Composition, Properties and Uses of Polymer Questions in English

(D) Polymethyl methacrylate $(PMMA)$ is a transparent and rigid thermoplastic. Due to its high optical clarity and resistance to shattering,it is widely used in the manufacturing of optical lenses.

(D) Bakelite is a thermosetting polymer formed by the condensation polymerization of $Phenol$ and $Formaldehyde$ $(HCHO)$ in the presence of an acid or base catalyst.
The reaction involves the formation of $o$- and $p$-hydroxymethylphenol intermediates,which further undergo polymerization to form a cross-linked structure known as $Bakelite$.

(D) The reaction proceeds in two steps:
$1$. Nucleophilic substitution: The amino group of glycinamide attacks the acid chloride to form an amide linkage,releasing $HCl$. Triethylamine $(Et_3N)$ is used to neutralize the $HCl$ produced.
$2$. Free radical polymerization: The resulting monomer,which contains a vinyl group,undergoes free radical polymerization to form the final polymer product.
The structure of the final polymer is shown in option $D$.

(D) $PHBV$ is a biodegradable aliphatic polyester copolymer.
It is obtained by the copolymerization of $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.

(C) Nylon $-6$ is synthesized by the ring-opening polymerization of caprolactam at $533 \ K$ in an inert atmosphere of $N_2$.
The repeating unit of Nylon $-6$ contains $6$ carbon atoms in total ($5$ from the methylene groups and $1$ from the carbonyl group).
The structure is represented as $-[ CO - (CH_2)_5 - NH ]_n$.

(A) The given structure $[HN-CO-NH-CH_2]_n$ represents the repeating unit of Urea-Formaldehyde resin.
It is formed by the condensation polymerization of Urea $(NH_2-CO-NH_2)$ and Formaldehyde $(HCHO)$.
Thus,Formaldehyde is one of its constituents.

(D) High density polythene is prepared using Ziegler-Natta catalyst $(III)$.
$(b)$ Polyacrylonitrile is prepared by addition polymerization using peroxide catalyst $(I)$.
$(c)$ Novolac is a linear polymer of phenol and formaldehyde prepared using acid or base catalyst $(IV)$.
$(d)$ Nylon-$6$ is prepared by heating caprolactam at high temperature and pressure $(II)$.
Therefore,the correct match is $a \to III, b \to I, c \to IV, d \to II$.

(B) Thermosetting polymers are cross-linked polymers that undergo extensive cross-linking in molds during molding,which makes them hard and infusible.
Bakelite is a classic example of a thermosetting polymer,formed by the condensation reaction of phenol and formaldehyde.

(D) The given structure is the repeating unit of a polymer formed from the monomer isobutylene $(CH_2=C(CH_3)_2)$.
Upon polymerization,the double bond breaks to form a chain,resulting in the polymer polyisobutylene.

(B) Teflon is a polymer of tetrafluoroethylene,which has the chemical formula $(CF_2=CF_2)_n$. It contains fluorine atoms in its structure.
Fluorescein and phenolphthalein are organic dyes/indicators that do not contain fluorine atoms.
Therefore,the correct answer is $B$.

(C) The polymers $Natural \ Rubber$,$Gutta \ percha$,and $Isoprene$ (as a monomer) are all related to the polyisoprene family.
$Natural \ Rubber$ is $cis-1,4-polyisoprene$.
$Gutta \ percha$ is $trans-1,4-polyisoprene$.
$Isoprene$ is the monomer unit for both.
$Neoprene$ is a synthetic polymer made from the monomer $chloroprene$ $(2-chloro-1,3-butadiene)$.
Therefore,$Neoprene$ does not match the others as it is a synthetic polymer based on $chloroprene$.

(B) The strength of intermolecular forces in polymers depends on their structure:
$1$. Nylon $6,6$ is a fiber. It contains strong hydrogen bonding between the polymer chains,which results in the strongest intermolecular forces.
$2$. Polyethene is a thermoplastic polymer with weak van der Waals forces between the chains.
$3$. Buna-$S$ is an elastomer. It has the weakest intermolecular forces,which allow the polymer chains to be stretched.
Therefore,the decreasing order of intermolecular forces is: Nylon $6,6$ (fiber) $>$ Polyethene (thermoplastic) $>$ Buna-$S$ (elastomer).
This corresponds to the order: $a > c > b$.

(D) $Terylene$ is a synthetic polymer formed by the condensation polymerization reaction of terephthalic acid and ethylene glycol.
It is formed by a step-growth polymerization mechanism.
$Terylene$ is a thermoplastic,not a thermosetting plastic,because it can be remelted and reshaped multiple times without significant chemical degradation.
Therefore,the statement that it is a thermosetting plastic is incorrect.

(A) The strength of intermolecular forces in polymers follows the order: Fibres > Thermoplastics > Elastomers.
$1$. $Nylon-6$ $(A)$ is a fibre,which contains strong hydrogen bonding between the polymer chains,resulting in the strongest intermolecular forces.
$2$. $Polyvinyl$ $chloride$ $(C)$ is a thermoplastic,which has dipole-dipole interactions that are stronger than the weak van der Waals forces found in elastomers but weaker than hydrogen bonds.
$3$. $Neoprene$ $(B)$ is an elastomer,which has weak van der Waals forces between the polymer chains,making it the weakest among the three.
Therefore,the correct order of strength is $A > C > B$.

(D) $1$. Teflon $(CF_2=CF_2)$ is formed by addition polymerization,which involves $C-C$ bond formation.
$2$. Natural rubber is a polymer of isoprene $(CH_2=C(CH_3)-CH=CH_2)$,which involves $C-C$ bond formation.
$3$. Terylene is a polyester formed by the condensation of ethylene glycol and terephthalic acid,involving $C-O$ bond formation,but the backbone also contains $C-C$ bonds.
$4$. Bakelite is a phenol-formaldehyde resin formed by condensation polymerization. The linkage between phenol units is through methylene $(-CH_2-)$ bridges,involving $C-C$ bond formation between the benzene ring and the methylene group.
$5$. However,in the context of condensation polymers like Terylene (polyester) or Nylon (polyamide),the primary linkage formed is $C-O$ or $C-N$ respectively. Among the given options,Terylene is a polyester where the ester linkage $(R-COO-R')$ is formed,primarily involving $C-O$ bond formation during the condensation reaction between the carboxylic acid and the alcohol group.

(A) Acrilan is the commercial name for Polyacrylonitrile $(PAN)$.
It is a synthetic polymer produced from the monomer acrylonitrile $(CH_2=CH-CN)$ through free radical polymerization.
It is characterized as a hard,horny,and high-melting material.
Its structure is represented as $[-CH_2-CH(CN)-]_n$.

(B) Silicone is a polymeric organo silicon compound which is chemically inert and thermally stable.

(B) The condensation polymerization of ethylene glycol $(HO-CH_2-CH_2-OH)$ and terephthalic acid $(C_6H_4(COOH)_2)$ results in the formation of Terylene (also known as Dacron).
This is a polyester fiber.
Therefore,the correct option is $B$.

(C) Natural rubber is a linear polymer of isoprene ($2$-methyl-$1,3$-butadiene).
The monomer unit is $H_2C=C(CH_3)-CH=CH_2$.

(D) polyamide is a polymer containing monomers of amides joined by peptide bonds.
$1$. $Nylon$ (e.g.,$Nylon-6,6$) is a synthetic polyamide containing $-CONH-$ linkages.
$2$. $Silk$ is a natural fiber composed of proteins,which are polypeptides containing peptide (amide) linkages.
$3$. $Proteins$ are polymers of $\alpha$-amino acids linked by peptide bonds $(-CONH-)$.
Therefore,all the given options contain polyamide linkages.

(C) Natural rubber is a linear polymer of isoprene ($2-$methyl-$1,3-$butadiene).
Its chemical structure is $(C_5H_8)_n$.

(A) The monomers of Nylon $-6, 6$ are adipic acid $(HOOC(CH_2)_4COOH)$ and hexamethylene diamine $(H_2N(CH_2)_6NH_2)$.
These monomers undergo condensation polymerization to form amide linkages $(-CONH-)$.
Therefore,Nylon $-6, 6$ is a polyamide.

(A) $PHBV$ is a biodegradable polymer.
$PHBV$ stands for Poly($3$-hydroxybutyrate-co-$3$-hydroxyvalerate).
It is a copolymer formed by the combination of $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.

(D) Nylon $2-$ Nylon $6$ is a polyamide copolymer formed by the condensation polymerization of glycine $(H_2N-CH_2-COOH)$ and amino caproic acid $(H_2N-(CH_2)_5-COOH)$.
It is a biodegradable polymer because it can be broken down by microorganisms.
Therefore,all the given options are correct.

(D) . Biodegradable polymers are those that can be decomposed by microorganisms.
$PHBV$ (Poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) is a well-known biodegradable aliphatic polyester.
$PMMA$,$PVC$,and $PAN$ are synthetic non-biodegradable polymers.

(C) Silicones are synthetic organosilicon polymers which have the general formula $(R_2SiO)_n$,where $R$ is a methyl or phenyl group.
These polymers contain $(R_2Si-O)$ repeating units held together by $Si-O-Si$ linkages.
Therefore,the repeating unit is $(- R_2SiO -)_n$.

(D) $1$. Nylon-$2$-Nylon-$6$ is a polyamide copolymer of glycine and amino caproic acid,which is indeed a biodegradable polymer.
$2$. Dacron (also known as Terylene) is a polyester formed by the condensation polymerization of ethylene glycol and terephthalic acid.
$3$. BuNa-$S$ is a synthetic rubber (styrene-butadiene rubber),which is classified as an elastomer.
$4$. Bakelite is a phenol-formaldehyde resin,which is formed by condensation polymerization,not addition polymerization. Therefore,the statement 'Bakelite: Addition polymer' is false.

(D) Nylon $6, 6$ is formed by the condensation polymerization of hexamethylenediamine and adipic acid.
$1$. It is a $Copolymer$ because it is formed from two different types of monomers.
$2$. It is a $Fiber$ because it has strong intermolecular forces like hydrogen bonding,which makes it suitable for spinning into fibers.
$3$. It is a $Step \text{ } growth \text{ } polymer$ because the polymerization proceeds through the formation of intermediate species in a step-wise manner.
Therefore,all the given options are correct.

(B) The strength of intermolecular forces in polymers follows the order: Fibres > Thermoplastics > Elastomers.
$Dacron$ (also known as Terylene) is a polyester fibre.
Fibres possess strong intermolecular forces like hydrogen bonding or dipole-dipole interactions,which lead to close packing of chains and high crystallinity.
$PVC$,$Neoprene$,and $Buna-N$ are elastomers or thermoplastics,which have weaker intermolecular forces compared to fibres.
Therefore,$Dacron$ has the strongest intermolecular forces of attraction among the given options.

(A) Polyamides are polymers that contain the amide linkage $(-CONH-)$ in their backbone.
Nylon $6,6$ is a polyamide formed by the condensation polymerization of hexamethylenediamine and adipic acid.
Therefore,Nylon $6,6$ contains amide linkages.

(D) Orlon,also known as polyacrylonitrile $(PAN)$,is a synthetic polymer formed by the polymerization of acrylonitrile $(CH_2=CH-CN)$.
Therefore,the correct option is $D$.

(D) Condensation polymers are formed by the repeated condensation reaction between two different bi-functional or tri-functional monomeric units,often involving the elimination of small molecules like $H_2O$,$HCl$,or $NH_3$.
$PVC$ (Polyvinyl chloride),Plexiglass (Polymethyl methacrylate),and Polyisoprene (Natural rubber) are all addition polymers formed by the polymerization of unsaturated monomers.
Bakelite is a phenol-formaldehyde resin,which is a classic example of a condensation polymer formed by the reaction of phenol and formaldehyde with the elimination of water molecules.

(C) Formaldehyde $(HCHO)$ is a common monomer used in the preparation of condensation polymers like Bakelite,Novolac,and Melamine resin.
$1$. Bakelite and Novolac are formed by the condensation reaction of phenol and formaldehyde.
$2$. Melamine resin is formed by the condensation reaction of melamine and formaldehyde.
$3$. Orlon (also known as polyacrylonitrile) is an addition polymer formed by the polymerization of acrylonitrile $(CH_2=CH-CN)$.
Therefore,formaldehyde is not a monomer in the formation of Orlon.

(A) During the vulcanization of rubber,natural rubber is heated with sulphur and an appropriate additive at a temperature range of $373 \ K$ to $415 \ K$. This process forms sulphur bridges between the polymer chains,which increases cross-linking and improves the mechanical properties of the rubber.

(A) Nylon-$6,6$ is a polyamide formed by the condensation polymerization of hexamethylenediamine and adipic acid.
It contains the characteristic amide linkage,represented as $-CONH-$,in its polymer chain.

(A) Teflon is a polymer of tetrafluoroethene.
The chemical formula of tetrafluoroethene is $CF_2 = CF_2$.
Therefore,the monomer of Teflon is $CF_2 = CF_2$.

(A) Bakelite is a phenol-formaldehyde resin.
It is a cross-linked polymer where the phenol rings are joined together by methylene bridges ($-CH_2-$ groups) at the ortho and para positions.

(D) $1$. $Nylon-6$ is prepared by the polymerization of caprolactam. This is correctly matched.
$2$. $PHBV$ (poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) is a well-known biodegradable polymer. This is correctly matched.
$3$. Dacron (also known as Terylene) is a polyester used as a fibre. This is correctly matched.
$4$. Low density polyethene $(LDPE)$ is prepared by free radical polymerization of ethene at high pressure and temperature. Ziegler-Natta catalyst is used for the preparation of High Density Polyethene $(HDPE)$. Therefore,this is incorrectly matched.

(NONE) The correct pairings are as follows:
$1$. $\text{Novolac}$ is formed from $\text{Phenol}$ and $\text{Formaldehyde}$. (Correct)
$2$. $\text{Nylon } 6$ is formed from $\text{Caprolactam}$. (Correct)
$3$. $\text{BuNa-}N$ is formed from $1,3\text{-Butadiene}$ and $\text{Acrylonitrile}$. (Correct)
$4$. $\text{Natural rubber}$ is a polymer of $\text{cis-1,4-polyisoprene}$,where the monomer is $\text{Isoprene}$ $(2\text{-methyl-1,3-butadiene})$. While the option says $\text{cis-Isoprene}$,$\text{Isoprene}$ itself is the monomer. However,in standard chemistry nomenclature,$\text{Nylon } 6$ is derived from $\text{Caprolactam}$ (spelled with an 'a'). All given options are technically correct in their chemical associations. If this is a multiple-choice question where one must be incorrect,there might be a typo in the provided options. Given the standard curriculum,all these pairs are correct.

(C) Rayon is a semi-synthetic fiber obtained from natural sources.
It is manufactured from wood pulp,which is primarily composed of $Cellulose$.
Therefore,$Cellulose$ is the polymer used in the manufacturing of rayon.

(D) Thermosetting polymers are cross-linked or heavily branched molecules,which on heating undergo extensive cross-linking in molds and again become infusible. Thus,they do not melt or soften on heating. They are generally insoluble in common solvents due to their rigid network structure. Therefore,both statements $B$ and $C$ are correct,making $D$ the correct answer.

(D) Thermosetting polymers are cross-linked polymers that undergo extensive cross-linking in molds during their formation and become infusible and insoluble on heating.
Examples include Bakelite,urea-formaldehyde resins,etc.
Polyethylene,Neoprene,and $PVC$ are thermoplastic polymers.

(B) $Nylon-6,6$ is a polyamide polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid.
These polymer chains are held together by strong intermolecular hydrogen bonds between the carbonyl oxygen $(C=O)$ of one chain and the amide hydrogen $(N-H)$ of the adjacent chain.
These hydrogen bonds provide high crystallinity and high tensile strength to the polymer.

(A) Elastomers are polymers in which the polymer chains are held together by the weakest intermolecular forces. These weak forces permit the polymer to be stretched. Buna-$S$ is a synthetic rubber,which is a classic example of an elastomer. Nylon and Terylene are fibers,and $PVC$ is a thermoplastic.

(D) Cross-linked polymers are formed from bi-functional and tri-functional monomers and contain strong covalent bonds between various linear polymer chains.
Bakelite is a classic example of a cross-linked polymer formed by the condensation reaction of phenol and formaldehyde.
Polypropylene,Nylon-$66$,and Nylon-$6$ are linear polymers.

(D) In the manufacturing of tires,rubber is reinforced to increase its durability and hardness.
Carbon black is added to the rubber to improve its tensile strength and resistance to wear and tear,making it suitable for tire production.

(D) Polyvinyl chloride $(PVC)$ is inherently a hard and brittle polymer. To make it flexible and suitable for applications like pipes,cables,and films,additives known as plasticizers (such as di$-2-$ethylhexyl phthalate) are added during the processing or polymerization stage. These molecules insert themselves between the polymer chains,increasing the free volume and reducing intermolecular forces,which results in increased flexibility.

(C) Terylene (also known as Dacron) is a polyester polymer.
It is formed by the condensation polymerization of ethylene glycol $(HO-CH_2-CH_2-OH)$ and terephthalic acid $(C_6H_4(COOH)_2)$.
The reaction involves the formation of an ester linkage $(-COO-)$ between the monomer units.
Nylon contains amide linkages,Bakelite is a phenol-formaldehyde resin,and $PVC$ is a vinyl polymer.

(B) The correct answer is $B$.
$Teflon$ is a polymer of tetrafluoroethylene $(CF_2=CF_2)$,which is a thermoplastic.
Phenol and formaldehyde form $Bakelite$,which is a cross-linked thermosetting polymer.
$Terylene$ is indeed a condensation polymer of terephthalic acid and ethylene glycol.
$Perspex$ (or $PMMA$) is a homopolymer of methyl methacrylate.
$Synthetic$ $rubber$ (like $Buna-S$) is a co-polymer of $1,3-butadiene$ and styrene.

(A) Melamine is a heterocyclic organic compound with the formula $C_3H_6N_6$.
Its structure consists of a $1, 3, 5-$triazine ring substituted with three amino groups at the $2, 4,$ and $6$ positions.
Therefore,its $IUPAC$ name is $2, 4, 6-$triamino$-1, 3, 5-$triazine.