Conservation Science

Textiles 61

(2%). Cellulose itself is a polymer built from glucose, although the repeat unit
is generally taken as the dimer, cellobiose (1,4--D-glucopyranosyl-D-glucose;
see Figure 3).
For undegraded cellulose in linen, the degree of polymerisation is typically of
the order of 10,000–20,000. The straight chain nature of the polymer allows
ready interaction between adjacent chains, and strong intermolecular attraction
is possible, resulting from hydrogen bonding involving the hydroxyl groups
(Figure 4a). This intermolecular association leads to a high degree of crys-
tallinity (typically 70% for linen), which results in the suitability of cellulose as
a structural material in plants, and also conveys a high degree of chemical resis-
tivity (Figure 4b).
The fibres possess a complex hierarchical microstructure, in which regions
of well-ordered crystalline cellulose are interspersed with areas of random

O

O

O

O

O

O

O

OH O

OH

OH

OH

HO

HO

HO

HO

OH OH

OH OH

1

3 2

(^465)
Figure 3Space-filling and structure diagrams of a short section of a cellulose chain. The
repeat unit, cellobiose (1,4--D-glucopyranosyl-D-glucose) is indicated
O
O O
O O
O O
O O
O
O
O
O
O O O O
O O O O
H
H
H
H
H
H H
H
O
O O
O O
O O
O O
O
O
O
O
O O O O
O O O O
H
H
H
H
H
H H
H H
H H
H
H
H H
H
H
H
O
O
O O H
H H
H
H
O
O
O
O O
O
H
H
H
H
H
H

• Intramolecular
  Hydrogen Bond


• Intermolecular
  Hydrogen Bond

Figure 4aHydrogen bonding between cellulose chains