The suitability of dissolving pulps can be adequately determined only by simulating

The conversion processes to the final products (e.g., to regenerated fibers or

Cellulose derivatives) on a small scale. Sometimes, even pilot plant or mill-scale

Tests are needed to approve the dissolving pulp for further processing. This is particularly

True in the case of new applications such as the Lyocell process. Since the

Early days of cellulose research, much effort has been undertaken to develop analytical

Methods that provide rapid and reliable assessment of the quality of dissolving

pulp. There are many established methods for evaluating pulp quality [1–3],

but they are insufficient to provide a full picture of the dissolving pulps′ properties.

The relationships between structure, chemical composition and behavior

With regard to topochemical reactions are too complex. The difficulty of reliable

Cellulose characterization has been expressed appropriately by L.E. Wise, an

Important pioneer of cellulose chemistry and technology, by the statement that

“Cellulose is a system, not a pure individual” [1].

Dissolving Grade Pulp

The processability of a dissolving pulp is often characterized as its reactivity

Towards derivatizing chemicals or solvents. Reactivity is related to the accessibility

Of chemicals to the cellulose, which virtually means the relative ease by which the

Hydroxyl groups can be reached by the reactants. The structure and morphology

Of cellulose is responsible for the homogeneity of the conversion process and the

Final product quality. A reliable analysis of the property profile of dissolving pulps

Involves the extensive characterization of the cellulose structure at three different

levels: (a) the molecular level of the single macromolecule; (b) the supramolecular

Level of aggregation of macromolecules to highly ordered structural entities; and

(c) the morphological level comprising the architecture of well-organized fibrillar

elements [4]. Moreover, the pore system providing access to the molecular structure

Is an important characteristic of dissolving pulps. Finally, the qualitative and

Quantitative determination of organic and inorganic impurities completes the analytical

Characterization of a dissolving pulp.

The quality profile of dissolving pulps is comparatively evaluated in the following

Sections of this chapter, according to the following scheme (see Tab. 11.4).

Tab. 11.4 Characterization scheme of dissolving pulps.

Pulp Origin, Pulp Consumers

Chemical properties (molecular level)

Дата добавления: 2015-10-21