Dissolved and colloidal substances from mechanical pulp suspensions — stability and flocculation behaviour

摘要

The stability of the colloidal material present in unbleached thermomechanical pulp suspensions was investigated. Flocculation was induced with linear cationic polyacrylamides having different charge densities but equal molecular weights. The results indicate that the formation of polyelectrolyte complexes plays an important role in the destabilization of the colloidal particles in the suspension. The properties of the polyelectrolyte complexes formed between dissolved wood polymers and added cationic polyelectrolytes were observed to be dependent on the charge density of the cationic polyelectrolyte. Very large non-stoichiometric polyelectrolyte complexes seemed to be formed. Complex formation on the particle surfaces was found to be of importance for the flocculation and stability behaviour of the colloidal particles.