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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 ...
Polymers with microcrystalline regions are generally tougher (can be bent more without breaking) and more impact-resistant than totally amorphous polymers. [47] Polymers with a degree of crystallinity approaching zero or one will tend to be transparent, while polymers with intermediate degrees of crystallinity will tend to be opaque due to ...
Polymers are composed of long molecular chains which form irregular, entangled coils in the melt. Some polymers retain such a disordered structure upon freezing and readily convert into amorphous solids. In other polymers, the chains rearrange upon freezing and form partly ordered regions with a typical size of the order 1 micrometer. [3]
In the case of polymers, conformational changes of segments, typically consisting of 10–20 main-chain atoms, become infinitely slow below the glass transition temperature. In a partially crystalline polymer the glass transition occurs only in the amorphous parts of the material. The definition is different from that in ref. [9]
Elastomers are amorphous polymers maintained above their glass transition temperature, so that considerable molecular reconformation is feasible without breaking of covalent bonds. At ambient temperatures, such rubbers are thus relatively compliant (E ≈ 3 MPa) and deformable. [citation needed] IUPAC definition for an elastomer in polymer ...
Amorphous polymers are polymers that can behave differently at different temperatures. They may behave like a glass at low temperatures (the glassy region), a rubbery solid at intermediate temperatures (the leathery or glass transition region), and a viscous liquid at higher temperatures (the rubbery flow and viscous flow region).
Polyamorphism is the ability of a substance to exist in several different amorphous modifications. It is analogous to the polymorphism of crystalline materials. Many amorphous substances can exist with different amorphous characteristics (e.g. polymers).
Polymers that are formed by free-radical mechanisms, such as polyvinyl chloride are usually atactic. [citation needed] Due to their random nature atactic polymers are usually amorphous. [citation needed] In hemi-isotactic macromolecules every other repeat unit has a random substituent. [citation needed]