Date of Award
Bachelor of Science
Pulp and Paper Technology
Stock of 50:50 bleached Kraft softwood and hardwood run through the Valley beater at 350 CSF with high fines content (25-30% fines from softwood and hardwood fractions run through a Wiley mill) was prepared and tested for fines fractionation, fines retention, and system surface charge at 10, 25, 40, and 55°C using a Dow Chemical cationic polymer of 1,000,000 molecular weight: SEPARAN CP-7. The Britt Dynamic Drainage Jar was used for fines fractionation and retention data and Halabisky's Colloid Titration Technique for surface charge data. Cationic polymer loadings were taken at 0.25, 0.50, and 0.75 pounds of polymer per ton of paper produced (pulp present). Rotor or agitation speed for retention determinations was held constant at 1000 rpm. Surface charge reagents were not diluted (5X) as suggested by Halabisky.
Fines fractionation decreased on rising temperature to show increased fines to fiber attraction. An increase in SEPARAN CP-7 loading increased fines retention though instabilities existed below room temperature. The optimum retention temperature was around 40°C then fell off from there while there was no point of diminishing returns on retention with loading. Because of strong polymer-temperature interactions, may unexpected charge decreases and charge inversions appeared upon cationic loading increases through data error was very high. Extensive temperature range; pH; polymer molecular weight, combination, and charge nature; stock alteration; filler; and agitation effects were suggested as important parameters to research in terms of temperature effects of fine and filler retention and surface charge.
McRae, Danny R., "Temperature Dependence of the Retention of Organic Fines Using a Cationic Retention Aid" (1977). Paper Engineering Senior Theses. 339.