Crystal Morphology Control of Nano-/Micro-sized Calcium Carbonate using Reverse Microemulsion Technique
Date Issued
2004
Date
2004
Author(s)
Chen, Chih-Kuang
DOI
zh-TW
Abstract
Abstract
Calcium carbonate, one of the most abundant resources on earth, which is massively used for inorganic filler in various industrial fields, including rubber, plastic, painting, pharmacy, seal etc.. Particle size, particle morphology and crystal morphology of calcium carbonate affect the performance of matrix materials strongly. Nano-sized calcium carbonate has been proved to reduce its usage and to improve the mechanical strength of matrix materials effectively. Cubic shape is the general form of commercial nano-sized calcium carbonate. The Objective of this study is to control particle morphology of nano-/micro-sized calcium carbonate using the two-reverse-microemulsion technique. Therefore, a composite formed by mixing a matrix with calcium carbonate of distinctive shape may possess high mechanical strength due to the well-aligned structure.
The AOT/isooctane/water reverse microemulsion system was selected in this research. The water phases of the two emulsions are CaCl2 and Na2CO3 aqueous solution, respectively. When the two reverse microemulsions are mixed together, calcium carbonate will precipitate. The effects of several operating variables, including ω values(molar ratio of water/surfactant), S values(molar ratio of water/oil), type and concentration of additives, R values(total molar ratio) and reaction temperature on the particle size and morphology of calcium carbonate were investigated.
This study has successfully synthesized CaCO3 particle with disk, hexagonal plate, rhombohedron, sphere-like, spindle, twin-rosette, doughnut, rods and filament in shapes. The size of the sphere-like particle can be reduced to 100~200nm, of the disk, rhombohedron, and spindle particles,to 200~300nm, of doughnut particle to 1~1.5μm. Doughnut-like particle has a specific surface area as high as 42m2/g, which is expected to be a high-performance absorbent.
Subjects
晶貌
碳酸鈣
逆微乳膠法
Calcium carbonate
particle morphology
reverse microemulsion
Type
thesis
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