Classification of composites

FIGURE 4-27 Classification of composite electrodes used in controlled-potential electrochemical techniques. (Reproduced with permission from reference 87.)... 

To this point we have focused on reactions with rates that depend upon one concentration only. They may or may not be elementary reactions indeed, we have seen reactions that have a simple rate law but a complex mechanism. The form of the rate law, not the complexity of the mechanism, is the key issue for the analysis of the concentration-time curves. We turn now to the consideration of rate laws with additional complications. Most of them describe more complicated reactions and we can anticipate the finding that most real chemical reactions are composites, composed of two or more elementary reactions. Three classifications of composite reactions can be recognized (1) reversible or opposing reactions that attain an equilibrium (2) parallel reactions that produce either the same or different products from one or several reactants and (3) consecutive, multistep processes that involve intermediates. In this chapter we shall consider the first two. Chapter 4 treats the third. 

TABLE 25.8 Classification of composites based on their reinforcement morphology... 

Chirality of polarised light, 289 Chronological development of commercial polymers, 44 Circular anisotropy, 289 Clarity, 313, 316 Classification of composites, 843... 

Figure 15.1 Classification of composites according to the reinforcement forms.

Classification of composites by the phase inclusion size bears a philosophical aspect how small should a component in the matrix be not to make the term composite material so universal as to include in fact all materials Interatomic distances in molecules and crystals are of 1.5 10 m dimensionality, distances between iterative elements of the crystalline structure are 10 —10 m, while the size of the smallest intermolecular voids in polymers is 10 m. Note that mean nanoparticle size (plastic pigments are 10-8-10 m in size, the diameter of monocrystalline fibers or whiskers is 10 —10 m, glass microspheres are 10 —10 m) is commensurate with parameters of monolithic simple materials. This means that in the totality of engineering materials, nanocomposites occupy a place at the boundary between composite and simple materials. 

The size range of the filler particles was the basis of an early classification of composite resins [102], Though the range of particle sizes has now been extended to include nano-particles [103], this is still a useful approach to classifying these materials. Table 3.1 shows the order of development of composite resins based on the particle size of their fillers. 

Table 1 shows the classification of composites in general use along with examples of applications. 

The classification of composites can be done in different ways. The composites can be classified on the basis of the form of their structural components (i) fibrous where the... 

FIGURE 3.10 Classification of composite isotherms. (After Nagy, L.G and Schay, G., Mag. Kem. Foly, 66, 31, 1960. With permission.)... 

The adsorption from binary solutions on sohd adsorbents in general and on activated carbons in particular is discussed in Chapter 3. The nature and types of adsorption and adsorption isotherms from dilute solutions and from completely miscible binary solutions are described. The composite isotherm equation is derived. The shapes and classification of composite isotherms and the influence of adsorbate-adsorbent interactions, the heterogeneity of the carbon surface, and the size and orientation of the adsorbed molecules on the shapes are examined. The thickness of the adsorbed layer and the determination of individual adsorption isotherms from a composite isotherm are also described. 

In another classification of composite components attention is paid to their characteristic form. The continuous phase (matrix) embeds the dispersed phase (inclusions). The inclusions may have the form of more or less regular particles and grains, fibres and pores or voids separated or interconnected. The terms matrix and inclusions may be used at different levels the matrix itself may be composed of inclusions embedded in a binder. 

The diverse shapes of inclusions may be used for a classification of composites, as shown for the basic cases of particulate, fibrous, and lamellar topologies in Figure 5.1. There are also composites which represent a combination of these inclusion types. In steel concrete, for example, mineral particles and metal fibers are joined by a binder material. For aerospace applications, the... 

Fig. 5.1. Classification of composites by the spatial extent of inclusions (a) particulate, (b) fibrous, (c) lamellar.

Table 5. Classification of Composite Vulnerability Index (CVI) to Setubal. 

Steinfink also refined the structure of a regular one-layer triclinic polytype having the M structure (II6-4). The specimen used was a corundophilite (or sheridanite in Foster s classification) of composition ... 

Another classification of composite materials is based on the morphology of the reinforcement introduced into the matrix. The composites therefore could be categorised into two main groups continuous reinforced system and discontinuous reinforced system. In the former, the matrix contains continuous fibres or filaments, which typically distribute in a uniaxial direction and enhance the strength and creep resistance of the matrix. In the latter, the matrix contains particulates, whiskers or chopped fibres, which distribute in the matrix uniformly in random orientations. Moderate toughening and reasonable levels of strengthening can be achieved. 

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