Chemical hydration

In order for starch molecules to become detached from one another, they must be hydrated, a process accomplished in water slurry by using either thermal or chemical energy. Only then will the molecules be separated and uncoiled enough to be able to latch onto other separate particles and act as an adhesive. The most common form of chemical hydration of starch is through the use of aqueous alkali. Sodium hydroxide is capable of hydrating starch molecules without heat, but a specific minimum concentration must be reached for that to occur (2). 

Salt Melting point Dimensions of unit cell Vol. Meas. density g/cc at 5 °C 0.005 Hydration number (chemical) Hydration number (crystal) Number of formula units per unit cell... 

Hydration of the cement takes place in the presence of moisture at temperatures above 50°F. It is necessary to maintain such a condition in order that the chemical hydration reaction may take place. If drying is too rapid, surface cracking takes place. This would result in reduction of concrete strength due to cracking as well as the failure to attain full chemical hydration. 

From 2,5-dihydrofuran, the most obvious derivative is tetrahydrofuran (THF), formed by the hydrogenation of the C=C bond. The C=C bond is also reactive for hydroformylation and olefin metathesis to add additonal functionality and structure. As stated earlier, the next intermediate, 2,3-dihydrofuran (2,3-DHF) serves as the gateway to CPCA family of chemicals. Hydration of 2,3-DHF produces 2-hydroxytetrahydrofuran, which can be readily converted to gamma-butyrolactone, pyrrolidinone (and N-substituted pyrrolidinones). Finally hydrogenation of hydroxytetrahydrofuran yields 1,4-butanediol in high yields. 

In such cathodic regions on the steel Fe ions react with the oxygen in the air and forms rust which is chemically hydrated iron (III) oxide of variable composition. The reaction may simplified be written as ... 

The mechanism of dry-strength improvement by wet-end starch is based on interfiber bonding. The free glucose hydroxy groups of starch participate in hydrogen bonding with cellulose molecules on fiber surface. This actually results in a kind of "chemical hydration" of the fiber network. Additionally, starch improves retention of fines and fillers as well as contributes to more uniform distribution of bonds between fibers. In other words, in addition to strength boost, the wet-end starch improves the sheet formation. 

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