Composition, Properties and Uses of Polymer Questions in English

(N/A) Preparation: It is prepared by the condensation polymerization of hexamethylenediamine with adipic acid under high pressure and at high temperature $(553 \ K)$.
Chemical Reaction:
$nHOOC(CH_2)_4COOH + nH_2N(CH_2)_6NH_2$ $\xrightarrow{553 \ K, \text{high pressure}} [-NH(CH_2)_6NHCO(CH_2)_4CO-]_n + 2nH_2O$
Properties:
$1$. Nylon-$6,6$ is a fibre-forming solid.
$2$. It possesses high tensile strength due to strong intermolecular forces like hydrogen bonding.
$3$. These strong forces lead to close packing of chains,imparting a crystalline nature.
Uses:
It is used in making sheets,bristles for brushes,and in the textile industry.

(N/A) Preparation: Nylon-$6$ is obtained by heating caprolactam with water at a high temperature $(533-543 \ K)$.
Chemical Reaction:
Caprolactam $\xrightarrow{533-543 \ K, H_2O}$ Nylon-$6$
Uses: Nylon-$6$ is used for the manufacture of tyre cords,fabrics,and ropes.

(N/A) Dacron or Terylene are well-known examples of polyesters.
These are polycondensation products of dicarboxylic acids and diols.
Preparation of Terylene or Dacron:
It is manufactured by heating a mixture of ethylene glycol and terephthalic acid at $420 \ K$ to $460 \ K$ in the presence of a zinc acetate-antimony trioxide catalyst through condensation polymerization.
The chemical reaction is as follows:
$n(HO-CH_2-CH_2-OH) + n(HOOC-C_6H_4-COOH) \xrightarrow{\Delta, \text{catalyst}} [-O-CH_2-CH_2-O-CO-C_6H_4-CO-]_n + 2nH_2O$
Properties:
Dacron fibre (Terylene) is crease-resistant and is used in blending with cotton and wool fibres.
Uses:
It is used in the manufacture of wash-and-wear garments,as glass-reinforcing materials in safety helmets,and in industrial applications like conveyor belts.

(N/A) Phenol-formaldehyde polymers are the oldest synthetic polymers. These are obtained by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst.
One common polymer in this category is $Bakelite$.
$Preparation$:
The reaction starts with the initial formation of $o-$ and/or $p-$hydroxymethylphenol derivatives,which further react with phenol to form compounds having rings joined to each other through $-CH_2-$ groups. The initial product could be a linear product called $Novolac$,which is used in paints. On further heating with formaldehyde,$Novolac$ forms a cross-linked fusible product known as $Bakelite$.
$Properties$:
$Bakelite$ is a thermosetting polymer. It is hard,rigid,and has high thermal stability and electrical insulation properties.
$Uses$:
It is used for making electrical switches,handles of various utensils,computer discs,and phonograph records.

(N/A) Melamine-formaldehyde polymer is formed by the condensation polymerization of melamine and formaldehyde.
The reaction involves the formation of a resin intermediate,which then undergoes further condensation polymerization to form the final polymer.
It is used in the manufacture of unbreakable crockery.

(N/A) Copolymerization is a polymerization reaction in which a mixture of more than one monomeric species is allowed to polymerize and form a copolymer.
The copolymer can be made not only by chain growth polymerization but by step growth polymerization also.
It contains multiple units of each monomer used in the same polymeric chain.
For example,a mixture of $1,3$-butadiene and styrene can form a copolymer as shown below:
$nCH_2=CH-CH=CH_2 + nC_6H_5CH=CH_2 \rightarrow -[CH_2-CH=CH-CH_2-CH(C_6H_5)-CH_2]_n-$
Copolymers have properties quite different from homopolymers.
For example,butadiene-styrene copolymer is quite tough and is a good substitute for natural rubber.
It is used for the manufacture of autotyres,floor tiles,footwear components,cable insulation,etc.

(N/A) Rubber is a natural polymer and possesses elastic properties.
It is also termed as an elastomeric polymer. In elastomeric polymers,the polymer chains are held together by weak intermolecular forces. These weak binding forces permit the polymer to be stretched.
$A$ few 'crosslinks' are introduced in between the chains,which help the polymer to retract to its original position after the force is released.
Rubber has a variety of uses. It is manufactured from rubber latex,which is a colloidal dispersion of rubber in water.
This latex is obtained from the rubber tree,which is found in India,Sri Lanka,Indonesia,Malaysia,and South America.
Natural rubber may be considered as a linear polymer of isoprene ($2$-methyl-$1,3$-butadiene) and is also called $cis$-$1,4$-polyisoprene.
The $cis$-polyisoprene molecule consists of various chains held together by weak van der Waals interactions and has a coiled structure.
Thus,it can be stretched like a spring and exhibits elastic properties.
The chemical structure is as follows:
Isoprene: $CH_2=C(CH_3)-CH=CH_2$
Natural rubber: $-(CH_2-C(CH_3)=CH-CH_2)_n-$

(N/A) Natural rubber becomes soft at high temperatures $( >335 \ K)$ and brittle at low temperatures $( < 283 \ K)$ and shows high water absorption capacity. It is soluble in non-polar solvents and is non-resistant to attack by oxidizing agents.
To improve upon these physical properties,a process of vulcanization is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between $373 \ K$ to $415 \ K$. On vulcanization,sulphur forms cross-links at the reactive sites of double bonds and thus the rubber gets stiffened.
In the manufacture of tyre rubber,$5 \%$ of sulphur is used as a cross-linking agent. The probable structures of vulcanized rubber molecules are shown below:
(Structure Image: $939-$s48)

(N/A) Preparation: Neoprene (polychloroprene) is formed by the free radical polymerization of chloroprene ($2$-chloro$-1,3-$butadiene).
Reaction: $nCH_2=C(Cl)-CH=CH_2 \xrightarrow{\text{Polymerization}} [-CH_2-C(Cl)=CH-CH_2-]_n$
Properties: It has superior resistance to vegetable and mineral oils.
Uses: It is used for manufacturing conveyor belts,gaskets,and hoses.

(N/A) $4 \%$ solution of nitrocellulose in a mixture of alcohol and ether is called collodion.

(N/A) Preparation: Buna-$N$ is obtained by the copolymerization of $1,3-$butadiene and acrylonitrile in the presence of a peroxide catalyst.
The reaction is as follows:
$nCH_2=CH-CH=CH_2 + nCH_2=CH(CN) \xrightarrow{\text{Copolymerization}} [-CH_2-CH=CH-CH_2-CH_2-CH(CN)-]_n$
Uses: It is resistant to the action of petrol,lubricating oil,and organic solvents and is used in making oil seals,tank lining,etc.

(N/A) The properties of polymers are closely related to their molecular mass,size,and structure.
During the synthesis of polymers,the growth of the polymer chain depends on the availability of monomers in the reaction mixture.
As a result,a polymer sample contains chains of varying lengths,meaning the molecules are not uniform in size.
Therefore,the molecular mass of a polymer is always expressed as an average value,such as the number-average molecular mass $(M_n)$ or weight-average molecular mass $(M_w)$.

(B) large number of synthetic polymers are highly resistant to environmental degradation processes,leading to the accumulation of persistent polymeric solid waste.
These wastes cause severe environmental pollution and remain undegraded for very long periods.
To address the growing concern regarding the environmental impact of these non-biodegradable wastes,scientists have designed and developed new biodegradable synthetic polymers that can be broken down by microorganisms.

(N/A) The full form of $PHBV$ is poly $\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate $(PHBV)$.
Preparation: It is obtained by the copolymerization of $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.
The reaction is as follows:
$n CH_3-CH(OH)-CH_2-COOH + n CH_3-CH_2-CH(OH)-CH_2-COOH$ $\rightarrow -[O-CH(CH_3)-CH_2-CO-O-CH(CH_2CH_3)-CH_2-CO]_n- + 2n H_2O$
Uses: $PHBV$ is used in speciality packaging,orthopaedic devices,and in the controlled release of drugs.
$PHBV$ undergoes bacterial degradation in the environment.

(N/A) The details for the requested polymers are provided in the table below:
| Name of Polymer | Monomer | Structure | Uses |
| :--- | :--- | :--- | :--- |
| Polypropene | Propene | $(-CH_2-CH(CH_3)-)_n$ | Manufacture of ropes,toys,pipes,fibres,etc. |
| Polystyrene | Styrene | $(-CH_2-CH(C_6H_5)-)_n$ | As insulator,wrapping material,manufacture of toys,radio and television cabinets. |
| Polyvinyl chloride $(PVC)$ | Vinyl chloride | $(-CH_2-CH(Cl)-)_n$ | Manufacture of rain coats,hand bags,vinyl flooring,water pipes. |
| Urea-formaldehyde Resin | Urea,Formaldehyde | $(-NH-CO-NH-CH_2-)_n$ | For making unbreakable cups and laminated sheets. |
| Glyptal | Ethylene glycol,Phthalic acid | $(-OCH_2-CH_2OOC-C_6H_4-CO-)_n$ | Manufacture of paints and lacquers. |
| Bakelite | Phenol,Formaldehyde | $(-C_6H_3(OH)-CH_2-)_n$ | For making combs,electrical switches,handles of utensils and computer discs. |

(N/A) This process is known as vulcanization of rubber and the product is known as vulcanized rubber. In this process,sulphur forms cross-links at the reactive sites of double bonds in the polymer chains,making the rubber harder and more durable. The structure of vulcanized rubber is represented as follows:
$\sim CH_2-C(CH_3)-CH-CH_2 \sim$
$| \quad \quad \quad |$
$S \quad \quad \quad S$
$| \quad \quad \quad |$
$\sim CH_2-C(CH_3)-CH-CH_2 \sim$

(N/A) The polymer shown in the image is $cis-polyisoprene$,which is commonly known as natural rubber.
It is formed by the $1,4$-polymerization of $2-methylbuta-1,3-diene$ (isoprene) units.
The stereochemistry of the double bonds in natural rubber is exclusively $cis$.

(N/A) Rubbers are called elastomers because they possess weak intermolecular forces of attraction between the polymer chains. These weak forces allow the polymer to be stretched. Upon applying a force,they change their shape,and upon removal of the force,they regain their original shape due to the presence of cross-links between the chains.

(B) Natural rubber is soft and sticky at high temperatures and brittle at low temperatures.
To improve its physical properties,such as elasticity and strength,cross-links are introduced between the polymer chains through the process of vulcanization.
This makes the rubber more durable and suitable for practical applications.

(B) The elastic property of $cis-polyisoprene$ (natural rubber) is due to the presence of weak Van der Waals forces between its polymer chains.
These weak forces allow the polymer chains to slide over each other when stretched and return to their original position when the stretching force is removed,providing elasticity.

(N/A) $HDP$ (High Density Polyethylene) consists of linear molecules,which allow for close packing,resulting in high density and a translucent appearance.
$LDP$ (Low Density Polyethylene) has a highly branched structure,which prevents close packing,resulting in low density and a transparent appearance.
Due to these structural differences,$HDP$ is used for making buckets,dustbins,and pipes,while $LDP$ is used in the manufacture of squeeze bottles,toys,and flexible pipes.

(B) Nylon contains amide groups $( -CONH- )$ in its backbone,which facilitate strong intermolecular hydrogen bonding. This,combined with its linear structure,allows the polymer chains to pack closely together,resulting in a crystalline character.

(N/A) The polymer used in laminating sheets is Urea-formaldehyde resin.
Its monomeric units are Urea $(NH_2CONH_2)$ and Formaldehyde $(HCHO)$.
The reaction is a condensation polymerization:
$nNH_2CONH_2 + nHCHO \rightarrow [-NH-CO-NH-CH_2-]_n + nH_2O$

(A-V, B-III, C-I, D-II, E-IV) The correct matches are as follows:
$A$. High density polythene is formed from $v$. Ethene.
$B$. Neoprene is formed from $iii$. Chloroprene.
$C$. Natural rubber is formed from $i$. Isoprene.
$D$. Teflon is formed from $ii$. Tetrafluoroethene.
$E$. Acrilan is formed from $iv$. Acrylonitrile.
Thus,the correct sequence is $A-v, B-iii, C-i, D-ii, E-iv$.

(A) The correct matches are:
$A-i$ (Nylon-$6$ is polycaprolactum)
$B-ii$ ($PVC$ is polyvinyl chloride)
$C-iii$ (Acrilan is polyacrylonitrile)
$D-iv$ (Natural rubber is cis-polyisoprene)
$E-v$ ($LDP$ is low density polythene)
Therefore,the correct sequence is $A-i, B-ii, C-iii, D-iv, E-v$.

(A) The correct matches are:
$A$ (Bakelite) $\rightarrow$ $iv$ (Electrical switches)
$B$ (Low density polythene) $\rightarrow$ $v$ (Squeeze bottles)
$C$ (Melamine-formaldehyde resin) $\rightarrow$ $i$ (Unbreakable crockery)
$D$ (Nylon $-6$) $\rightarrow$ $vi$ (Tyre cords)
$E$ (Polytetrafluoroethene) $\rightarrow$ $ii$ (Non-stick cookwares)
$F$ (Polystyrene) $\rightarrow$ $iii$ (Packaging material for shock)
Thus,the correct sequence is: $A-iv, B-v, C-i, D-vi, E-ii, F-iii$.

(A) (Terylene) contains ester linkages $(ii)$.
$B$ (Nylon) contains amide linkages $(iv)$.
$C$ (Cellulose) contains glycosidic linkages $(i)$.
$D$ (Protein) contains peptide linkages (a type of amide linkage,but in this context,it is distinct; however,based on the options provided,$D$ corresponds to amide linkage $iv$ if we consider the general structure,but typically $D$ is peptide. Given the options,$A-ii, B-iv, C-i, D-iv, E-iii$ is the mapping).
Correct matching: $A-ii, B-iv, C-i, D-iv, E-iii$.

(D) The correct matches are as follows:
$A$. Acrilan (Polyacrylonitrile) has the repeating unit $-[CH_2-CH(CN)]_n-$ $(iv)$.
$B$. Polystyrene is formed from styrene,so its repeating unit is $-[CH_2-CH(C_6H_5)]_n-$ $(ii)$.
$C$. Neoprene is polychloroprene,with the repeating unit $-[CH_2-C(Cl)=CH-CH_2]_n-$ $(iii)$.
$D$. Novolac is a linear polymer of phenol and formaldehyde $(v)$.
$E$. Buna-$N$ is a copolymer of $1,3$-butadiene and acrylonitrile,with the repeating unit $-[CH_2-CH=CH-CH_2-CH_2-CH(CN)]_n-$ $(i)$.
Therefore,the correct match is $A-iv, B-ii, C-iii, D-v, E-i$.

(N/A) Synthetic polymers are resistant to environmental degradation,leading to the accumulation of solid waste.
Biodegradable synthetic polymers are designed by incorporating functional groups similar to those found in biopolymers,such as aliphatic polyesters (e.g.,$PHBV$).
Biopolymers are polymers produced by living organisms. They may or may not be biodegradable. For example,$Protein$ and $starch$ are biodegradable,whereas $Keratin$ is non-biodegradable.
Biodegradable polymers are specifically designed to be broken down by microorganisms into simpler,non-toxic substances in the environment. An example is $PHBV$ (poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate).

(N/A) Phenol and formaldehyde undergo condensation to give a polymer $Novolac$ $(A)$,which on heating with formaldehyde gives $Bakelite$ $(B)$ as a thermosetting polymer.
$Novolac$ is a linear polymer,while $Bakelite$ is a cross-linked polymer.
The reactions involved in the formation of $Novolac$ are:
$1$. Phenol reacts with formaldehyde in the presence of an acid or base catalyst to form $o$-hydroxybenzyl alcohol and $p$-hydroxybenzyl alcohol derivatives.
$2$. These derivatives undergo condensation polymerization to form the linear polymer $Novolac$.

(N/A) Low density polythene $(LDPE)$ and high density polythene $(HDPE)$ are both polymers of ethene $(CH_2=CH_2)$,but they are synthesized under different conditions,leading to distinct structural features.
$LDPE$ is obtained by the polymerization of ethene under high pressure $(1000-2000 \ atm)$ and temperature $(350-570 \ K)$ in the presence of traces of dioxygen or a peroxide initiator. It has a highly branched structure,which results in low density and flexibility.
$HDPE$ is formed by the addition polymerization of ethene in the presence of a catalyst like triethylaluminium and titanium tetrachloride ($Ziegler-Natta$ catalyst) at low pressure $(6-7 \ atm)$ and temperature $(333-343 \ K)$. It consists of closely packed linear molecules,which results in high density and greater mechanical strength.

(B) The correct matches are as follows:
$a$. Natural rubber is a polymer of isoprene ($2-$methyl$-1,3-$butadiene). Thus,$a-IV$.
$b$. Neoprene is a polymer of chloroprene ($2-$chloro$-1,3-$butadiene). Thus,$b-III$.
$c$. Buna$-N$ is a copolymer of $1,3-$butadiene and acrylonitrile. Thus,$c-II$.
$d$. Buna$-S$ is a copolymer of $1,3-$butadiene and styrene. Thus,$d-I$.
Therefore,the correct sequence is $a-IV, b-III, c-II, d-I$.

(C) The polymerization of ethene in the presence of a Ziegler-Natta catalyst (triethylaluminium and titanium tetrachloride) at low pressure and temperature produces High Density Polyethylene $(HDPE)$.
$HDPE$ consists of linear chains that are closely packed,resulting in high density and chemical inertness.
Due to these properties,$HDPE$ is used in the manufacture of buckets,dustbins,bottles,and pipes.
Therefore,both the Assertion $(A)$ and Reason $(R)$ are correct,and $(R)$ is the correct explanation of $(A).$

(B) Bakelite is a thermosetting polymer formed by the condensation reaction of phenol and formaldehyde. It possesses a highly cross-linked structure,which makes it hard and infusible.

(A) $i$. Buna-$S$ is a copolymer formed from $1,3$-butadiene and styrene $(P)$.
$ii$. Terylene (Dacron) is a polyester formed from ethylene glycol $(Q)$ and terephthalic acid.
$iii$. Neoprene is a type of elastomer formed from the monomer chloroprene $(R)$.
Therefore,the correct matching is $i-P, ii-Q, iii-R$.

(C) Urea-formaldehyde resin is widely used in the manufacture of wood laminates and adhesives for bonding wood.

(C) Caprolactum is the monomeric unit of polymer Nylon$-6$.
$(b)$ $2-$Chloro$-1,3-$butadiene is the monomeric unit of polymer Neoprene.
$(c)$ Isoprene ($2-$methylbuta$-1,3-$diene) is the monomeric unit of Natural rubber.
$(d)$ Acrylonitrile $(CH_2=CH-CN)$ is one of the monomeric units of polymer Buna$-N$.
Therefore,the correct matching is: $(a)$ $\rightarrow (iii), (b)$ $\rightarrow (iv), (c)$ $\rightarrow (i), (d)$ $\rightarrow (ii)$.

(A) The provided image shows the polymerization of $1,3-butadiene$ and styrene to form $Buna-S$ in the presence of nascent oxygen as an initiator.
$Buna-S$ is a synthetic elastomer (a type of rubber),not a thermosetting polymer.
$Neoprene$ is a homopolymer of $chloroprene$,not a copolymer.
$Buna-N$ is a synthetic copolymer,not a natural polymer.
Therefore,the statement that the synthesis of $Buna-S$ requires nascent oxygen is correct based on the provided reaction scheme.

(A) Neoprene is a polymer of chloroprene ($2-$chloro$-1,3-$butadiene). Its structure is formed by the polymerization of the monomer $CH_2=C(Cl)-CH=CH_2$. The resulting polymer is $n[CH_2=C(Cl)-CH=CH_2] \rightarrow [-CH_2-C(Cl)=CH-CH_2-]_n$.

(D) Buna-$S$ is a copolymer formed by the polymerization of $1,3$-butadiene and styrene.
In the name Buna-$S$,'Bu' stands for $1,3$-butadiene,'na' stands for sodium (catalyst),and '$S$' stands for styrene.

(B) $Dacron$ (also known as $Terylene$) is a polyester polymer.
It is formed by the condensation polymerization of $Ethylene \ glycol$ $(HO-CH_2-CH_2-OH)$ and $Terephthalic \ acid$ $(HOOC-C_6H_4-COOH)$.
The reaction is as follows:
$n(HOOC-C_6H_4-COOH) + n(HO-CH_2-CH_2-OH) \rightarrow [-OC-C_6H_4-CO-O-CH_2-CH_2-O-]_n + 2n(H_2O)$
Thus,the correct option is $B$.

(A) Orlon is a commercial name for polyacrylonitrile $(PAN)$.
It is prepared by the addition polymerization of acrylonitrile $(CH_2=CH-CN)$ in the presence of a peroxide catalyst.
The reaction is as follows:
$n(CH_2=CH-CN) \xrightarrow{\text{Polymerization}} [-CH_2-CH(CN)-]_n$
Thus,Orlon fibres are made up of polyacrylonitrile.

(C) Bakelite is a thermosetting polymer formed by the condensation polymerization of phenol and formaldehyde.
Initially,the reaction produces a linear polymer called Novolac.
Upon further heating with formaldehyde,Novolac undergoes cross-linking to form the infusible,hard,and cross-linked polymer known as Bakelite.

(A) The correct matches are as follows:
$(a)$ Chloroprene is $CH_2=C(Cl)-CH=CH_2$,which corresponds to $(ii)$.
$(b)$ Neoprene is the polymer $[-CH_2-C(Cl)=CH-CH_2-]_n$,which corresponds to $(iii)$.
$(c)$ Acrylonitrile is $CH_2=CH-CN$,which corresponds to $(iv)$.
$(d)$ Isoprene is $CH_2=C(CH_3)-CH=CH_2$,which corresponds to $(i)$.
Therefore,the correct matching is $a-ii, b-iii, c-iv, d-i$.

(A) Novolac is a linear polymer formed by the condensation reaction of phenol and formaldehyde in the presence of an acid catalyst.
The repeating unit consists of phenol rings linked by methylene $(-CH_2-)$ bridges at ortho or para positions,as shown in the structure.

(C) biodegradable polyamide,known as nylon-$2$-nylon-$6$,is a copolymer formed by the condensation polymerization of glycine $(NH_2CH_2COOH)$ and aminocaproic acid $(NH_2(CH_2)_5COOH)$.

(A) The correct matching is as follows:
$(a)$ Nylon-$6$ is formed from $(v)$ Caprolactam.
$(b)$ Dacron is formed from $(i)$ Ethylene glycol and terephthalic acid.
$(c)$ Glyptal is formed from $(iii)$ Ethylene glycol and phthalic acid.
$(d)$ Novolac is formed from $(iv)$ Phenol and formaldehyde.
Therefore,the correct sequence is $(a)-(v), (b)-(i), (c)-(iii), (d)-(iv)$.

(C) Thermosetting polymers are cross-linked polymers that undergo extensive cross-linking during molding,making them hard and infusible. Therefore,they cannot be reshaped or reused upon heating.

(D) . Polyesters are polymers that contain the ester functional group in their main chain.
$PHBV$ (Poly-$ \beta $-hydroxybutyrate-co-$ \beta $-hydroxy valerate) is a biodegradable aliphatic polyester formed by the copolymerization of $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.

(C) The monomer unit of Novolac is $o$-hydroxybenzyl alcohol (saligenin),which has the chemical formula $C_7H_8O_2$.
The molecular mass of the monomer unit is $(7 \times 12) + (8 \times 1) + (2 \times 16) = 84 + 8 + 32 = 124 \ g/mol$.
Novolac is formed by the condensation polymerization of phenol and formaldehyde,where water molecules are eliminated.
For a polymer chain consisting of $n$ monomer units,$(n-1)$ molecules of water are removed.
The mass of the polymer is given by: $Mass_{polymer} = (n \times Mass_{monomer}) - ((n-1) \times Mass_{water})$.
Substituting the given values: $963 = (n \times 124) - ((n-1) \times 18)$.
$963 = 124n - 18n + 18$.
$963 - 18 = 106n$.
$945 = 106n$.
$n = 945 / 106 \approx 8.91$.
Rounding to the nearest integer,the number of monomer units $n = 9$.