1. The wool fibre and its applications
Dr Geoff Naylor CSIRO

2. This lecture
 Introduction to the fascinating world of the wool fibre and its wonderful structure, which results in its many splendid properties.
 Start with a close look at the fibre.

4. Wool Structure: not just a ‘soup’ of wool molecules

6. Warmth
 In cold environments an important function of textiles is to keep the body warm.
 Clothing reduces the rate of heat loss from the body.
 This physical property is called thermal insulation.

7. Warmth
 Still air is nature’s best insulator – much better than any fibre.
 It is the air or spaces in textiles that give warmth.
 Wool’s natural crimp and high bulk means it naturally traps lots of air. Hence it is famous for warmth, particularly in bulky knits.

8. Wool: naturally absorbs water vapour and is breathable
 Wool is an active fibre.
 It is able to absorb and desorb moisture vapour as conditions around it change.
 This gives wool is its fantastic ‘comfort’ properties and makes it ‘breathable’.

9. Wool: naturally absorbs water vapour and is breathable40 30
wool
cotton polyester
 Scientifically, the amount of water a fibre can absorb internally, i.e. without feeling wet, is called its ‘regain’.
 This depends on the relative humidity of the surrounding air.
 Wool comes first in this comparison, being able to absorb up to 35% of its weight in water before feeling wet.
Re g ain 20 10
Re lative H u m id ity
Fib re
Sa tu ra tio n re g a in %
Wo o l
35%
Co tto n
24%
Po lyam id e 7%
Po lye s te r 1%
Po lyo le fin
.05%
Po lyac rylo n itrile
A ra m id
6.5%

10. Wool: naturally absorbs water vapour and is breathable
 The human skin is very sensitive to very small changes in temperature and humidity in the microclimate next to the skin.
R a te o f m o is tu re va p o u r p re s su re in c re a s e
polyester
sweating starts
Moisture Evaporation and Transport
sportwool 4
m in u te s o f e xe rc ise 2 6 8
 During physical activity wool can significantly reduce feelings of dampness and moisture discomfort.
Heat Loss
Pressure

11. Wool: naturally absorbs water vapour and is breathable
Synthetic Fibre
Wool Fabric
Rainproof fabric Synthetic
fibres absorb very little moisture vapour
Rainproof fabric
Wool absorbs moisture vapour rapidly
Skin
Big build-up of humidity
Skin
Reduced humidity
Wool is hygroscopic which means it can easily absorb water vapour. This property counteracts the build-up of clammy, humid conditions within clothing.

12. Active heating  When wool absorbs water it actually generates heat!
 The amount of heat can be quite significant. When a kilogram of dry wool is placed in a moist environment the amount of heat it releases is about the same as an electric blanket running for eight hours.
 This active generation of heat is unique and can reduce ‘thermal shock’ during the transition from indoors to outdoors in wet winter climates.

13. Wool: water repellent
 As well as absorbing moisture vapour, the surface of the wool fibre naturally repels water.
Small drops of water do not readily soak into a wool fabric but stay on the surface as droplets, which can easily be shaken off.
 This is great for outdoor clothing, such as golf wear.

14. Wool: water repellent and anti- soiling
and spills on wool carpets.

15. Wool – naturally flame resistant
Ignition Source
 Fuel, heat and oxygen are all essential for combustion. Remove one and the fire extinguishes.
 Wool contains high levels of nitrogen and sulphur, which are natural fire retardants, i.e. hard to ignite.
 A natural black char forms, creating an insulating layer separating the fuel and oxygen.
Fuel Oxygen
The Fire Triangle

16. Wool: shape retention
 Wool has excellent tailorability, drape, style and shape retention.
 It can be shaped and set in a multiplicity of ways; for example, the three-dimensional shapes required for a suit.

17. Glass Transition Thermal Splicing Yarns
Wool: shape retention
 Depending on temperature and water content (regain) wool can be (i) stiff or ‘glass like’ or (ii) softer or ‘rubber like’.
 This is used in tailoring to form and lock in the required shape.
Co h e s ive / Te m p o ra r y S e ttin g o f Wo o l
18 0
160
14 0
12 0
10 0 80 60 40 20
-­‐2 0
-­‐4 0
Pressing a Crease
Glass Transition Thermal Splicing Yarns
Removing Twist Liveliness
Rubber Like
Te m p e ratu re (o C )
Glass Like
0 5 10
Re g ain ( % ) 30 35 40

18. The wool fibre contains a number of
Wool: shape retention
Pe rm a n e n t S e ttin g o f Wo o l
H O H O H O N C C N C C N C C
 Permanent creases can be achieved by rearranging the internal bonds in the wool fibre.
H R1
H CH2 H R3 S S
H R4 H R5 H H2C H R6
N C C N C C N C C N C C H O H O H O H O
The wool fibre contains a number of S S
S S S S S - S S S-
S S S S
S S S S
When the fibre is understress, the dissulfide bonds can rearrange

19. Wool: exquisite drape

20. Elasticity

21. Elasticity
 Wool wears well not because of its strength but because of its high extensibility. This allows wool to stretch and recover with minimal breakage or damage.
300
250
200
15 0
10 0 50
S tra in / % 0%
28%
84%
100%
S tre s s/ M Pa

22. Odour absorption
 Sweating is the body’s natural way to regulate its temperature.
 If sweat remains on the body for several hours, bacteria can develop and lead to body odour.
 The moisture absorbing nature of wool and its breathability helps control this.