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The Global ETD Search service is a free service for researchers
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Showing 1 to 2 of 2 (0.231 seconds)Spelling suggestions: "subject:"precipitated calcium carbonate"" "subject:"precipitateda calcium carbonate""
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Synthesis of Precipitated Calcium Carbonate Nanoparticles Using Modified Emulsion MembranesGupta, Ritika 08 April 2004 (has links)
The synthesis of precipitated calcium carbonate nanoparticles with the use of double water in oil emulsion has been developed. Restricting the mass of calcium ions present in the system makes it possible to predict particle size precipitated. A model was developed to calculate the concentration required to synthesize a desired particle size. This model took into account a coalescence factor. The coalescence factor is described at the probability of two emulsion droplets, with separate nucleation processes within them, colliding and forming one nucleation process. The Ca2+ ions diffused through the oil membrane into the emulsion droplets with (CaCO3)2- ions by concentration gradients and facilitated transport. The size and shape of precipitated calcium carbonate synthesized was confirmed using scanning electron microscope and light scattering. Particles ranging from 100 nm to 1200 nm have been synthesized using mass restriction. The effect of temperature on the crystalline structure of precipitated calcium carbonate was studied. This was done by x-ray diffraction, where it was found that calcite was the dominating crystalline structure.
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Impact of Particle Morphology on the Rheology of PCC-Based CoatingsMichel-Sanchez, Enrique 18 May 2005 (has links)
The impact of particle size, size distribution, and particle shape on the rheology of precipitated calcium carbonate (PCC) based coatings was studied. Evaluating the interactions between different particle sizes and shapes leads to a better understanding of the packing fraction of PCC. HIgh packing fraction is desirable because of the positive impact on the fluidity of suspensions. Suspension with higher levels of fluidity can potentially load larger amounts of solids while keeping low viscosities. High solids suspensions are key factors to improve the efficiency of coating processes. To address this issue, PCC of different sizes and shapes where mixed in different ratiosto find mixtures with higher packing fractions that could result in coatings with lower viscosities. When coatings containing 90% of large particles and 10% by weight of small particles of different shape, viscosity decreases by 50% for one combination. The effect is caused by the higher packing fraction achieved. Future research is also described here.
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