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Its Transformation (its + transformation)

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Chemistry100%

Selected Abstracts

Mesoscopic Structure and Properties of Liquid Crystalline Mesophase Pitch and Its Transformation into Carbon Fiber

THE CHEMICAL RECORD, Issue 2 2002
Isao Mochida
Abstract The history and present state of the art in the chemistry of mesophase pitch, which is an important precursor for carbon fiber and other high-performance industrial carbons, are reviewed relative to their structural properties. The structural concepts in both microscopic and macroscopic views are summarized in terms of the sp2 carbon hexagonal plane as a basic unit common to graphitic materials, its planar stacking in clusters, and cluster assembly into microdomains and domains, the latter of which reflect the isochromatic unit of optical anisotropy. Such a series of structural units is described in a semiquantitative manner corresponding to the same units of graphitic materials, although the size and stacking height of the hexagonal planes (graphitic sheets) are very different. Mesophase pitch is a liquid crystal material whose basic structural concepts are maintained in the temperature range of 250 to 350,°C. The melt flow and thermal properties are related to its micro- and mesoscopic structure. The structure of mesophase-pitch,based carbon fiber of high tensile strength, modulus, and thermal conductivity has been formed through spinning, and has inherited the same structural concepts of mesophase pitch. Stabilization settles the structure in successive heat treatments up to 3000,°C. Carbonization and graphitization enable growth of the hexagonal planes and their stacking into units of graphite. Such growth is governed and controlled by the alignment of micro- and mesoscopic structures in the mesophase pitch, which define the derived carbon materials as nanostructural materials. Their properties are controlled by the nanoscopic units that are expected to behave as nanomaterials when appropriately isolated or handled. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2:81,101, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10016 [source]

ChemInform Abstract: Synthesis of a Solid Solution Series of Layered EuxGd1-x(OH)2.5Cl0.5·0.9 H2O and Its Transformation into (EuxGd1-x)2O3 with Enhanced Photoluminescence Properties.

CHEMINFORM, Issue 28 2010
Linfeng Hu
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Synthesis of a Layered Zinc Phosphate, [NH3(CH2)2NH2 (CH2)3NH3] [Zn2(PO4)(HPO4)2] ×H2O, and Its Transformation to an Extra-Large Pore Three-Dimensional Zinc Phosphate, [NH3(CH2)2NH2 (CH2)3NH3] [Zn3(PO4)(HPO4)3].

CHEMINFORM, Issue 28 2002
Srinivasan Natarajan
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

A Zeolite-Like Zinc Phosphonocarboxylate Framework and Its Transformation into Two- and Three-Dimensional Structures

CHEMISTRY - AN ASIAN JOURNAL, Issue 12 2007
Zhenxia Chen
Abstract Three zinc phosphonocarboxylates, Zn2(pbc)2,Hdma,H3O,2H2O (1), Zn(pbc),Hdma (2), and Zn4.5(pbc)3(OH)(H2O)0.5,Hdma (3) (H3pbc=4-phosphonobenzoic acid, dma=dimethylamine) were synthesized by the mixed solvothermal reaction of Zn(Ac)2,2H2O and 4-phosphonobenzoic acid in N,N -dimethylformamide (DMF) and water. The zigzag and ladderlike chains completely constructed by triply fused 4-membered rings (denoted SBU-1) are linked by the organic moieties to form the 3D zeolite-like structure 1 and the layered structure 2, respectively. As for structure 3, a new second building unit (SBU-2) formed by the inset of the [Zn3O12] trimer into the 4-membered ring as well as SBU-1 is observed. The connections between the two types of SBUs lead to a "zinc phosphate" layer, which is linked by the organic groups to generate a 3D pillar-layered structure. Both solution-mediated and solid-state transformations of 1 to 2 and 3 were observed. A possible mechanism for the transformation is proposed. Gas sorption studies show that 1 has accessible pores for methanol and water and exhibits size selectivity for alcohols. [source]