Distribution of chemical components in the walls of kraft and bisulphite pulp fibres

Fines removed from the surfaces of Pinus radiata fibres by beating were identified and characterised in terms of microfibril orientations in the surfaces of beaten fibres. Fines fractions subjected to chemical analyses were selected so that chemical component data could be related to specific layers or lamellae in fibre walls. Carbohydrate distributions within the walls of kraft fibres differed from those in bisulphite fibres. In the kraft fibres, glucomannan increased and other hemicelluloses decreased from the primary wall to the outer lamellae of the S2 layer of the secondary wall. In the bisulphite fibres, hemicelluloses were uniformly distributed throughout the outer wall layers, i. e., the primary wall and the S1 and outer lamellae of the S2 layers of the secondary wall. More galactan but less arabinan, xylan, and glucomannan were found in the outer layers than in the inner layers of the bisulphite fibres. Carbohydrate distributions were determined for a range of bisulphite pulp yields (53 to 80 percent). The outer layers of the bisulphite fibres contained more Klason lignin than the inner layers. Acid-soluble lignin contents were similar in the inner and outer layers.