Fagus sylvatica

Aspen

Populus tremulus

Eucalypt

E. globulus

Birch

Betula pendula

Spruce

Picea abies

Carbohydrates 72.8 75.2 71.8 73.6 70.0

Glucose 42.6 49.9 48.1 39.7 45.7

Xylose 19.5 15.9 14.5 22.1 6.6

Arabinose 0.7 0.1 0.5 0.5 1.0

Galactose 0.8 0.4 1.5 1.0 1.6

Mannose 1.1 2.6 0.5 1.3 12.0

Rhamnose 0.5 0.1 0.5 0.3

Acetyl 4.5 3.7 3.4 5.1 1.4

Uronic acid 3.1 2.5 2.7 3.5 1.8

Lignin 24.5 22.0 26.2 23.3 27.2

Klason 21.0 18.9 20.6 19.7 27.0

Acid–soluble 3.5 3.1 5.6 3.6 0.2

Extractives 1.8 1.0 0.2 1.9 1.0

DCM 0.2 1.0 0.2 1.9 1.0

Et-OH 1.6 n.a. n.a. n.a.

Ash 0.4 0.3 0.3 0.3 0.2

Total 99.5 98.5 98.5 99.0 98.5

n.a. = not applicable.

The main target parameter for dissolving pulp production is the average molecular

weight of the polysaccharide fraction, expressed as the CED-intrinsic viscosity;

this was adjusted solely by the H-factor. All other parameters were kept constant.

The relationships between viscosity and H-factor indicate the depolymerization

behavior of the investigated wood species, which is an important criterion in

case of blending of wood chips. The data in Fig. 4.171 show that beech, aspen and

birch show virtually the same degradation characteristics, whereas (surprisingly)

eucalyptus is ahead and spruce behind their course of viscosity degradation. The

higher resistance towards cellulose degradation of spruce can be explained by its

higher lignin content.

4.3 Sulfite Chemical Pulping 451

Tab. 4.62 Important cooking parameters applied in the course of

one-stage acid sulfite cooking of beech, aspen, eucalyptus, birch

and spruce (according to [14]).

Wood

Species

RSO2

[mol L–1]