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Semi-crystalline polymers with strong crystalline regions resist deformation and cavitation, the formation of voids in the amorphous phase, drives yielding. [25] As done in crystalline materials, particles can be added to semi-crystalline polymers to change the mechanical properties.
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is a characteristic of a crystal. The terms " glass " and "glassy solid" are sometimes used synonymously with amorphous solid; however, these terms refer specifically to amorphous materials that ...
Common examples include chocolates, candles, or viruses. Water ice and dry ice are examples of other materials with molecular bonding. [22] Polymer materials generally will form crystalline regions, but the lengths of the molecules usually prevent complete crystallization—and sometimes polymers are completely amorphous.
Depending on its processing and thermal history, polyethylene terephthalate may exist both as an amorphous (transparent) and as a semi-crystalline polymer. The semicrystalline material might appear transparent (particle size less than 500 nm ) or opaque and white (particle size up to a few micrometers ) depending on its crystal structure and ...
Amorphous materials, such as liquids and glasses, represent an intermediate case, having order over short distances (a few atomic or molecular spacings) but not over longer distances. Many materials, such as glass-ceramics and some polymers, can be prepared in such a way as to produce a mixture of crystalline and amorphous regions. In such ...
Semicrystalline: A solid state in complex organic chemistry where molecules are packed in a regular order but have substantial local disorder. Different structural phases of polymorphic materials are considered to be different states of matter in the Landau theory. For an example, see Ice § Phases. Liquid: A mostly non-compressible fluid. Able ...
It is analogous to the polymorphism of crystalline materials. Many amorphous substances can exist with different amorphous characteristics (e.g. polymers). However, polyamorphism requires two distinct amorphous states with a clear, discontinuous (first-order) phase transition between them.
All polymers (amorphous or semi-crystalline) go through glass transitions. The glass-transition temperature (T g) is a crucial physical parameter for polymer manufacturing, processing, and use. Below T g, molecular motions are frozen and polymers are brittle and glassy. Above T g, molecular motions are activated and polymers are rubbery and ...