SYNTHETIC FIBERS AND PLASTICS
 
1.Synthetic fibres andplastics, similar to natural fibres are made up of very large units which in turn are made up of many similiar or combination of small units. The larger units are called polymers.
 
2.Natural fibres are obtained from plant and animal sources, synthetic fibres are obtained by chemical processing of petrochemicals. The synthetic fibres can be woven into a fabric, just like natural fibres.
 
3.Synthetic fibres have its wide range of uses ranging from many household articles like ropes, buckets, furniture, containers, etc. to highly specialized used in aircrafts, ships, spacecrafts, health care, etc.
 
4.Depending upon the types of chemicals used for the manufacture of some synthetic fibres are, named as Rayon, Nylon, Polyester and Acrylic.
 
5.Rayon or Artificial Silk
  1. It is a man-made fibre obtained from a natural source wood pulp.
  2. It can be dyed in a wide variety of colors.
  3. Rayon is mixed with cotton to make bedsheets or mixed with wool to make carpets.
 
6. Nylon
  1. It was the first fully synthetic fibre. It was prepared from coal water and air.
  2. Nylon fibres are strong elastic and light, lusturus and easy to wash.

                                                              Fig. 3.1.Various articles made from Nylon
 
 
  1. It is used to make many items like socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, curtains etc.
  2. Nylon is also used for making parachutes and ropes for rock climbing.
 
7.Polyester
  1. It remains crisp, wrinkle free and easy to wash, so it is quite suitable for making dressing material.
  2. Terylene,can be drawn into very fine fibres that can be woven like any other yarn
  3. PET,is used for making bottles, utensils, films, wires and many other useful products.
 
8. Acrylic is an artificial wool.
 
9. Characteristics of Synthetic Fibres:They dry up soon, are durable, less expensive, readily available and easy to maintain
 
10. Plastics
  1. Plastics can be easily moulded into any shape.
  2. Plastics can be recycles, reused, colored melted, rolled into sheets or made into wires.
  3. Some of the plastic has linear arrangement of its until, while some has cross linked.
  4. Thermoplasticis a plastic which gets deformed easily on heating and can be bent easily e.g., Polythene and PVC. These are used for manufacturing toys, combs, cargrills and various types of containers.
  5. Thermosetting Plastics:There are some plastics which when moulded once cannot be softened by heating. These are called thermosetting plastics e.g., bakelite and melamine. Bakelite is used for making electrical switches, handles of various utensils etc. Melamine is used for making floor tiles, kitchenware etc.
 
 

Articles made of thermosetting plastics                   Articles made of thermoplastics
 

                                   Fig 3.2.Some articles made of plastic
 
11. Today life without plastics cannot be imagined. The day starts with the use of these materials e.g., use of toothbrush, bathroom slippers etc., and ends with the same, e.g., use of etc.
bed 
 
12.The waste created by the synthetic fibres and plastics is not environment or eco-friendly. On burning they create poisonous gases. On dumping in the ground they may take years to degenerate. This is because of their non-biodegradable nature.
 
13.We need to use synthetic fibres and plastics in such a manner that we can enjoy their good qualities and at the same time minimize the environmental hazards for the living communities.
 
14. Petrochemicals:All the synthetic fibres are prepared by a number of processes using raw materials of petroleum origin, called petrochemicals.
 
15. Biodegradable:Materials which get decomposed through natural processes are called biodegradable.
 
16. Non-biodegradable:Those materials which are not easily decomposed by natural process are called non-biodegradable.
 
 
 
 

 
Q. 1. Explain why some fibres are called synthetic.

Ans.
Some fibres are called synthetic because they are made by human beings.
 
Q. 2. Mark (?) the correct answer.
         Rayon is different from synthetic fibres because
  1. it has a silk like appearance
  2. it is obtained from wood pulp
  3. its fibres can also be woven like those of natural fibres
Ans.b. It is obtained from wood pulp.
 
Q. 3. Fill in the blanks with appropriate words:
  1. Synthetic fibres are also called ……... or …….. fibres.
  2. Synthetic fibres are synthesised from raw material called …….... .
  3. Like synthetic fibres, plastic is also a ...........
Ans.  (a) artificial, man-made.
          (b) petrochemicals.
          (c) artificial sources.
 
Q. 4. Give examples which indicate that nylon fibres are very strong.
Ans.Parachutes and ropes for rock climbing.
 
Q. 5. Explain why plastic containers are favoured for storing food.
Ans. Three main advantages of using plastic containers for storing food are:
  1. They do not react with food items.
  2. They do not get rusted.
  3. They are light, strong and durable.
 
Q. 6. Explain the difference between thermoplastic and thermosetting plastic
Ans.Thermoplastics can be softened on heating and can be bent easily where as thermosetting plastics cannot be softened on heating and it breaks when forced to bend.
 
Q. 7. Explain why the following are made of thermosetting plastics.
        (a) Saucepan handles
        (b) Electric plugs/switches/plug boards.
Ans.Above articles are made up of bakelite (a thermosetting plastic) because it is--
        (i) poor conductor of electricity
        (ii) heat resistant.
 
Q. 8. Categorise the materials of the following products into `can be recycled'
         and ‘cannot be recycled':
         Telephone instruments, plastic toys, cooker handles, carry bags, ball point pens, plastic bowls, plastic covering on electrical wires, plastic chairs, electrical switches.
Ans.
Can be recycledCannot be recycled
Toys, carry bags, plastic bowls, electric wire
cove ring, plastic chairs.
Telephone instruments, cooker handles, ball point pens, electrical switches.
 
Q. 9.Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana, giving your reason.
Ans.The absorbing capacity of synthetic fibres is less than cotton fibres, so the synthetic fabric soaks less water than cotton fabric. In summers we have extensive sweating which must be soaked up by our clothing. Since synthetic fabric is poor in this property we prefer cotton clothes in summers.
 
Q.10. Give examples to show that plastics are noncorrosive in nature.
 Ans.(i) It does not react with the chemical or other items stored in the containers made of it.
         (ii) It does not get rusted when exposed to moisture and air.
        (iii) It does not decompose when left in open for a long period.
           
Q. 11. Should the handle and bristles of a toothbrush be made of the same material? Explain your answer.
Ans.The bristles of the toothbrush is more flexible than the handle. An as per the use of toothbrush, both must made up of different materials.
 
Q. 12. ‘Avoid plastics as far as possible.’ Comment on this advice.
Ans. Since plastic takes several years to decompose, it is not environment friendly. It causes environmental pollution. Besides, when the synthetic material is burnt it takes a long time to get completely burnt. In the process it releases a lot of poisonous fumes into the atmosphere causing air pollution.
 
Q. 13. Match the terms of Column A correctly with the phrases given in Column B
            Column A                             Column B
           (i) Polyester                   (a)  Prepared by using wood pulp
          (ii) Teflon                        (b) Used for making parachutes and stockings
         (iii) Rayon                       (c) Used to make non-stick cookwares 
          (iv) Nylon                       (d) Fabrics do not wrinkle easily 
Ans.      Column A                       Column B
             (i) Polyester                 (d) Fabrics do not wrinkle easily 
             (ii) Teflon                     (c) Used to make non-stick cookwares 
            (iii) Rayon                    (a) Prepared by using wood pulp 
            (iv) Nylon                     (b) Used for making parachutes and stockings
 
Q. 14. Manufacturing synthetic fibres is actually helping conservation of forests.' Comment.
Ans. In the manufacturing of synthetic fibres we use no material from natural sources thus in turn, we conserve forests which may otherwise been destroyed. When we use articles made of plastics we also save thousands of trees which otherwise have to be cut if we used articles made of wood or natural fibres,
 
Q. 15. Describe an activity to show that thermoplastic is a poor conductor of electricity.
  Ans.A thermoplastic (or plastic) is poor conductor of electricity. It can be shown by           using a plastic wire as a connecting wire in a circuit. In this condition the bulb will not glow.
 
 
                                              ADDITIONAL IMPORTANT QUESTIONS

 
Q. 1. What is polymer?
Ans.It is a chain of small units, that joins together to form a synthetic fibre.
 
Q. 2. Name some natural fibres.
Ans.Cotton, wool, silk etc., are natural fibres.
 
Q. 3. Name some artificial fibres.
Ans.Nylon, Terylene, Teflon, PET, acrylic etc., are artificial fibres.
 
Q. 4. What is cellulose? 
Ans.Cellulose is a polymer made up of a large number of glucose units.
 
Q. 5. Which fibre is known as artificial silk?
Ans.Rayon.
 
Q. 6. Name the first fully synthetic fibre.
Ans.Nylon.
 
Q. 7. Why are switches and plugs made of plastic?
Ans.Because plastic is a poor conductor of heat and electricity.
 
Q. 8. Name any twothermoplastics.
Ans. Polythene and PVC (Poly Vinyl Chloride).
 
Q. 9. Name any two thermosetting plastics.
Ans.Bakelite and melamine.
 
Q. 10. Write two important properties of bakelite.
 Ans. (i) It is a poor conductor of electricity.
         (ii) It is heat resistant.
 
Q. 11. Write some uses of Bakelite.
 Ans. Bakelite is a poor conductor of electricity. It is also heat resistant and used for making electrical switches, handles of various utensils, etc.
 
Q. 12. Which raw material is used for making synthetic fibres?
 Ans.All synthetic fibres are prepared from raw materials of petroleum origin called petrochemicals.
 
Q. 13. Write some properties and uses of melamine.
 Ans.Melamine is a versatile material. It resists fire and can tolerate heat better than other plastics. It is used for making floor tiles, kitchenware and fabrics which resist fire.
 
Q. 14. What is PET?
 Ans. PET is a form of polyester. It is a synthetic material used to manufacture bottles, wires, utensil, films etc.
 
Q. 15. Write some characteristics of synthetic fibres which make them popular dress materials.
 Ans.Synthetic fibres possess unique characteristics which make them popular dress materials. They dry up soon, are durable, less expensive, readily available and easy to maintain.
 
Q. 16. Why is it advised not to wear synthetic clothes while working in a laboratory or working with fire in the kitchen?
Ans.The synthetic fibres melt on heating. This is actually a disadvantage with synthetic Fibres. If the cloth catches fire it can be very disastrous. The fabric melts and sticks to the Body of the person wearing it. It is therefore advised not to wear synthetic clothes while working in a laboratory or working with fire in the kitchen.
 
Q. 17. By which material artificial wool is formed? Why artificial wool has become more popular than natural wool?
Ans.Artificial wool is prepared from another type of synthetic fibre called acrylic. The obtained from natural sources is quite expensive whereas materials made from acrylic are relatively cheap. They are available in a variety of colors. Synthetic fibres are more durable and affordable which makes them more popular than natural fibres.
 
Q. 18. What is thermoplastic and thermosetting plastic?
Ans.Some plastics can bend easily while some break when forced to bend. When we add  hot water to a plastic bottle, it gets deformed. Such plastic which gets deformed easily on heating and can be bent easily is known as thermoplastic.
            On the other hand, there are some plastics which when moulded once, cannot be softened
by heating. These are called thermosetting plastics.
 
Q. 19. What is rayon? Write its some uses.
Ans.Rayon is obtained from a natural source, wood pulp, it is a man-made fibre. It is chapter than silk,, but can be woven like silk fibres. It can also be dyed in a wide variety of colors. Rayon is mixed with cotton to make bed sheets or mixed with wool to make carpets (fig. 3.3)
 

 
Fig. 3.3.Picture of articles made of rayon
 
Q. 20. Why polyester is quite suitable for making dress materials? Name any two types of polyesters and their uses.
Ans.Fabric made from polyester 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 n ice polyester shirts and other dresses. Terylene is a type of popular polyester. It can be drawn into very fine fibres that can be woven like any other yarn.
             PET is a very familiar form of polyester. It is used for making bottles, utensils, films, wires and many other useful products.
 
Q. 21. Write some properties of plastic which make them as materials of choice.
   Ans.Some characteristic properties of plastic are:
           (i)  Plastic is non-reactive and non-corrosive.
           (ii) Plastic is light, strong and durable.
          (iii) Plastics are poor conductors of heat and electricity.
 
Q. 22. Write short notes on the following:
(a) Plastic and health care industry           (b) Plastic cookware
(c) Teflon                                                  (d) Fire proof plastic.
 
Ans.(a) Plastic and Health Care Industry: Plastics find extensive use in the health care industry. Some examples of their use in. health care are the packaging of tablets, threads used for stitching wounds, syringes, doctor's gloves, a number of medical instruments etc.
 
(b) Plastic Cookware: Plastic cookware is used in microwave ovens for cooking food. The heating process is different in microwave ovens. The heat cooks the food but does not affect the plastic vessel.
 
(c) Teflon: Teflon is a non-stick plastic used as non-stick coating in cookware. It is also used as tape for sealing purposes.
 
(d) Fire Proof Plastic: Although synthetic fibre catches fire easily, it is interesting to know that the fire proof material is made from synthetic plastics.
 
Q. 23. What are biodegradable and non-biodegradable materials?
Ans.A material which gets decomposed through natural processes, by the action of microbes is called biodegradable. A material which is not easily decomposed by natural processes is termed as non-biodegradable.
 
Q. 24. Write some disadvantages of synthetic fibres.
Ans.
  1. Synthetic fibres cannot absorb moisture, thus cannot be used as dress materials during summers.
  2. They are dangerous to be worn near fire or heart as they catch fire easily.
  3. They cannot be easily ironed
 
Q. 25. Write the properties and uses of Nylon.
Ans.Nylon fibre is strong, elastic and light. It is lustrous and easy to wash. So, it is very popular for making clothes.
we use many items made from nylon like socks, ropes, tents, toothbrushes, car seat, belts, sleeping bags, curtains, etc. Nylon is also used for making parachutes and ropes for rock climbing.
 
Q. 26. What is the chemical nature of polyester? What are polycot and polywool?
Ans.Polyester (Poly + ester ) is actually made up the repeating units of a chemical Called an ester. Esters are the chemicals which give characteristics smell like fruits. 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.
 
Q. 27. Why are plastics considered a threat to our environment?
Ans.Plastics cannot be easily decomposed. When it is burnt to get rid of waste, it gives out poisonous gases and do not burn completely. They are non-biogradable substances. Thus plastics are considered a threat to our environment.
 
Q. 28. Whether following materials are biodegradable or non-biodegradable?
  1. Peels of vegetable and fruit.
  2. Paper
  3. Cotton cloth
  4. Wood
  5. Woollen items
  6. Tin, aluminium, and other metal cans
  7. Plastic bags.
 
 
Ans.
  1. Biodegradable
  2. Biodegradable
  3. Biodegradable
  4. Biodegradable
  5. Biodegradable
  6. Non- biodegradable
  7. Non- biodegradable
 
 
OBJECTIVE TYPE QUESTIONS
 
Q. 1. Fill in the blanks with appropriate words:
  1. Synthetic fibres are made by ……….. .
  2. Many small units combine to form a large single unit called a ……... .
  3. A nylon wire is ………. .
  4. All the synthetic fibres are prepared using raw materials of petroleum origin called.............. .
  5. Plastics are........... .
  6. Nylon was prepared from........... .
 
Q. 2. Match the following items given in Column ‘A’ with that in Column ‘B’:
 
Column 'A'Column 'B’
  1. Cotton
  2. Nylon
  3. PVC
  4. Bakelite
  5. PET
  6. Acrylic
  7. Cellulose
  8. Paper
  9. Plastic bags
  10. Teflon
  1. Thermoplastic
  2. Polyester
  3. Biodegradable
  4. Artificial fibres
  5. Artificial wool
  6. Chain of glucose units
  7. Non-biodegradable
  8. Natural fibre
  9. Cook wares
  10. Thermosetting
 
 
Q. 3. State whether the statements given below are True or False:
  1. All fibres are made up of very large units which in turn are made up of many small units.
  2. Nylon was also known as artificial silk in China.
  3. Acrylic is an artificial wool.
  4. Plastics are light , strong and durable
  5. It is not advised to store food items in plastic containers as it may react with the walls of container
  6. Bakelite is poor conductor of electricity.
 
Q. 4. Choose the correct option in the following questions:
        (i) What is the other name for artificial silk?
                  (a) Nylon                                 (b) Rayon
                  (c) Acrylic                               (d) Polyester
 
        (ii) Which fibre is used as artificial wool?
                  (a) Acrylic                               (b) Rayon 
                  (c) Nylon                                 (d) Cotton
 
        (iii) Polymers are made up of small units called
                   (a) layers                                 (b) molecules
                   (c) cells                                   (d) monomers
 
        (iv) The strongest synthetic fibre is
                   (a) nylon                                  (b) rayon
                   (c) polyester                            (d) acrylic
 
        (v) Wood pulp is used to make
                  (a) plastic                                (b) wool
                  (c) jute                                    (d) rayon
 
        (vi) Which of the following is a natural fibre?
                 (a) Wool                                 (b) Nylon
                 (c) PVC                                  (d) Polythene
 
        (vii) Melamine is
                 (a) thermoplastic polymer     (b) thermosetting polymer
                 (c) fibre                                  (d) elastomer
 
        (viii) Fibre produced in factories is called
                (a) man-made fibre               (b) natural fibre
                (c) synthetic fibre                  (d) both (a) and (c)
 
         (ix) PET is a
                (a) polyester                           (b) polyamide
                (c) nylon                                (d) thermosetting polymer
 
         (x) Which of the following cannot be recycled?
               (a) Toys                                 (b) Cooker handles
               (c) Carry bags                       (d) Plastic chair
 
         (xi) Synthetic fibres synthesised from raw materials are called
               (a) jute                                  (b) rayon
               (c) petrochemicals                (d) bakelite
 
         (xii) Bakelite is an example of
              (a) fibre                               (b) elastomer
              (c) nylon                              (d) thermosetting polymer
 
        (xiii) Which term is used for polymers made up of a large number of glucose units?
                  (a) Protein                           (b) Fructose
                 (c) Cellulose                        (d) Polyester
 
        (xiv) Which of the following is non-biodegradable?
                (a) Paper                              (b) Cotton cloth
                (c) Wood                             (d) Plastic
 
        (xv) Which of the following is natural fibre obtained from plants?
               (a) Cotton                            (b) Wool
        (c) Rayon                            (d) Ketone
 
 
 
 
 
ANSWERS TO OBJECTIVE TYPE QUESTIONS
 
Q. 1. Fill in the blanks:
         (i) human beings    (ii) polymer     (iii) stronger       (iv) petrochemicals
         (v) poor                  (vi) coal, water, air.
 
Q. 2. Match the items under Column 'A' and Column `B':
 
Column 'A'Column 'B’
  1. Cotton
  2. Nylon
  3. PVC
  4. Bakelite
  5. PET
  6. Acrylic
  7. Cellulose
  8. Paper
  9. Plastic bags
  10. Teflon
  1. Natural fibre
  2. Artificial fibres
  3. Thermoplastic
  4. Thermosetting
  5. Polyester
  6. Artificial wool
  7. Chain of glucose units
  8. Biodegradable
  9. Non-biodegradable
  10. Cook wares
 
 
Q. 3. True or False:
     i) True                 ii) False                iii) True                  iv) True            
    v) False               vi) True
 
Q. 4. Choose the correct option:
      (i) (b)                   (ii) (a)                  (iii) (d)                (iv) (a)                   (v) (d)
     
    (vi) (a)                 (vii) (b)                 (viii) (d)               (ix) (a)                   (x) (b)
 
    (xi) (c)                 (xii) (d)                 (xiii) (c)              (xiv) (d)                 (xv) (a).