Page 98 - Handbook of Properties of Textile and Technical Fibres

Properties of wool 79

3.0

2.6
Relative modulus 2.2

1.8

1.4

1.0
0 20 40 60 80 100
Relative humidity (%)
Figure 3.19 Variation of the relative modulus of a wool fiber as a function of relative humidity.
Figure adapted from Huson MG: Physical properties of wool fibres in electrolyte solutions, Text
Res J 68:595e605, 1998, data from Feughelman M, Robinson MS: Some mechanical properties
of wool fibres in the “Hookean” region from zero to 100% relative humidity, Text Res J 41:
469e474, 1971 (-), and Feughelman M, Robinson MS: The relationship between some
mechanical properties of single wool fibers and relative humidity, Text Res J 37:441e446, 1967
(,).

When strength is plotted against diameter, an unfailing result for all wools tested
has been the decrease in intrinsic strength for larger diameter fibers (Fig. 3.20)(Huson
and Turner, 2001). This occurs both within sheep and also across sheep when sheep
averages are considered. It is a result that is consistent with other workers (Gourdie
et al., 1992; Thompson, 1998) who have used the diameter at break to normalize
the force data, but in contrast to workers (Burgmann, 1959; Shah and Whiteley,
1966; Collins and Chaikin, 1968) who have used some average measure of diameter

300
Intrinsic fiber strength (MPa) 200

100

0
10 15 20 25 30
Diameter (μm)
Figure 3.20 Intrinsic strength of single wool fibers in water, as a function of the diameter at the
break.