Original scientific paper

Viscosimetric Determination of Latex Coagulation

I. Jalšenjak ; Department of Pharmaceutical Technology, Faculty . of Pharmacy and Biochemistry, University of Zagreb
I. Štivić ; Department of Pharmaceutical Technology, Faculty . of Pharmacy and Biochemistry, University of Zagreb
J . J. Petres ; Institute of Immunology, 41000 Zagreb, Croatia, Yugoslavia

Abstract

The viscosity of latices was investigated in dependence upon
the pH value of suspensions, their aging and the concentration of
added electrolyte. The systems used were well-defined monodisperse
polystyrene latices within the concentration range from 0.1 to 10/o,
and with a high negative charge oh the latex particle surface. It
was found that viscosity measurement in a dispersion at a certain
concentration of the dispersed phase could be used for latex coagulation
determination. On the basis of this finding an attempt was
made to determine the critical coagulation concentration. The values
obtained were concordant with those determined by t4rbidity
measurements. In order to determine the exact pH region in which
a decrease in the pH value leads to a sudden change of stability,
viscosity measurements were performed in relation to the pH value
of latex suspensions. The limiting pH value was independent of the
time of measuring, latex concentration, and the ionic strength of
the added electrolyte. In our opinion this value is characteristic of
a given system and it points to the dependence of the destabilization
of a dispersion on the pH value. Therefore, it can be called »critical
pH value« by analogy to the term »critical coagulation concen
tra ti on«.

Keywords

Hrčak ID:

195958

URI

https://hrcak.srce.hr/195958

Publication date:

26.9.1978.

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