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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 ...
An amorphous metal (also known as metallic glass, glassy metal, or shiny metal) is a solid metallic material, usually an alloy, with disordered atomic-scale structure. Most metals are crystalline in their solid state, which means they have a highly ordered arrangement of atoms. Amorphous metals are non-crystalline, and have a glass-like structure.
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 ...
This has an impact on the crystallinity (amorphous or semi-crystalline) and the thermal properties (expressed as glass transition point T g and melting point T m). The term tacticity describes for polypropylene how the methyl group is oriented in the polymer chain. Commercial polypropylene is usually isotactic.
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 ...
Solid-phase epitaxy (SPE) is a transition between the amorphous and crystalline phases of a material. It is usually produced by depositing a film of amorphous material on a crystalline substrate, then heating it to crystallize the film. The single-crystal substrate serves as a template for crystal growth.
Polyamorphism is also an important area in pharmaceutical science. The amorphous form of a drug typically has much better aqueous solubility (compared to the analogous crystalline form) but the actual local structure in an amorphous pharmaceutical can be different, depending on the method used to form the amorphous phase.