Different Types of Clays

The eomposition, origin and uses of some common types of cl s and argilloids are given below. 

An argilloid is a fine-grained material that contains clay minerals in considerable proportions and has some similarities with clay pertaining to origin, and industrial uses, but not plastic when wet. 

In flint clay, diagenetically formed kaolinite is the main clay mineral and quartz, siderite, iron oxide etc. are present in considerable proportions. It is non-slaking and non-plastic, and suitable only for use in refractories. 

Fuller s earth contains montmorillonite and sometimes palygorskite-sepiolite. Some of the other minerals that may be present in Fuller s earth are calcite, dolomite, and quartz. It has sedimentary, residual and hydrothermal origin. It is a non-plastic, thixotropic material. It has long been used to clean raw wool from grease and dirt. It is also used for decolourizing, filtering, and purifying oils and animal fat. 

Comprehensive description of the composition, physical and chemical properties of different types of clays are given in the subsequent chapters of this Part. The industrial uses of these clays and their constituents are systematically described in Part II. 

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More than 20 different types of clay can be actually distinguished. Those most appreciated for making ceramics, for example, kaolinite, are built up of combinations of the basic structural units described above. The particles of most consist of platelets (very small, flat sheets) that, when stacked together, form layered arrangements having extensive surface areas, much like the pages of a book. Other common clay particle shapes are fibrous or tubular. 

Table 5 Curing characteristics and physical properties of CR vulcanizates reinforced with different types of clay...

Before elaborating on the different types of clay, it is important to clearly define the terms clay and clay body. A clay is a material with plastic properties, formed by natural forces and found in nature. Some examples are ... 

Clay is a fascinating material from which to make musical instruments because it can produce a multitude of sounds. Different types of clay and various firing techniques can be employed to create musical instruments that sound quite dissimilar to each other. And the plasticity of clay, before firing, makes it possible to create a variety of unusually shaped air chambers and resonators for wind and percussion instruments. 

Table 9 Water content and maximum yield point for different types of clays [14] ...

Different types of clay are found in different regional locations. Often, red clay can be found about 12 inches below grass and dirt. When digging becomes difficult, clay is usually the reason. 

We can show by DMTA and DSC that lamellar clays partially restrict the mobility of the starch chains [PAR 02], Nanoclays are also known for having an impact on the permeabihty to water vapor of the corresponding nanocomposites, particularly when they are correctly oriented. Park et al. looked at the permeabihty of nanobiocomposites to water vapor with different types of clay [PAR 02]. According to those authors, all the films analyzed showed decreased permeability to water vapor in comparison to the matrix alone. Such results were not confirmed in the case of OMMT-CS, which has a very highly plasticized matrix [CHI 10a]. In this case, the high affinity of the clay platelets with starch-rich phases creates preferential diffusion pathways through the glycerol-rich phases, in which the platelets tend to be absent. 

Maiti and co-workers [43] investigated the effect of organic modifiers of various chain lengths in different types of clays, smectite, MMT, and mica on the degree of dispersion of clay in PLA. They observed that the nanocomposites of MMT and mica are intercalated and well-ordered compared to smectite. The... 

These interlayer cations may be readily replaced by other cations when the mineral surface is in contact with a liquid containing different types of cations like Cu ", Pb ", Zn, Cd ", Mn etc. This is known as cation exchange property of clay minerals. The cation exchange capacity is different in different types of clay minerals, as shown in table 7.2. 

Table 7.2. Cation exchange capacities of different types of clay minerals.

For the different types of clays, mentioned above, the mining methods and source areas have been discussed here to get a clear picture of their subsequent effect on enviromnent. 

The biological effects of clay minerals are influeneed by their mineral eomposition and particle size. The decreasing rank order of the potencies of quartz, kaolinite, and montmorillonite to produee lung damage is consistent with their known relative active surfaee areas and surfaee chemistry. Biodegradations are variable in nature, owing to different types of clay. 

How does the nature of pollutants vary with mining of different types of clays Give examples. 

How does the exposme level of different types of clays affect the human life ... 

Cite examples with respect to different types of clay related industries, how the gemerated wastes can be reeyeled ... 

Extensive research work has been going on for the safe disposal of radioactive wastes in different parts of the world, especially in the North American and West European countries where fission reactors are aplenty. Different types of clays and cl -derivatives are found to be more effective in safe disposal of different types of radioactive wastes. The clays are easily available than any other buffer materials, and the procedures of waste disposal with clay buffer are less expensive. This encoimages the researchers to explore further possibilities of application of cl s in this field. 

How can the cation-exchange capacity of different types of clays be used in waste management ... 

Reference (4) provides detailed information about the sorption of polar and nonpolar sorbates (both gases and liquids) on many different types of clays, current to 1978. Rutherford et al. reported adsorption isotherms as recently as 1997 of various ion-exchanged montmorillonites (45). They found that the lateral dimen-... 

Clays are abundant throughout the world approximately 4250 distinct clay minerals have been identified (98), of both natural and synthetic origin. Clays are phyllosiUcate minerals, so-caUed because of their sheet-like (1 20 thicknessilength) structure (99). The sheets (phyllo) consist of aluminosilicate networks composed of silicon oxide tetrahedra (Si04) or aluminum oxide octahedra (AlOg). These sheets form layers (platelets) when oxygen atoms are shared between two or more adjacent sheets, and can combine in various ways to form many different types of clays. 

TABLE 1 Summary of tensile mechanical properties for starch/PVOH composites with different types of clay and clay content. 

Nanoclay fillers are categorized as platelet-like nanoclays or layered silicates and tubular nanoclays in terms of filler shape. With the configuration of two tetrahedral sheets of silicate and a sheet layer of octahedral alumina, platelet-like nanoclays or phyllosilicates are formed, which include smectite, mica, vermiculite, and chlorite. In particular, smectite clays are widely employed with further subcategories of MMT, saponite, hectorite, and nontronite. The typical MMT clays are regarded as one of the most effective nanofillers used in polymer/clay nanocomposites due to their low material cost and easy intercalation and modification (Triantafillidis et al., 2002). On the other hand, the fundamental structure of tubular nanoclays contains an aluminum hydroxide layer and a silicate hydroxide layer. They are also known as dio-ctahedral minerals with two different types of halloysite nanotubes (HNTs) and imo-golite nanotubes (INTs). Notwithstanding their material role as clay minerals, these two types of tubular nanoclays resemble the hollow tubular structure of carbon nanotubes (CNTs). In this section, three different types of clay nanofillers, namely MMTs, HNTs, and INTs are reviewed in detail along with the development of clay modification. 

Figure 6.6 Different types of clay structures when dispersed into polymer matrices, (a) microcomposite structure, (b) intercalated structure, (c) exfoliated structure. Reprinted from Alexander and Dubois (2000) with permission from Elsevier.

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