AP State Syllabus AP Board 8th Class Physical Science Solutions Chapter 4 Synthetic Fibres and Plastics Textbook Questions and Answers.
AP State Syllabus 8th Class Physical Science Solutions 4th Lesson Synthetic Fibres and Plastics
8th Class Physical Science 4th Lesson Synthetic Fibres and Plastics Textbook Questions and Answers
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Explain why some fibres are called synthetic.
Unlike natural fibres, synthetic fibres are made from petroleum based chemicals or petrochemicals. Petrochemicals are subjected to various chemical processes to obtain synthetic fibres. Due to this they are called artificial fibres or synthetic fibres.
Give reasons why plastic containers are used as storage devices.
Plastic containers are used as storage devices because
- They are non-reactive: Metals like iron get rusted when they left exposed to moisture and air. But plastic do not react with water and air. So they are not corroded easily.
- Plastic is light, strong and durable: Plastics are very strong, light and durable can be moulded into different shapes.
- Lower price: Plastics have relatively lower price when compared with metals.
Classify following materials which can be, cannot be recycled.
Plastic toys, electrical switches, plastic chairs, ball point pens, plastic containers, cooker handles, plastic bottles, carry bags, tumblers, tooth brush, plastic chapels, plastic plates, plastic buckets.
|Plastic toys||– recycled|
|Plastic chairs||– recycled|
|Ball point pens||– not recycled|
|Tooth brush||– not recycled|
|Cooker handles||– not recycled|
|Plastic containers||– recycled|
|Plastic bottles||– recycled|
|Carry bags||– not recycled|
|Electrical switches||– not recycled|
|Plastic chapels||– recycled|
|Plastic plates||– not recycled|
|Plastic buckets||– recycled|
If electric switches are made by thermoplastics what would happen?
Thermoplastics are become soft on heating and they can change their shape. Heat developed due to electricity may change the shape of switches and they become soft whereas thermosetting plastics once moulded does not change their shape and they comparatively bad conductors of heat and electricity than thermoplastics. So thermo-plastics are not preferable in making of electrical switches.
Thermoplastics are ecofriendly than thermosetting plastics. What do you say? Why?
Yes, they are ecofriendly when compared with thermosetting plastics. The reason is plastics are non-biodegradable material. Land filling of plastic and burning of plastic in incenerators are the ways of disposal of plastic. These two ways are harmful to environment. The better method is recycling of plastic. Which is possible with only thermoplastics and thermosetting plastics cannot be recycled. Therefore we consider thermoplastics as ecofriendly.
Explain the following.
a) Blending: Any synthetic fibre can be combined with two or more other fibres is called blending. Natural and synthetic fibres are often blended for preparing better fabric.
When first fibre is blended with second fabric it gives us a blended fabric which possess the best quality of both.
Eg: We know cotton wearing is comfortable and polyester is wrinkle free. When cotton and polyester blend the end result of fabric formed is comfortable and wrinkle free.
b) Biodegradable: A material which is easily decomposed by natural process is called biodegradable. Eg: Vegetables, fruits, paper, cotton, clothes, woolen clothes, etc.
c) Recycling: Recycling is a process of conversion of broken plastic material into new plastic products.
d) Decomposition: Certain materials can break down in to smaller fragments in the presence of water, sunlight and oxygen. These fragments get further broken down by bacteria. This is called decomposition.
Match the following.
Group – A Group – B
1. Polyester ( ) A) Kitchenware
2. PET ( ) B) Artificial silk
3. Rayon ( ) C) Many monomers
4. Nylon ( ) D) Electric switches
5. Melamine ( ) E) Code 1
6. Polyethene ( ) F) Popular dress material
7. Bakelite ( ) G) Stronger than any fiber
Fill in the blanks.
i) Synthetic fibres are called as …………….. fibres.
ii) Synthetic fibres are synthesized from raw material called ……………. .
iii) Like synthetic fibre, plastic also ……………… .
iv) Clothing labels are
A) Required by law
B) Identify fabric content
C) Both A and B
D) None of the above
v) Rayon is made of
vi) A silk fibre’s smooth surface absorbs light
C) Can’t say
iv) B) Identify fabric content
v) D) Cellulose
vi) B) No
Where do we use the process of recycling? How is it useful? Give examples.
The process of recycling is useful for plastic which are non-biodegradable material. The broken plastic material articles collected from the households and send it for recycling. From this recycled plastic new products are prepared after giving it a proper treatment.
e.g.: Pet bottles, plastic carry bags, coffee cups, egg boxes.
Prepare a table of various synthetic fibers which are used to make household articles from them.
|Synthetic fibre||Household item|
|Nylon||It is used in most hosiery articles such as stockings. Also tooth brush bristles, ropes, tents, sarees, socks, car seat belts, sleeping bags, curtains, carpets, fishing nets, etc.|
|Synthetic fibre||Bead necklace, paper clip, paper clip, chain, etc.|
|Rayon||It is used to prepare sarees, bed sheets, carpets, fashion and home furnishings, sanitary products, diapers and bandages and lints for dressing wounds, etc.|
|Acrylic||It is used in knitted apparels such as fleece, socks, sportswear and sweaters.
It is also used in craft yarns, upholstery fabrics, carpets, luggage awnings and vehicle covers, etc.
|Polyesters||Polyester is used to make dresses, PET bottles, utensils, fibres, wires etc.|
|Polyesters||Polyester is made by reacting dicarboxylic acid with dihydric alcohol.|
|Nylon||Nylon is made of chemical units called polyamides (carbon, oxygen, nitrogen)|
|Rayon||The cellulose collected from plants is treated with sodium hydroxide, carbon disulphide and into dilute sulphuric acid.|
|Acrylic||It is made from the combination of coal, air, water, oil and limestone.|
Explain the differences between the thermoplastics and thermosetting plastics with the help of a diagram explaining in terms of arrangements of monomers.
Introduction of synthetic fibres in the textile industry brought revolutionary change across the world in the dressing patterns irrespective of culture and customs. How do you appreciate this?
Synthetic fibres are used everywhere in the world due to their specific characteristics that is they are durable, less expensive, readily available, affordable and are easy for maintenance. So they are decreasing the boundaries of races. So synthetic fibres are one of the factor which make the people unite irrespective of culture and costumes.
How synthetic fibres changed our everyday life?
Synthetic fibres are more comfortable and wrinkle free. They does not shrinks. They exists in different colours. They are less expensive. They absorb less water and dry at a faster rate. They exists in different designs. They are durable and readily available. Different synthetic fibre clothes are available for different seasons. Now synthetic fibres are essential part of our life. So synthetic fibres changed our life.
Nibha wants to buy clothes to parents for winter wear. What type of clothes would you suggest? Specify reasons.
We would suggest clothes made of acrylic. The reason is it is affordable and accessible. It is cheap and easily available. It has all the characteristics of wool so considered as artificial wool. So it is preferable to wear clothes made of acrylic in winter.
If plastic is not properly disposed, what could be the consequences?
Plastics take several years to decompose. Slow decomposition of plastics causes environment pollution. The polythene bags thrown around are responsible for clogging drains. The animals in urban areas are dying due to eating of polythene bags containing food material. They not only posed a great threat to nature and environment but also to the human race itself. The burning process of plastic is also very slow and cannot be burnt completely. The process of burning release a lot of poisonous fumes in to air causing air pollution. So plastics should be properly disposed that is recycling process is used.
Indiscriminate usage of plastic is a serious threat to bio-diversity. What are the efforts of government and non-government organization in this regard?
Efforts of government and non-government organisation:
- Andhra Pradesh based NGO’s drawing court attention that 30 – 60 kg of plastic bags recovered from the stomache of cows.
- Private institutions in Kozikode, Kerala fighted against plastic wastes and their consequences on environment.
- Government has burned plastic carry bags less than 40 microns.
- Many non-government organisations are giving publicity about the harmful effects of plastics. They are encouraging people to use bags made of cotton.
- Various non-government organisations are collecting plastics from households and send it for recycling.
- Government is planning to solid plastic waste into resources such as electricity, heat, compost.
Take hair, wool, silk, paper, cotton thread, piece of plastic, thread of sweater, piece of rope and carefully conduct a flame test. Based on smell and type of melting classify them as natural or artificial fibres.
If they burn with black deposit of carbon then the fibres are natural. If they melt they are artificial fibres.
|Fibre||Natural / Artificial|
|5. Cotton thread||Natural|
|6. Piece of plastic||Artificial|
|7. Thread of sweater||Natural|
|8. Piece of rope (Plastic)||Artificial|
Prepare a chart which can explain recycling codes, full name and acronym of plastic and its usage for various household articles, recycled or not, if recycled what will be made from that?
Recycle code symbols:
8th Class Physical Science 4th Lesson Synthetic Fibres and Plastics InText Questions and Answers
8th Class Physical Science Textbook Page No. 45
Are all of our clothes made of natural fibres?
No, there are two types of fibres. They are natural fibres and synthetic fibres. Nowadays we make up artificial fibres from natural fibres by adding petroleum products.
8th Class Physical Science Textbook Page No. 46
What do you know about synthetic fibres? How are they manufactured?
The artificial fibres obtained from plant or animal source are called synthetic fibres. They are made by the raw materials obtained from petroleum, e.g.: Polyester, nylon and acrylic.
What does polymer mean?
The word polymer was derived from Greek. Poly means many and mer means part/unit.
8th Class Physical Science Textbook Page No. 53
Why are soft drinks stored in PET bottles?
Soft drinks are carbonated so they are stored in PET bottles which are non-reactive with carbonated drinks.
Think and Discuss
8th Class Physical Science Textbook Page No. 46
What made the human beings to search for the alternative for natural fibres?
Human beings used to wear clothes made by natural fibres like cotton, wool, silk, etc.
They do not have uniform thickness, they are costly, less durable, not readily avail¬able, they are not wrinkle free, they do not have water proof, they are not lustrous. So in order to avoid these advantages of natural fibres human beings made search for alternative for natural fibres.
Which fibre source is not exhaustible? Why?
Natural fibre source is not exhaustible because they are made from plants and animals. Where as artificial fibres are made from petrochemicals which are exhaustible.
8th Class Physical Science Textbook Page No. 47
How synthetic fibres evolved to the present position?
Synthetic fibres are cheap, durable, readily available, wrinkle free, they are affordable and easy maintenance made them to evolve the present position.
8th Class Physical Science Textbook Page No. 49
If we use cotton cloth and cotton ropes in preparing a parachute, what will happen?
Cotton thread does not resist to higher weights. So the rope breaks. So it is not preferable to use cotton cloth and cotton rope in preparing parachutes.
Traditionally fishermen used cotton nets. Now they are using nylon nets. What is the advantage of using nylon nets?
Cotton does not resist to higher weight and it is not strong. It is easily breakable with small weights. So nowadays fisherman are using nets which are made of nylon which resist to higher weights and are strong.
Nylon sarees are much better than the cotton sarees. It is better to use only nylon sarees. Do you agree with this ? Why?
Nylon fibre is strong, elastic and light weight. Cloth made of nylon are lustrous and easy to wash. Nylon does not absorb water. So in general nylon clothes are better than cotton clothes but it has some limitations that is static electricity is easily created in nylon fabric. It also easily catches to fire and nylon clothes stick to human body so we should not wear nylon clothes while cooking, welding or working near a fire or using heavy machineries. So wearing nylon sarees always is not preferable.
8th Class Physical Science Textbook Page No. 50
What characteristics make rayon better than natural silk?
Artificial rayon is cheaper than silk and can be woven like silk fibre. It can be dyed in a wide variety of colours. So artificial rayon is better than natural silk.
If you want to purchase a doormat made of synthetic fibre, which synthetic fibre doormat will you select? Why?
We would prefer nylon for door mats because it is strong, elastic, cheap, easy to wash, does not absorb water and lustrous.
If sanitary diapers and bandages are made up of nylon, what will happen?
Nylon fibres are strong. So they are difficult to cut. So they are not preferable for sanitory diapers and bandages.
8th Class Physical Science Textbook Page No. 51
Which type of blended fabrics do you find more comfortable in winter? Why?
We would find terriwool are more comfortable in winter. The reason is terriwool is similar to wool so protect us from cold.
The fabrics namely natural, synthetic and blended are available for garments. Which fabrics will you prefer to wear for rare occasions like functions and in routine? Why?
We will prefer to wear blended fabric in rare occasions like functions because it possess best qualities of natural and artificial fibre. Generally we will prefer artificial fibre because it is cheap, durable and easily available.
8th Class Physical Science Textbook Page No. 52
Which fabric do you prefer? Natural or synthetic? Why? Discuss comparatively.
We would prefer synthetic clothes generally because they are durable, less expensive, readily available, affordable, they absorb less water and dry at faster rate, they are lustrous and they are easy for maintenance. But we would not prefer for synthetic clothes for those who are working in the kitchens and laboratories. The reason is synthetic fibres are easily catch fire and the fabric melts and sticks to the body of the person who wears it.
What is the difference between washing of clothes at home and washing by dry cleaning at laundary?
At home for washing of clothes we use detergent or washing powder and water. Whereas dry cleaning is the process conducted in the absence of water for those clothes which should not be washed with water. So in laundry dry cleaning is carried out by using organic liquids like petrol, benzene, acetone, etc.
8th Class Physical Science Textbook Page No. 57
Certain fry pans are said to be non-stick. What made them as non-stick?
Teflon is special plastic on which oil and water do not stick. It is used for non-stick coating on cookwares.
Firemen wear dress which does not catch fire. What type of fabric it is made of?
Melamine is a plastic which is fire resistable and flame resistant is used to make the dress of firemen.
8th Class Physical Science 4th Lesson Synthetic Fibres and Plastics Activities
Activity – 1
Identify household articles made up of natural and synthetic fibres.
Identify the articles around you in your surroundings and write their names against relevant category in the table.
|1. Natural fibres from plants||Cotton saree, dresses, curtains, kerchiefs.|
|2. Natural fibres from animals||Silk clothes, Woolen clothes.|
|3. Synthetic fibres||Nylon clothes, rayon clothes, polyester clothes, plastic chairs, plastic carry bags, electric switches, plastic bottles, T.V. cabinets, etc.|
Activity – 2
Beads and paper clips pattern.
Take a few paper clips and join together as shown. Observe the pattern of clips.
a) Do you find any similarity between the pattern of beads in necklace and the pattern of paper clips in the chain.
Yes, each unit of paper clips or beads can be joined together to form a long chain structure.
b) What happens if small unit of chemical substance is combined together?
It forms a large unit of polymer.
c) How does we obtain synthetic fibres?
Synthetic fibres are obtained from polymers.
d) What are the source of synthetic fibres?
Activity – 3
Identifying fibres – burning test
You can do a fibre burning test. Unravel several wrap and weft yarns. Using tweezers hold the yarn to the edge of a flame. Observe, the changes.
a) If it smells like burning hair, what is the yam is wool or silk?
It is wool or silk.
b) If it smells like burning paper, what is the yam?
The yarn may be cotton or rayon.
c) If the yam melts in the flame, what is the yam?
The yarn is synthetic fibre such as nylon and acrylic.
Activity – 4
How strong is nylon?
Take an iron stand with a clamp. Take cotton, wool, nylon and silk thread about 50 cm in length. Tie cotton thread to stand so that it hangs freely from it. At the free end, attach a pan so that a weight can be placed on it. Add weight starting from 10 grams one by one till the thread breaks down. Note down the total weight required to break the thread. Repeat the same activity with threads of wool, silk and nylon.
a) Arrange the thread in the order of increasing strength.
Cotton < Wool < Silk < Nylon
b) Do you know that if you compare nylon thread with a steel wire of same thickness, nylon will be as strong as steel wire?
Yes, it is the strongest man made fibre.
Activity – 5
Why do we combine fibres?
a) Whenever you buy clothes or ready made garments observe the brand label. What do you notice?
There is some information about cloth is written on the brand label.
b) What do you see?
We can see quality, shade no, width, contents and wash care of the cloth.
c) What is the percentage of fibres?
40% polyester and 60% cotton.
d) Why do we combine fibres? What is the process called?
We would combine two fabrics to get a fabric which has best qualities of both. This process is called blending.
Activity – 6
How can you say a bottle is PET bottle?
Collect different kinds of water bottles of your classmates and look at them carefully.
a) Do you observe any triangle shaped symbol at the bottom of the bottle or on the brand label of the sticker?
b) What number is marked at the center of the triangle?
I had observed number 5.
c) If code no. is 1 what it indicates?
It indicates PET bottle.
Activity – 7
Identification of various articles with recycling codes.
Collect bottles of soft drinks (500 ml or more), bottles of juice and containers of fruit jam, Ketchup, shampoo, coffee powder and try to look for the triangle. You can also go to the near by shop and request the shopkeeper show you the bottle.
a) What are these codes?
These are recycling codes of various types of plastic material.
b) What is the use of these codes?
We can identify what kind of material is used for the preparation of article by seeing the code at the bottom of the article.
c) Are all bottles found with codes?
Yes, all bottles have codes.
d) What code is observed for soft drinks and juices?
We can observe code T marked in the middle of triangle.
e) What about Boost or Boumavita bottles?
We can observe code 5 marked in the middle of triangle which tells us the bottle is made up of polypropylene.
Activity – 8
Types of plastics.
Let us take two bottles made up of plastic. One is PP bottle and another ordinary (PET) Pour some hot water in both.
What do you notice?
The ordinary bottle get deformed.
a) What is the code of the deformed bottle?
Code No. 2.
b) What is the name given to plastics which are deformed easily on heating?
c) What is the name given to plastics which are molded once can’t be s heating?
d) Can you tell Topper ware is thermosetting plastic or thermo plastic?
Identify whether given plastic material is thermoplastic or thermosetting plastic by using flame test. (OR)
Conduct a flame test to identify thermoplastics and thermosetting plastics. (OR)
You are given a comb, tooth brush handles, plastic bucket, handle of utensil, Electric switch, piece of melamine of meals plate and coffee mug. Explain how can you identify which object is a thermoplastic or thermosetting plastic through an activity.
Aim: Identifying thermoplastics and thermosetting plastics by flame test.
Material required: Pair of tongs, spirit lamp, samples of plastics (pieces of comb, tooth brush handle, plastic bucket, handle of utensil, electric switch, piece of melamine of meals plate and coffee mug).
- Take a spirit lamp and light it.
- Clamp one piece of plastic sample say piece of tooth brush with tong.
- Place the sample on spirit lamp flame.
- Observe the changes during the burning of sample.
- Note your observations like, whether sample is being softened or burnt with smell or become hard, etc.
- Repeat the procedure with other samples.
- Record your observations sample wise in the table.
Name of the plastic sample Softened / burnt with burning smell and become hard Thermoplastic/ Thermosetting plastic Tooth brush handle Softened Thermoplastic Comb Softened Thermoplastic Piece of bucket Softened Thermoplastic Handles of utensil Burn with burning smell and become hard Thermosetting plastic Electric switch Burn with burning smell and become hard Thermosetting plastic Meals plate Softened Thermoplastic Coffee mug Softened Thermoplastic
Activity – 9
Biodegradable – Non-biodegradable:
Let’s take peels of fruits and vegetables, left over food stuff, waste paper, cotton cloth and plastic bag. Keep this material in a pit. Open the pit after some days and list the material which remain a long time and those that disappear quickly.
|Type of waste||Approximate time to disappear||Change|
|1. Peels of fruits and vegetables||1 to 2 weeks||degradable|
|2. Left over food stuff||1 to 2 weeks||degradable|
|3. Waste paper||10 to 30 days||degradable|
|4. Cotton cloth||2 to 5 months||degradable|
|5. Plastic bag||Several years||non-degradable|
a) What is the name given to certain material which can be break down into smaller fragments in the presence of water, sun light and oxygen and by bacteria?
b) What do we call the material which are not decomposed by natural process?