DISSOLVED AND COLLOIDAL SUBSTANCES FROM MECHANICAL PULP SUSPENSIONS -STABILITY AND FLOCCULATION BEHAVIOR

The stability of the colloidal material present in unbleached thermome chanical pulp suspensions was investigated. Flocculation was induced w ith linear cationic polyacrylamides having different charge densities but equal molecular weights. The results indicate that the formation o f polyelectrolyte complexes plays an important role in the destabiliza tion of the colloidal particles in the suspension. The properties of t he polyelectrolyte complexes formed between dissolved wood polymers an d added cationic polyelectrolytes were observed to be dependent on the charge density of the cationic polyelectrolyte. Very large non-stoich iometric polyelectrolyte complexes seemed to be formed. Complex format ion on the particle surfaces was found to be of importance for the flo cculation and stability behaviour of the colloidal particles.