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IUPAC definition for a crosslink in polymer chemistry In chemistry and biology , a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural polymers (such as proteins ).
The cross-linking of polymer molecules that occurs in the curing process is exothermic, resulting in a negative peak in the DSC curve that usually appears soon after the glass transition. [15] [16] [17] In the pharmaceutical industry it is necessary to have well-characterized drug compounds in order to define processing parameters. For instance ...
Unlike other crosslinking agents, aldehyde-induced crosslinking is an intrinsically reversible process. NMR structure of these types of agents as interstrand crosslinks show that a 5'-GC adduct results in minor distortion to DNA, however a 5'-CG adduct destabilizes the helix and induces a bend and twist in the DNA.
Curing is a chemical process employed in polymer chemistry and process engineering that produces the toughening or hardening of a polymer material by cross-linking of polymer chains. [1] Even if it is strongly associated with the production of thermosetting polymers , the term "curing" can be used for all the processes where a solid product is ...
Cross-linking may refer to Cross-link, a chemical bond of one polymer chain to another; Corneal collagen cross-linking, a parasurgical treatment for corneal ectasia ...
In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change ΔH⚬ is negative." [ 1 ] [ 2 ] Exothermic reactions usually release heat . The term is often confused with exergonic reaction , which IUPAC defines as "... a reaction for which the overall standard Gibbs energy change Δ G ⚬ is negative."
Therefore, by definition, the transition state for tertiary reactions will be at a lower energy than for secondary reactions. However, the BEP principle cannot justify why the energy is lower. Using Hammond's postulate, the lower energy of the tertiary transition state means that its structure is relatively closer to its reactants R(tertiary)-X ...
Dissolution by most gases is exothermic. That is, when a gas dissolves in a liquid solvent, energy is released as heat, warming both the system (i.e. the solution) and the surroundings. The temperature of the solution eventually decreases to match that of the surroundings.