Synthetic Fibres and Plastics CBSE Class Eight Trend setter Study Notes

8^th synthetic materials

Þ       Synthetic materials are kinds of materials obtained from the synthesis of chemicals.

Þ     The chemicals used for synthetic materials are obtained from petroleum and natural gas(methane)

Þ     Petroleum and natural gas is compound of hydrogen and oxygen called hydrocarbon.

Þ     Monomers are simple chemical molecules of hydrocarbon.

Þ     When monomers join end to end form a long chain of monomers called polymers. The process of the formation of polymers is called polymerization.

Þ     Cellulose [beet root] is polymers of glucose while Hemoglobin is polymers of amino acid.

Þ     Fibres are thin thread like materials used to prepared cloths.

Þ     Fibres obtained on mixing natural and synthetic fiber are called semi synthetic fibre. e.g. rayon

Rayon

Þ     Rayon is synthetic fibres obtained from cellulose.

Þ     Rayon are of three types: Viscose Cupreammonium (cupro)  and acetate rayons.

Viscose Rayon

Þ     In industry cellulose dissolved in mixture of sodium hydroxide (NaOH) and CS₂ (carbon disulphide) to get Viscous liquid [semi solid] called viscose.

Þ     Viscose is forced to spinnerets [an apparatus having small holes like shower] into an acid bath [through solution of acid like H₂SO₄] . Thus filaments of rayon are obtained which is spun into thread.

Cupro Rayon

Þ     Cupro Rayon are obtained on dissolving cellulose into solution of CuSO₄ and NH₄ . The dissolve solutions forced to spinnerets into an acid bath to get filaments of cuprammonium rayon are obtained which is spun into thread.

Acetate Rayon

Þ     Acetate Rayon is obtained on dissolving cellulose into solution of Acetate and H₂SO₄.

Rayon in our daily life

Þ     Rayon mixed with cotton or silk to make smooth and silky cloth in textile industry.

Þ     Rayon mixed with wool to make carpet.

Þ     Rayon are also used for making reinforced tyre, bangles and surgical dressing

Þ     The name Nylon derived from the New York [NY] and London[LON] as Nylon was first produce in both places at same time.

NYLON

Þ     Nylon (polyamides) was first prepared in 1935 chemically.

Þ     Nylon are prepared using cyclic hydrocarbon Benzene(C6H6)

Þ     Nylon has silk like texture and high tensile strength[Drawn into long thin straps]

Nylon in our daily life

Þ     Nylon is mainly used for making ropes, woman’s wear, fishing net, sari socks and tie

Polyster

Þ     Polyster is obtained from polymer of ethene. It has maximum stretchable strength.

Þ     Terylene, Dacron are kinds of Polyster used for dress, cloth and curtain.

Þ     Terylene mixed with cotton and wood to produce terycot and terry wool respectively.

Þ     Polysters are also used for making sail for sail boat and conveyor belts.

 Acrylics

Þ     Acrylics fibres are obtained on dissolving acetylene[C₂H₂] into suitable solvent like HCN and then forced to spinneret because acetylene decompose without melting.

 Acrylics in our daily life

Þ     They are light and soft like wool. The y are crimpy (wavy) and straight like Polyster thus appear to be bulky and look like wool.

Þ     They are resistant to weather as they are not easily acted upon by moisture.

Advantages of synthetic fibres

Þ     Having long lasting luster and do not turn yellow with age

Þ     Easy to clean and dry up quickly

Þ     Durable and do not shrink on washing

Þ     They are less expensive than cotton

Þ     They do not depend on plants or animal like cotton

Advantages of synthetic fibres

Þ     The get electrically charged in dry weather and cause skin irritation

Þ     The melt and form sticky beads  on heating. There is always a risk of getting burn in kitchen

Þ     They are hydrophilic as do not absorb sweat and moisture thus uncomfortable to wear.

Þ     They are non bio degradable and cause pollution.

Þ     They are good absorber of radiant heat and not fit in summer.

Good to more good

To make make wide spread use of synthetic material it is mixed with natural fibre .There are called blend fibre.

PLASTIC

Þ     Plastic : Any material which can be molded into any desirable shape on heating is called plastic

Þ     Petroleum product such that Ethane, propane, benzene ,toluene etc are used for manufacturing plastic.

		Plastic
	Thermoplastic			Thermosetting

Thermosetting Plastic

Þ     Thermosetting plastics are kind of plastic which once moulded cannot moulded again by heating.

Þ     Thermosetting plastics are kind of plastic whose polymers form highly cross linked chain on heating.

Þ     Bakellite , melanin, Formaldehyde are some of the examples of Thermosetting Plastic

Thermoplastic Plastic

Þ     Thermoplastic are kind of plastic which can be moulded again and again by heating and easily reused.

Þ     PVS, Polysterine , nylon , polythine are some of the examples of Thermoplastic Plastic

Þ     Polymers of thermoplastic Plastic  have long chain without cross linked to each other.

Characteristics of plastic

Þ     Plastic has much less toughness as compared to metal

Þ     having light weight

Þ     It is not affected by acids and bases.

Þ     Plastic are non bio degradable as it is weather resistant

Þ     Plastic are bad conductor of heat and electricity

Þ     Plastic melts on heating

Some of the  common plastics are

a. Polythene

Þ     it is obtained from polymerization of ethene. it is non bio degradable .

Þ     it is a kind of thermosetting plastic

Þ     it is insoluble in any solvent

Þ     it is light weight

Þ     it is anti corrosion and insulator

Þ     it is used for making bag ,adhesive tap, electric wire cover and can

b. Polyvinyl chloride (PVC)

Þ     it is use for making sole of shoe

Þ     it is use for making covering of electric wire

Þ     it is use for making sanitary fittings

c. Polysterine

Þ     It is a polymer of polythene .

Þ     it is a kind of thermosetting plastic

Þ     it is highly transparent

Þ     it is use for making cups of hot drink , toy etc.

Þ     it is use for safe packaging of expensive items

Þ     it is use for making Styrofoam[themocole]

Þ     it is use as insulating material in refrigerator

d. Teflon

Þ     It is prepared by using tera- fluroethene.

Þ     Heat and chemical are not effective on Teflon

Þ     it is use for making non stick cooking were

Þ     it is use for making corrosive proof coating in industry

e. Bakelite

Þ     it is a kind of thermosetting plastic

Þ     it is use for making electrical switches and plug

Þ     it is use for making gear wheel

Þ      it is use for making table top

Þ     it is use for making comb, pen bodies and photograph records

f. Melanin

Þ     It is hard and highly polished polymers used for making unbreakable kitchen were.

Some of the common synthetic polymers not used in textiles industry
S. No.	Polymers	Use to make
1.	Polythene	Packaging material, carry bag, bottle
2.	Polypropene	Bottles, Crates
3.	PVC	Pipes, Insulation
4.	Teflon	Non stick Kitchen were
5.	Polystyrene	Foam, Thermocol
6.	Bakelite	Electrical insulation, Button]
7.	Lexan	Bulletproof glass
8.	Melanin	Crockery
9.	Perspex	Window of car, train and aircraft
10.	Vinyl rubber	Rubber, eraser
11.	Neoprene	Rubber
12.	Poly[styrene –butadiene]	Rubbers ,Bubble gums

Study in Depth Trend Setter

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