Page 130 - Handbook of Properties of Textile and Technical Fibres

110 Handbook of Properties of Textile and Technical Fibres

carried out by Leeder et al. (1985) on wool. Rivett et al. (1988) indicate that the amount
and influence of this surface lipid is different for other animal fibers.
Animal fibers can be considered as an assembly of cuticle and cortical cells held
together by a “cell membrane complex” (CMC) (see Fig. 3.5 in Chapter 3 on wool).
The CMC constitutes only a few percent of the weight of the fiber, but is of great
importance since it controls or influences most fiber properties. Mechanical properties
such as abrasion resistance or wear life are dependent on the CMC and, because the
CMC constitutes the only continuous phase in the fiber, the diffusion of dyestuffs
and other chemical processing reagents into and through the fiber also occurs via
the CMC (Leeder et al., 1990). The epicuticle is considered to be a component of
the CMC (Leeder, 1986).
Logan et al. (1989) analyzed lipids of wool, mohair, alpaca, llama, and rabbit hair.
The extractable matter in alpaca was more than twice as high as any other animal fiber.
Tucker et al. (1990b) examined the internal lipids amounting to about 0.1%e0.2% of
the mass of the cashmere. The lipid composition of cashmere was different to wool and
the lipid composition of fiber from cross-bred goats was different to fiber from feral
goats.

4.2.2 Physical properties

All animal fibers have a similar physical or morphological composite structure. The
main physical differences occur in the shape and arrangement of the outer cuticle scale
cells and the existence of a central core (medulla) in many rare animal fibers. Both the
length of cuticle scales and the height of the edge of the cuticle scales are important
(Fig. 4.1). Medullation is also an important economic and performance feature of
mohair, cashmere, alpaca, angora, and yak.

Figure 4.1 Surface features of the cuticle scales of a cashmere fiber (McGregor, unpublished).