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Research article - Peer-reviewed, 2004

Micro-morphological observations on spruce TMP fibre fractions with emphasis on fibre cell wall fibrillation and splitting

Fernando D, Daniel G


A detailed electron microscope study was performed on thermomechanical spruce fibre BauerMcNett pulp fractions to obtain a greater insight into the origin and development of splits and fibrillation within the fibre wall during primary refining. Two major types of fibre fibrillation occurred: "flake-like" derived from the S1 layer and "sheet and thin ribbon" fibrillation from the S2 cell wall layer for both early- and latewood fibres. Fibrillation developed from the initial cracking and subsequent splitting of the individual fibre cell wall layers along the orientation of the native cellulose microfibrils. Flake-like fibrillation was derived from the perpendicular fragmentation of shorter pieces from the S1 layer. S2 fibrillation was derived from helical cracking of the cell wall layer following the microfibril angle. The outer fibre S2 wall split into regular sized concentrically oriented lamellar-sheets and/or thin ribbons; each ribbon composed of a set number of sub-aggregates. Fibre cell wall splitting developed between the aggregates rather than across them. Additional sites for the initiation of splits included bordered- and cross-field simple pits. Severe splitting of the fibre wall from the pits in earlywood fibres resulted in fibre "opening" and collapse. In addition to providing details on the effects of refining on fibre wall structure, novel information was obtained on fibre cell wall architecture. Results suggest that fibre fibrillation during industrial thermomechanical pulp refining is regulated by the native fibre micro- and nanostructure. A better understanding of fibre structure and the energy needed for individual fibre splitting and delamination should provide important clues for a more effective energy saving process during thermomechanical pulping

Published in

Nordic Pulp and Paper Research Journal
2004, volume: 19, number: 3, pages: 278-285

Authors' information

Swedish University of Agricultural Sciences, Forest economy
Swedish University of Agricultural Sciences, Department of Forest Products

UKÄ Subject classification

Forest Science

URI (permanent link to this page)