NCERT Textbook - Synthetic Fibers And Plastics Class 8 Notes | EduRev

General Science(Prelims) by IRS Divey Sethi

UPSC : NCERT Textbook - Synthetic Fibers And Plastics Class 8 Notes | EduRev

 Page 1


SYNTHETIC FIBRES AND PLASTICS
SYNTHETIC FIBRES AND PLASTICS
T
he clothes which we wear are
made of fabrics. Fabrics
are made from fibres obtained
from natural or artificial sources. Can
you name some natural fibres? Fibres
are also used for making a large variety
of household articles. Make a list of some
common articles made from fibres. Try
to separate them into those made from
natural fibres and those made from
artificial fibres. Make entries in Table 3.1.
Why did you label some fibres as
artificial?
You have read in your previous
classes that natural fibres like cotton,
wool, silk, etc., are obtained from plants
or animals. The synthetic fibres, on the
other hand, are made by human beings.
That is why these are called synthetic
or man-made fibres.
3.1 What are Synthetic
Fibres?
Try to recall the uniform pattern found
in a necklace of beads joined with the
help of a thread [Fig. 3.1(a)]. Or, try to
join a number of paper clips together to
make a long chain, as in Fig. 3.1 (b). Is
there any similarity between the two?
Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : ( ( ( ( (a a a a a) ) ) ) ) Beads and (b (b (b (b (b) ) ) ) ) Paper clips
joined to form long chains
(a) (b)
Table 3.1 : Natural and Artificial
Fibres
S. No. Name of Type of Fibre
Article (Natural/
artificial)
A synthetic fibre is also a chain of
small units joined together. Each small
unit is actually a chemical substance.
Many such small units combine to form
a large single unit called a polymer. The
word ‘polymer’ comes from two Greek
words; poly meaning many and mer
meaning part/unit. So, a polymer is made
of many repeating units.
2020-21
Page 2


SYNTHETIC FIBRES AND PLASTICS
SYNTHETIC FIBRES AND PLASTICS
T
he clothes which we wear are
made of fabrics. Fabrics
are made from fibres obtained
from natural or artificial sources. Can
you name some natural fibres? Fibres
are also used for making a large variety
of household articles. Make a list of some
common articles made from fibres. Try
to separate them into those made from
natural fibres and those made from
artificial fibres. Make entries in Table 3.1.
Why did you label some fibres as
artificial?
You have read in your previous
classes that natural fibres like cotton,
wool, silk, etc., are obtained from plants
or animals. The synthetic fibres, on the
other hand, are made by human beings.
That is why these are called synthetic
or man-made fibres.
3.1 What are Synthetic
Fibres?
Try to recall the uniform pattern found
in a necklace of beads joined with the
help of a thread [Fig. 3.1(a)]. Or, try to
join a number of paper clips together to
make a long chain, as in Fig. 3.1 (b). Is
there any similarity between the two?
Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : ( ( ( ( (a a a a a) ) ) ) ) Beads and (b (b (b (b (b) ) ) ) ) Paper clips
joined to form long chains
(a) (b)
Table 3.1 : Natural and Artificial
Fibres
S. No. Name of Type of Fibre
Article (Natural/
artificial)
A synthetic fibre is also a chain of
small units joined together. Each small
unit is actually a chemical substance.
Many such small units combine to form
a large single unit called a polymer. The
word ‘polymer’ comes from two Greek
words; poly meaning many and mer
meaning part/unit. So, a polymer is made
of many repeating units.
2020-21
Polymers occur in nature also. Cotton,
for example, is a polymer called
cellulose. Cellulose is made up of a
large number of glucose units.
3.2 Types of Synthetic Fibres
Rayon
You have read in Class VII that silk fibre
obtained from silkworm was discovered
in China and was kept as a closely
guarded secret for a long time. Fabric
obtained from silk fibre was very costly.
But its beautiful texture fascinated
everybody. Attempts were made to make
silk artificially. Towards the end of the
nineteenth century, scientists were
successful in obtaining a fibre having
properties similar to that of silk. Such a
fibre was obtained by chemical
treatment of wood pulp. This fibre was
called rayon or artificial silk.  Although
rayon is obtained from a natural source,
wood pulp, yet it is a man-made fibre. It
is cheaper than silk and can be woven
like silk fibres. It can also be dyed in a
wide variety of colours. Rayon is mixed
with cotton to make bed sheets or mixed
with wool to make carpets. (Fig. 3.2.)
Nylon
Nylon is another man-made fibre. In
1931, it was made without using any
natural raw material (from plant or
animal). It was prepared from coal, water
and air. It was the first fully synthetic
fibre.
Nylon fibre was strong, elastic and
light. It was lustrous and easy to wash.
So, it became very popular for making
clothes.
We use many articles made from
nylon, such as socks, ropes, tents,
toothbrushes, car seat belts, sleeping
bags, curtains, etc. (Fig. 3.3). Nylon is
SYNTHETIC FIBRES AND PLASTICS 33
Fig. 3.2 : Articles made of rayon
Fig. 3.3: Various articles made from nylon
Is nylon fibre
really so strong
that we can make
nylon parachutes
and ropes for rock
climbing?
2020-21
Page 3


SYNTHETIC FIBRES AND PLASTICS
SYNTHETIC FIBRES AND PLASTICS
T
he clothes which we wear are
made of fabrics. Fabrics
are made from fibres obtained
from natural or artificial sources. Can
you name some natural fibres? Fibres
are also used for making a large variety
of household articles. Make a list of some
common articles made from fibres. Try
to separate them into those made from
natural fibres and those made from
artificial fibres. Make entries in Table 3.1.
Why did you label some fibres as
artificial?
You have read in your previous
classes that natural fibres like cotton,
wool, silk, etc., are obtained from plants
or animals. The synthetic fibres, on the
other hand, are made by human beings.
That is why these are called synthetic
or man-made fibres.
3.1 What are Synthetic
Fibres?
Try to recall the uniform pattern found
in a necklace of beads joined with the
help of a thread [Fig. 3.1(a)]. Or, try to
join a number of paper clips together to
make a long chain, as in Fig. 3.1 (b). Is
there any similarity between the two?
Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : ( ( ( ( (a a a a a) ) ) ) ) Beads and (b (b (b (b (b) ) ) ) ) Paper clips
joined to form long chains
(a) (b)
Table 3.1 : Natural and Artificial
Fibres
S. No. Name of Type of Fibre
Article (Natural/
artificial)
A synthetic fibre is also a chain of
small units joined together. Each small
unit is actually a chemical substance.
Many such small units combine to form
a large single unit called a polymer. The
word ‘polymer’ comes from two Greek
words; poly meaning many and mer
meaning part/unit. So, a polymer is made
of many repeating units.
2020-21
Polymers occur in nature also. Cotton,
for example, is a polymer called
cellulose. Cellulose is made up of a
large number of glucose units.
3.2 Types of Synthetic Fibres
Rayon
You have read in Class VII that silk fibre
obtained from silkworm was discovered
in China and was kept as a closely
guarded secret for a long time. Fabric
obtained from silk fibre was very costly.
But its beautiful texture fascinated
everybody. Attempts were made to make
silk artificially. Towards the end of the
nineteenth century, scientists were
successful in obtaining a fibre having
properties similar to that of silk. Such a
fibre was obtained by chemical
treatment of wood pulp. This fibre was
called rayon or artificial silk.  Although
rayon is obtained from a natural source,
wood pulp, yet it is a man-made fibre. It
is cheaper than silk and can be woven
like silk fibres. It can also be dyed in a
wide variety of colours. Rayon is mixed
with cotton to make bed sheets or mixed
with wool to make carpets. (Fig. 3.2.)
Nylon
Nylon is another man-made fibre. In
1931, it was made without using any
natural raw material (from plant or
animal). It was prepared from coal, water
and air. It was the first fully synthetic
fibre.
Nylon fibre was strong, elastic and
light. It was lustrous and easy to wash.
So, it became very popular for making
clothes.
We use many articles made from
nylon, such as socks, ropes, tents,
toothbrushes, car seat belts, sleeping
bags, curtains, etc. (Fig. 3.3). Nylon is
SYNTHETIC FIBRES AND PLASTICS 33
Fig. 3.2 : Articles made of rayon
Fig. 3.3: Various articles made from nylon
Is nylon fibre
really so strong
that we can make
nylon parachutes
and ropes for rock
climbing?
2020-21
SCIENCE 34
Fig. 3.4: Use of nylon Fibres
Fig. 3.5: An iron stand with a thread hanging
from the clamp
also used for making parachutes and
ropes for rock climbing (Fig. 3.4). A
nylon thread is actually stronger than
a steel wire.
Let us find out.
Activity 3.1
Take an iron stand with a clamp.
Take a cotton thread of about 60
cm length. Tie it to the clamp so
that it hangs freely from it as shown
in Fig. 3.5. At the free end suspend
a pan so that weight can be placed
in it. Add weight one by one till the
thread breaks. Note down the total
weight required to break the thread.
This weight indicates the strength
of the fibre. Repeat the same activity
with threads of wool, polyester, silk
and nylon. Tabulate the data as
shown in Table 3.2. Arrange the
threads in order of their increasing
strength.
Observation Table 3.2
S. No. Type of Total Weight required
Thread/Fibre to break the Thread
1. Cotton
2. Wool
3. Silk
4. Nylon
You may use a hook or a nail on
the wall for hanging the fibres and
a polythene bag at the other end.
In place of weights you may
use marbles (or pebbles) of
similar size.
(Precaution : Note that all threads
should be of the same length and
almost of the same thickness.)
Polyester and Acrylic
Polyester is another synthetic fibre.
Fabric made from this fibre does not get
wrinkled easily. It remains crisp and is
easy to wash. So, it is quite suitable  for
making dress material. You must have
seen people wearing polyester shirts and
other dresses. Terylene is a popular
polyester. It can be drawn into very fine
2020-21
Page 4


SYNTHETIC FIBRES AND PLASTICS
SYNTHETIC FIBRES AND PLASTICS
T
he clothes which we wear are
made of fabrics. Fabrics
are made from fibres obtained
from natural or artificial sources. Can
you name some natural fibres? Fibres
are also used for making a large variety
of household articles. Make a list of some
common articles made from fibres. Try
to separate them into those made from
natural fibres and those made from
artificial fibres. Make entries in Table 3.1.
Why did you label some fibres as
artificial?
You have read in your previous
classes that natural fibres like cotton,
wool, silk, etc., are obtained from plants
or animals. The synthetic fibres, on the
other hand, are made by human beings.
That is why these are called synthetic
or man-made fibres.
3.1 What are Synthetic
Fibres?
Try to recall the uniform pattern found
in a necklace of beads joined with the
help of a thread [Fig. 3.1(a)]. Or, try to
join a number of paper clips together to
make a long chain, as in Fig. 3.1 (b). Is
there any similarity between the two?
Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : ( ( ( ( (a a a a a) ) ) ) ) Beads and (b (b (b (b (b) ) ) ) ) Paper clips
joined to form long chains
(a) (b)
Table 3.1 : Natural and Artificial
Fibres
S. No. Name of Type of Fibre
Article (Natural/
artificial)
A synthetic fibre is also a chain of
small units joined together. Each small
unit is actually a chemical substance.
Many such small units combine to form
a large single unit called a polymer. The
word ‘polymer’ comes from two Greek
words; poly meaning many and mer
meaning part/unit. So, a polymer is made
of many repeating units.
2020-21
Polymers occur in nature also. Cotton,
for example, is a polymer called
cellulose. Cellulose is made up of a
large number of glucose units.
3.2 Types of Synthetic Fibres
Rayon
You have read in Class VII that silk fibre
obtained from silkworm was discovered
in China and was kept as a closely
guarded secret for a long time. Fabric
obtained from silk fibre was very costly.
But its beautiful texture fascinated
everybody. Attempts were made to make
silk artificially. Towards the end of the
nineteenth century, scientists were
successful in obtaining a fibre having
properties similar to that of silk. Such a
fibre was obtained by chemical
treatment of wood pulp. This fibre was
called rayon or artificial silk.  Although
rayon is obtained from a natural source,
wood pulp, yet it is a man-made fibre. It
is cheaper than silk and can be woven
like silk fibres. It can also be dyed in a
wide variety of colours. Rayon is mixed
with cotton to make bed sheets or mixed
with wool to make carpets. (Fig. 3.2.)
Nylon
Nylon is another man-made fibre. In
1931, it was made without using any
natural raw material (from plant or
animal). It was prepared from coal, water
and air. It was the first fully synthetic
fibre.
Nylon fibre was strong, elastic and
light. It was lustrous and easy to wash.
So, it became very popular for making
clothes.
We use many articles made from
nylon, such as socks, ropes, tents,
toothbrushes, car seat belts, sleeping
bags, curtains, etc. (Fig. 3.3). Nylon is
SYNTHETIC FIBRES AND PLASTICS 33
Fig. 3.2 : Articles made of rayon
Fig. 3.3: Various articles made from nylon
Is nylon fibre
really so strong
that we can make
nylon parachutes
and ropes for rock
climbing?
2020-21
SCIENCE 34
Fig. 3.4: Use of nylon Fibres
Fig. 3.5: An iron stand with a thread hanging
from the clamp
also used for making parachutes and
ropes for rock climbing (Fig. 3.4). A
nylon thread is actually stronger than
a steel wire.
Let us find out.
Activity 3.1
Take an iron stand with a clamp.
Take a cotton thread of about 60
cm length. Tie it to the clamp so
that it hangs freely from it as shown
in Fig. 3.5. At the free end suspend
a pan so that weight can be placed
in it. Add weight one by one till the
thread breaks. Note down the total
weight required to break the thread.
This weight indicates the strength
of the fibre. Repeat the same activity
with threads of wool, polyester, silk
and nylon. Tabulate the data as
shown in Table 3.2. Arrange the
threads in order of their increasing
strength.
Observation Table 3.2
S. No. Type of Total Weight required
Thread/Fibre to break the Thread
1. Cotton
2. Wool
3. Silk
4. Nylon
You may use a hook or a nail on
the wall for hanging the fibres and
a polythene bag at the other end.
In place of weights you may
use marbles (or pebbles) of
similar size.
(Precaution : Note that all threads
should be of the same length and
almost of the same thickness.)
Polyester and Acrylic
Polyester is another synthetic fibre.
Fabric made from this fibre does not get
wrinkled easily. It remains crisp and is
easy to wash. So, it is quite suitable  for
making dress material. You must have
seen people wearing polyester shirts and
other dresses. Terylene is a popular
polyester. It can be drawn into very fine
2020-21
SYNTHETIC FIBRES AND PLASTICS 35
My mother always
buys PET bottles and
PET jars for storing
rice and sugar. I
wonder what PET is!
Oh! Now I understand why
my mother never wears
polyester clothes while
working in the kitchen.
PET (polyethylene terephthalate) is
a very familiar form of polyester. It is
used for making bottles, utensils, films,
wires and many other useful products.
Look around and make a list of
things made of polyester.
Polyester (Poly+ester) is actually made
up of the repeating units of a chemical
called an ester. Esters are the
chemicals which give fruits their smell.
Fabrics are sold by names like polycot,
polywool, terrycot, etc. As the name
suggests, these are made by mixing two
types of fibres. Polycot is a mixture of
polyester and cotton. Polywool is a
mixture of polyester and wool.
We wear sweaters and use shawls
or blankets in the winter. Many of these
are actually not made from natural
wool, though they appear to resemble
wool. These are prepared from another
type of synthetic fibre called  acrylic.
The wool obtained from natural
sources is quite expensive, whereas
clothes made from acrylic are relatively
cheap. They are available in a variety
of colours. Synthetic fibres are
more durable and affordable which
makes them more popular than
natural fibres.
You have already performed an
activity of burning natural and
synthetic fibres (Activity 3.6 of Class
VII). What did you observe? When you
burn synthetic fibres you find that
their behaviour is different from
that of the natural fibres. You must
have noticed that synthetic fibres
melt on heating. This is actually a
disadvantage of synthetic fibres. If the
clothes catch fire, it can be disastrous.
The fabric melts and sticks to the body
of the person wearing it. We should,
therefore, not wear synthetic clothes
while working in in the kitchen or in
a laboratory.
All the synthetic fibres are prepared
by a number of processes using raw
materials of petroleum origin, called
petrochemicals.
3.3 Characteristics of
Synthetic Fibres
Imagine that it is a rainy day. What kind
of umbrella would you use and why?
Synthetic fibres possess unique
characteristics which make them
popular dress materials. They dry up
quickly, are durable, less expensive,
readily available and easy to maintain.
Perform the following activity and learn
for yourself.
fibres that can be woven like any
other yarn.
2020-21
Page 5


SYNTHETIC FIBRES AND PLASTICS
SYNTHETIC FIBRES AND PLASTICS
T
he clothes which we wear are
made of fabrics. Fabrics
are made from fibres obtained
from natural or artificial sources. Can
you name some natural fibres? Fibres
are also used for making a large variety
of household articles. Make a list of some
common articles made from fibres. Try
to separate them into those made from
natural fibres and those made from
artificial fibres. Make entries in Table 3.1.
Why did you label some fibres as
artificial?
You have read in your previous
classes that natural fibres like cotton,
wool, silk, etc., are obtained from plants
or animals. The synthetic fibres, on the
other hand, are made by human beings.
That is why these are called synthetic
or man-made fibres.
3.1 What are Synthetic
Fibres?
Try to recall the uniform pattern found
in a necklace of beads joined with the
help of a thread [Fig. 3.1(a)]. Or, try to
join a number of paper clips together to
make a long chain, as in Fig. 3.1 (b). Is
there any similarity between the two?
Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : Fig. 3.1 : ( ( ( ( (a a a a a) ) ) ) ) Beads and (b (b (b (b (b) ) ) ) ) Paper clips
joined to form long chains
(a) (b)
Table 3.1 : Natural and Artificial
Fibres
S. No. Name of Type of Fibre
Article (Natural/
artificial)
A synthetic fibre is also a chain of
small units joined together. Each small
unit is actually a chemical substance.
Many such small units combine to form
a large single unit called a polymer. The
word ‘polymer’ comes from two Greek
words; poly meaning many and mer
meaning part/unit. So, a polymer is made
of many repeating units.
2020-21
Polymers occur in nature also. Cotton,
for example, is a polymer called
cellulose. Cellulose is made up of a
large number of glucose units.
3.2 Types of Synthetic Fibres
Rayon
You have read in Class VII that silk fibre
obtained from silkworm was discovered
in China and was kept as a closely
guarded secret for a long time. Fabric
obtained from silk fibre was very costly.
But its beautiful texture fascinated
everybody. Attempts were made to make
silk artificially. Towards the end of the
nineteenth century, scientists were
successful in obtaining a fibre having
properties similar to that of silk. Such a
fibre was obtained by chemical
treatment of wood pulp. This fibre was
called rayon or artificial silk.  Although
rayon is obtained from a natural source,
wood pulp, yet it is a man-made fibre. It
is cheaper than silk and can be woven
like silk fibres. It can also be dyed in a
wide variety of colours. Rayon is mixed
with cotton to make bed sheets or mixed
with wool to make carpets. (Fig. 3.2.)
Nylon
Nylon is another man-made fibre. In
1931, it was made without using any
natural raw material (from plant or
animal). It was prepared from coal, water
and air. It was the first fully synthetic
fibre.
Nylon fibre was strong, elastic and
light. It was lustrous and easy to wash.
So, it became very popular for making
clothes.
We use many articles made from
nylon, such as socks, ropes, tents,
toothbrushes, car seat belts, sleeping
bags, curtains, etc. (Fig. 3.3). Nylon is
SYNTHETIC FIBRES AND PLASTICS 33
Fig. 3.2 : Articles made of rayon
Fig. 3.3: Various articles made from nylon
Is nylon fibre
really so strong
that we can make
nylon parachutes
and ropes for rock
climbing?
2020-21
SCIENCE 34
Fig. 3.4: Use of nylon Fibres
Fig. 3.5: An iron stand with a thread hanging
from the clamp
also used for making parachutes and
ropes for rock climbing (Fig. 3.4). A
nylon thread is actually stronger than
a steel wire.
Let us find out.
Activity 3.1
Take an iron stand with a clamp.
Take a cotton thread of about 60
cm length. Tie it to the clamp so
that it hangs freely from it as shown
in Fig. 3.5. At the free end suspend
a pan so that weight can be placed
in it. Add weight one by one till the
thread breaks. Note down the total
weight required to break the thread.
This weight indicates the strength
of the fibre. Repeat the same activity
with threads of wool, polyester, silk
and nylon. Tabulate the data as
shown in Table 3.2. Arrange the
threads in order of their increasing
strength.
Observation Table 3.2
S. No. Type of Total Weight required
Thread/Fibre to break the Thread
1. Cotton
2. Wool
3. Silk
4. Nylon
You may use a hook or a nail on
the wall for hanging the fibres and
a polythene bag at the other end.
In place of weights you may
use marbles (or pebbles) of
similar size.
(Precaution : Note that all threads
should be of the same length and
almost of the same thickness.)
Polyester and Acrylic
Polyester is another synthetic fibre.
Fabric made from this fibre does not get
wrinkled easily. It remains crisp and is
easy to wash. So, it is quite suitable  for
making dress material. You must have
seen people wearing polyester shirts and
other dresses. Terylene is a popular
polyester. It can be drawn into very fine
2020-21
SYNTHETIC FIBRES AND PLASTICS 35
My mother always
buys PET bottles and
PET jars for storing
rice and sugar. I
wonder what PET is!
Oh! Now I understand why
my mother never wears
polyester clothes while
working in the kitchen.
PET (polyethylene terephthalate) is
a very familiar form of polyester. It is
used for making bottles, utensils, films,
wires and many other useful products.
Look around and make a list of
things made of polyester.
Polyester (Poly+ester) is actually made
up of the repeating units of a chemical
called an ester. Esters are the
chemicals which give fruits their smell.
Fabrics are sold by names like polycot,
polywool, terrycot, etc. As the name
suggests, these are made by mixing two
types of fibres. Polycot is a mixture of
polyester and cotton. Polywool is a
mixture of polyester and wool.
We wear sweaters and use shawls
or blankets in the winter. Many of these
are actually not made from natural
wool, though they appear to resemble
wool. These are prepared from another
type of synthetic fibre called  acrylic.
The wool obtained from natural
sources is quite expensive, whereas
clothes made from acrylic are relatively
cheap. They are available in a variety
of colours. Synthetic fibres are
more durable and affordable which
makes them more popular than
natural fibres.
You have already performed an
activity of burning natural and
synthetic fibres (Activity 3.6 of Class
VII). What did you observe? When you
burn synthetic fibres you find that
their behaviour is different from
that of the natural fibres. You must
have noticed that synthetic fibres
melt on heating. This is actually a
disadvantage of synthetic fibres. If the
clothes catch fire, it can be disastrous.
The fabric melts and sticks to the body
of the person wearing it. We should,
therefore, not wear synthetic clothes
while working in in the kitchen or in
a laboratory.
All the synthetic fibres are prepared
by a number of processes using raw
materials of petroleum origin, called
petrochemicals.
3.3 Characteristics of
Synthetic Fibres
Imagine that it is a rainy day. What kind
of umbrella would you use and why?
Synthetic fibres possess unique
characteristics which make them
popular dress materials. They dry up
quickly, are durable, less expensive,
readily available and easy to maintain.
Perform the following activity and learn
for yourself.
fibres that can be woven like any
other yarn.
2020-21
SCIENCE 36
(a)
Fig. 3.6 : (a) Linear (b) Cross-linked
arrangements
(b)
Fig. 3.7 : Various articles made of plastics
Activity 3.2
Take two cloth pieces of the same
size, roughly half a metre square
each. One of these should be from
natural fibre. The other could be a
synthetic fibre. You can take help
of your parents in selecting these
pieces. Soak the pieces in different
mugs each containing the same
amount of water. Take the pieces
out of the containers after five
minutes and spread them in the sun
for a few minutes. Compare the
volume of the water remaining in
each container.
Do synthetic fabrics soak less/more
water than the natural fabrics? Do they
take less/more time to dry?
What does this activity tell you about
the characteristics of the synthetic fabrics?
Find out from your parents about the
durability, cost and maintenance of these
fabrics, compared to the natural fabrics.
3.4 Plastics
You must be familiar with many plastic
articles used everyday. Make a list of
such items and their uses.
Plastic is also a polymer like the
synthetic fibre. All plastics do not
have the same type of arrangement of
units. In some it is linear, whereas in
others it is cross-linked. (Fig. 3.6).
Plastic articles are available in all
possible shapes and sizes as you can
see in Fig. 3.7. Have you ever
wondered how this is possible? The
fact is that plastic is easily mouldable
i.e. can be shaped in any form. Plastic
can be recycled, reused, coloured,
melted, rolled into sheets or made into
wires. That is why it finds such a
variety of uses.
Polythene (Poly+ethene) is an example
of a plastic. It is used for making
commonly used polythene bags.
Now, try to bend a piece of plastic
yourself. Can all the plastic articles be
bent easily?
You will observe that some plastic
articles can bend easily while some
break when forced to bend. When we
2020-21
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,

Extra Questions

,

Free

,

shortcuts and tricks

,

pdf

,

Viva Questions

,

NCERT Textbook - Synthetic Fibers And Plastics Class 8 Notes | EduRev

,

Summary

,

Important questions

,

ppt

,

study material

,

Previous Year Questions with Solutions

,

Objective type Questions

,

Semester Notes

,

NCERT Textbook - Synthetic Fibers And Plastics Class 8 Notes | EduRev

,

past year papers

;