SYNTHETIC FIBRES CHEMISTRY CLASS VIII

1. Dr. Meeta Goklani

2. What are Fibers?
Fibers are the basic units of all textiles.
Fibers are put together to form a
continuous strand, making a yarn.
 Yarns are woven or knitted together to
make fabrics.

3. Fibres
• Plant Source- Cotton, Jute
and Linen.
• Animal Source- Wool and
silk.
Natural
Fibres
• Semi Synthetic Fibres-
Rayon
• Fully Synthetic Fibres-
Nylon, Polyester, Acrylic.
Synthetic
Fibres

4. NATURAL FIBRES
COTTON FLAX

5. Fibres are Polymers
 Monomers (Mono = one, mer = unit)
 Single unit of a substance is called a monomer.
 Polymers (Poly= many, Mer = units)
 A polymer is a large molecule made up of chains of
repeating basic molecular units called monomers.

8. POLYMERISATION
The process of
joining
together
monomers to
form a polymer
is called
Polymerisation
.

9. Synthetic Fibres are Polymers
 These are called as synthetic fibres because these
fibres are synthesised in the laboratory.
 Man Made fibres
 Artificial Fibres

10. Synthetic Fibres
 Synthetic fibres are man-made fibres.
 Synthetic fibres are made from different chemicals,
hence each kind of synthetic fibres have their own
properties.
 Synthetic fibres are more in length and are long
lasting.
 The only limitation in synthetic fibres is that they are
poor absorbents of moisture and they catch fire easily.

11. POLYMER MONOMER
Protein Amino Acids
Cellulose Glucose
Rayon Cellulose
Nylon amide
Polyester Ester
Acrylic Acrylonitrile
Polyethene Ethene
Poly Vinyl Chloride Vinyl Chloride

12. Rayon First man made fibre.
 Rayon is prepared from
cellulose (wood pulp).
Though cellulose is a
natural polymer it needs
extensive chemical
treatment to form
Rayon.
 Hence, it is also
considered a semi
synthetic fibre.

13. Rayon
 First Synthetic Fibre
 Rayon was called artificial silk as it is lusturous.
 Rayon fibre has the same comfort property as natural
fibres.
 Rayon is recognised by the name viscose rayon in the
textile industry.
 It is cheaper than silk.

14. Process of making Rayon
Cellulose + Sodium Hydroxide
Viscose
Passed through Spinneret in dil.
Sulphuric acid
Rayon Fibres

15. HOW SYNTHETIC FIBRES ARE
MADE?

16.  Rayon is similar to cotton as they both contain
cellulose but it has a shine like silk.
 Thus, it is also known as Artificial Silk.
 1. Rayon is used to make curtains, car upholstery etc.
 2. It is used to make carpets.
 3. It is used to making surgical dressings.
 4. It is used to make reinforced automobiles tyres.
Rayon- Artificial
silk

19. Nylon
 First fully synthetic fibre produced by man in 1935.
 64 million pairs of nylon stockings were sold in the
first year itself.
 Nylon got its name from the cities of New York and
London where it was marketed initially.
 Nylon is a thermoplastic( that melts on heating).

20.  Nylon are synthetic fibres made from petrochemicals.
 The nylons are polyamides with recurring amide
groups.
 They contain carbon, oxygen, nitrogen and hydrogen
elements.

21. Properties of Nylon
1. Strong (High Tensile Strength)
2. Light weight
3. Moth Resistant
4. Durable and Long Lasting
5. Elasticity and strechability
6. Cleanliness and Washability
7. Lustrous
8. Affinity to Dye

22.  Variation of luster: nylon has the ability to be very
lustrous, semilustrous or dull.
 Durability: its high tenacity fibers are used for seatbelts,
tire cords, ballistic cloth and other uses.
 High elongation and elasticity.
 Excellent abrasion resistance.
 Highly resilient (nylon fabrics are heat-set)
 Paved the way for easy-care garments.
 Nylon fabrics have low absorbency.
 Nylon fabrics are smooth, non-absorbent and dry quickly.
Dirt doesn’t cling to this smooth fibre, which can be
washed easily or can be even cleaned by using a damp
cloth.

23. Fishing Nets

24. Ropes- high tensile strength

25. High tensile strength and Elasticity

26. Ropes- Abrasion resistant and
strong

27. Nylogrip Tyres

28. Nylo grip tyres

29. Polyester are made of many ester
linkages.

30. Polyester
 Polyesters are a group of synthetic fibres that have
properties similar to nylon.
 Some popular polyester fabrics are
 terylene,
 polythene,
 Tetraphthalate and
 Acrylon

31. Properties which make it a popular
fabric
 Polyester fabric is strong.
 Wrinkle resistant.
 Softer.
 Easy to wash and dry.
 Moth and fungus resistant.
 Resistant to ordinary chemicals.
 High Abrasion resistant.

32. Blended Fabrics
 Sometimes natural fabrics like cotton and wool are
mixed with polyester(or terylene) to make blended
fabrics.
 Blended fabrics are fabrics made by mixing or
blending two types of fibres.
 Polycot = Polyester + cotton
 Polywool = Polyester + Wool
 They have properties of both natural fibre and
polyester.

33.  Terycot, for example is a popular fabric used for
making dresses.
 It is a mixture of terylene and cotton.
 This combination is easier to wear in summer due to
its cotton content with all the advantages of synthetic
fibre.

34. Uses of Polyester Fabrics
 Used to make blended fabrics like polycot, polywool
which are used to make pants, shirts, suits and other
dresses.
 Polyester is uesd for making sails of sail boats.

36. sails

37. Polyester
Water Hoses in fire fighting
operations Conveyer Belts

38. ADVANTAGES OF SYNTHETIC
FIBRES
 Tensile strength
Synthetic fibres are strong so they can take up heavy things easily.
 Retain their original shape
Synthetic fibres retain their original shape so it's easy to wash and wear.
 Elastic
Can easily be stretched out.
 Soft
Synthetic fibres are generally soft so they are used in clothing materials.
 Can be dyed in various colours
Varieties of colours are available as they are manufactured.
 Cost Effective
Clothes made by synthetic fibres are generally cheaper than those
made by natural fibres.
 Do Not Shrink.

39. DISADVANTAGES OF SYNTHETIC
FIBRES
 Does not absorb moistures
Synthetic fibres do not absorb sweat, trapping heat in
our body.
 Rough feel
Synthetic fibres may give rough feel, making it
unsuitable for pyjamas, underwear, etc.
 Catches Fire
polymer based fibres will melt on heating and stick to
skin.