Amorphous material, forms

As both layers are blaek and the interface is not easy to distinguish, careful separation is necessary. In addition, black amorphous material forms at the interface, making the separation difficult. It can be coagulated by standing or removed by filtration. 

These results, which indicate the presenee of extra-lattice A1 (Aivi) even in the mordenites dealuminated by acid treatment, are in agreement with our previous results obtained with 2 a1 MAS NMR (3). This suggests that the amorphous material formed by the extraction process of lattice alumina w is not eliminated. This difficulty in eliminating the extra-lattiee A1 altogether has also been observed in other studies (7,8). 

It is clear from Figure 5a that the sample containing unmodified clay has both crystalline and amorphous content present in the composite, as do the oPC and dPC samples. A small peak is noticed at 21.8° for the DdPC sample but this disappears completely for the remaining nanocomposites. This indicates that as the length of the alkyl chain increases, the amount of amorphous material forming in the composite decreases, producing a more uniform y-type crystal... 

Iron(III) hydroxide [1309-33-7], FeH02, is a red-brown amorphous material that forms when a strong base is added to a solution of an iron(III) salt. It is also known as hydrated iron(III) oxide. The fully hydrated Fe(OH)3 has not been isolated. The density of the material varies between 3.4-3.9 g/cm, depending on its extent of hydration. It is insoluble in water and alcohol, but redissolves in acid. Iron(III) hydroxide loses water to form Fe203. Iron(III) hydroxide is used as an absorbent in chemical processes, as a pigment, and in abrasives. Salt-free iron(III) hydroxide can be obtained by hydrolysis of iron(III) alkoxides. 

Pyrolusite is a black, opaque mineral with a metallic luster and is frequendy soft enough to soil the fingers. Most varieties contain several percent water. Pyrolusite is usually a secondary mineral formed by the oxidation of other manganese minerals. Romanechite, a newer name for what was once known as psilomelane [12322-95-1] (now a group name) (7), is an oxide of variable composition, usually containing several percent water. It is a hard, black amorphous material with a dull luster and commonly found ia the massive form. When free of other oxide minerals, romanechite can be identified readily by its superior hardness and lack of crystallinity. 

The properties of elastomeric materials are also greatly iafluenced by the presence of strong interchain, ie, iatermolecular, forces which can result ia the formation of crystalline domains. Thus the elastomeric properties are those of an amorphous material having weak interchain iateractions and hence no crystallisation. At the other extreme of polymer properties are fiber-forming polymers, such as nylon, which when properly oriented lead to the formation of permanent, crystalline fibers. In between these two extremes is a whole range of polymers, from purely amorphous elastomers to partially crystalline plastics, such as polyethylene, polypropylene, polycarbonates, etc. 

The regular syndiotactic and isotactic structures are capable of crystallisation whereas the atactic polymer carmot normally do so. In the case of polypropylene the isotactic material is a crystalline fibre-forming material. It is also an important thermoplastic which can withstand boiling water for prolonged periods. Atactic polypropylene is a dead amorphous material. Polystyrene as commonly encountered is atactic and glass-like but the syndiotactic material... 

It is known that mechanical and physical properties of the amorphous and crystalline phases differ significantly [80T01]. For this reason, it is anticipated that properties of the mechanically and electrically treated film will depend explicitly on its history. Shock-compression measurements such as those carried out on amorphous materials in a thick form [80M01] will not prove characteristic of thin, treated films. 

C), and is much less reactive it is therefore safer and easier to handle, and is essentially non-toxic. The amorphous material can be transformed into various crystalline red modifications by suitable heat treatment, as summarized on the right hand side of Fig. 12.3. It seems likely that all are highly polymeric and contain three-dimensional networks formed by breaking one P-P bond in each P4 tetrahedron and then linking the remaining P4 units into chains or rings of P atoms each of which is pyramidal and 3 coordinate as shown schematically below ... 

Contrary to widespread opinion, the value of Ea is not a constant quantity. As was proved previously [52], the value of E is variable, since it depends on the ordering of macromolecules in the amorphous material of the fiber. At the same time, one can suppose that this ordering will be affected by the specificity of the fine structure of the fiber, and particularly by the type of substructure of the fiber. The relationship determining the modulus Ea appropriate for a definite type of fiber substructure can be derived from Eq. (11) when appropriate values of A are assumed. In the case of the microfibrillar substructure, i.e., for A < I, typical of PET fibers stretched, but not subjected to annealing, this equation has the form [52] ... 

In the studies carried out by one of the authors [52], the values of Ea and E were determined for PET fibers of the microfibrillar and of the lamellar substructure. The results have been presented in Tables 8 and 9. The results obtained show that for both types of substructure the resistance to deformation, that is, the value of E, depends on the degree of molecular orientation of the amorphous material of the fiber fa) and the density of this amorphous phase of the fiber da)- However, this dependence assumes a different form for the microfibrillar and for the lamellar substructure. In the first case, it has the form ... 

Although vitreous silica is nominally a homogeneous isotropic amorphous material, and should normally remain so during its service life, it is in fact in a metastable condition. The tendency to revert to crystalline forms with attendant deterioration in mechanical durability places severe limitations on the range of applications. Figure 18.2 illustrates the polymorphic forms of silica, and the dimensional changes accompanying each transition. 

Beside the crystalline material, a certain portion of amorphous lead dioxide is always observed. In the working electrode such amorphous material is apparently hydrated and forms a gel structure at the phase boundary between the solid material and the electrolyte (cf. Ref. [6]). 

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