Tab. 11.1 Continued.

Parameter Pine Spruce Eucalyptus Beech Spruce Spruce Beech

Kraft Kraft Sulfite Sulfite

ECF TCF ECF ECF TCF ECF TCF

Hexenuronic acid (HexA) lmol g–1 1.1 1.5 1.4 1.1 0.7 0.7 0.6

Organochloric compounds ppm 130 33 203 n.d. <6 61 <6

Functional groups

Copper number % 0.3 0.2 0.8 0.5 1.0 1.3 1.4

Carbonyl groups (CCOA) lmol g–1 15 9 12 57 37

Carboxyl groups lmol g–1 37 46 84 131 54 40 70

Inorganic Compounds

Total ash % 0.33 0.19 0.19 0.34 0.30 0.20 0.23

Ca ppm 199 130 175 1208 655 453 916

Mg ppm 404 195 70 319 550 130 237

Si ppm 293 50 59 73 115 63 10

Fe ppm 49 11 6 16 25 4 2

Mn ppm 1.7 2.0 2.3 2.7 4.1 < 0.2 0.4

Water retention value (WRV) % 83.7 80.6 78.3 92.8 76.2 81.2 84.3

Zero-Span tensile index

dry Nm g–1 130.8 133.7 147.1 n.d. 113.1 103.6 98.8

rewetted Nm g–1 116.2 109.4 n.d. n.d. 96.5 82.9 84.4

The residual lignin content of all ECF- and the TCF-bleached softwood kraft

Pulps is far below 1, indicating a low tendency of light-induced yellowing. The

Two TCF-bleached sulfite pulps reveal slightly elevated kappa numbers, which

May be attributed to the applied bleaching concept, namely sequential alkaline

Oxidative bleachings step comprising oxygen delignification and hydrogen peroxide

Bleaching.

There are also some noticeable differences in pulp viscosity ranging from low

Level in the case of TCF-bleached softwood kraft pulp to generally high levels in

The case of the TCF-bleached sulfite pulps. The high bleaching selectivity of the

Latter is reflected in the high viscosity at a given brightness level.

Paper-Grade Pulp

The extractives content of a fully bleached commercial pulp depends on many

Different parameters, with the wood species, pulping, and bleaching processes

Being the most important influencing factors. The data in Tab. 11.1 confirm the

Predominant influence of the cooking process on the extractives content when

Comparing sulfite and kraft pulps based on spruce wood. The bleaching sequence,

However, seems not to exhibit a major influence on the extractives content. TCFand

ECF-bleached spruce sulfite pulps reveal similar resin contents. A further significant

Decrease in the extractives content due to bleaching operations may only

Be expected when high dosages of, for example, ozone, or other bleaching chemicals

Of high oxidation potential are applied.

The alkali resistance determined at 18% (R18) and 10% (R10) NaOH concentration

At room temperature is a measure of estimating the cellulose content (total

For R18 and long-chain cellulose for R10), and is usually used to characterize the

Degree of purity of dissolving pulps (see Tab. 11.7, Dissolving pulp characterization).

Although not very common in paper pulp analysis, the R-values provide

Insight into many aspects of pulp origin and properties, including the type of

Pulp, wood species (at least allowing a distinction to be made between hardwood

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