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Introduction to Polymer Chemistry, EXERCISE [PAGES 337 - 339], Exercise | Q 1.01 | Page 337, Choose the correct option from the given alternatives., Nylon fibres are ______, 1. semisynthetic fibres, 2. polyamide fibres, 3. polyester fibres, 4. cellulose fibres, Solution: Nylon fibres are polyamide fibres., Exercise | Q 1.02 | Page 337, Choose the correct option from the given alternatives., Which of the following is naturally occurring polymer?, 1. Teflon, 2. Polyethylene, 3. PVC, 4. Protein, Solution: Protein, Exercise | Q 1.03 | Page 337, Choose the correct option from the given alternatives., Silk is a kind of _____ fibre., 1. Semisynthetic, 2. Synthetic, 3. Animal, 4. Vegetable, Solution: Silk is a kind of animal fibre., Exercise | Q 1.04 | Page 337, Choose the correct option from the given alternatives.
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Dacron is another name of ______., 1. Nylon 6, 2. Orlon, 3. Novolac, 4. Terylene, Solution: Dacron is another name of terylene., Exercise | Q 1.05 | Page 337, Choose the correct option from the given alternatives., Which of the following is made up of polyamides?, 1. Dacron, 2. Rayon, 3. Nylon, 4. Jute, Solution: Nylon, Exercise | Q 1.06 | Page 337, Choose the correct option from the given alternatives., The number of carbon atoms present in the ring of ɛ-caprolactam is, 1. Five, 2. Two, 3. Seven, 4. Six, Solution: Six, Exercise | Q 1.07 | Page 337, Choose the correct option from the given alternatives., Terylene is _____., 1. polyamide fibre, 2. polyester fibre, 3. vegetable fibre, 4. protein fibre, Solution: Terylene is polyester fibre.
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Exercise | Q 1.08 | Page 337, Choose the correct option from the given alternatives., PET is formed by _______., 1. addition, 2. condensation, 3. alkylation, 4. hydration, Solution: PET is formed by condensation., Exercise | Q 1.09 | Page 337, Choose the correct option from the given alternatives., Chemically pure cotton is _______., 1. acetate rayon, 2. viscose rayon, 3. cellulose nitrate, 4. cellulose, Solution: Chemically pure cotton is cellulose., Exercise | Q 1.1 | Page 337, Choose the correct option from the given alternatives., Teflon is chemically inert, due to presence of _______., 1. C-H bond, 2. C-F bond, 3. H- bond, 4. C=C bond, Solution: Teflon is chemically inert, due to presence of C-F bond., Exercise | Q 2.1 | Page 337, Answer the following in one sentence., Identify 'A' and 'B' in the following reaction ___.
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Solution: Polymer ‘A’ is:, , Exercise | Q 2.1 | Page 337, Answer the following in one sentence., Identify 'A' and 'B' in the following reaction ___., , Solution:, , Exercise | Q 2.2 | Page 337, Complete the following statement., Caprolactam is used to prepare _______., Solution: Caprolactam is used to prepare Nylon 6., Exercise | Q 2.2 | Page 337, Complete the following statement., Novolac is a copolymer of _______ and _______., Solution: Novolac is a copolymer of Phenol and formaldehyde., Exercise | Q 2.2 | Page 337, Complete the following statement., Terylene is _______ polymer of terephthalic acid and ethylene glycol, Solution: Terylene is condensation polymer of terephthalic acid and ethylene glycol., Exercise | Q 2.2 | Page 337, Complete the following statement.
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Benzoyl peroxide used in addition polymerisation acts as _______., Solution: Benzoyl peroxide used in addition polymerisation acts as initiator., Exercise | Q 2.2 | Page 337, Complete the following statement., Polythene consists of polymerized_______., Solution: Polythene consists of polymerized ethene., Exercise | Q 2.3 | Page 338, Draw the flow chart diagram to show the classification of polymers based on the type of, polymerization., Solution:, , Exercise | Q 2.4 | Page 338, Answer the following in one sentence., Write examples of addition polymers and condensation polymers., Solution:, 1. Addition polymers:, Polythene, Teflon, Polyacrylonitrile, Polyvinylchloride (PVC), etc., 2. Condensation polymers:, Terylene, Nylon-6,6, Bakelite, Novolac, etc., Exercise | Q 2.5 | Page 338, Answer the following in one sentence., Name some chain-growth polymers., Solution:, Chain growth polymers are. polyacrylonitrile, polyvinylchloride, polythene, etc, Exercise | Q 2.6 | Page 338, Answer the following in one sentence., Define the term: Monomer, Solution:
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Small molecules that are interlinked together to form polymers are called as monomers., Exercise | Q 2.6 | Page 338, Answer the following in one sentence., Define the term: Vulcanization, Solution:, The process by which a network of cross-links is introduced into an elastomer is called, vulcanization., Exercise | Q 2.6 | Page 338, Answer the following in one sentence., Define the term: Synthetic fibres, Solution:, Man-made polymeric solids which form threads are called synthetic fibres., Exercise | Q 2.7 | Page 338, Answer the following in one sentence., What type of intermolecular force leads to high-density polythene?, Solution:, Van der Waals forces between closely packed linear polymeric chains are responsible, for high-density polythene., Exercise | Q 2.8 | Page 338, Answer the following in one sentence., Give one example each of copolymer and homopolymer., Solution:, 1. Copolymer: Buna-S., 2. Homopolymer: Polythene., Exercise | Q 2.9 | Page 338, Answer the following in one sentence., Identify thermoplastic and thermosetting plastic from the following:, 1. PET, 2. Urea formaldehyde resin, 3. Polythene, 4. Phenol formaldehyde resin, Solution:, 1. Thermoplastic: Polythene, PET
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2. Thermosetting plastic: Urea formaldehyde resin, Phenol formaldehyde resin, Exercise | Q 3.01 | Page 338, Answer the following., Write the names of classes of polymers formed according to intermolecular forces and, describe briefly their structural characteristics., Solution:, 1. Polymers are classified into various categories on the basis of intermolecular forces, as follows:, •, •, •, •, , Elastomers, Fibres, Thermoplastic polymers, Thermosetting polymers, 2. Their structural characteristics are as follows:, i. Elastomers:, , •, •, •, , Elastomers have the property of elasticity in which a substance gets stretched by, external force and restores its original shape on the release of that force., Elastomers, the elastic polymers, have weak van der Waals type of intermolecular, forces that permit the polymer to be stretched., A few crosslinks between the chains help the stretched polymer to retract to its original, position on removal of applied force., e.g. Vulcanized rubber, Buna-S, Buna-N, neoprene, etc., ii. Fibres:, , •, •, •, , Polymeric solids which form threads are called fibres., The fibres possess high tensile strength which is a property to have resistance to, breaking under tension., High tensile strength is due to the strong intermolecular forces like hydrogen bonding, and strong dipole-dipole forces. Due to these strong intermolecular forces, the fibres are, crystalline in nature., e.g. Polyamides (nylon 6,6), polyesters (terylene), etc., iii. Thermoplastic polymers:, , •, •, •, , Thermoplastic polymers have the property of plasticity, that is, these polymers can be, easily shaped or moulded., They are capable of repeated softening on heating and hardening on cooling., These polymers possess moderately strong intermolecular forces that are intermediate, between elastomers and fibres., e.g. Polythene, polystyrene, polyvinyls, etc., iv. Thermosetting polymers:, , •, , Thermosetting polymers are rigid polymers.
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•, , •, , During their formation, they have the property of being shaped on heating; but they get, hardened while hot. Once hardened, they cannot be softened by heating and therefore, cannot be remoulded., This characteristic is the result of extensive cross-linking by covalent bonds formed in, the moulds during hardening/setting process while hot., e.g. Bakelite, urea-formaldehyde resin, etc., Exercise | Q 3.02 | Page 338, Answer the following., Write the reaction of the formation of Nylon 6., Solution:, , Exercise | Q 3.02 | Page 338, Answer the following., Write the reaction of the formation of Terylene., Solution:, , Exercise | Q 3.03 | Page 338, Answer the following., Write structure of natural rubber and neoprene rubber along with the name and, structure of their monomers., Solution:
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Exercise | Q 3.04 | Page 338, Answer the following., Name the polymer type in which following linkage is present., , Solution:, The polymer containing ester linkage is called polyester., Exercise | Q 3.05 | Page 338, Answer the following., Write structural formula of the following synthetic rubbers:, SBR rubbe, Solution:
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Exercise | Q 3.05 | Page 338, Answer the following., Write structural formula of the following synthetic rubbers:, Buna-N rubber, Solution:, , Exercise | Q 3.05 | Page 338, Answer the following., Write structural formula of the following synthetic rubbers:, Neoprene rubber, Solution:, , Exercise | Q 3.06 | Page 338, Answer the following., Match the following pairs:, Name of polymer, , Monomer, , 1. Teflon, , a. CH2 = CH2, , 2. PVC, , b. CF2 = CF2, , 3. Polyester, , c. CH2 = CHCl, , 4. Polythene, , d. C6H5OH and HCHO, , 5. Bakelite, , e. Dicarboxylic acid and, polyhydoxyglycol, , Solution:
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Name of polymer, , Monomer, , 1. Teflon, , b. CF2 = CF2, , 2. PVC, , c. CH2 = CHCl, , 3. Polyester, , e. Dicarboxylic acid and polyhydoxyglycol, , 4. Polythene, , a. CH2 = CH2, , 5. Bakelite, , d. C6H5OH and HCHO, , Exercise | Q 3.07 | Page 338, Answer the following., Draw the structures of polymers formed from the following monomers, n HOOC–R–COOH + n HO–R'–OH, Solution:, , Exercise | Q 3.07 | Page 338, Answer the following., Draw the structures of polymers formed from the following monomers, H2N–(CH2)5 – COOH, Solution:, [- NH - (CH2)5 - CO-]n, Exercise | Q 3.08 | Page 338, Answer the following., Name and draw structure of the repeating unit in natural rubber., Solution:, Repeating unit in natural rubber is obtained from the monomer isoprene., Structure of repeating unit is:
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Exercise | Q 3.09 | Page 338, Answer the following., Classify the following polymers as natural and synthetic polymers, a. Cellulose, b. Polystyrene, c. Terylene, d. Starch, e. Protein, f. Silicones, g. Orlon (Polyacrylonitrle), h. Phenol-formedehyde resins, Solution:, Polymer, a. Cellulose, , Type of polymer, Natural, , b. Polystyrene, , Synthetic, , c. Terylene, , Synthetic, , d. Starch, , Natural, , e. Protein, , Natural, , f. Silicones, , Synthetic, , g. Orlon (polyacrylonitrile), , Synthetic, , h. Phenol-formaldehyde resins, , Synthetic, , Exercise | Q 3.1 | Page 338, Answer the following.
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What are synthetic resins? Name some natural and synthetic resins., •, , Solution:, Synthetic resins:, These polymers are artificially prepared by polymerization of one monomer or, copolymerization of two or more monomers., e.g. nylon and terylene., Synthetic polymers are further divided into three subtypes: fibres, synthetic rubbers, and, plastics., , •, •, , Natural resins: Natural rubber, silk, wool, etc., Synthetic resins: Nylon, terylene, neoprene, etc., Exercise | Q 3.11 | Page 338, Answer the following., Distinguish between thermosetting and thermoplastic resins. Write example of both the, classes., Solution:, Thermosetting resin, They do not soften on heating, They cannot be remoulded or reshaped., They possess extensive cross-linking, formed by covalent bonds., They are rigid polymers., e.g. Bakelite, urea-formaldehyde resins,, etc., , Thermoplastic resin, They soften on heating and harden on, cooling, These can be remoulded or reshaped., They possess moderately strong, intermolecular forces that are intermediate, between elastomers and fibres., They are not rigid polymers., e.g. PVC, polythene, polystyrene, etc., , Exercise | Q 3.12 | Page 338, Answer the following., Write name and formula of raw material from which bake lite is made., Solution:, Bakelite is made by condensation of two different monomers:, a. Phenol:
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b. Formaldehyde: CH2O, Exercise | Q 4.1 | Page 338, Identify condensation polymers and addition polymers from the following., , Solution: It is an Addition polymer., Exercise | Q 4.1 | Page 338, Identify condensation polymers and addition polymers from the following., -(CH2 - CH = CH - CH2 -)n, Solution: It is an Addition polymer., Exercise | Q 4.1 | Page 338, Identify condensation polymers and addition polymers from the following., -(CO(CH2)4 - CONH(CH2)6NH-)n, Solution: It is a Condensation polymer., Exercise | Q 4.1 | Page 338, Identify condensation polymers and addition polymers from the following., , Solution:, It is a Condensation polymer., Exercise | Q 4.2 | Page 339, Attempt the following:, Write the chemical reactions involved in the manufacture of Nylon 6,6., Solution:
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Exercise | Q 4.3 | Page 339, Attempt the following:, Explain the vulcanisation of rubber. Which vulcanizing agents are used for the following, synthetic rubber., a. Neoprene, b. Buna-N, Solution:, a. Neoprene: MgO is used to vulcanize neoprene., b. Buna-N: Sulfur is used to vulcanize Buna-N., Exercise | Q 4.4 | Page 339, Write chemical reaction to prepare the following polymer: Teflon, Solution:, , Exercise | Q 4.4 | Page 339, Write the reaction involved in the formation of:, Bakelite, Solution:, Step 1:
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Step 2:, , Step 3:, , Exercise | Q 4.5 | Page 339, Attempt the following:, What is meant by LDP and HDP? Mention the basic difference between the same with, suitable examples., Solution:, 1. What is meant by LDP and HDP? Mention the basic difference between the same with, suitable examples., 2. LDP is a branched polymer of ethene with polymeric chains loosely held. Hence, even, though it is tough, it is extremely flexible. Therefore, LDP is used in producing extruded
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films, sheets, mainly for packaging and household uses like in preparation of squeeze, bottles, attractive containers, etc. where low tensile strength and flexibility is required., On the other hand, HDP is a linear polymer of ethene with closely packed polymeric, chains. Hence, it is much stiffer than LDP and has high tensile strength and hardness., Therefore, HDP is used in the manufacture of toys and other household articles like, buckets, dustbins, bottles, pipes, laboratory wares and other objects where high tensile, strength and stiffness is required., Exercise | Q 4.6 | Page 339, Attempt the following:, Write preparation, properties and uses of Teflon., •, , Solution:, Preparation of teflon:, 1. The monomer used in preparation of teflon is tetrafluoroethylene, (CF2 = CF2), which, is a gas at room temperature., 2. Tetrafluoroethylene is polymerized by using free-radical initiators such as hydrogen, peroxide or ammonium persulphate at high pressure to produce polytetrafluoroethylene, (teflon)., , •, , Properties of teflon:, 1. Teflon is tough, chemically inert and resistant to heat and attack by corrosive, reagents., 2. C - F bond is very difficult to break and remains unaffected by corrosive alkali,, organic solvents., , •, , Uses:, Teflon is used in making non-stick cookware, oil seals, gaskets, etc., Exercise | Q 4.7 | Page 339, Attempt the following:, Classify the following polymer as straight-chain, branched-chain and cross-linked, polymers.
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Solution:, Straight chain polymer, Exercise | Q 4.7 | Page 339, Attempt the following:, Classify the following polymer as straight-chain, branched-chain and cross-linked, polymers., , Solution:, Branched-chain polymer, Exercise | Q 4.7 | Page 339, Attempt the following:, Classify the following polymer as straight-chain, branched-chain and cross-linked, polymers.
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Solution: Crosslinked polymer, Exercise | Q 5.1 | Page 339, Answer the following, How is polythene manufactured? Give their properties and uses., Solution:, i. LDP is prepared by polymerization of ethylene under high pressure (1000 - 2000 atm), and temperature (350 - 570 K) in presence of traces of O2 or peroxide as initiator., , ii. The mechanism of this reaction involves free radical addition and H-atom abstraction., The latter results in branching., iii. Polymeric chains are loosely held due to branching and the polymer has low density., iv. Properties of low-density polyethylene:, a. LDP films are extremely flexible but tough, chemically inert, and moisture resistant. b., It is a poor conductor of electricity with a melting point 110 °C., v. Uses of low-density polyethylene:, a. It is mainly used in the preparation of pipes for agriculture, irrigation, domestic water, line connections as well as insulation to electric cables., b. It is also used in submarine cable insulation., c. It is used in producing extruded films, sheets, mainly for packaging and household, uses like in preparation of squeeze bottles, attractive containers, etc., vi. HDP is a linear polymer with high density due to close packing., vii. It is obtained by polymerization of ethene in presence of Zieglar-Natta catalyst,, which is a combination of triethyl aluminium with titanium tetrachloride., viii. Polymerization of ethene is carried out at a temperature of 333 K to 343 K and a, pressure of 6-7 atm., , ix. Properties of high-density polyethylene:, a. HDP is crystalline, melting point in the range of 144 - 150 °C., b. It is much stiffer than LDP and has high tensile strength and hardness.
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c. It is more resistant to chemicals than LDP., x. Uses of high-density polyethylene:, a. HDP is used in the manufacture of toys and other household articles like buckets,, dustbins, bottles, pipes, etc., b. It is used to prepare laboratory wares and other objects where high tensile strength, and stiffness is required., Exercise | Q 5.2 | Page 339, Answer the following., Is synthetic rubber better than natural rubber? If so, in what respect?, Solution:, Yes, synthetic rubber is superior to natural rubber., 1. Synthetic rubber has high mechanical strength., 2. It has high abrasion resistance., 3. It is resistant to petroleum, vegetable oils, light as well as heat., Exercise | Q 5.3 | Page 339, Answer the following., Write main specialities of Buna-S, Neoprene rubber?, Solution:, 1. Buna-S:, It has mechanical strength and has abrasion resistance. Hence, it is used in tyre, industry., 2. Neoprene:, • Neoprene is particularly resistant to petroleum, vegetable oils, light as well as heat., • Hence, it is used in making hose pipes for the transport of gasoline and making gaskets., • It is used for manufacturing insulator cable, jackets, belts for power transmission and, conveying., Exercise | Q 5.4 | Page 339, Answer the following., Write the structure of isoprene and the polymer obtained from it., Solution:
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Exercise | Q 5.5 | Page 339, Answer the following., Explain in detail free radical mechanism involved during preparation of addition polymer., Solution:, The free radical mechanism is most common in addition to polymerization. It is also, called a chain reaction which involves three distinct steps. These are as follows:, i) Step 1: Chain initiation:, a. The chain reaction is initiated by a free radical which is formed from an initiator, (catalyst) such as benzoyl peroxide, acetyl peroxide, tert-butyl peroxide, etc., b. For example, acetyl peroxide generates methyl radical as shown below:, , c. The free radical (say R•) so formed attaches itself to the olefin (vinyl monomer) and, produces a new radical, made up of two parts, namely, the attached radical and the, monomer unit.
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ii. Step 2: Chain propagation:, a. The new radical formed in the initiation step reacts with another molecule of vinyl, monomer, forming another still bigger sized radical, which in turn reacts with another, monomer molecule., b. The repetition of this sequence takes place very rapidly. It is called chain, propagation., , c. This step is very rapid and leads to high molecular mass radical., iii. Step 3: Chain termination:, a. At some stage, termination of the growing chain takes place. It may occur by several, processes., b. One mode of termination is by combination of two growing chain radicals.
