1 Synthetic Fibres and Plastics || Shashaank Blogspot

 

1   Synthetic Fibres and Plastics

 

SUB- TOPICS

 Introduction

 Definitions

 Types of synthetic fibers

 Characteristics of Synthetic Fibres

 Advantages and Disadvantages of synthetic fibres

 Types of Plastics

 Characteristics of Synthetic plastics

 Common plastics and their uses

 Plastics and Environment

 

 

INTRODUCTION

 All fabrics are made of fibre. These fibres are then used for making fabrics.

 These fabrics are further used for making clothes, utensils etc. Since clothes

are important human need, protects our body from extreme temperature and

climate changes, hence making fabrics is very important for us.

 Fibre can be obtained from various sources, and are classified as follows :

NATURAL FIBRE

Natural fibres are obtained from natural sources (animal & plants). The natural

fibre used in day to day life like cotton, jute, silk, wool.

Cotton – obtained from cotton plants

Jute – obtained from plants

Silk – obtained from silk moth.

Wool – obtained from Sheep, Yak, Camel.

 Since natural fibres are obtained from plants and animals and they should be

cultivated and reared through a life time to obtain fibre.

 The plants and animals should also be taken care off and would sometime even

lent insufficient produce to meet the needs of the population.

Hence using natural source and by applying chemical method semi-synthetic

fibres were obtained.

For eg : Rayon, Cellulose (wood pulp) obtained from trees is treated with

chemicals to form Rayon.

 

SYNTHETIC FIBRE

 Also many new compounds were synthesized and the fibres obtained from manmade

source were called synthetic fibres.

Eg : Polyester, Dacron

 Synthetic fibre is a chain of small units, single unit join with other such unit to

make long chains, like pattern found in a necklace of beads.

 Single unit joining together to form a long chain are called Monomer – ‘MONO’ –

single: ‘MER’ – unit.

 These monomers repeating and forming long chains form a Polymer – ‘POLY’ –

many; ‘MER’ – unit.

 

TYPES OF SYNTHETIC FIBRES

 Rayon / Artificial Silk : You have learnt that silk was discovered in China and

was kept as closely guarded secret for a long time. Fabrics made from the silk

were very costly.

 However, the beautiful texture of silk fascinated everybody.

 Attempts were made by the chemists to make artificial silk, and they were

successful by the end of the nineteenth century.

 The product they developed is called rayon and has similar properties to the

silk, so it is known as artificial silk.

 Although rayon is obtained from a natural source, wood pulp, yet it is a man

made fibre and cheaper than silk.

 It can also be dyed in a wide variety of colours.

 Rayon is some times called regenerated fibre because it is produced by

modifying the natural fibre.

 Rayon is produced from the natural fibre in the following steps:

1. Pure cotton or cellulose is soaked in 30% solution of caustic soda for three

hours.

2. The caustic soda solution is then removed and the product is gently

warmed with carbon disulphide. The product so formed is called cellulose

xanthate.

3. Cellulose xanthate is again dissolved in caustic soda solution, when it

forms another product commonly called viscose solution. This solution is

carefully filtered to remove any insoluble impurities.

4. The viscose solution is then slowly passed through a spinneret placed in

the bath of dilute sulphuric acid. The viscose hardens to form a very fine

filament. The filament is then wound on a spool.

 

USES

 Rayon mixed with cotton is used for making bed-sheets. It is easier to wash and

is more hygienic.

 Rayon mixed with wool is used to make carpets. It makes them lighter and

more durable.

 Rayon guaze is used in bandaging. It can absorb over 90% of its own weight of

water. Rayon guaze do not adhere to wounds.

 

NYLON

 It is another man made superior type of artificial fibre which is truly artificial.

In 1931, it was made without using any natural raw material (from plant or

animal).

 Nylon word comes from NY (New York in USA) and LON from London. Because

it was developed by the collective effort of scientists of two countries and where

it was first marketed.

 It is prepared by the polymerization of amide molecules which are obtained

from coal, water and air (i.e. petroleum products) by complex chemical process.

 The Nylon fabric consists of a very long chain of polyamide molecules.

 The nylon fibres are elastic, strong and water resistant.

NYLON

 

 It is another man made superior type of artificial fibre which is truly artificial.

In 1931, it was made without using any natural raw material (from plant or

animal).

 Nylon word comes from NY (New York in USA) and LON from London. Because

it was developed by the collective effort of scientists of two countries and where

it was first marketed.

 It is prepared by the polymerization of amide molecules which are obtained

from coal, water and air (i.e. petroleum products) by complex chemical process.

 The Nylon fabric consists of a very long chain of polyamide molecules.

 The nylon fibres are elastic, strong and water resistant.

 The women’s stockings made from Nylon were instant hit in the market, when

they were introduced in 1939.

 However, in 1939 when this product was introduced, the World War II started.

So, most of its production was diverted for making parachutes.

 However, when the war ended in 1945, the production of stocking again

started. Supply could not match the great demand of stockings. There was a

huge black market for this product. Women had to wait for hours in queues to

get a pair of stockings.

 

USES

 We use many articles made from Nylon such as socks, ropes, tents, tooth

brushes, car seat belts, sleeping bags, curtains.

 It is used for making fabric for clothing and parachutes and also for making

stockings on account of its high elasticity.

 It is used for making ropes for rock climbing and fishing nets.

 It is used for making the cords and strings for tennis rackets.

 It is used for making small parts of machines, such as washing pulleys.

 

POLYESTER

 Polyester is manufactured from petroleum.

 Polyester (poly + ester) is actually made up of the repeating units of a chemical

called an ester.

 Esters are the compounds formed when alcohol reacts with organic acids such

as Acetic Acid, Phthalic Acid in presence of concentrated sulphuric acid.

 The esters have fruity smell and can be polymerized to form polyester which can

be drawn into very fine filaments so as to form artificial fibre.

 This fibre is suitable for making dress material because it does not get wrinkled

easily, retains crease and is easy to wash.

 There are a number of varieties of esters depending upon the alcohol and the

organic acid used to form the molecule of ester.

 

DIFFERENT TYPES OF POLYESTER FIBRES

TERYLENE OR TERENE OR DACRON

 

 Terylene is a popular polyester and are obtained by polymerizing the molecules

of phthalic acid and ethylene glycol.

 Terylene filaments are similar but superior in properties than nylon.

 

USES OF TERYLENE

 

 For making fabrics for shirts, trousers, sarees and other dress materials and

sold as a trade names of poly cot or terry cot, poly wool etc.

 Poly cot is a mixture of polyester and cotton. While poly wool is a mixture of

polyester and wool.

 Used for making sails for sailing boats, conveyor belts.

 

POLYETHYLENE TEREPHTHALATE (PET)

 

 It is prepared by the polymerization of ethylene Tere phthalate. It can be easily

drawn into very fine filaments, which can be worn like any other yarn.

 PET is a very familiar form of polyester. It is useful for making bottles, utensils,

films, wires and many other useful products.

 For making synthetic clothes having permanent crease and are easy to wash.

 For making magnetic tape used in audio cassette recorders and video cassette

recorders.

ACRYLIC FIBRES / ORLON

 Acrylic fibre is obtained by the polymerization of molecules of acrylonitrile

(which is a complex molecule obtained by complex chemical processes from

petroleum products)

 These synthetic fibres are very light and soft like wool i.e. resembles wool.

USES

 These are more durable and affordable which makes them more popular than

natural fibres.

 They are used for making yarn for hand knit sweaters, shawls and blankets.

KOROSEAL

 It is the trade name for the polymer vinyl chloride.

USES

 It is water proof as well as air proof.

 Useful for coating fabrics of Silk, Rayon or Cotton to make them water proof.

 Water proof fabrics so obtained can be used on rainy days or as bathroom

curtains.

CHARACTERISTICS OF SYNTHETIC FIBRE

 They are strong, wrinkle free, elastic (ability to regain original shape after being

stretched), mothproof, easy to wash and last for a longer time.

 They do not absorb water or sweat, clothes made of synthetic fibres are not very

comfortable to wear.

 In hot and humid weather, these clothes stick to the body and make us feel

uncomfortable.

 Some synthetic fibres catch fire very readily. They are easily inflammable since

made up of petroleum products. Also, they melt on heating and stick to the

body of the person wearing them.

 They cause severe burn injuries.

ADVANTAGES AND DISADVANTAGES OF SYNTHETIC FIBRES

ADVANTAGES

 They have high lustre and do not turn dull with age.

 They do not shrink on washing.

 They need very little or no ironing.

 They last longer as compared to natural fibres.

 They are easy to clean and dry quickly.

 They are less expensive than the natural fibres.

DISADVANTAGES

 Since synthetic fibres melt on heating. The fabric easily melts and sticks to the

body of the person wearing it. So, we should not wear synthetic clothes while

working in the Kitchen or in a laboratory.

 Unlike natural fibres, they do no absorb sweat. Therefore, clothes made from

synthetic fibres are not comfortable to wear in summer season.

 They get electrically charged in dry weather. Spark come out from blankets

made from synthetic fibre during night. These electric charge can cause skin

problems also.

 They are non biodegradable and hence, cause a lot of pollution.

PLASTICS

 A material is said to be ‘plastic’ if it can be moulded or re-shaped into different

shapes. Thus, dough and plasticine are plastics, so is clay and heated glass.

 However, the word plastics is now commonly used for several human-made

materials that can be moulded into desired shapes or drawn into fibres. All

these materials have one common property – they are made of polymers.

 Scientists have created an enormous range of human-made plastics with

different properties.

 The main source of these plastics is crude oil.

CHARACTERISTICS OF SYNTHETIC PLASTICS

 Plastic is also a polymer like the synthetic fibre.

 All kinds of synthetic plastics can be easily moulded i.e. can be re-shaped in

any other form.

 Plastic can be recycled, reused, coloured, melted, rolled into sheets or made

into wires, that is why it finds such a variety of use. Such plastics that can be

drawn into very fine filaments on spinning, form synthetic fibres.

 Plastics are non-reactive i.e. it does not react with water and air.

CHARACTERISTICS OF PLASTICS

 Chemical resistance: Synthetic plastics are hardly affected by strong

chemicals such as acids and alkalis. They do not react with water and air.

 Weather resistant: Synthetic plastics are non biodegradable. Unlike natural

plastics such as cotton and wool.

 Light weight : Plastic materials are light. Hence easy to carry and transport.

 Toughness or Tensile Strength: Synthetic plastics can withstand a lot of force

without getting broken.

 Insulation : Electric wires are covered with plastic insulation.

 Appearance : Synthetic plastic materials can be made as transparent as glass,

in any desired colour or texture and can be used for making a large variety of

house hold products. COMMON PLASTICS AND THEIR USES

(a) Polythene (Poly – ethene)

 It is prepared by the polymerization of ethene (CH2 = CH2).

 Not attacked by strong chemicals and non biodegradable.

Uses

(1) It is used for making thin films which are used for making carry bags,

adhesive tapes etc.

(2) It is used for making kitchen and laboratory ware such as caps and bottles.

(3) It is used as insulation for electric wires.

(4) It is used as an anti-corrosion coating on the articles made from iron or

copper.

(b) Poly Propene

 It is prepared by the polymerization of propene gas (CH2CH=CH2)

molecules.

Uses

(1) For making ropes, packaging materials and containers.

(2) For making synthetic carpets

(3) For making the body of automobile batteries

(4) For making collapsible toys.

(c) Polyvinyl chloride (PVC)

It is prepared by the polymerization of vinyl chloride molecules.

Uses

(1) For making hand bags, rain coats

(2) For making decorative vinyl flooring

(3) For making soles of shoes

(4) For making gramophone records.

(5) For making water pipes, water tanks and sanitary fittings.

(6) Superior insulation of electric wires.

(d) Teflon (Polytetra Fluoroethene)

It is prepared by the polymerization of tetraflouroethene molecules. It is

unaffected by heat and chemicals.

Teflon is special plastic on which oil and water do not strike.

Uses

(1) It has non-stick properties so is coated on the surface of baking or frying

utensils.

(2) It is used as a lubricant, especially in those parts of machine where oil

cannot be easily applied.

(e) Poly styrene

It is a lighter polymer of polythene. It can be easily moulded on heating. When

air is blown through molten polystyrene, it forms a very light foam which is an

excellent insulating and packaging material.

Uses

(1) It is commonly employed in insulating refrigerators and cold stores.

(2) It is used for making containers, which are used as ice box.

(3) It is used for packaging of expensive items, such as cell phones, T. V. etc

TYPES OF PLASTICS

On the basis of cross linking of monomers plastics are classified as :

1. Thermoplastics : Plastics can be easily moulded, recycled, reused, coloured,

melted, rolled into sheets or made into wires.

a) It has low melting points.

b) Can be remoulded

c) Has low tensile strength

Example : PVC, Polythene

2. Thermosetting : These are plastics which when molded once, cannot be softed

by heating.

a) It has high melting points.

b) Can be remoulded but lose shape

c) Has high tensile strength

Example : Bakelite, Melamine

 

PLASTICS AND ENVIRONMENT

 All plastic bags or wrappers ultimately find their way to the garbage.

 The disposal of the plastic garbage is a major problem all over the world.

It is because plastic does not get decomposed by material processes such as

action of bacteria.

BIODEGRADABLE MATERIALS

 The materials which get decomposed through natural processes such as action

of bacteria are termed bio-degradable. E.g. parts of vegetables, fruits, left over

food ,paper etc.

NON BIODEGRADABLE MATERIALS

 The materials which are not easily decomposed by natural processes such as

action of bacteria are termed as non-biodegradable e.g. all kinds of plastics,

artificial fibres, Tin, Aluminium etc.

 

Types of Waste	Approximate Time taken to Degrade	Nature of Material
Peels of vegetable and fruits, leftover foodstuff, etc.	1 to 2 weeks	Biodegradable
Paper	10 to 30 days	Biodegradable
Cotton cloth	2 to 5 months	Biodegradable
Wood	10 to 15 years	Biodegradable
Woolen clothes	About a year	Biodegradable
Tin, Aluminium, and other metal cans	100 to 500 years	Non-Biodegradable
Plastic bags	Several years	Non-Biodegradable

 

DAMAGE CAUSED BY PLASTIC WASTE

 Since plastic takes several years to decompose, it causes environmental

pollution.

 Plastic carry bags choke the digestive tract of animals, thereby causing death.

 Plastic bags disposed in open field does not allow the wastes to seep in the soil,

which has adverse effect on the plants as well as recharging of ground water.

 Plastic carry bags and other articles clog the city drainage system as well as

small fresh water drains.

 The burning process of synthetic material is quite slow and it does not get

completely burnt easily. It releases lots of poison.

 Oil fumes in the atmosphere causes air pollution during the process.

METHOD TO CONTROL PROBLEMS CAUSED BY PLASTICS

 Avoid the use of plastics as far as possible. Instead, use carry bags made of

cotton or jute when you go for shopping.

 The biodegradable and non-biodegradable wastes should be collected separately

and disposed off separately.

 Plastic wrapper should not be thrown on road carelessly, they are ultimately

carried to city sewage system.

 As a responsible citizen remember 4R’ principle

Reduce – Reuse – Recycle – Recover

KEY POINTS

 

1. Acrylon or Acrylic or Orlon : A synthetic fibre obtained by the polymerizing

acrylonitrile molecules obtained from petroleum products – these fibres are very

light and soft like wool.

2. Koroseal : Trade name of high polymer of vinyl chloride.

3. Monomer: The simplest chemical molecule in a chain of polymer.

4. Nylon : A superior synthetic fibre made by the polymerization of amide molecules

obtained from petroleum products. It was the first fully synthetic fibre.

5. Polymer : The product formed by the combination of a large number of

monomers in a straight or crossed chain.

6. Polymerization : The process of combining of a large number of monomers in a

straight or crossed chain.

7. Polypropene : The plastic material prepared by carrying out the polymerization

of propene.

8. Polythene : A plastic material prepared by polymerization of ethene gas. 9. Polystyrene : A lighter polymer of polyethene.

10. Polyvinyl chloride (PVC) : A plastic material prepared by the polymerization of

vinyl chloride.

11. Plastic : Plastic is also a polymer like the synthetic fibre. Which can be easily

moulded into various forms.

12. Plasticity : The property of a material due to which it can be moulded into

various forms is called plasticity.

13. Polyester or Terylene or Dacron : A synthetic fibre obtained by polymerizing

molecules of phthalic acid and ethylene glycol.

14. Rayon (Artificial Silk) : The fibre which was obtained by chemical treatment of

wood pulp. This fibre was called rayon or artificial silk or a regenerated cotton

fibre by using chemical methods, which is smooth as silk.

15. Teflon (poly tetra fluoroethene) : A plastic material prepared by the

polymerization of tetra fluoroethene.

16. Thermoplastics : Synthetic plastic materials obtained by gentle heating and

moulding, such that the moulded materials can be reshaped by gentle heating

e.g. polythene, polyvinyl chloride, polystyrene, Nylon and Terylene.

17. Thermosetting plastics : Synthetic plastic materials obtained by gentle heating

and moulding such that the moulded materials cannot be reshaped by gentle

heating E.g. bakelite, urea formaldehyde, melamine.