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A polymer (/ ˈ p ɒ l ɪ m ər / [4] [5]) is a substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeating subunits derived from one or more species of monomers. [6]
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
The melting point of ordinary hexagonal ice falls slightly under moderately high pressures, by 0.0073 °C (0.0131 °F)/atm [h] or about 0.5 °C (0.90 °F)/70 atm [i] [53] as the stabilization energy of hydrogen bonding is exceeded by intermolecular repulsion, but as ice transforms into its polymorphs (see crystalline states of ice) above 209.9 ...
In the following table, material data are given with a pressure of 611.7 Pa (equivalent to 0.006117 bar). Up to a temperature of 0.01 °C, the triple point of water, water normally exists as ice, except for supercooled water, for which one data point is tabulated here. At the triple point, ice can exist together with both liquid water and vapor.
The melting point of α-crystalline regions is given as 185 [15] [16] to 220 °C, [15] [17] the density as 0.936 to 0.946 g·cm −3. [ 18 ] [ 19 ] The β-modification is in comparison somewhat less ordered, as a result of which it forms faster [ 20 ] [ 21 ] and has a lower melting point of 170 to 200 °C.
Superabsorbent polymer: Polymer that can absorb and retain extremely large amounts of a liquid relative to its own mass. [5] Notes: The liquid absorbed can be water or an organic liquid. The swelling ratio of a superabsorbent polymer can reach the order of 1000:1. Superabsorbent polymers for water are frequently polyelectrolytes.
For example, the melting point of silicon at ambient pressure (0.1 MPa) is 1415 °C, but at pressures in excess of 10 GPa it decreases to 1000 °C. [13] Melting points are often used to characterize organic and inorganic compounds and to ascertain their purity. The melting point of a pure substance is always higher and has a smaller range than ...
[3] [4] Furthermore, other molecules in the polymer solution, such as salts or proteins, can alter the cloud point temperature. [ 5 ] [ 6 ] Since PNIPA expels its liquid contents at a temperature near that of the human body , PNIPA copolymers have been investigated by many researchers for possible applications in tissue engineering [ 7 ] [ 8 ...