Search results
Results from the WOW.Com Content Network
For example, pharmaceuticals that pick up more than 5% by mass, between 40 and 90% relative humidity at 25 °C, are described as hygroscopic, while materials that pick up less than 1%, under the same conditions are regarded as non-hygroscopic. [32] The amount of moisture held by hygroscopic materials is usually proportional to the relative ...
A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccants for specialized purposes may be in forms other than solid, and may work through other principles, such ...
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
A humectant / h juː ˈ m ɛ k t ən t / is a hygroscopic (water-absorbing) substance used to keep things moist. They are used in many products, including food, cosmetics, medicines and pesticides. When used as a food additive, a humectant has the effect of keeping moisture in the food. [1]
An example of these amphiphilic molecules is the lipids that comprise the cell membrane. Another example is soap , which has a hydrophilic head and a hydrophobic tail, allowing it to dissolve in both water and oil.
The packaging material should conduct heat well; and it should be durable enough to withstand frequent changes in the storage material's volume as phase changes occur. It should also restrict the passage of water through the walls, so the materials will not dry out (or water-out, if the material is hygroscopic).
A material property is an intensive property of a material, i.e., a physical property or chemical property that does not depend on the amount of the material. These quantitative properties may be used as a metric by which the benefits of one material versus another can be compared, thereby aiding in materials selection.
Caking mechanisms depend on the nature of the material. Caking is a consequence of chemical reactions of grain surfaces. Often these reactions involve adsorption of water vapor or other gases. Crystalline solids often cake by formation of liquid bridge between microcrystals and subsequent fusion of a solid bridge.