The document discusses the classification, identification, and properties of various textile fibers including natural fibers like cotton, silk and wool as well as man-made fibers. It describes how burning and solubility tests can identify fibers and provides details on the physical and chemical properties of cotton, silk, and wool fibers such as their strength, absorbency, and reactions to acids, alkalis and bleaching agents.

1. Unit 4
Classification textile fibres
1.Narural fibre such as animal, from sericteries,silk vegtable,seed cotton
.2. man made fibire artifical,sythetic
Difference between cellulosic and synthetic fibres
Cellulos fibre comes from plants sythetic fibre are made by humans with
chemical synthesis.
Identification of fibres by burning and solubility test
Burning test is a relativity simple test1.approaching flame 2.behaviour
inside the flame. Solubility test is a some specific chemical reagent.
Physical and chemical properties of cotton ,silk ,wool
Cotton physical length 0.5”-2.5” strength 3-5 chemical,action with
alkali, action of acid action of bleaching.
Silk physical colour yellow brown, strength strong fibre luster bright.
chemical effect of acid ,effect of alkaloids, effect of organic solvent.
Wool physical elasticity ,feel soft, dimentional stability bad. chemical
effect of acids effect of alkali, effect of insects

2. Classification of fibres

3.  Strength: it’s stronger than silk Once wet wool looses regarding twenty
fifth of its strength. Longer the fibre the somebody are going to be the
strength of yarn.
 Resiliency: Wool is extremely resilient and involves its original form once
hanged once wrinkled or created.
 Stretchability: Wool is extremely elastic. It’s ten to half-hour stretched
once dry. It is also forty to five hundredth once wet upon receiving pressure
upon drying it regarding original dimensions.
 Shrink ability: Wool is resistant shrinkage. But long exposure to wetness
could cause shrinkage.
 Effect of friction: Friction can soften the wool fibre. Particularly once wet
and so is advantageous in maintaining sleek, soft texture of materials.
 Crimps: Wool fibre is additional or less wavy and has twists. This waviness
is termed as ‘crimp’. Finer the wool the additional are going to be the
crimps in it. Merino sheep wool has thirty crimps per in, whereas coarse
wool has one or 2.
 Effect of moisture: Wool s that the most absorptive in nature. It will
absorb up to five hundredth of its weight. It also carry upto 2 hundredth
weight, while not giving the sensation of being wet. Upon drying it losses
wetness. It slowly preventing speedy evaporation so avoiding chilling feel
to the user. It absorbs perspiration once violent exercise and guards the
body against fulminant amendment in temperature

4. Chemical properties wool
 Action of acids: Dilute acids have very little result however either hot
or focused acids weaken or dissolve the wool fibres.
 Action of alkalis: Alkalis tend to create whereas wool xanthous,
robust solutions of washing soda once heated destroys the fibre
hydroxide is extremely injurious to the wool fibre but mineral and
ammonia haven’t any harmful influence on wool.
 Action of bleaching agents: robust bleaching agents like salt have
harmful effects on wool., permanganate, metal peroxide and peroxide
but will safely be used for bleaching and stain removal.
 Effects of lepidopteran and mildew : Wool is definitely broken by
moths that is why throughout storage of woolen clothes special case is
required. but mildews donot effects clothes.
 Finishes given to wool: Felting, fulling, lepidopteran proofing,
crabbing, decanting, london shrinking, napping, singeing and
steaming.
Wool blends: Wool polyster, wool acrylic, wool nylon, silk and wool.

5. Physical properties silk
 Silk fibers from the Bombyx mori silkworm have a triangular cross
section with rounded corners, 5–10 μm wide.
 The fibroin-heavy chain is composed mostly of beta-sheets, due to a
59-mer amino acid repeat sequence with some variations.
 The flat surfaces of the fibrils reflect light at many angles, giving silk a
natural sheen.
 The cross-section from other silkworms can vary in shape and
diameter: crescent-like for Anaphe and elongated wedge for tussah.
 Silkworm silk was used as the standard for the denier, a measurement
of linear density in fibers. Silkworm silk therefore has a linear density
of approximately 1 den, or 1.1 dtex.
 Comparison of silk fibersLinear density (dtex)Diameter
(μm)Coeff. variation
 Moth: Bombyx mori
 1.17 12.9 24.8%
 Spider: Argiope aurentia
 0.14 3.57 14.8%

6. silk
 Silkworm fibers are naturally extruded from two silkworm
glands as a pair of primary filaments (brin), which are stuck
together, with sericin proteins that act like glue to form a
bave Bave diameters for tussah silk can reach 65 μm.
 See cited reference for cross-sectional SEM photographs.[

7. Chemical properties of silk
 Silk emitted by the silkworm consists of two main proteins, sericin and
fibroin, fibroin being the structural center of the silk, and serecin being the
sticky material surrounding it.
 Fibroin is made up of the amino acids Gly-Ser-Gly-Ala-Gly-Ala and forms
beta pleated sheets.
 Hydrogen bonds form between chains, and side chains form above and
below the plane of the hydrogen bond network.
 The high proportion (50%) of glycine allows tight packing. This is because
glycine's R group is only a hydrogen and so is not as sterically constrained.
 The addition of alanine and serine makes the fibres strong and resistant to
breaking.
 This tensile strength is due to the many interceded hydrogen bonds, and
when stretched the force is applied to these numerous bonds and they do
not break.
 Silk is resistant to most mineral acids, except for sulfuric acid, which
dissolves it. It is yellowed by perspiration. Chlorine bleach will also destroy
silk fabrics.

8. Physical Properties of Cotton Fibre:
Cotton fibre has some physical characteristics which are pointed out in the
below:
1.Length: 0.5ʺ - 2.5”
2.Strength, tenacity (gm per denier): 3 – 5
3.Dimensional stability: medium
4.Heat preventive power: medium
5.Moisture regain: 7-10% (standard 8.5%)
6.Stiffness: 57-60 g/d due to high crystallinity
7.Elasticity: 1.50- 1.58
8.Resiliency: low
9.Abrasion resistance: medium
10.Density (gm/cc): less than both silk and wool but more than linen.
11.Color: cream or yellowish like clean white.
12.Specific gravity: 1.52-1.55

9. Chemical Properties of Cotton Fibre:
 The main chemical characteristics of cotton fiber have presented in
the following:
 1. Action with alkali:
 Here, preventive power is good. Alkali does not damage cotton
fibre.
 2. Action with acid:
 Strong acid damage the fibres. Concentrated sulphuric acid and
hydrochloric acid damage the fibre. But weak acid does not damage
the fibre.
 3. Action with bleaching:
 No damaging event is occurred here. Cotton is converted into oxi-
cellulose in strong oxidizing bleaching.
 4. Action with organic solvent:
 Resistance so dry is possible here.

10. proerties
 5. Sunlight preventive power:ss
 Ultraviolet ray converts the cotton into oxi-cellulose.
 6. Mildew preventive power:
 Untreated not easy. There is possibility to be affected.
 7. Dye ability:
 Affinity to color is good. Direct, reactive, sulphur and vat dyes
are used.
 8. Insects preventive power:
 Not affected by moth.
 9. Heat:
 Conductive ironing temperature is 150°C where decompose is
2400°C and ignition temperature is 390°C.