Hygroscopicity


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Related to Hygroscopicity: polymorphism

Hygroscopicity

 

the ability of materials to absorb moisture from the air.

Hygroscopicity is a property of wettable (hydrophilic) materials of capillary-porous structure (such as wood and grain), in whose fine capillaries moisture condenses; of water-soluble substances such as table salt, sugar, and concentrated sulfuric acid; and especially of chemical compounds that form, with water, crystalline hydrates. The amount of water absorbed by a porous material (hygroscopic wetness, or Whyg) increases as the moisture content of the air increases, reaching a maximum when the relative humidity of the air is 100 percent. For wood, the maximum Whyg is about 30 percent (in terms of weight), whereas for wheat it is about 35 percent. It is important to know the hygroscopicity of a material in order to determine drying and wetting processes. Hygroscopicity is also considered in long-term storage and transportation of materials, especially by sea. Hygroscopicity explains the dampening and even deliquescence of a number of salts when stored in the open air. Some hygroscopic substances, such as concentrated sulfuric acid, are used to dry the air.

References in periodicals archive ?
Analysis of variance showed that the quadratic polynomial models were highly significant (P [less than or equal to] 0.001) for solubility (Y5) and yield (Y6) and less significant for bulk density (Y2), activity water (Y1), hygroscopicity (Y3), and reduced sugar (Y4).
TPV A is fully crosslinked but is known to have problems with hygroscopicity and color.
If there is not a full hydration, the MBs may still contain portions of Portland cement still intact which would not participate in the gain of resistance and, after the contact with water in the tests of absorption, would tend to absorb it in larger amount due to their high natural hygroscopicity.
This suggests that hardness reduction on radial and tangential surfaces caused by increasing the EMC may be a result of the hygroscopicity and expansion of hemicellulose.
This was related to the hygroscopicity of solvent and the increase in inflow rate of water as aforementioned with the prolonged evaporation time.
Applications include the impact of hygroscopicity, water sorption kinetics and water induced morphology changes (such as amorphous content) in pharmaceutical powders, tablets, APIs and excipients.
The hygroscopicity and substantivity of L-Carnitine coupled with the superior humectancy of decaglycerol provides truly multi-functional properties with excellent moisturizing capacity.
Here, the role of the microencapsulation is to avoid hygroscopicity, minimize interactions and eliminate oxidation of these materials.
It does not react with amino acids and has moderate hygroscopicity, high solubility and is an effective bulking agent.
The experimental data of equilibrium water content were fitted to mathematical models frequently used to predict the hygroscopicity of plant products, as shown in Eqs.
To these we add particle hygroscopicity, mass, and composition, which are critical for treating aerosol direct and indirect forcing in climate models and for air quality applications.
Basic properties (i.e., moisture content, bonding strength, and formaldehyde emission), mechanical properties (including modulus of rupture and modulus of elasticity), and hygroscopicity were also investigated.