Composition, Properties and Uses of Polymer Questions in English

(C) Dacron,also known as terylene,is a condensation polymer formed by the polymerization of terephthalic acid $(HOOC-C_6H_4-COOH)$ and ethylene glycol $(HO-CH_2-CH_2-OH)$.
This reaction occurs by heating the mixture at $420-460 \ K$ in the presence of zinc acetate and antimony trioxide as a catalyst,resulting in the elimination of water molecules.

(B) Elastomers are polymers that possess weak intermolecular forces of attraction,allowing them to be stretched.
Nylon-$6,6$ is a fibre,not an elastomer,because it has strong intermolecular forces like hydrogen bonding.
Artificial silk (rayon) is indeed derived from cellulose.
Natural rubber is a polymer of isoprene ($2$-methyl-$1,3$-butadiene).
Both starch and cellulose are natural polymers of glucose.
Therefore,the statement that Nylon-$6,6$ is an elastomer is false.

(B) Biodegradable polymers are polymers that can be decomposed by microorganisms.
Option $B$ involves $H_2N-CH_2-COOH$ (Glycine) and $H_2N-(CH_2)_5-COOH$ (Aminocaproic acid). These monomers undergo condensation polymerization to form Nylon-$2$-Nylon-$6$,which is a well-known biodegradable polyamide polymer.
Therefore,the correct set is $B$.

(A) $Terylene$ is a polyester because it contains ester linkages $(-COO-)$ in its backbone.
It is formed by the condensation polymerization of monomer units,terephthalic acid $(C_6H_4(COOH)_2)$ and ethylene glycol $(HO-CH_2-CH_2-OH)$.

(A) Neoprene is a synthetic rubber produced by the free radical polymerization of chloroprene ($2$-chloro-$1,3$-butadiene).
The repeating unit of neoprene is formed by the polymerization of $CH_2=C(Cl)-CH=CH_2$.
The resulting structure is $[-CH_2-C(Cl)=CH-CH_2-]_n$.

(A) Neoprene is a polymer of chloroprene ($2$-chloro-$1,3$-butadiene). Its correct repeating unit is $[ - CH_2 - C(Cl) = CH - CH_2 - ]_n$. The structure provided in option $(A)$ is incorrect because it contains an extra $-CH_2-$ group in the main chain.

(D) Natural rubber is $cis-1,4-polyisoprene$ and has all $cis$ configurations about the double bond as shown in the structure. It is prepared from latex which is obtained as the $cis$ form,called $Havea$ Rubber,from the rubber tree ($Havea$ $brasiliensis$). Therefore,the statement that natural rubber has $trans$-configuration is false.

(B) Buna-$N$ is a synthetic rubber formed by the copolymerization of $1,3$-butadiene $(CH_2=CH-CH=CH_2)$ and acrylonitrile $(CH_2=CH-CN)$ in the presence of a peroxide catalyst.

(D) Bakelite is used for making gears,protective coatings,and electrical fittings.
$(b)$ Glyptal is used in the manufacture of paints and lacquers.
$(c)$ $PP$ (Polypropene) is used in the manufacture of textiles,packaging materials,etc.
$(d)$ Polyvinyl chloride $(PVC)$ is used in the manufacture of raincoats,handbags,and leather clothes.

(B) Low density polythene $(LDPE)$ is a poor conductor of electricity.
Its synthesis involves the polymerization of ethene at high pressure $(1000-2000 \ atm)$ and temperatures $(350-570 \ K)$ in the presence of traces of dioxygen or a peroxide initiator as a catalyst.
$LDPE$ is chemically inert and tough but flexible,making it suitable for squeeze bottles,toys,and flexible pipes.
High density polythene $(HDPE)$ is used in the manufacture of buckets,dust-bins,and bottles.
Therefore,the statement that $LDPE$ is used in the manufacture of buckets and dust-bins is $FALSE$.

(C) The starting material is $o$-methylacetophenone (or $2-$methylacetophenone).
Treatment with $KMnO_4/KOH$ followed by acidification with $dil. H_2SO_4$ leads to the oxidation of both the acetyl group $(-COCH_3)$ and the methyl group $(-CH_3)$ attached to the benzene ring into carboxylic acid groups $(-COOH)$.
The product $(Q)$ is phthalic acid (benzene$-1,2-$dicarboxylic acid).
Phthalic acid is a key monomer used in the synthesis of the polymer Glyptal (polyethylene phthalate) by reacting it with ethylene glycol.

(A) The intermolecular forces in polymers depend on their structure and the presence of functional groups.
$1$. $(Q)$ Buna $-S$ is an elastomer,which has weak van der Waals forces of attraction between polymer chains.
$2$. $(R)$ Polythene is a thermoplastic polymer with intermediate van der Waals forces.
$3$. $(P)$ Nylon $-6,6$ is a fiber,which possesses strong hydrogen bonding between the polymer chains.
Therefore,the increasing order of intermolecular forces is: $\text{Elastomer} < \text{Thermoplastic} < \text{Fiber}$.
Thus,the correct order is $(Q) < (R) < (P)$.

(C) Glyptal is a polyester formed by the condensation polymerization of ethylene glycol $(HO-CH_2-CH_2-OH)$ and phthalic acid $(C_6H_4(COOH)_2)$.
The structure shown in option $C$ represents the repeating unit of glyptal,which is formed by the esterification of phthalic acid with ethylene glycol.

(B) An addition polymer is formed by the repeated addition of monomer molecules possessing double or triple bonds.
$A$ homopolymer is a polymer formed from only one type of monomer unit.
$1$. Buna-$S$ is a copolymer formed from styrene and butadiene.
$2$. Gutta-percha is a naturally occurring isomer of polyisoprene,formed by the polymerization of isoprene $(C_5H_8)$ units. It is an addition homopolymer.
$3$. Nylon-$6,10$ is a condensation copolymer formed from hexamethylenediamine and sebacic acid.
$4$. Nylon-$6,6$ is a condensation copolymer formed from adipic acid and hexamethylenediamine.
Therefore,Gutta-percha is the correct answer.

(A) $1$. Nylon-$6,6$ is formed by the condensation polymerization of hexamethylenediamine and adipic acid,which contains amide linkages. Thus,it is a polyamide. This statement is correct.
$2$. Bakelite is a thermosetting polymer formed by the condensation of phenol and formaldehyde,resulting in a highly cross-linked structure. Thus,the statement that it is not cross-linked is incorrect.
$3$. The Ziegler-Natta catalyst is a mixture of titanium tetrachloride $(TiCl_4)$ and triethylaluminium $(Al(C_2H_5)_3)$. This statement is also correct.
$4$. Nylon-$6$ is a fiber,not an elastomer. This statement is incorrect.
Note: In many standard chemistry contexts,both $A$ and $C$ are chemically accurate statements. However,$A$ is the most fundamental classification.

(A) Thermosetting polymers are cross-linked or heavily branched molecules that undergo extensive cross-linking in molds during hardening,becoming infusible and insoluble.
$Bakelite$ is a classic example of a thermosetting polymer formed by the condensation reaction of phenol and formaldehyde.
Natural rubber,Teflon,and Acrilan are thermoplastic polymers.

(B) Thermosetting polymers are cross-linked polymers that become hard and infusible on heating and cannot be remolded.
Examples include Bakelite and $Urea-formaldehyde$ resin.
Polystyrene,Terylene,and Buna-$S$ are examples of thermoplastic or elastomeric polymers.

(A) Neoprene is a synthetic rubber produced by the free radical polymerization of chloroprene ($2$-chloro-$1,3$-butadiene).
The polymerization reaction is:
$n CH_2=C(Cl)-CH=CH_2 \xrightarrow{\text{Polymerization}} [-CH_2-C(Cl)=CH-CH_2-]_n$
Thus,the correct structure of neoprene is $[-CH_2-C(Cl)=CH-CH_2-]_n$.

(D) Polyamide fibres contain the amide linkage $(-CONH-)$ in their structure.
$Nylon-6,6$ and $Nylon-6$ are synthetic polyamide fibres.
Silk is a natural polyamide fibre.
Terylene is a polyester fibre,which contains the ester linkage $(-COO-)$ in its structure.
Therefore,Terylene is not a polyamide fibre.

(D) . Biodegradable polymers are polymers that degrade by microbial action.
$PHBV$ (poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) and $Nylon-2-Nylon-6$ are well-known examples of biodegradable polymers.
Many biodegradable polymers are synthesized via condensation polymerization (e.g.,$PHBV$ and $Nylon-2-Nylon-6$).
Therefore,the statement that they cannot be synthesized by condensation reactions is false.

(C) Caprolactam is a cyclic amide with a $7-$membered ring containing one nitrogen atom and one carbonyl group.
Its chemical formula is $C_6H_{11}NO$.
The structure consists of a $7-$membered ring with five methylene $(-CH_2-)$ groups,one carbonyl $(C=O)$ group,and one amino $(-NH-)$ group.
Therefore,the correct structure is a $7-$membered cyclic amide.

(C) The reaction between melamine ($2,4,6-$triamino$-1,3,5-$triazine) and formaldehyde proceeds via a nucleophilic addition reaction to form a methylol derivative.
Specifically,the reaction of one molecule of melamine with one molecule of formaldehyde yields monomethylol melamine,which acts as an intermediate in the synthesis of melamine-formaldehyde resin.
The structure shown in option $C$ represents this monomethylol melamine intermediate,where one of the $-NH_2$ groups has reacted with formaldehyde to form $-NHCH_2OH$.

(A) Tetrafluoroethylene,$CF_2 = CF_2$,is the monomer of Teflon,which is polytetrafluoroethylene $\left(-CF_2-CF_2-\right)_n$.
The polymerization reaction is:
$nCF_2 = CF_2 \rightarrow \left(-CF_2-CF_2-\right)_n$

(B) The strength of intermolecular forces in polymers follows the order: $\text{Thermosetting polymers} > \text{Fibres} > \text{Thermoplastics} > \text{Elastomers}$.
$1$. Bakelite is a thermosetting polymer,which has the strongest intermolecular forces due to cross-linking.
$2$. Nylon-$6,6$ is a fibre,which has strong hydrogen bonding (dipole-dipole interactions).
$3$. Teflon (Polytetrafluoroethylene) is a thermoplastic,which has intermediate forces.
$4$. Buna-$S$ is an elastomer,which has the weakest intermolecular forces.
Therefore,the correct decreasing order is: Bakelite $(A)$ $>$ Nylon-$6,6$ $(D)$ $>$ Teflon $(B)$ $>$ Buna-$S$ $(C)$.

(D) $1$. $Terylene$ (also known as $Dacron$) is a polyester formed by the condensation of ethylene glycol and terephthalic acid.
$2$. $Glyptal$ is a polyester resin formed by the reaction of ethylene glycol and phthalic acid.
$3$. $PHBV$ (poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) is a biodegradable polyester.
$4$. $Novolac$ is a phenol-formaldehyde resin,which is a cross-linked polymer,not a polyester.

(A) The strength of intermolecular forces in polymers follows the order: Fibres > Thermoplastics > Elastomers.
$Terylene$ is a polyester fibre,which contains strong dipole-dipole interactions and hydrogen bonding between its polymer chains.
$Buna-S$ and $Neoprene$ are elastomers,which have weak van der Waals forces.
$Polythene$ is a thermoplastic with intermediate forces.
Therefore,$Terylene$ has the strongest intermolecular forces.

(C) The given structure represents $Melamine-formaldehyde$ polymer.
It is formed by the condensation reaction between $Melamine$ and $Formaldehyde$.
It is a cross-linked polymer due to the formation of three-dimensional networks.
Since it is formed from two different monomers ($Melamine$ and $Formaldehyde$),it is a copolymer.
Therefore,the statement that it is a $Homopolymer$ is incorrect.

(D) Bakelite is a thermosetting polymer formed by the condensation polymerization of phenol and formaldehyde.
It possesses a highly cross-linked structure,which makes it hard and infusible.
Since it is prepared in the laboratory,it is classified as a synthetic polymer.
Therefore,it is both a cross-linked polymer and a synthetic polymer.

(C) Caprolactam is used for the manufacture of Nylon $-6$.
Caprolactam is heated at $533 \ K$ in an inert atmosphere to form Nylon $-6$.

(B) Natural rubber is cis$-1,4-$polyisoprene,meaning it has the cis configuration at every double bond,not trans. Therefore,statement $B$ is incorrect. Vulcanisation involves cross-linking with sulphur to improve mechanical properties. Buna-$S$ is indeed a copolymer of $1,3-$butadiene and styrene. Nylon-$6, 6$ is a polyamide formed by the condensation of hexamethylenediamine and adipic acid,containing amide linkages.

(B) $Neoprene$ is a synthetic rubber formed by the free radical polymerization of chloroprene ($2$-chloro-$1,3$-butadiene).
The repeating unit of $Neoprene$ is $(-CH_2-C(Cl)=CH-CH_2-)_n$.

(B) Biodegradable polymers are those that can be broken down by microorganisms in the environment.
Nylon-$2$-Nylon-$6$ is a biodegradable polyamide copolymer of glycine and amino caproic acid.
Buna-$S$ and $PVC$ are synthetic,non-biodegradable polymers.
Therefore,the correct option is Nylon-$2$-Nylon-$6$.

(D) $Novolac$ is a linear polymer formed by the condensation reaction of phenol and formaldehyde in the presence of an acid catalyst.
It is used in paints and as a coating material.
When $Novolac$ is heated with formaldehyde,it undergoes cross-linking to form an infusible solid mass known as $Bakelite$.
Therefore,the statement that $Novolac$ is a cross-linking polymer is incorrect,as it is a linear polymer that forms a cross-linked structure only upon further heating with formaldehyde.

(C) $PHBV$ (Poly($3$-hydroxybutyrate-co$-3-$hydroxyvalerate)) is a biodegradable polymer.
It is formed by the copolymerization of $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.

(C) The $C-O-C$ linkage is known as a glycosidic linkage.
Starch is a polysaccharide composed of glucose units linked by $\alpha$-glycosidic bonds,which are $C-O-C$ linkages.
Bakelite is a phenol-formaldehyde resin containing $C-CH_2-C$ linkages.
Melamine formaldehyde resin contains $C-N-C$ linkages.
Therefore,only starch contains the $C-O-C$ linkage.

(B) The monomer of $Nylon-6$ is caprolactam. $Caprolactam$ is a seven-membered cyclic amide (lactam) containing six carbon atoms and one nitrogen atom in the ring. Among the given options,the structure representing caprolactam is the seven-membered ring with a $C=O$ group adjacent to the $NH$ group.

(C) Nylon $-6,6$ is a polyamide.
It contains amide linkages $(-CONH-)$ in its structure.
The presence of $N-H$ and $C=O$ groups allows for strong intermolecular $H$-bonding between the polymer chains,which contributes to its high crystalline nature and high melting point.

(B) $Nylon-6,6$ is a polyamide polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid.
The structure of $nylon-6,6$ contains amide groups $(-CONH-)$.
The hydrogen atom attached to the nitrogen atom of one amide group forms a strong hydrogen bond with the carbonyl oxygen atom $(C=O)$ of another amide group in the adjacent polymer chain.
Therefore,the primary intermolecular force present in $nylon-6,6$ is hydrogen bonding.

(D) $MeSiCl_3$,$Me_2SiCl_2$,and $PhSiCl_3$ are monomers used for the synthesis of high molecular mass silicone polymers because they possess multiple reactive $Cl$ atoms,allowing for chain propagation.
However,$Me_3SiCl$ is not a monomer for a high molecular mass silicone polymer because it contains only one $Cl$ atom,which terminates the chain growth and can at best form a dimer.
Hence,the correct answer is option $D$.

(D) Low density polythene $(LDPE)$ is prepared by the polymerization of ethene under high pressure and temperature.
It has a highly branched structure,which makes it chemically inert and a poor conductor of electricity.
It is generally tough and flexible.
Therefore,the statement that it is 'chemically high reactive' is incorrect,as $LDPE$ is chemically inert.

(B) Elastomers are polymers that possess elastic properties,typically due to weak intermolecular forces and cross-linkages.
Nylon-$6,6$ is a fiber,not an elastomer; it is a polyamide formed by the condensation polymerization of adipic acid and hexamethylenediamine.
Artificial silk (rayon) is indeed derived from cellulose.
Natural rubber is a polymer of isoprene ($2$-methyl-$1,3$-butadiene).
Both starch and cellulose are natural polysaccharides composed of glucose units.
Therefore,the statement that Nylon-$6,6$ is an elastomer is false.

(B) The reaction sequence is as follows:
$1$. Phenol $(C_6H_6O)$ undergoes catalytic hydrogenation with $H_2/Ni$ to form cyclohexanol $(A)$.
$2$. Cyclohexanol $(A)$ is oxidized using $Cu$ (dehydrogenation) to form cyclohexanone $(B)$.
$3$. Cyclohexanone $(B)$ reacts with hydroxylamine $(NH_2OH)$ to form cyclohexanone oxime $(C)$.
$4$. Cyclohexanone oxime $(C)$ undergoes Beckmann rearrangement in the presence of acid $(H^+)$ to form caprolactam $(D)$.
$5$. Caprolactam $(D)$ undergoes ring-opening polymerization in the presence of base $(HO^-)$ to form Nylon $6$ $(E)$.

(B) The given polymer is polystyrene,which is formed by the addition polymerization of styrene $(C_6H_5CH=CH_2)$.
In the polymer chain,the repeating unit is $-[CH_2-CH(Ph)]_n-$.
By identifying the repeating unit,we can determine that the monomer is styrene,which has the structure $Ph-CH=CH_2$.

(A) biodegradable polymer is one that can be broken down by microorganisms.
$Nylon-2-nylon-6$ is a biodegradable polyamide copolymer of glycine $(H_2N-CH_2-COOH)$ and aminocaproic acid $(H_2N-(CH_2)_5-COOH)$.
The structure is:
$[-NH-CH_2-CO-NH-(CH_2)_5-CO-]_n$
This corresponds to the structure given in option $A$.

(B) Both the assertion and the reason are correct statements,and the reason is the correct explanation for the assertion.
Assertion:
Rayon (specifically cellulose acetate) is a semi-synthetic polymer that exhibits superior properties compared to natural cotton fiber.
Reason:
The mechanical and aesthetic properties of cellulose are significantly enhanced through the process of acetylation. Since rayon is produced via the acetylation of cellulose,it possesses improved characteristics over natural cotton.
Conclusion:
Therefore,the reason correctly explains why rayon has better properties than natural cotton.

(D) The correct matching is as follows:

Polymer	Use
$(A)$ Polystyrene	$(iii)$ Manufacture of toys
$(B)$ Glyptal	$(i)$ Paints and lacquers
$(C)$ Polyvinyl chloride	$(ii)$ Rain coats
$(D)$ Bakelite	$(iv)$ Computer discs

Thus,the correct sequence is $(A)-(iii), (B)-(i), (C)-(ii), (D)-(iv)$.

(C) Neoprene is a synthetic rubber formed by the free radical polymerization of chloroprene ($2$-chloro-$1,3$-butadiene).
The repeating unit of the polymer is $[CH_2-C(Cl)=CH-CH_2]_n$.

(B) Buna-$S$ is a copolymer formed by the polymerization of $1,3$-butadiene $(CH_2=CH-CH=CH_2)$ and styrene $(C_6H_5-CH=CH_2)$.
Its structure consists of repeating units derived from these two monomers,represented as $-(CH_2-CH=CH-CH_2-CH(C_6H_5)-CH_2)_n-$.

(D) Polymers which change irreversibly into hard and rigid material on heating are known as thermosetting polymers.
For example,$Bakelite$ is a thermosetting polymer.

(A) Given,
Degree of polymerization of first polymer $= 100$
Degree of polymerization of second polymer $= 200$
Number of moles ratio $n_1 : n_2 = 2 : 3$
The monomer of polythene is ethylene $(C_2H_4)$ with molar mass $M_0 = 28 \ g/mol$.
Molar mass of first polymer fraction: $M_1 = 100 \times 28 = 2800 \ g/mol$.
Molar mass of second polymer fraction: $M_2 = 200 \times 28 = 5600 \ g/mol$.
The weight average molecular weight is given by the formula:
$\overline{M}_w = \frac{\sum n_i M_i^2}{\sum n_i M_i} = \frac{n_1 M_1^2 + n_2 M_2^2}{n_1 M_1 + n_2 M_2}$
Substituting the values:
$\overline{M}_w = \frac{2 \times (2800)^2 + 3 \times (5600)^2}{2 \times 2800 + 3 \times 5600}$
$\overline{M}_w = \frac{2 \times 7840000 + 3 \times 31360000}{5600 + 16800}$
$\overline{M}_w = \frac{15680000 + 94080000}{22400}$
$\overline{M}_w = \frac{109760000}{22400} = 4900 \ g/mol$.