A method commonly used to measure surface charge is the quantification of the polyelec-trolyte adsorption capacity of the fibers.A linear cationic polyelectrolyte with high charge density and high molecular mass,pDMDAAC(poly-dimethyldiallylammonium chloride),is used under the assumption that it does not penetrate the micropores of the celt wall.Pulp samples are added to solutions of different concentrations of pDMDAAC to build the adsorption isotherm.After equilibrium is reached,the concentration of polymer in the solution is determined by polyelectrolyte titration.A simple equation is proposed for use in measuring the surface charge.This equation allows the isotherms to be analyzed with a uniform criterion.
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