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Dinesh Fernando, Peter Rosenberg, Erik Persson, Geoffrey Daniel
Ultrastructural aspects of fibre development during the stone groundwood process: New insights into derived pulp properties
Keywords: Delamination, fibre development, fibrillation, juvenile wood, mature wood, microfibril angle (MFA), S1 layer, S2 layer, scanning electron microscopy (SEM), stone groundwood (SGW), ultrastructure of the cell wall
A study was performed on stone groundwood (SGW) pulps produced on a pilot scale. The behaviour of selected juvenile and mature Norway spruce wood samples was investigated. As revealed by standard tests, sheets formed from juvenile wood showed improved light scattering properties, improved tear and tensile strength, and higher sheet density compared to those formed from mature wood. Scanning electron microscopy indicated that the differences are likely related to the manner of fibre processing and development at the ultrastructural level. Mature wood fibres showed greater fibre end breakage, a smaller long-fibre fraction, enhanced S1 fibrillation and frequently open fibres. In contrast, juvenile fibres had a 14% higher long-fibre fraction and showed typical S2 fibrillation. Fibre development of juvenile wood showed fibrillation features similar to those previously reported for thermomechanical pulp fibres. In both cases, the structural hierarchy of the wood fibre cell wall and the microfibril angle of S2 and S1 layers govern cell-wall splitting and fibrillation progression. The superior quality of the fibre furnish prepared from juvenile fibres compared to mature fibres with SGW pulping may offer an alternative process for more effective utilisation of raw materials such as top logs rich in juvenile wood.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 61, 08/2007
Pages: 532 - 538