Surface Modification of Cellulose Acetate with Cutinase and ...

Subchapter 3.1
Wool is a complex natural fibre being mainly composed of proteins (97%) and lipids
(1%). 82% of total protein content of wool is keratinous proteins, which are
characterized by a high concentration of cystine. Approximately 17% of wool is
composed of proteins which have been termed non keratinous, because of their
relatively low cystine content (Feughelman, 1997 Rippon, 1992).
Figure 1. Cross-section diagram of a merino wool fibre showing the structure at
progressive magnification (Feughelman, 1997).
Wool fibres have approximately the form of elliptical cylinders, with average diameters
ranging from 15 μm to 50 μm and lengths depending of the rate of growth and the
shearing regimes, as previous mentioned (Makinson, 1979). The wool fibre consists of
two major morphological parts: cuticle and cortex. The cuticle (also referred as scale
layer of wool) is composed of laminar and rectangular structures which form a sheath of
overlapping scales enveloping the cortex (Speakman, 1985; Naik and Speakman, 1993).
It is normally one cell thick and usually constitutes about 10% by weight of the total
fiber. The cuticle is subdivided into three layers: exocuticle (which is subdivided into
two main layers, A and B that differ mainly in the cystine content), endocuticle, and an
outermost membrane called the epicuticle (Figure 2).
164