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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 ...
In vulcanization, sulfur is the cross-linking agent. Its introduction changes rubber to a more rigid, durable material associated with car and bike tires. This process is often called sulfur curing. In most cases, cross-linking is irreversible, and the resulting thermosetting material will degrade or burn if heated, without melting.
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 ...
A mixture of acrylic acid, water, cross-linking agents and UV initiator chemicals are blended and placed either on a moving belt or in large tubs. The liquid mixture then goes into a "reactor" which is a long chamber with a series of strong UV lights. The UV radiation drives the polymerization and cross-linking reactions.
Exothermic refers to a transformation in which a closed system releases energy (heat) to the surroundings, expressed by > When the transformation occurs at constant pressure and without exchange of electrical energy, heat Q is equal to the enthalpy change, i.e.
In general, the polymerization is an exothermic process, i.e. negative enthalpy change, since addition of a monomer to the growing polymer chain involves the conversion of π bonds into σ bonds, or a ring–opening reaction that releases the ring tension in a cyclic monomer.
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 physical geography, a dell is a grassy hollow—or dried stream bed—often partially covered in trees. [1] [2] In literature, dells have pastoral connotations, frequently imagined as secluded and pleasant safe havens. The word "dell" comes from the Old English word dell, which is related to the Old English word dæl, modern 'dale'.