Polymer Notes

Polymers Definition Polymers which are obtained from animal and plants are known as natural polymers. Macromolecules y Individual molecule of very high molecular weight. e.g., Heamoglobin, Chlorophyll etc. Monomer y Monomer is the molecule that forms the basic unit for Polymer. e.g., Propene, Styrene, Vinyl chloride etc. The number of monomers Polymer y Natural, semisynthetic compounds consisting Concept Ladder and of synthetic number of molecules (monomers) called Polymer. e.g., which are joined together in a polymer constitutes the degree of polymerization. Polypropene, Polystyrene, PVC, Nylon-6 etc. I. Classification Based upon source (1) Natural polymers Polymers which are found in nature. eg. Starch, cellulose and natural rubber, Silk, Proteins, Nucleic acid. Semisynthetic polymers It is obtained from naturally occuring Why all polymers macromolecules but macromolecules are polymers. are all not polymers by chemical treatment. Most of the semisynthetic polymers are prepared 1. Polymers (2) ...etc. Rack your Brain from cellulose. eg. cellulose acetate, cellulose nitrate, cellulose xanthate and Concept Ladder rayon. (3) Synthetic polymers Man maid polymers are known as synthetic Polymers in which repeating units are derived from two or more types of monomers units are called copolymers. eg. nylon-6,6; Buna-S; Buna-N; Polyesters. polymer. eg. PVC, polyethylene, polystyrene, nylon-6, nylon-6,6; nylon-6,10; terylene, synthetic rubbers etc. Classification Based upon structure 1. Linear polymers Monomers are joined together to form long straight chains. The various linear polymeric chains are stacked over one another to give a well packed structure close packed in nature, having high densities, high melting point and high tensile (pulling) strength. Note: All fibers are linear polymers. eg. cellulose, silk, nylon, terylene etc. Definition Man-made Polymers in which the monomeric units i.e. polymers prepared in laboratory are 2. Branched chain polymers polymers, known as synthetic polymers. constitute a branched chain. Branched chain polymers have lower melting point low densities and tensile strength as compared to linear polymers. Examples are amylopectin, glycogen, low density polyethylene and all vulcanized rubbers. 3. Cross linked or Three-Dimensional network polymers When linear polymeric chains are joined together to form a three dimensional Polymers network structure. These polymers are hard, Previous Year’s Question Which compound forms linear polymer due to H-bond? [AIPMT] (1) H2O (2) NH3 (3) HF (4) HCl 2. rigid and brittle. Cross linked polymers are always condensation polymers. Resins are cross linked polymers. Classification Based upon molecular force 1. Elastomers Polymers in which the intermolecular foreces of attraction between the polymer chains are the weakest (weak van der Waals forces of attraction) these polymers consist Concept Ladder Polymers whose repeating structural units are derived from only one type of monomer units are called homopolymers. nCH = CH2  →— [ CH2 —CH2— ]n 2 Ethene (Monomer ) Polythene (polymer ) of randomly coiled molecular chains of irregular shape having a few cross links. Examples are natural rubber, Buna-S, Buna-N etc. 2. Fibres Those polymers in which teh intermolecular forces of attraction are the strongest are called fibers. These polymers held together by H-bonding or dipole-dipole interaction. Rack your Brain Fibres have high tensile strenght, least Why branched chain polymers elasticity having high melting point and low do not pack well? solubility. 3. Thermoplastics In thermoplastics intermolecualr forces of attraction are in between those of elastomers and fibres. Thermoplastics become soft and viscous on heating and rigid on cooling. etc. 4. Thermosetting polymers These polymers have low molecular masses and are semi-fluid substances. These polymers are hard and infusible. Examples are melamine-formaldehyde, bakelite (phenol-formaldehyde) etc. Concept Ladder Linear polymers may be condensation as well as addition polymers. Examples are cellulose, polypeptide, nucleic acid, nylon, terylene etc. 3. Polymers Examples are polythene, nylon-6, nylon-6,6 Classification based upon polymerisation 1. Addition polymerization (a) Addition polymers are those in which addition reaction takes place (b) If monomer is ethylene, then addition polymer may be of are branched either linear polymer chain polystyrene, Concept Ladder polymer. Examples Addition polymerization takes place in three steps: Initiation, chain propagation and chain termination. polytetrafluoroethylene, polyacrylonitrile etc. (c) If monomer is 1,3–butadiene or 2– substituted-1, 3–butadiene , then polymer is always branched chain polymer. G G |   n CH2  C CH  CH2    CH  C CH  CH    n Monomer  Polymer  | Monomer (a) G=H: 1,3-Butadiene (b) G-CH3 : 2-Methyl-1, 3-butadiene or isoprene (ii) Polyisoprene (c) G=Cl; 2-Chloro-1, 3-butadiene or chloroprene (iii) Polychloroprene (Neoprene) (d) (i) Polybutadiene Addition polymers are also known as chain growth polymers. Polymers Polymer Previous Year’s Question Regarding cross-linked or network polymers, which of the following statements is incorrect? [NEET] (1) They conttain covalent bonds between various linear polymer chains. (2) They are formed from bi-and tri-functional monomers. (3) Examples are bakelite and melamine. (4) They contain strong covalent bonds in their polymer chains. 4. Types of Addition Polymerisation (a) Free Radical Polymerisation (i) Free radical polymerisation takes in the presence of radical initiators. Such as dioxygen, benzoyl peroxide, acetyl peroxide etc. For example, polymerization of ethene is carried out at high temperatures (350570K) and at high pressure (1000-2000 atm) in presence of dioxygen or a small amount of benzoyl peroxide as radical initiator. Previous Year’s Question Which can absorb over 90% of its own mass of water and does not stick to wound? [AIPMT] (1) Rayon (2) Gun cotton (3) Thiokol (4) Saran Mechanism Chain initiating steps: Chain propagating steps: Chain terminating steps: 5. Polymers Step 1 : By combination of free radicals (II) Step 2 : By disproportionation of free radicals (II) (b) Cationic Polymerisation Cationic polymerisation takes place in the presence of strong protonic acids such as H2SO4, AlCl3, BF3 etc. (c) Anionic Polymerization In anionic polymerisation, it takes place in the presence of strong bases such as KNH2, NaOH, KOH, some organometallic Polymers compounds etc. 2. Condensation polymerization (a) They are formed due to condensation reactions. 6. (b) Condensation polymerization is also known as step growth polymerization. (c) For condensation polymerization, monomers may should have at least two functional groups. (functional groups may be same or different). Previous Year’s Question Which one of the following is not a condensation polymer? [AIPMT] (1) Melamine (2) Glyptal (3) Dacron (4) Neoprene For example, (d) During condensation elimination of small molecules like ammonia, alcohol, water, HCl takes place. O ||   Condensation NH R C        n  1  n NH2  R  COOH     reaction 2  Polyamide    n  Monomer having three functional groups always gives cross linked polymer. Examples are : Urea formaldehyde resin, phenolformaldehyde resin. Concept Ladder Monomers having only two functional group always give linear polymer. 7. Polymers (e) Natural Rubber The main source of natural rubber is Concept Ladder braziliensis tree. Natural rubber is obtained from Natural rubber is a polymer of 2-methyl-1, 3-butadiene (isoprene). On average, molecules of rubber contain 5000 isoprene units held together by head to tail. All the double bonds in rubber are cis, hence natural rubber is cis-polyisoprene. latex. Again latex is coagulated with acetic acid and formic acid and coagulated mass is then squeezed. Natural rubber is a sticky, gummy & soft and insoluble in water, alkalies & dilute acids. Natural rubber soluble in non-polar solvents. It has low elasticity and low tensile strength. Example : Polyisoprene. CH3 | CH3 | n CH2  C CH  CH2 [ CH2  C CH CH2 ]n Isoprene Polyisoprene Polymerization Structure of Natural Rubber (cis-polyisoprene) Synthetic Rubber or Polymerisation of Dienes Polymers of 1,3-butadienes are called synthetic rubbers because they have some properties of natural rubber. Synthetic rubber are water proof and great elasticity. 1. Homopolymers Monomer of this class is 2-substituted -1,3-butadienes. where G = H, Cl or CH3. Zieglar-Natta catalyst is used Previous Year’s Question natural rubber is a polymer of [AIPMT] (1) Styrene (2) Ethyne (3) Butadiene (4) Isoprene for Polymers polymerisation which gives stereo regular polymers. 8. Concept Ladder Synthetic rubbers have some improved properties. Dieprene (Neoprene) was the first They are more flexible, synthetic rubber manufactured on large tougher and more durable scale. It is the monomer of chloroprene than natural rubber. (2-chlorobutadiene). 2. Copolymers Copolymers are derived from two or more types of monomer units. Example of copolymers are : Buna-S, SBR (StyreneButadiene rubber) 2 Buna-N, NBR (NitrileButadiene rubber) 3 Butyl rubber 4 ABS; Acrylonitrile, Butadiene, Styrene C6H5 − CH = CH2 + CH2 = CH − CH = CH2 (25%) CH2 = CH − CN + CH2 = CH − CH = CH2 (25%) Buna-S rubber is a copolymer of three moles of butadiene and one mole styrene. is (75%) CH2 = CH — CN+ CH2 = CH2 = CH — CH = CH2 +C6H5CH = CH2 Buna-S (SSR : Styrene-butadiene rubber) Buna-S (75%) generally compounded with Rack your Brain Which polymer is used to make ‘non-stick’ cookware? 9. Polymers (a) 1 carbon black and vulcanised with sulpur. It is extremely resistant to tear & wear Concept Ladder and therefore used in the manufacture of tyres and other mechanical rubber goods. It is obtained as a result of free radical copolymerisation of its monomers. (b) Buna -N Buna-N is obtained by copolymerisation of butadiene and acrylonitrile (General In Buna-S, ‘Bu’ stands for butadiene, ‘na’ for symbol of sodium (Na) which is a polymerizing agent and ‘S’ stands for styrene. It is an elastomer (General purpose styrene Rubber or GRS). purpose Rubber acrylonitrile or GRA) Buna-N is rigid and resistant to the action of organic solvents, lubricating oil and petrol. It is also used for making fuel tanks. Q1 Polymers Sol. Buna-S is also called __________? (1) Polyurethane (2) SBR (3) Teflon (4) Bakelite (2) SBR is known as styrene butadiene. 10. Vulcanisation of rubber Natural rubber soft & sticky and becomes even more so at high temperatures and brittle at low temperanures. Therefore, rubber is generally used in the temperature range 283-335 K where its elasticity is maintained. It has a large water absorption capacity, has low tensile strength and low resistance to abrasion. It is also not-resistant to the action of organic solvents and is also easily attacked by axidising agents. These properties can be improved markedily by a process called Concept Ladder Synthetic rubbers are either homopolymers of 1, 3-butadiene or its derivatives or are copolymers of 1, 3-butadiene or its derivatives with another unsaturated monomer. vulcanization. It consists of heating raw rubber with sulphur at 373-415 K. Since this process is slow, therefore, additives like zinc oxide, are used to acoelerate the rate of vulcanization The vulcanized rubber thus obtained has excellent elasticity, low water absorption tendency and is resistant to the action of organic solvents and oxidising agents During vulcanization, sulphur bridges or crosslinks between polymer chans are introduced either reactive allylic positions or at the sites of Rack your Brain How does rubber get stiffness? the double bonds. Previous Year’s Question Nylons are prepared by the condensation polymerisation of dibasic acids with diamines. Nylon contain amide linkages having a protein like structure. Nylon is an example of [NEET] (1) polyamide (2) polythene (3) polyester (4) polysaccharide 11. Polymers Nylon (1) Nylon–6,6 (Nylon–six, six) It is obtained by condensation polymerisation of a diamine with six carbon atoms (hexamethylenediamine) and a dibasic acid having 6 carbon atoms (adipic acid). (2) (3) Nylon–6,10 (Nylon–six, ten) It is obtained by condensation polymerisation of six carbon atoms (hexamethylenediamine) and a dibasic acid with 10 carbon atoms (sebacic acid). These fibres are light, very strong, flexible and elastic having retain creases and drip dry property. These polyemrs are inert towards biological and chemicals agents. These polymers can be blended with wool to make carpets, garments, tyre cords, ropes, etc. Nylon–6 (Perlon L) A polyamide closely related to nylon is known as perlon L (Germany) or Nylon–6 (USA). During prolonged heating of caprolactum at 260–270°C. It is formed by self condensation of a large number of molecules of amino caproic acid. Since, caprolactum is more easily available, it is used for polymerization, with is carried out in the presence of H2O that first hydrolysis the lactam to amino acid. Subsequently, the amino acid can react with the lactam and the process goes on and onto formed by polyamide polymer. Polymers Caprolactam is obtained by Backman Concept Ladder Nylon fibres are stronger than natural fibres and so are used in making cords and ropes. Previous Year’s Question Nylon-6, 6 is a polyamide obtained by the reaction of [AIPMT] (1) COOH(CH2)4COOH + H2NC6H4NH2 (p) (2) COOH(CH2)4COOH + NH2(CH2)6NH2 (3) COOH(CH2)4COOH + NH2(CH2)4NH2 (4) COOHC6H4COOH (p) + NH2(CH2)6NH2 12. rearrangement of cyclohexanone oxime. Polytetrafluoroethene (PTEE) or Teflon Teflon is manufactured by heating tetrafluoroethene in presence of peroxides or ammonium persulphate catalyst at high pressures. (NH ) S O 4 2 2 8 n F2C  CF2   High pressure Tetrafluoroethene Rack your Brain Why the articles made from melamine do not break even if they fall from several heightes? [ F C C F ] 2 2 n Polytetrafluoroethene or Teflon Polyacrylonitrile (PAN) or Orlon During Polymerisation of acrylonitrile in the presence of a peroxide catalyst gives polyacrylonitrile. nCH2  CH    CH2  CH   | |     CN CN   Peroxides Melamine-formaldehyde resin This resin is formed by condensation polymerization of melamine and formaldehyde. It is a quite hard polymer and is used widely for making plastic crockery under the name melamine. The articles made from this polymer do not break even when dropped from Concept Ladder PAN is used as a substitute for wool in the manufacture of orlon and acrilan fibres which are used for making clothes, carpets and blankets. considerable height. Sol. What is the monomer of bakelite? Bakelite is a polymer formed by the monomers of phenol and formaldehyde. This phenol-formaldehyde resin is a thermosetting polymer. 13. Polymers Q2 Bakelite Phenol-formaldehyde resins are obtained by the reaction of phenol and formaldehyde in the presence of either an acid or a basic catalyst. It starts with the initial formation of ortho and para hydroxymethyl phenol derivatives, which further react with phenol to form compounds where rings are joined to each other with –CH2 groups. This reaction involves the formation of methylene bridges in ortho, para or both ortho and para positions. Linear or cross- linked materials Previous Year’s Question The bakelite is prepared by the reaction between [AIPMT] (1) Phenol and formaldehyde (2) Tetramethylene glycol (3) Urea and formaldehyde (4) Ethylene glycol are obtained depending on the condition of the Polymers reaction. 14. Polyesters Dacron is a common polyester, prepared using ethylene glycol and terephthalic acid. The reaction is carried out at 140°C to 180°C in the presence of zinc acetate and Sb2O3 as catalyst. The dacron is crease resistant and has low moisture absorption. It has high tensile strength. It is mainly used in making wash and wear gamets, in blending with wood to provide better crease and wrinkle resistance. Previous Year’s Question Of the following which one is classified as polyester polymer? [AIPMT] (1) Terylene (2) Bakelite (3) Melamine (4) Nylon-6, 6 Molecular mass of polymer. Normally, a polymer contains chains of varying lengths and therefore, its molecular mass is always expressed as an average. In contrast, natural polymers such as protein contains chain of identical length and hence, have definite molecular mass. Number average molecular mass Mn Mn = ∑ NM ∑N i i ( ) Definition The ratio of the weight and number i average molecular masses (Mw / Mn ) is called Poly i Dispersity Index (PDI). Here Ni is the number of molecules of molecular mass Mi Sol. The number average molecular mass and mass average molecular mass of a polymer are 30,000 and 40,000 respectively. the PDI of the polymer is : PDI (Polydispersity Index) is the ratio of the mass average molecular mass to the number average molecular mass. Therefore, PDI = 40000 = 1.33 30000 Thus, PDI of the polymer is >1. 15. Polymers Q3 Here Ni is the number of molecules of molecular mass Mi. Methods such as light scattering and ultracentrifuge depend on the mass of the individual molecules and yield weight as average molecular masses. Mn is determined by osmotic pressure measurement (colligative properties). Some natural polymers, which are generally monodispersed, the PDI is unity (i.e. Mw = Mn ). In synthetic polymers, which are always polydisperse, PDI > 1 because Mw is always higher than Mn . Concept Ladder Weight average molecular ( ) mass Mw Mw = ∑ NM ∑ Nm i i 2 i i i Biodegradable Polymers: Many polymers are quite resistant to the environmental degradation processes and are thus responsible for the accumulation of polymeric solid waste materials (environmental polution). These solid wastes cause acute environmental and health problems and remain undegraded for quite a long time (100 — 1000 years). For general awareness and concern, the problems created by the polymeric solid wastes, certain new biodegradable synthetic polymers have been designed and developed. These polymers contain functional groups similar to the Previous Year’s Question Which of the following is a biodegradable polymer? [AIIMS] (1) Cellulose (2) Polythene (3) Polyvinyl chloride (4) Nylon-6 functional groups present in biopolymers. Q4 Polymers Sol. Identify the type of polymer. —A—A—A—A—A—A— Here the monomer is –A-. Since the same or identical monomer is being repeated to form this above polymer, so this is a homopolymer. (‘Homo’ means same or identical) 16. By far the most important class of biodegradable polymers are aliphatic polyesters and polyamides. Some of these are discussed below : (i) Nylon-2-Nylon-6 It is an alternating polyamide of glycine (containing two carbon atoms) and e-aminocaproic acid or 6-aminohexanoic acid. (containing six carbon atoms) (ii) PHBV It is a thermoplastic co-polymer of 3-hydroxy-butanoic acid and 3-hydroxypentanoic acid in which the two monomer units are 17. Polymers connected by ester linkages. Q5 Sol. Q6 Sol. Q7 Sol. Q8 Sol. Q9 Polymers Sol. Identify the type of polymer. —A—B—B—A—A—A—B—A— Monomers ‘A’ and ‘B’ are being joined in a random manner in the same polymer chain. It is the example of a copolymer. Copolymers are formed by the mixture of two or more unsaturated monomers reacts to each other. Why are rubbers called elastomers? Rubbers can be stretched by applying mechanical forces and come back to its original position after the removal of applied force. So they are called elastomers. Can the enzyme be called a polymer? The enzyme are the catalysts which enhances the biological (bio-chemical) reactions. Enzymes are made up of proteins (monomeric units are amino acids). Thus, enzymes are also polymers. Can nucleic acids, proteins and starch be considered as step growth polymers? Step growth polymers are condensation polymers. Proteins, starch and nucleic acids can be considered as step-growth polymers. Those polymers in which monomers possess bifunctional or trifunctional functional groups can combine by the loss of a simple molecule. To have practical applications why are cross-links required in rubber? In order to increase the quality of rubber, cross-linking is done which helps to increasing elastomeric properties and thermal stability. 18. Q10 Why does cis-polyisoprene possess elastic property? Sol. Q11 Sol. Q12 Sol. Q13 Sol. cis-polyisoprene has a coiled structure and does not have a straight chain. It can be streched like a spring. On stretching, the molecules become partially aligned with respect to each other and on withdrawing the force, the chains come back to their original coild state. What is the structural difference between HDP and LDP? How does the structure account for different behaviour and nature, hence the use of a polymer? Low density polymer is a low density structure which has branched structure and high density polymer is a high-density polymer which has a linear structure. Low density polymer is a lower melting point and flexible whereas high density polymer is chemically inert and has a higher melting point. Assertion: Rayon is a semi-synthetic polymer and is taken as a better choice than cotton fabric. Reason: Mechanical and aesthetic properties of cellulose can be improved by acetylation. Assertion and reason both are correct statements and reason explain the assertion. Which factor imparts crystalline nature to a polymer like nylon? One molecule of Nylon can join another by intermolecular H –bonding which is present between two terminal groups –C=O and –NH. Since intermolecular H – bonding is relatively strong, it can lead to close packing of chains that impacts the crystalline character of Nylon. Q14 Name the polymers used in laminated sheets and give the name of monomeric Sol. Urea-formaldehyde resin is used in laminated sheets. For the formation of laminated sheets, urea and formaldehyde are the monomeric units. 19. Polymers units involved in its formation. Q15 Sol. Q16 Sol. Which of the follownig polymer is stored in liver of animals? (1) Amylose (2) Cellulose (3) Amylopectin (4) Glycogen (4) Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals. Glycogen is the analogue of starch, a glucose polymer in plants, having a siimilar structure of amylopectin, but more extensively branched and compact than starch. Starch is polymer of a-glucose and consist of two components anylose and amylopectin. Amylose is water soluble component which constitutes about 15-20% of starch. Amylose and amylopectin is involuble in water and constitutes about 80-85% of starch. Amylose and amylopectin are the main storage polysaccharide of plants. Cellulose occurs exclusively in plants and it is the most abundant organic substance in plant kingdom. it is a predominant constituent of cell wall of plants cells. Natural ruberr is a polymer of (1) cis-isoprene (2) trans-isoprene (3) both (1) and (2) (4) None of the above (1) Natural rubber is a polymer of cis-isoprene, [2-methyl-1, 3-butadiene]. CH3 | CH2  C CH  CH2 Q17 Polymers Sol. A condensation polymer among the following polymers is (1) teflon (2) polystyrene (3) PVC (4) dacron (4) The polymer formed by the condensation polymerisation is known as condensation polymer. Dacron (terylene) is a condensation polymer. It is formed by the condensation polymerisation of terephthalic acid and ethylene glycol. 20. Chapter Summary 1. Have high molecular mass and formed by union of monomers. 2. Chain growth polymers or addition polymers are formed by successive addition of monomers without loss of simple molecules like H2O, NH3 etc. 3. Step growth or condensation polymers : these are formed through series of independent steps. Each step involves condensation between two monomers leading to formation of polymers. More than one monomer unit is involved. 4. Homopolymers : Polymers made of same monomer. 5. Copolymers : Polymers made of different types of monomers. 6. Elastomers : The strands of polymer are held together by weak inter molecular forces (van der wall’s). e.g. - Vulcanised rubber. 7. Fibres are held together by hydrogen bonds. e.g. - nylon, polyester, polyamide. 8. Thermoplastics can be easily moulded on heating. They don’t have cross-links, e.g.- polyethene. 9. Thermosetting polymers have cross links, cannot be remolded on heating. e.g. Bakelite. 21. Polymers 10. Plastisizer are high boiling esters which are added to plastic to make it soft and rubber like. Polymers SOME COMMON ADDITION POLYMERS/ CHAIN GROWTH POLYMER (HOMOPOLYMERS) S. No. Name(s) Formula Monomer Uses 1. Polyethylene (low density (LDPE)) –(CH2-CH2)n– CH2=CH2 (ethylene) film wrap, plastic bags 2. Polyethylene (high density (HDPE)) –(CH2-CH2)n– CH2=CH2 (ethylene) electrical insulation bottles, toys 3. Polypropylene (PP) different grades CH2=CHCH3 (propylene) similar to LDPE carpet, upholstery 4. Poly vinyl chloride (PVC) CH2=CHCl (vinyl chloride) pipes, siding, flooring 5. Poly(vinylidene chloride) (Saran A) CH2=CCl2 (vinylidene chloride) seat covers, films 6. Polystyrene (PS) (Styron) CH2=CHC6H5 (styrene) toys, cabinets packaging (foamed) 7. Polyacrylonitrile (PAN, Orlon, Acrilan) CH2=CHCN (acrylonitrile) rugs, blankets clothing 8. Polytetrafluoroethylene (PTFE, Teflon) CF2=CF2 (tetrafluoroethylene) non-stick surfaces electrical insulation –(CF2-CF2)n– 22. 9. Poly(methyl methacrylate) (PMMA, Lucite, Plexiglas, perspex) –[CH2C(CH3) CO2CH3]n– CH2=C(CH3) CO2CH3 (methyl methacrylate) lighting covers, signs skylights 10. Poly(vinyl acetate) (PVAc) –(CH2CHOCOCH3)n– CH2=CHOCOCH3 (vinyl acetate) latex paints, adhesives –[CH2CH=C(CH3)CH2]n– CH2=CHC(CH3)=CH2 (isoprene) requires vulcanization for practical –[CH2CH=CCl-CH2]n– CH2=CH-CCl=CH2 (chloroprene) synthetic rubber oil resistant 11. 12. Polychloroprene (cis + trans) (Neoprene) S. No. Name(s) 1. Polyester/ Dacron/ Terylene/Mylar 2. Glyptal or Alkyds resin Formula Monomer Uses HO2C C6H4 CO2H (Terephthalic acid) HO– CH2CH2–OH Ethylene glycol Copolymer Step growth, Linear Polymer HO2C–C6H4–CO2H (Phthalic acid) HO–CH2CH2–OH Copolymer Step growth, Linear Polymer 23. Polymers Some Condensation POLYMERS (Step Growth Polymers) Polymers 3. Polycarbonate Lexan (HO—C6H4—)2 C(CH3)2 (Bisphenol A) X2C=O (X = OCH3 or Cl) 4. Polyamide (Nylon 6,6) HO2C–(CH2)4– CO2H H2N– (CH2)6–NH2 Copolymer Step growth, Linear Polymer 5. Nylon 6,10 HOOC–(CH2)8– COOH H2N–(CH2)6–NH2 Copolymer Step growth, Linear Polymer 6. Bakelite PhOH + HCHO in (excess) Copolymer Cross-linked polymer Step growth 7. Ureaformaldehyde resin 8. Melamine formaldehyde resin ~[CO(CH2)4CO–NH(CH2)6NH]n~ (–NH–CO–NH–CH2–)n H2N–CO–NH2 (Urea) HCHO (Formaldehyde) Melamine + Formaldehyde Copolymer Step growth, linear Polymer Copolymer Step growth Cross-linked polymer Cross-linked polymer 24. Some Useful Copolymers Monomer B H2C=CHCl H2C=CCl2 H2=CH–CH=CH2 1, 3-Butdiene Copolymer Uses Saran films & fibers Buna Rubber (Homo-polymer) In manufacture of tyres, hoses, etc. H2C=CHC6H5 H2C=CHCH=CH2 SBR styrene butadiene rubber (Buna-S) Tires H2C=CHCN H2C=CHCH=CH2 Nitrile Rubber (Buna-N) Adhesives hoses H2C=CHCN H2C=CHCH=CH2 + H2C=CHC6H5 ABS rubber Fuel tanks 25. Polymers Monomer A