Chitosan as cationic polyelectrolyte in wet-end papermaking systems

This paper provides the experimental results evidencing the potential of chitosan utilisation as a wet-end additive in papermaking. The research analyzes the colloidal behaviour of chitosan, investigated in terms of its interactions with the anionic polymers (carboxymethylcellulose - CMC, and anionic Polyacrylamide PAA), as well as with the colloidal and dissolved material (CDM) of papermaking process water. The shape of colloidal titration curves and particle size distribution of process water, measured by laser diffraction, have indicated that chitosan has a higher ability to form polyelectrolyte complexes (PEC), comparatively with other cationic additives frequently used in wet-end systems, such as PDADMAC and polyethylenimine (PEI). Lab tests simulating short circuit of paper machine have shown that chitosan and PDADMAC have similar effectiveness in reducing the accumulation rate of CDM, even if the effects on paper stock drainage and paper strength are much higher in the case of chitosan.