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Branching also affects chain entanglement, the ability of chains to slide past one another, in turn affecting the bulk physical properties. Long chain branches may increase polymer strength, toughness, and the glass transition temperature (T g) due to an increase in the number of entanglements per chain. A random and short chain length between ...
Other materials, such as many polymers, lack a well defined crystalline state and easily form glasses, even upon very slow cooling or compression. The tendency for a material to form a glass while quenched is called glass forming ability. This ability depends on the composition of the material and can be predicted by the rigidity theory. [12]
Statistical measures, such as the atomic density function and radial distribution function, are more useful in describing the structure of amorphous solids. [1] [3] Glass is a commonly encountered example of amorphous solids. Although amorphous materials lack long range order, they exhibit localized order on small length scales. [1]
It can be appreciated that the siloxanes would have low barriers for rotation about the Si−O bonds as a consequence of low steric hindrance. This geometric consideration is the basis of the useful properties of some siloxane-containing materials, such as their low glass transition temperatures.
Lyotropic main chain LCPs have rigid mesogen cores (such as aromatic rings) in the backbones. [12] This type of LCPs forms liquid crystals due to their rigid chain conformation but not only the aggregation of mesogen cores. Because of the rigid structure, strong solvent is needed to dissolve the lyotropic main chain polymers.
The most common applications are in the making of pottery, glass, and some types of food, but there are many others, such as the vitrification of an antifreeze-like liquid in cryopreservation. In a different sense of the word, the embedding of material inside a glassy matrix is also called vitrification. An important application is the ...
The structure of glasses differs from the structure of liquids just above the glass transition temperature T g which is revealed by the XRD analysis [10] and high-precision measurements of third- and fifth-order non-linear dielectric susceptibilities. [11] Glasses are generally characterised by a higher degree of connectivity compared liquids. [12]
In polymer science, the polymer chain or simply backbone of a polymer is the main chain of a polymer. Polymers are often classified according to the elements in the main chains. The character of the backbone, i.e. its flexibility, determines the properties of the polymer (such as the glass transition temperature).