We introduce a facile method to synthesize a new class of coreshell microspheres composed of resin core particles coated with various carbon materials. The coreshell microspheres were prepared by a one-pot process in which carbon materials such as edge-exfoliated graphite and expanded graphite were dispersed together with core substrates like polystyrene and poly(styrene/2-hydroxyethyl methacrylate) spherical particles in supercritical carbon dioxide. The obtained microspheres were characterized by thermogravimetric analysis, Raman spectroscopy, and scanning electron microscopy. The results indicate that the carbon shells are tightly attached to the surface of the core substrates. Furthermore, because of excellent adhesion, the carbon-coated polymer particles exhibited extremely high electrical conductivity with particle resistance of less than 50 ³ cm despite the presence of an insulating polymeric core material.
Sensitive and rapid methods have been proposed for the determination of pert per billion levels of elements in polycarbonate(PC) used as optical materials. The contents of Cr, Mn, Fe, Co, Ni, Cu and Na were determined directly by graphite furnace atomic absorption spectrometry(GFAAS) with a solid sampling method. Na+ and Cl" were analyzed by ultrapure water extraction-GFAAS and ion chromatography, respectively. The accuracy of these methods was confirmed by comparative analyses. The proposed methods were applied to optical fiber and disk of PC. The analysis time required a few hours.
Abstract:The contents in a glass kohl bottle excavated from the stratum of the 14th-15th centuries, al-Tur in South Sinai, Egypt were analyzed to find their characteristics and provenances. The contents of the bottle were found to be mainly phosgenite and laurionite by X-ray diffraction and X-ray fluorescence analysis.As a reference, a black pigment used for a modern kohl in Egypt was also analyzed and the results were discussed.
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