ABSTRACT
Calcium carbonate is an important inorganic filler that is easily available and has a low cost. It has been widely used in household plastics, rubber, the paint and paper industry, and has become an important polymer material filler with a huge potential development. Calcium carbonate can be divided into ground calcium carbonate and light calcium carbonate based on its source. Light calcium carbonate for industrial applications currently includes mainly three kinds: calcite, aragonite, and vaterite.1 Common calcite generally has some defects, such as holes, impurities, incomplete grain boundary and structure, and so on. Calcium carbonate whiskers with almost no structural defects have the structure of aragonite and substantially overcome these drawbacks.2 Similar to other whiskers, calcium carbonate whiskers have a slender and integrated structure, with the advantages of high strength, high modulus, high whiteness, high filling capacity, good thermostability, thermal
resistance, and insulation. The diameter of calcium carbonate whiskers is 0.5-1.0 μm, and the length is 20-30 μm. Because there is no crystal water of crystallization at the molding temperature, the products will not form crazes due to crystal water evaporation in material. Meanwhile, because it has a special shape and the linear expansion coefficient is close to that of the plastic, the whiskers have good compatibility with the matrix resin and therefore can improve the processing performance of the products, such as the mechanical properties, surface smoothness, and abrasion resistance.3-8
Calcium carbonate whiskers are produced with calcite, marble, or limestone as raw materials, and the process is simple. Compared with other whiskers obtained from more complex and high-temperature processes, calcium carbonate whiskers have lower cost and more significant economic value, leading to their large-scale use for industrial and consumer products.9 In addition, calcium carbonate whiskers are nontoxic and biodegradable in an acidic environment; thus environmental pollution and any unfavorable effects on humans are low as well.10,11
The infrared spectrum of calcium carbonate whiskers is shown in Figure 5.1; thermal analysis is shown in Figure 5.2; x-ray diffraction is shown in Figure 5.3; a scanning electron
micrograph (SEM) is shown in Figure 5.4; and an energy spectrum is shown in Figure 5.5.
