Determination of surface area and particle size of synthetic latex by adsorption. III. Latices of high initial soap content

Abstract

The soap titration method for determination of particle size and specific surface area of synthetic latices can be applied only to latices the initial soap content of which is less than that required to yield the critical micelle concentration of soap in solution. To handle latices the soap contents of which exceed the cmc, a procedure has been developed involving the titration of the latex with another the surface of which is still unsaturated by soap. The latter latex is used to take up the excess soap and to yield both latices in equilibrium with the cmc of the soap. The end point of the titration can be determined, as before, by conductance. The end points are sharp, and the requisite data obtained permit a ready calculation of the latex particle size for both fatty and rosin soap latices. Further, the results obtained are in excellent agreement with those obtained by soap titration.