A hygroscopic substance is one that readily attracts water from its surroundings, through either absorption or adsorption.
Examples include honey, glycerin, ethanol, methanol, concentrated sulfuric acid, and concentrated sodium hydroxide (lye).
Calcium chloride is so hygroscopic that it eventually dissolves in the water it absorbs: this property is called deliquescence.
Materials and compounds exhibit different hygroscopic properties, and this difference can lead to detrimental effects, such as stress concentration in composite materials.
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