(iii) Nylon-6, 6 (Comptt. 15.15. Write the names and structures of the monomers of the following polymers: (Delhi 2013) The reaction is carried out at 420 – 460 K in presence of a catalyst consisting of a mixture of zinc acetate and antimony trioxide. The close packing results in high densities, tensile strength and also high melting and boiling points. (ii) PVC Question 58. Identify the monomer in the following polymeric structures: Differentiate between condensation and addition polymerisations. (i) Nylon-6,6 : It has two repeating two monomers This hardening on heating is due to cross- linking between different polymeric chains to give a three dimensional network solid. The monomer used in preparation of teflon is tetrafluoroethylene, (CF2 = CF2), which is a gas at room temperature. Give one example of each. How do you explain the functionality of a monomer? 3. (ii) Nylon-6 What is the primary structural feature necessary for a molecule to make it useful in a condensation polymerization reaction? (ii)Neoprene < Polyvinyl chloride < Nylon 6. This process normally occurs at high temperature and under high pressure in presence of small amounts of benzoyl peroxide as the initiator in three steps: Write the free radical mechanism for the polymerisation of ethene. A few common polymers belonging to this class are nylon – 66, terylene and polyacrylonitrile etc. Differentiate between thermoplastic and thermosetting polymers. Answer: Question 42. Answer: Question 25. Buna-N (Nitrile rubber): h is a co-polymer of buta-1. Give one example of each. Give an example of elastomers. (b) Melamine-formaldehyde polymer These cis-double bonds do not allow the polymer chains to come closer for effective interactions and hence intermolecular forces are quite weak. Question 48. 2. Example : Polyethene, PVC, teflon. 15.5. Write the mechanism of free radical polymerization of ethene. Monomers are the. Write the monomers of the following polymers and classify them as addition or condensation polymers : 15.6. (i) (i) It is used in making handles of utensils. Delhi 2013) The development of the fluorocarbon industry coincided with World War II. (ii) Also used in production of billiard balls, dominoes and pieces for games like chess. (ii) Nylon-6 : The monomeric repeating unit of Nylon-6 is. Answer: 15.1. (ii) Monomers of nylon-6, 6 are : Adipic acid and Hexamethylene diamine. Answer: Question 31. Ans: 15.17. (iii) Nylon-66 : Manufacture of sheets, bristles from brushes, textiles etc. (All India 2009) Question 34. Delhi 2013) Question 45. Answer: (i) Polyvinylchloride (ii) Teflon (All India 2010) (d)It is easily attacked by oxygen and other oxidising agents. Draw the structures of the monomers of the following polymers : (All India 2010) Write the structures of the monomers used for getting the following polymers: Fibres possess high tensile strength because the chains possess strong intermolecular forces such as hydrogen bonding. Answer: Question 41. (iii), Question 54. (a) Differentiate between chain growth and step growth polymerization. All India 2016) (iii). Nylon ‘6,6’ implies that it is a condensation polymer of two types of monomer molecules each containing six carbon atoms i.e. (iii) Teflon (Delhi 2013) (a) Homopolymers : Polymers whose repeating structural units are derived from only one type of monomer units are called homopolymers. Nylon, Neoprene, PVC (All India 2013) NCERT INTEXT QUESTIONS. (ii) condensation polymers Ans: On the basis of structure, polymers are classified into three types. (b) Teflon is used for making non-stick cooking utensils. (b) Sulphur introduces sulphur bridges or cross-links between polymer chains thereby imparting more tensile strength, elasticity and resistance to abrasion. It is formed as follows: 15.6. Ans: Dacron is obtained by condensation polymerization of ethylene glycol and terephthalic acid with the elimination of water molecules. (iii) Neoprene (Comptt. Natural polymers: The polymers which occur in nature mostly in plants and animals are called natural polymers. Answer: (i) Nylon 6,6, Buna-S, Polythene Answer: Question 21. (Delhi 2013) Explain the term co-polymerization and give two examples of copolymers and the reactions for their preparations. Answer: (b) What is the role of Benzoyl peroxide in preparation of Polythene? How can you differentiate between addition and condensation polymerisatiop? Example : Formation of polyethene. (b)It has large water absorption capacity, has low tensile strength and low resistance to abrasion. These forces are also responsible for close packing of the chains. Some examples are polythene, nylon-66, bakelite, rubber, etc. Answer: (Delhi 2013) Answer: Question 31. Write the names and structures of the monomers of the following polymers: (Delhi 2013) (Comptt. In which classes, are the polymers classified on the basis of molecular forces? These are linear chain polymers, branched chain polymers and crossedlinkedpolymers. Preparation of teflon: 1. The polymer formed by the polymerization of a single/same monomeric species is known as homopolymerization. Question 29. (ii) Answer: Discuss the main purpose of vulcanisation of rubber. For example, monomers like propene, styrene, acrylonitrile have functionality of one which means that have one bonding site. (iii) Nylon-6,6 : Manufacture of sheets, bristles from brushes, textiles etc. (ii) Dacron (i) Terylene All India 2012) Natural rubber is the most popular example of elastomers. Answer: Buna-S < Polystyrene < Terylene. (i) Monomers of terylene are : Ethylene glycol and Terephthalic acid. (i) Polythene In this polymer, double bonds are located between C2 and C3 of each isoprene unit. Protein is a natural polymer. ASTM A193 GRADE B7 TEFLON COATED STUD BOLTS GOVERNING STANDARDS: ASTM A193/A193M Standard specification for alloy-steel and stainless steel bolting for high temperature or high pressure service and other special purpose applications. Ans: Polymers whose repeating structural units are derived from only one type of monomer units are called homopolymers, e.g., PVC polyethene, PAN, teflon, polystyrene, nylon- 6 etc. (i) Buna-S Which of the following is a fibre? (a) How are thermosetting polymers different from thermoplastic polymers? . (Delhi 2011) Answer: Answer: Question 20. Monomers such as ethylene glycol, hexamethylenediamine, adipic acid have functionality of two which means that they have two bonding sites. Give one example. 3. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Define the term, ‘homopolymerisation’ giving an example. Ans: Polymers are classified into four classes on the basis of molecular forces. The elasticity can be further increased by introducing some cross – links in the polymer chains. Natural rubber is yet another useful polymer which is obtained from the latex of the rubber tree. (i) Polypropylene Bio-degardable polymer : All those biopolymers which disintegrate by themselves in biological systems during certain period of time by enzymatic hydrolysis are called biodegradable polymers. Question 28. The monomer used in preparation of teflon is tetrafluoroethylene, (CF 2 = CF 2), which is a gas at room temperature.. 2. What is a biodegradable polymer ? 15.3. They condense in the presence of Na. Ans: Addition polymers: Polyvinyl chloride, Polythene (i) t-butyl peroxide acts as a radical initiator or chain initiator in the polymerization of ethene. Question 57. mass polymer from one or more monomers by linking together a large number of repeating structural units through covalent bonds. Ans: Polymers are high molecular mass substances consisting of a very large number of simple repeating structural units joined together through covalent bonds in a regular fashion. (i) Monomer ➝ Phenol and Formaldehyde A few common examples are starch, cellulose, proteins, rubber nucleic acids, etc. This initiator readily decomposes on mild heating to form initiator free radicals which adds to double bond of ethene molecule to form a new and larger free radical. What is Teflon? Question 26. A few more examples are of: buna-S, buna-N and neoprene. (ii) Nylon 6 (Delhi 2011) Answer: (ii) Neoprene (i) Bakelite : Monomers are Question 19. (i) Polystyrene (All India 2010)
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