Rheology and Extrusion of Low-Grade Paper and Sludge, 1999 Environmental Conference Proceedings

C. Tim Scott

USDA, Forest Service

Stefan Zauscher & Daniel J. Klingenberg

University of Wisconsin

This paper discusses efforts to characterize the rheological properties of pulps that include low-grade wastepapers and papermill sludges to determine their potential for extrusion and conversion into useful products. We investigated apparent changes in viscosity associated with the addition of typical inorganic paper fillers (calcium carbonate, kaolin clay, and titanium dioxide) to “clean” pulps. Addition of calcium carbonate significantly increased apparent pulp viscosity, but clay and titanium dioxide had minimal effects. When high molecular weight sodium carboxymethyl cellulose (CMC) was added to the pulps, fillers had a minimal effect on viscosity. We determined that a non-cleaned recycled magazine pulp (OMG) makes a suitable model sludge for extrusion purposes. Various levels of OMG were added to a variety of clean pulps and the pulps were extruded. As the ratio of OMG in the feed composition increased, the extrusion conditions (screw torque and die pressure) were reduced significantly, as were tensile properties.