Stearic acid

The stearic acid (of the Greek “ stear ”, which means Graisse tallow -->) or acid octadécanoïque (name IUPAC) is a Fatty-acid with long chain, which one symbolizes by the 18:0 numbers to indicate that it has 18 carbon atoms and any Covalent bond double: it is a saturated fatty-acid. With room temperature, it forms a white solid. Its melting point is D `approximately 70 °C. The stearic acid is abundant in all animal greases in the shape of the ester tristéarate of glycerin (Stéarine) C₅₇H₁₁₀O₆ (especially at the Ruminant S) or vegetable. It is industrially used to make Huile S, Bougie S and Savon S.

Its developed semi chemical formula is:

CH₃-₁₆-COOH.

The stearic acids, lauric, myristic and palmitic set up an important group of fatty-acids.

Role in the oil-base paint

The stearic acid is a saturated fatty-acid: it thus does not have non-saturation being able to be oxidized by oxygen in air. Thus, it does not polymerize like the fatty-acids unsaturate. It thus remains in its shape of soft solid to the free air and has room temperature and is used like plasticizer of the polymerized oily binders (with the Palmitic acid ).

Uses

The stearic acid is used like:

Binder or Pigment S for the rubber;
agent of Polymerization of phenylethylene (styrolene or vinylbenzene) and of the Butadiene in order to obtain synthetic rubber;
siccative of varnished;
Candle S in Wax;
soap (the stearic acid and the sodium hydroxide forms a Savon: the Stearate of sodium).

See too

Stearin

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