Sonochemical synthesis and rheological properties of shear thickening silica dispersions

A sonochemical method has been developed to synthesize shear thickening fluid. This shear thickening fluid (STF) is composed of hard silicon dioxide nanoparticles and polyethylene glycol (PEG) liquid polymer. The combination of flow-able and hard components at a particular composition, results a material with remarkable rheological properties that is suitable for liquid body armor applications. In the present study nine types of STF’s have been synthesized with two different types of silica nanoparticles (15 nm and 200 nm) and polyethylene glycol at various weight fractions using a high intensity ultrasonic irradiation. The resultant STF samples were tested for their rheological and thermal properties. The advantages and disadvantages of this process have been discussed.     

Weighted Projective Lines as Fine Moduli Spaces of Quiver Representations

We describe weighted projective lines in the sense of Geigle and Lenzing by a moduli problem on the canonical algebra of Ringel. We then go on to study generators of the derived categories of coherent sheaves on the total spaces of their canonical bundles, and show that they are rarely tilting. We also give a moduli construction for these total spaces for weighted projective lines with three orbifold points.     

Synthesis of Ferrocene-based Esters as Burning Rate Catalysts and their Anti-migration Study

Ferrocene-based (Fc-based) burning rate catalysts (BRCs) play an essential role in the solid rocket propellants. However, the migration problem during curing and storage limits their applications. To retard the migration problems of Fc-based BRCs and to increase the burning rate (BR) of AP-based propellants, Fc-based esters compounds (Es-Fcs) were synthesized. The synthesized Es-Fcs were characterized by X-ray diffraction, proton nuclear magnetic resonance (¹H NMR),¹³C NMR and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical behaviors of Es-Fcs were investigated by cyclic voltammetry (CV). The BR catalytic activity of Es-Fcs on thermal decomposition of AP were examined by thermogravimetry (TG). Thermal analysis results showed that these Es-Fcs had good BR catalytic effects on thermal decomposition of AP. It was found that the anti-migration performance of Es-Fcs were better than catocene and Fc.     

Sonochemical effect on size reduction of CaCO3 nanoparticles derived from waste eggshells

A novel combination of mechanochemical and sonochemical techniques was developed to produce high-surface-area, bio-based calcium carbonate (CaCO₃) nanoparticles from eggshells. Size reduction of eggshell achieved via mechanochemical and followed by sonochemical method. First, eggshells were cleaned and ground, then ball milled in wet condition using polypropylene glycol for ten hours to produce fine particles. The ball milled eggshell particles were then irradiated with a high intensity ultrasonic horn (Ti-horn, 20 kHz, and 100 W/cm²) in the presence of N,N-dimethylformamide (DMF); decahydronaphthalene (Decalin); or tetrahydrofuran (THF). The ultrasonic irradiation times varied from 1 to 5 h. Transmission electron microscopic (TEM) studies showed that the resultant particle shapes and sizes were different from each solvent. The sonochemical effect of DMF is more pronounced and the particles were irregular platelets of ～10 nm. The BET surface area (43.687 m²/g) of these nanoparticles is much higher than that of other nanoparticles derived from eggshells.