Microwave-synthesized freestanding iron-carbon nanotubes on polyester composites of woven Kevlar fibre and silver nanoparticle-decorated graphene

We synthesized Ag nanoparticle-decorated multilayered graphene nanosheets (Ag-graphene) from graphite nanoplatelets and silver nitrate through 90-100 s of microwave exposure, without the use of any mineral acids or harsh reducing agents. Fe nanoparticle-decorated carbon nanotubes (Fe-CNTs) were grown on polypyrrole (PPy) deposited on woven Kevlar fibre (WKF), using ferrocene as a catalyst, under microwave irradiation. Fe-CNTs grown on WKF and Ag-graphene dispersed in polyester resin (PES) were combined to fabricate Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites by vacuum-assisted resin transfer moulding. The combined effect of Fe-CNTs and Ag-graphene in the resulting composites resulted in a remarkable enhancement of tensile properties (a 192.56% increase in strength and 100.64% increase in modulus) as well as impact resistance (a 116.33% increase). The electrical conductivity significantly increased for Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites. The effectiveness of electromagnetic interference shielding, which relies strongly on the Ag-graphene content in the composites, was 25 times higher in Ag-graphene/Fe-CNT/PPy-coated WKF/PES than in neat WKF/PES composites. The current work offers a novel route for fabricating highly promising, cost effective WKF/PES composites through microwave-assisted synthesis of Fe-CNTs and Ag-graphene.ope

Preparation and characterization of SiO2-MxOy (M = V, Sn, Sb) thin films from silicic acid and metal chlorides

The preparation of SiO2-MxOy (M = V, Sn, Sb) binary oxide thin films by sol-gel method was investigated. The reaction of silicic acid with metal chloride (M = Sn and Sb) or oxychloride (M = V) formed homogeneous solutions. The dip-coating of slide glass and silicon wafer followed by heat treatment gave oxide films having Si-O-M bond. The changes of FT-IR spectra as a function of heat treatment temperature and molar composition confirmed the Si-O-M bonds. The sheet resistance of films increased with an increase on heat treatment temperature and decrease in the content of metal oxide MxOy. X-ray diffraction peaks were observed for the SiO2-V2O5 films with high V2O5 contents and heat-treated above 250 degrees C, while the others were amorphous. Oxide films heat treated at 500 degrees C had a thickness between 340-470 nm

Sol-gel preparation of borosilicates

Polyborosiloxanes as a precursor for borosilicate gel plates and fibers were obtained by the reaction of silicic acid and boron tri-n-butoxide followed by alkoxylation with 1-butanol. Gel fibers were prepared after concentration and aging of the polymer solutions with molar ratios of silicic acid to boron tri-n-butoxide of 7/3-2/3. Further aging of the solutions gave gel plates with cracking, depending on boron content. Spectral and chemical analyses showed that the borosiloxane bond formation initiated during polymerisation reaction and is enhanced by heat treatment. (C) 1999 Elsevier Science B.V. All rights reserved

A new study on spin-on-silica for multilevel interconnect applications

In this study, a new method for low temperature oxide deposition is discussed. Silicon dioxide was formed on silicon from silicic acid solution by using spin-on technology. Mechanical and planarizing properties of the silicon dioxide were investigated. Using this oxide a metal-silicon dioxide-wafer (MOS) structure was manufactured. Breakdown field strength and trap density of the MOS capacitance was measured. The method discussed in this paper shows a very low carbon contamination risk and does not suffer from crack formation. It is therefore suitable for a Variety of applications in VLSI and ULSI fabrication, which require low process temperatures or where high temperatures have drawbacks. (C) 1999 Elsevier Science Ltd. All rights reserved

Glycolysis of poly(ethylene terephthalate) wastes in xylene

To reclaim the monomers or prepare intermediates suitable for other polymers zinc acetate catalayzed glycolysis of waste poly(ethylene terephthalate) (PET) was carried out with ethylene or propylene glycol, with PET/glycol molar ratios of 1 : 0.5-1 : 3, in xylene at 170-245 degrees C. During the multiphase reaction, depolymerization products transferred to the xylene medium from the dispersed PET/glycol droplets, shifting the equilibrium to glycolysis. Best results were obtained from the ethylene glycol (EG) reaction at 220 degrees C, which yielded 80 mol % bis-2-hydroxyethyl terephthalate monomer and 20 mol % dimer fractions in quite pure crystalline form. Other advantages of employment of xylene in glycolysis of PET were improvement of mixing at high PET/EG ratios and recycling possibility of excess glycol, which separates from the xylene phase at low temperatures. (C) 1998 John Wiley & Sons, Inc