Interactions between cationic polyacryl amide and TMP

The interactions between peroxide-bleached thermomechanical pulp (TMP), dissolved and colloidal substances (DCS) released from the pulp and cationic polyactylamides (C-PAM) with different molar masses and charge densities were examined. The molar mass of the C-PAM varied between 6 and 12x10(6) g/mol, the charge density between 1.2 and 4.4 meq/g. The dissolved and colloidal substances were separated from the TMP fibers, the fibers were washed and added to the DO-water together with different amounts of C-PAM. The samples were prepared in a Dynamic Drainage Jar (DDJ) and stirred at 750 rpm for 10 minutes. The nitrogen amounts in the fiber cakes were analyzed in order to examine the adsorption of C-PAM on the fibers. Turbidity and zetapotential was measured and the extractive and carbohydrate amounts analyzed in the water samples. The results showed that the adsorption was increased with increasing amount of C-PAM. When the charge density of the C-PAM was held constant the adsorbed amount increased as the added C-PAM amount was increased. There could not be seen differencies in the adsorption behavior between the different polymers. The dissolved and colloidal substances did not significantly deteriorate the function of the polyacrylamides. The white water was stable only at low C-PAM amounts. C-PAM was adsorbed onto the fibers and a part of the extractives was flocculated with C-PAM. The amount of the extractives was considerably reduced after the C-PAM addition, especially the amount of steryl esters and triglycerides was decreased.