Page 185 - Handbook of Properties of Textile and Technical Fibres

162 Handbook of Properties of Textile and Technical Fibres

(c) (c) Fresh gland
(b) Fresh silk fibre
(a) Degummed cocoon fibre

ν
CH
ν
H O
2
ν NH c)
1)
Raman intensity 2800 3000 3200 a) 3400 3600 3800
b)

Degummed fibre ⊥
cocoon
Degummed fibre // 3288 Bombyx mori
3325
Fibroin film type D D
Fibroin film type O 3425
62
120 10K
54
O
2) 3)

RT
59
280
116
1500 1600 1700 3200 3400 3600
Wavenumber / cm –1
Figure 5.13 cont'd.

(Gillepie et al., 1994; Monti et al., 1998, 2001; Shao et al., 1999; Rousseau et al., 2004,
2006; Lef evre et al., 2007a,b), as it was made in the liquid state for peptides: regular a
helix at wc. 1650 cm 1 and for the b-sheet at c. 1690 cm 1 whatever the protein chain
(keratin, fibroin, spidroin, etc.). The slight difference between the Amide I signature of
dried gland (totally amorphous) and those from the fiber confirms the high disorder but
the limited modifications indicate limited structure difference between the different
states (fresh/dried gland, fibers). The component assigned to “b-sheet” (or more likely
to untwisted ribbons) is a maximum but remains weak in the fresh gland and in Type I
(fresh hand-spun fiber) and could be related to chains interacting with water.
The proportion between the different conformations remains debated. Most of the
authors claim that b-sheets are dominant, some others disagree (Colomban et al.,
2008a; dos Santos-Pintos et al., 2015). The differences could be related to the material
studied (silk in the gland or in the fiber, fibroin/spidroin) or to the method used, more