Amorphous glass structures

Relation of Structure to Thermal and Mechanical Properties AMORPHOUS,GLASS-LIKE CRYSTALLINE, FIBRE-FORMING... 

When the temperamre is lowered, rubbers become stiff and brittle. All rubbers eventually stiffen to a rigid, amorphous glass at the glass transition temperature (Tg). This temperature also indicates the low-temperature service limit of the rubber. Tg values are dependent on the structure, degree of cross-linking (vulcanization) and isomeric composition of the rubber. 

A method of characterising transport mechanisms in solid ionic conductors has been proposed which involves a comparison of a structural relaxation time, t, and a conductivity relaxation time, t . This differentiates between the amorphous glass electrolyte and the amorphous polymer electrolyte, the latter being a very poor conductor below the 7. A decoupling index has been defined where... 

Amorphous. Strictly speaking, characterized by noncrystalline structure, i.e., having no. lattice structure that most solids have. Liquids are amorphous. Glass is a solid but is amorphous because it is considered a high viscosity liquid.. 

Carbohydrates and proteins are typical hydrophilic components of concentrated food systems. These components tend to form amorphous, noncrystalline structures at low water contents (White et al. 1966 Slade et al. 1991 Roos 1995). Well-known food processes resulting in glass formation by amorphous or partially amorphous food components include baking, extrusion, dehydration and freezing (Roos 1995). In these processes, removal of water as part of the manufacturing process results in the formation of a noncrystalline, amorphous state, which is extremely sensitive to water and may show various time-dependent changes causing loss of quality and reduced shelf life. 

Figure 7.11 Two different two-dimensional network schemes of silica tetra-hedra (a) crystalline and (b) amorphous. Glass has an amorphous structure, i.e. devoid of any long-range order so characteristic of a crystalline material.

Very little is known about the influence of grain growth, or crystallization if the membrane is composed of an amorphous alloy, on membrane durability. The as-fabricated permselective metal membrane will be polycrystalline or amorphous, depending on the alloy composition and fabrication method. Amorphous, or metallic glass, structures are far less common than are polycrystalline structures. Both amorphous and polycrystalline structures are quasi-stable, meaning that structures are kinetically stabilized and slow to rearrange to the thermodynamically favored structure. In both cases, this would be a single crystal of the metal. 

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