Studies on the Physicochemical Properties of Aluminum Soaps. III
Composition of Aluminum Stearate and Structural Viscosity of Benzene Solution
1963 Volume 83 Issue 12 Pages 1137-1140
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1963 Volume 83 Issue 12 Pages 1137-1140
Aluminum stearates of various compositions were prepared and the structural viscosity of their benzene solutions was measured. Structural viscosity increased with the increase of St/Al ratio when the ratio was smaller than 2 and decreased when the ratio was greater than 2. Intrinsic viscosity [ηN], calculated from ηr(1/Q→0), had a maximum at the St/Al ratio a little smaller than 2 and then decreased abruptly with the decrease of St/Al ratio, and was nearly equal to zero when St/Al was smaller than 1.8. In the range of 2-2.4 of St/Al, ratio [ηN] was nearly constant and decreased abruptly to zero with the approach of St/Al ratio to 2.5.
It has become clear that [ηN] did not depend on the lot of Al-St nor on the method of the extraction of free acid, but only on the composition of aluminum stearate. The value of k, calculated according to Staudinger's equation, (ln ηr)/c=[η]-k[η]2c(at 1/Q→O), remained nearly constant in the range of 1.9-2.5 of St/Al, and was highly different from that in other ranges. It has, therefore, been considered that the soaps whose St/Al ratio is 1.9-2.5 are different from the soaps of the other compositions in the degree of polymerization or in the structure of polymer.
