtures with different Sm/Mg ratios as well as pure Sm and Mg samples were prepared. As a result of the low synthesis temperature the particles consist of amorphous metal carboxylate networks. The texture of the shells is governed by microporosity yielding the major part of the total surface area. A detailed investigation of thermal decomposition, crystallization, and grain growth behavior was carried out under constant heating rate conditions. The decomposition products are nanocrystalline Sm2O3 and MgO and corresponding two-phase nanocomposites. The pure samarium carboxylate gel features considerably higher thermal stability compared with the one comprised of only magnesium. Accordingly the decomposition behavior of mixed samples is dependent on the Sm/Mg ratio. Furthermore it is shown that small amounts of MgO are able to slow down the kinetics of grain growth of Sm2O3 whereas high amounts are necessary to significantly reduce the final grain size at 1000°C. [source]

Isotactic Poly(propylene)/Monoalkylimidazolium-Modified Montmorillonite Nanocomposites: Preparation by Intercalative Polymerization and Thermal Stability Study

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2004
Aihua He
Abstract Summary: Poly(propylene)/monoalkylimidazolium-modified montmorillonite (PP/IMMT) nanocomposites were prepared by in situ intercalative polymerization of propylene with TiCl4/MgCl2/MMT catalyst. The PP synthesized possessed high isotacticity and molecular weight. Both wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) examinations evidenced the nanocomposite formation with exfoliated MMT homogeneously distributed in the PP matrix. A thermal stability study revealed that the nanocomposites possess good thermal stability. X-ray diffraction patterns of PP/IMMT (MMT,=,2.2 wt.-%) nanocomposite before and after processing. [source]

Thermomagnetic monitoring of nanocomposite formation in mechanically alloyed Nd,Fe,B alloys

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004
H. W. Kwon
Abstract A mechanical alloying technique was applied to NdxFe94,xB6 (x = 5.5,11.0) alloys for preparing an exchange-coupled nanocomposite. The structural development during the nanocomposite formation was monitored by thermomagnetic means. The mechanically alloyed NdxFe94,xB6 alloys in the as-milled condition consisted of an amorphous Nd,Fe,B phase and ,-Fe nanocrystallites. The crystallisation temperature of the amorphous phase was independent of the milling time. The amorphous phase in the as-milled NdxFe94,xB6 alloys with higher Nd content had a lower crystallisation temperature. The NdxFe94,xB6 (x = 8.5) alloy milled for longer than 30 h consisted of a two-phase structure containing ,-Fe and Nd2Fe14B phases after being isothermally annealed at 600 °C for 20 min. This annealed powder showed a smooth demagnetisation curve, indicating an intergranular exchange coupling between the hard Nd2Fe14B and soft magnetic ,-Fe grains. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

A novel miniature mixing device for polymeric blends and nanocomposites

POLYMER ENGINEERING & SCIENCE, Issue 11 2009
Martin Sentmanat
A new miniature mixer has been developed to monitor and optimize the preparation protocol of various polymeric compounds and blend systems. The effect of mixing time and other basic processing parameters on the shear and extensional rheological properties of said compounds and blends is examined to understand the effect of undermixed and/or overmixed conditions on the rheological properties and thus the quality of the final products. Results from the new miniature mixer are compared with the results from other conventional mixing techniques to assess the scalability of the new mixing protocol. Two examples are used, those of polymer blending and nanocomposite formation. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers. [source]

Crown ether-modified clays and their polystyrene nanocomposites

POLYMER ENGINEERING & SCIENCE, Issue 9 2002
Hongyang Yao
Crown ether-modified clays were obtained by the combination of sodium and potassium clays with crown ethers and cryptands. Polystyrene nanocomposites were prepared by bulk polymerization in the presence of these clays. The structures of nanocomposites were characterized by X-ray diffraction and transmission electron microscopy. Their thermal stability and flame retardancy were measured by thermogravimetric analysis and cone calorimetry, respectively. Nanocomposites can be formed only from the potassium clays; apparently the sodium clays are not sufficiently organophilic to enable nanocomposite formation. The onset temperature of the degradation is higher for the nanocomposites compared to virgin polystyrene, and the peak heat release rate is decreased by 25% to 30%. [source]

In situ generated diphenylsiloxane-polyimide adduct-based nanocomposites

POLYMER ENGINEERING & SCIENCE, Issue 1 2005
Manisha G. Goswami
Arylsiloxane was incorporated into polyimide (PI) via electronic interaction with polyamic acid (PAA)/PI, and a wide spectrum of properties were evaluated for different compositions. The samples prepared with relatively low concentrations (0.0001,0.1%) of oligomers showed unusual synergism, which is attributed to the generation of nanostructures dispersed in the continuous PI matrix. The incorporation of siloxane with bulky phenyl groups contributed to enhanced thermal stability as determined by thermogravimetric analysis. Water uptake and methanol absorption by these composites were evaluated and correlated with the underlying micro- and nanostructures. Fourier Transform Infrared (FTIR) spectroscopy was used to elucidate the probable reaction mechanism (including in situ polymerization of arylsilanol), and to study the synthetic aspects associated with the molecular composites and nanocomposites formation. POLYM. ENG. SCI., 45:142,152, 2005. © 2004 Society of Plastics Engineers [source]