|Willett, Julious - J L|
Submitted to: TAPPI Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2000
Publication Date: N/A
Citation: Interpretive Summary: The pulp and paper industry needs new processes to convert low-quality recovered paper and paper sludges into useful, value-added products. However, these materials are not easy to process. We can overcome these processing obstacles by adding small amounts of water-soluble polymers, such as carboxymethyl cellulose (CMC), a common food additive. After addition of CMC, paper suspensions flow easily and can be extruded into various shapes and forms. This technology allows processing of low-grade wastepaper and sludges into useful products with properties similar to fiberboard. These results are of interest to scientists and engineers studying processing of fiber suspensions and to the paper industry.
Technical Abstract: Extrusion processing offers a method to convert recycled paper pulps and sludges into useful products. To process ultra-high consistencies (greater than 20%), two problems must be surmounted. First, fiber suspensions must be made to flow homogeneously. Second, fiber flocs must be dispersed. At pulp consistencies of 2% to 15%, conventional paper and board manufacture is generally not possible because drainage is too slow. At consistencies above about 15%, processing is impeded by severe flocculation and nonhomogeneous flow. At ultrahigh consistencies above 20%, suspension drainage becomes impractical, and another forming method must be used. When small amounts of water soluble polymers are added to fiber suspensions, consistencies as high as 45% can be extruded homogeneously. Suspension rheology can be controlled through polymer addition. Pulp type, filler content, polymer concentration, and consistency affect product mechanical properties. Strength and modulus increase with fiber length, increasing polymer concentration, decreasing filler content, and decreasing consistency.