Abigail Lee

Date of Defense

Spring 4-18-2006

First Advisor

John Cameron, Paper Engineering, Chemical Engineering, and Imaging

Second Advisor

Peter Parker, Paper Engineering, Chemical Engineering, and Imaging

Abstract

Refining of fibers is useful in the papermaking process to achieve optimal end properties of the desired product. Laboratory refining is essential in predicting the effectiveness of refining on various furnishes. However, due to varying mechanical actions found with refining, results from laboratory methods may not always mimic results of commercial refiners. Though laboratory refining methods offer suggestions concerning the suitability of the pulp for paper production, it is necessary to explore the relationship between commercial and laboratory refining. Northern softwood pulp was refined in a commercial disc refiner as well as three different laboratory refining devices. In the commercial refiner, the pulp was refined at 1000 and 750 RPMs with varied levels of refining from 0 to 60 horsepower. The Valley Beater was used to refine pulp from 30 to 77 minutes. The PFI Mill was used to refine pulp from 1000 to 3000 revolutions. The Mead Refiner was used to refine pulp from 45 to 105 seconds. Freeness as checked at each refining level before making testing physical properties of resulting handsheets. By comparison of the laboratory equipment to the commercial refiner, the laboratory refiners reduced the freeness of the pulp to a greater extent, while the disc refiner produced a higher percentage of fines. Though more fines theoretically improve bonding surface area for heightened strength properties, the laboratory refining equipment was able to produce greater tensile strength values with a smaller reduction in tear resistance than refining in the commercial refiner. Laboratory equipment produces a gentler, more deliberate process of internal and external fibrillation. Commercial refiners, in contrast, direct harsher action against the fibers which increases fiber cutting and improves strength properties to a lesser degree.

Access Setting

Honors Thesis-Campus Only

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