Page 167 - Handbook of Properties of Textile and Technical Fibres

144 Handbook of Properties of Textile and Technical Fibres

(a)
800 Type IV

Type I
600 Type II
Stress / MPa 400 Type III

200

0
0 4 8 12 16 20 24
Strain / %
(b)
Relaxation from 10%
480
420 Nephila
360
Bombyx mori yarn
Stress / MPa 240
300
Bombyx mory, degummed
180
120 Gonometa postica
Gonometa rufobrunea
60
0
0 2 4 6 8 10
Strain / %
Figure 5.3 (a) Representation of the four types of mechanical behaviors of Bombyx mori silk;
(b) comparison of the different stressestrain curves obtained with different silks; partial
reversibility is shown for fibers strained up to 10%.
After Colomban P, Dinh HM, Riand J, Prinsloo LC, Mauchamp B: Nanomechanics of single
silkworm and spider fibres: a Raman and micromechanical in situ study of the conformation
change with stress, J Raman Spectrosc 39:1749e1764, 2008a.

Type III: after elastic behavior up to 1.5% a continuous variation is observed in the
section above the linear behavior. This signature is observed for many degummed or
dyed fibers saturated with water.
Type IV: after the viscoelastic or plateau behavior, a hardening is observed up to the
breaking point. This behavior is rather common for spider silk but rare for silk obtained
from the B. mori.
Type V (not shown): the breaking point occurs in the elastic domain; dyed fibers or
chemically treated fibers show this behavior.
Some authors (Cunniff et al., 1994; Perez-Riguerro et al., 2000b; Vollrath and
Knight, 2001) report rather similar varieties of behavior but assign each one to a