Studies On Preparation And Formation Mechanism Of Aragonite Calcium Carbonate Whisker

Calcium carbonate whisker is a new-kind whisker material appeared in recent years, the strength of calcium carbonate whisker is better than ordinary reinforcements used at present, so it is a very perfect new kind reinforcement of compound materials. Calcium carbonate whisker has many perfect characteristics, such as heet-resistant, fire-resistant, high hardness, good mechanical strength, and high elastic coefficience. Therefore, Calcium carbonate whisker could be used in engineering plastics, polypropylene and nylon products. Furthermore, calcium carbonate whisker could also be used as reinforcement of degradable plastics, as keying agent of beaded paint, and as biological materials, it has special applications in medicine and medical drugs.At present, the main technologies for preparation of calcium carbonate whiskers are carb-onation process, replacement reaction method, urea hydrolysis, thermal decomposition of Ca (HCO₃)₂ and supergravity reaction-crystallization, and so on.Based on the replacement reaction method, a new technology was explored to solve the problems appeared in current methods, such as complicated technologies, bad products, low concentrations, et al. Under the optimum conditions (reaction time is 4h, reaction temperature is 80 ℃, and aging time is 1h), calcium carbonate whiskers with length of 30～40 μm, aspect ratio of 40～50 and purity above 95% could be prepared by cocurrent feed. Compared with the previous technologies, the concentration of the reactions of this technology could be elevated to about 0.2mol/ L, and the aspect ratio of the whiskers are higher. In addition, this technology is very simple, convenient to operate and of less cost. Calcium carbonate whiskers gained by this technology have good qualityies.The crystallization process and formation mechanism of calcium carbonate whisker were also preliminarily researched in the paper. At the same time, the important factors which affect the growth of calcium carbonate whisker were analyzed for the aim of providing theoretical basis for preparing aragonite calcium carbonate whiskers.