Crystal forms of anhydrous calcium stearate derivable from calcium stearate monohydrate

doi:10.1016/0095-8522(49)90037-9

Journal of Colloid Science

Volume 4, Issue 2, April 1949, Pages 93-101

Journal of Colloid S...

https://doi.org/10.1016/0095-8522(49)90037-9 Get rights and content

Abstract

Anhydrous calcium stearate can be obtained at room temperature in any one of three forms, or mixtures thereof, by dehydration of calcium stearate monohydrate. Calcium stearate VIA is believed to be the stable modification. Calcium stearate VIH is an anhydrous crystalline powder having the same X-ray diffraction pattern as calcium stearate monohydrate. Calcium stearate VIN is relatively amorphous with respect to interchain spacings although it exhibits a crystalline long spacing.

Samples of calcium stearate hydrate which yield calcium stearate VIH upon dehydration lack a second order thermal transition at 48°C. characteristic of calcium stearate hydrate samples which yield calcium stearate VIA upon dehydration. Evidence is presented supporting the interpretation that transformation of the hydrate type structure to the anhydrous type is inhibited by impurities in the calcium stearate, particularly adsorbed calcium salts and foreign fatty acid anions.

References (5)

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There are more references available in the full text version of this article.

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Both calcium silicate and silicon dioxide absorbed moisture at RHs lower than the deliquescence points for the individual deliquescent ingredients and binary blends. Calcium stearate (Fig. 3C) absorbed less than 2% of its weight as RH increased up to 90% RH, and this is most likely due to the formation of a monohydrate (theoretical amount is 2.88%) (Vold, Hattiangdi, & Vold, 1949). Calcium stearate is known to form a hydrate with water due to the hydrogen bonding between water and the calcium atoms (Dubinsksaya, Polyakov, Suponitskii, Dement'eva, & Bykov, 2010).
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^☆: This work is part of a project “Phase Studies of Greases” supported by the Office of Naval Research, Contract No. N6-onr-238-TO-2; NR057057.

²: Present address: National Bureau of Standards, Washington, D. C.

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Crystal forms of anhydrous calcium stearate derivable from calcium stearate monohydrate☆

Abstract

J. Colloid Sci.

J. Am. Oil Chemists' Soc.