Impact of Cellulase Enzymes on the Physical Characteristics of Softwood Kraft Fiber, 2009 TAPPI Engineering, Pulping, Environmental Conference

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The number of cellulase applications for fiber modification has grown rapidly over the past two years in part due to the increased availability of cellulase enzymes and also due to advancements in the understanding of industrial enzyme applications. The exact mechanisms by which enzymatic pulp fibrillation occurs are not well understood at this time. Additionally, it is not clear how different types of cellulase enzymes impact pulp fibers. The action of three different cellulase preparations was studied on a fully bleached Southern Pine pulp. Significant differences were seen both visually and in handsheet strength properties for the different cellulase preparations. The naturally occurring mixed cellulase treatment promoted the development of small fibrils while treatment with a monocomponent endoglucanase led to more fiber wall peeling and fiber collapse. Fiber strength, as measured by wet zero span tensile, decreased as the degree of fiber wall peeling and fiber collapse increased. Scanning electron micrographs of the fibers supported the changes observed in handsheet internal bond strength and fiber strength. The selection of the specific cellulase activities to employ for a given fiber modification application will be critical to the future commercial success of enzymatic fiber modification programs.