Composition, Properties and Uses of Polymer Questions in English

(A) The polydispersity index $(PDI)$ is defined as the ratio of weight average molecular mass $(M_w)$ to number average molecular mass $(M_n)$.
$PDI = \frac{M_w}{M_n}$
Given: $N_1 = 10$,$M_1 = 1.0 \times 10^4 = 10,000$; $N_2 = 10$,$M_2 = 1.0 \times 10^5 = 100,000$.
Number average molecular mass $(M_n)$:
$M_n = \frac{\sum N_i M_i}{\sum N_i} = \frac{(10 \times 10,000) + (10 \times 100,000)}{10 + 10} = \frac{100,000 + 1,000,000}{20} = \frac{1,100,000}{20} = 55,000$.
Weight average molecular mass $(M_w)$:
$M_w = \frac{\sum N_i M_i^2}{\sum N_i M_i} = \frac{10 \times (10,000)^2 + 10 \times (100,000)^2}{(10 \times 10,000) + (10 \times 100,000)} = \frac{10^9 + 10^{11}}{1,100,000} = \frac{101,000,000,000}{1,100,000} \approx 91,818$.
$PDI = \frac{91,818}{55,000} \approx 1.67$.

(A) The correct matches are as follows:
$A$. Urea-formaldehyde resin is used in making Laminated sheets $(III)$.
$B$. Glyptal is used in making Paints $(V)$.
$C$. Bakelite is used in making Safety Helmets $(I)$.
$D$. Nylon-$6,6$ is used in making Commercial fibres $(IV)$.
$E$. Phenol-formaldehyde is used in making Gaskets $(II)$.
Thus,the correct sequence is $A-III, B-V, C-I, D-IV$.

(B) The reaction between $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid leads to the formation of the copolymer $PHBV$ (poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate).
$PHBV$ is a well-known biodegradable polymer.
Therefore,the statement that it is non-biodegradable is incorrect.
$PHBV$ is a condensation polymer and is used in orthopaedic devices and controlled drug release.

(D) Fibres are polymers that have strong intermolecular forces between the chains,such as hydrogen bonds or dipole-dipole interactions. These forces lead to close packing,which imparts crystalline character and makes them long,thin,and thread-like,suitable for weaving into fabrics. Examples include nylon-$66$,silk,and terylene (also known as dacron). The structure given in option $D$ represents terylene (dacron),which is a polyester fibre formed by the condensation polymerization of ethylene glycol and terephthalic acid.

(A) $Terylene$:
The monomers for $Terylene$ are ethylene glycol and terephthalic acid. $Terylene$ is also known as $Dacron$ or polyester.
$Glyptal$:
The monomers for $Glyptal$ are ethylene glycol and phthalic acid. $Glyptal$ is an alkyd resin and a polyester.
$\therefore$ Ethylene glycol $(HO-CH_2-CH_2-OH)$ is the common monomer for both.

(B) The reaction of phenol with formaldehyde in the presence of a base $(OH^-)$ and heat leads to the formation of $Bakelite$.
$Bakelite$ is a thermosetting polymer formed by the condensation polymerization of phenol and formaldehyde.
It has a highly branched,three-dimensional structure,which is classified as a cross-linked polymer.
Therefore,$X$ is $Bakelite$ and it is a cross-linked polymer.

(A) $\text{Nylon-}2\text{-nylon-}6$ is a biodegradable polyamide copolymer. It is formed by the copolymerization of $\text{glycine}$ $(H_2N-CH_2-COOH)$ and $\text{aminocaproic acid}$ $(H_2N-(CH_2)_5-COOH)$.

(D) The polydispersity index $(PDI)$ is defined as the ratio of weight average molecular mass $(\overline{M}_{w})$ to number average molecular mass $(\overline{M}_{n})$.
$PDI = \frac{\overline{M}_{w}}{\overline{M}_{n}}$
Given,$PDI = 1.25$ and $\overline{M}_{n} = 800$.
Substituting the values: $1.25 = \frac{\overline{M}_{w}}{800}$.
Therefore,$\overline{M}_{w} = 800 \times 1.25 = 1000$.

(D) Polytetrafluoroethene $(PTFE)$,represented by the formula $[CF_2-CF_2]_n$,is a chemically inert polymer with high thermal stability. Due to its excellent resistance to corrosion and heat,it is widely used in making oil seals and gaskets.

(B) $PHBV$ (Poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) is a biodegradable,aliphatic polyester.
It is used in orthopaedic devices and in controlled release of drugs.

(B) Polyvinyl chloride,neoprene,and teflon are addition homopolymers. They do not contain polar groups capable of forming strong hydrogen bonds.
Nylon-$6, 6$ is a polyamide. It contains amide linkages $(-CONH-)$ where the $N-H$ group acts as a hydrogen bond donor and the $C=O$ group acts as a hydrogen bond acceptor,leading to strong inter-chain hydrogen bonding.

(B) Nylon-$6,6$ is a polyamide polymer.
It contains amide groups $(-CONH-)$ in its chain.
The presence of these groups allows for strong intermolecular hydrogen bonding between the polymer chains,which gives it the properties of a fibre.

(D) Caprolactam is an intermediate primarily used in the production of nylon-$6$ fibres and resins.
When caprolactam is heated with water at $533-574 \ K$,it undergoes ring-opening polymerization to form nylon-$6$.

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

(D) Nylon$-6, 6$ is a polyamide formed by the condensation polymerization of hexamethylenediamine $(H_2N-(CH_2)_6-NH_2)$ and adipic acid $(HOOC-(CH_2)_4-COOH)$.
Terylene (also known as Dacron) is a polyester formed by the condensation polymerization of ethylene glycol $(HO-CH_2-CH_2-OH)$ and terephthalic acid $(HOOC-C_6H_4-COOH)$.
Comparing these with the given options,option $D$ correctly identifies the monomers for both polymers.

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

(A) Nylon-$6,6$ is synthesized by the polycondensation of hexamethylenediamine and adipic acid.
$n HOOC-(CH_2)_4-COOH + n H_2N-(CH_2)_6-NH_2 \rightarrow [CO-(CH_2)_4-CO-NH-(CH_2)_6-NH]_n + 2n H_2O$
In hexamethylenediamine $(H_2N-(CH_2)_6-NH_2)$,the number of $-CH_2-$ groups is $6$.
In adipic acid $(HOOC-(CH_2)_4-COOH)$,the number of $-CH_2-$ groups is $4$.
Therefore,the number of $-CH_2-$ groups in $X$ and $Y$ are $6$ and $4$ respectively.

(A) Neoprene is obtained from chloroprene,which is $2-$chlorobuta$-1,3-$diene.
It is an addition homopolymer with rubber-like structure and properties.
The structure of neoprene is $[CH_2-C(Cl)=CH-CH_2]_n$.
Neoprene exhibits good chemical stability and maintains flexibility over a wide temperature range.

(A) Buna-$N$ is a synthetic rubber formed by the co-polymerization of $1,3-$Butadiene and Acrylonitrile $(CH_2=CH-CN)$.
Therefore,$\underline{X}$ is Acrylonitrile,which corresponds to option $A$.

(C) Ethylene $(CH_2=CH_2)$ reacts with Baeyer's reagent (cold,dilute alkaline $KMnO_4$ solution) to form ethylene glycol $(HO-CH_2-CH_2-OH)$,which is compound $A$.
Ethylene glycol is used as a monomer in the preparation of the co-polymer Glyptal (polyethylene terephthalate is a polyester,but Glyptal is specifically formed from ethylene glycol and phthalic acid).
Therefore,the correct answer is Glyptal.

(A) . Natural rubber becomes soft and sticky at high temperature,not hard. So,statement $a$ is incorrect.
$b$. Neoprene is formed by the polymerization of chloroprene ($2-$chloro$-1,3-$butadiene). So,statement $b$ is correct.
$c$. Nylon $6,6$ is formed by the condensation polymerization of hexamethylenediamine and adipic acid,which contains amide linkages. So,statement $c$ is correct.
$d$. Buna$-S$ is a copolymer formed from $1,3-$butadiene and styrene. So,statement $d$ is incorrect.
Therefore,statements $b$ and $c$ are correct.

(B) Biodegradable polymers are those that can be decomposed by microorganisms.
Among the given polymers:
$I$. $PHBV$ (Poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) is a well-known biodegradable polymer.
$II$. Nylon-$2$-nylon-$6$ is a polyamide copolymer of glycine and amino caproic acid,which is also biodegradable.
$III$. Glyptal is a condensation polymer of ethylene glycol and phthalic acid,which is non-biodegradable.
$IV$. Bakelite is a thermosetting phenol-formaldehyde resin,which is non-biodegradable.
Therefore,$I$ and $II$ are biodegradable polymers.

(C) Biodegradable polymers are polymers that can be decomposed by microorganisms or enzymes under aerobic or anaerobic conditions.
$A$. Nylon-$6,6$ is a synthetic polyamide and is non-biodegradable.
$B$. Nylon-$6$ is a synthetic polyamide and is non-biodegradable.
$C$. Nylon-$2$-nylon-$6$ is an alternating copolymer of glycine and amino caproic acid,which is a well-known biodegradable polymer.
$D$. Bakelite is a thermosetting phenol-formaldehyde resin and is non-biodegradable.
Therefore,the correct option is $C$.

(C) The reaction sequence is as follows:
$1$. $2 CH_3Cl + Si \xrightarrow[573 \ K]{Cu} (CH_3)_2SiCl_2$ $(X)$
$2$. $(CH_3)_2SiCl_2 + 2 H_2O \rightarrow (CH_3)_2Si(OH)_2 + 2 HCl$ $(Y)$
$3$. The hydrolysis product $(CH_3)_2Si(OH)_2$ undergoes polymerization to form silicone (polydimethylsiloxane).
$4$. The repeating structural unit in the resulting polymer $Z$ is $[-(CH_3)_2Si-O-]_n$.
This corresponds to the structure shown in option $C$.

(B) Cellulose is treated with concentrated $HNO_3$ in the presence of concentrated $H_2SO_4$ to produce cellulose nitrate.
Cellulose nitrate is an important substance used in the manufacture of explosives (gun cotton),lacquers,and plastics.

(B) Polymers held together by strong intermolecular forces like hydrogen bonding are known as fibres.
Nylon-$6,6$ is a common example of a fibre,which is a polyamide.
It is formed by the condensation polymerization of hexamethylenediamine ($H_2N(CH_2)_6NH_2$,labeled as $B$) and adipic acid ($HO_2C(CH_2)_4CO_2H$,labeled as $E$).
Therefore,the monomers $Y$ and $Z$ are $B$ and $E$.

(A) Bakelite is formed by the condensation polymerization of phenol and formaldehyde (methanal).
Melamine is formed by the condensation polymerization of melamine and formaldehyde (methanal).
Therefore,methanal is the common monomer present in both polymers.

(B) The given structure is $PHBV$,which stands for poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate.
It is a copolymer formed by the condensation polymerization of $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.
It is a biodegradable,thermoplastic polyester.
Therefore,statements $I$ (condensation and biodegradable),$II$ (biodegradable and thermoplastic),and $IV$ (polyester and thermoplastic) are correct.
Thus,the correct combination is $I$,$II$ and $IV$.

(D) The polydispersity index $(PDI)$ of a polymer is defined as the ratio of the weight average molecular mass $(\bar{M}_w)$ to the number average molecular mass $(\bar{M}_n)$.
$PDI = \frac{\bar{M}_w}{\bar{M}_n}$
It serves as a measure of the breadth or distribution of molecular weights in a polymer sample.

(B) The polymers which disintegrate by themselves during a certain period of time by enzymatic hydrolysis and to some extent by oxidation are known as biodegradable polymers.
Examples include:
$1$. Poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate $(PHBV)$,which is used in orthopaedic devices and in controlled drug release.
$2$. Poly(glycolic acid)-poly(lactic acid),commonly known as $Dexon$ (or dextron),which is used for stitching of wounds after surgery.

(C) $PHBV$ (Polyhydroxy butyrate-co-$\beta$-hydroxy valerate) is a biodegradable polymer.
It is obtained by the copolymerization of $3$-hydroxybutanoic acid and $3$-hydroxypentanoic acid.

(A) The polymer $X$ used for making unbreakable cups and laminated sheets is known as melamine-formaldehyde resin.
Melamine-formaldehyde resin is formed by the condensation polymerization of melamine and formaldehyde.
However,among the given options,the question refers to the formation of thermosetting plastics.
Specifically,urea-formaldehyde resin is used for making unbreakable cups and laminated sheets.
Therefore,the monomers of $X$ are urea and formaldehyde.

(B) Ethylene $(CH_2=CH_2)$ reacts with cold,dilute alkaline $KMnO_4$ (Baeyer's reagent) at $273 \ K$ to form ethylene glycol $(HO-CH_2-CH_2-OH)$,which is compound '$P$'.
Dacron (also known as Terylene) is a polyester formed by the condensation polymerisation of ethylene glycol and terephthalic acid $(HOOC-C_6H_4-COOH)$.
Therefore,the correct reactant is terephthalic acid.

(D) Neoprene is a synthetic rubber formed by the polymerization of chloroprene.
The chemical name of chloroprene is $2-$chloro$-1,3-$butadiene.
Therefore,the monomer $X$ is $2-$chloro$-1,3-$butadiene.

(B) Polyester is a polymer containing the ester functional group in the main chain. $Dacron$ (also known as $Terylene$) is a well-known polyester formed by the condensation polymerization of ethylene glycol and terephthalic acid.
Polyamide is a polymer containing the amide functional group in the main chain. $Nylon$ $6,6$ is a classic example of a polyamide,formed by the condensation polymerization of hexamethylenediamine and adipic acid.
Therefore,$X$ is $Dacron$ and $Y$ is $Nylon$ $6,6$.

(B) The correct matches are:
$A$. $CF_2=CF_2$ is the monomer for Teflon $(III)$.
$B$. $NH_2(CH_2)_6NH_2$ (hexamethylenediamine) and $HO_2C(CH_2)_4CO_2H$ (adipic acid) are monomers for Nylon $6, 6$ $(IV)$.
$C$. $C_6H_5OH$ (phenol) and $HCHO$ (formaldehyde) are monomers for Bakelite $(II)$.
$D$. $CH_2=CH(Cl)-CH=CH_2$ (chloroprene) is the monomer for Neoprene $(I)$.
Thus,the correct matching is $A-III, B-IV, C-II, D-I$.

(A) The reaction of ethylene glycol $(HO-CH_2-CH_2-OH)$ with phthalic acid produces Glyptal,which is used in the manufacture of paints. Thus,$X$ is phthalic acid.
The reaction of ethylene glycol with terephthalic acid produces Terylene (or Dacron),which is used in making safety helmets and synthetic fibers. Thus,$Y$ is terephthalic acid.
Therefore,$X$ is phthalic acid and $Y$ is terephthalic acid.

(B) Bakelite is a condensation polymer of phenol and formaldehyde. Thus,$A \rightarrow III$.
Natural rubber is an addition polymer of $2$-methyl-$1,3$-butadiene (isoprene). Thus,$B \rightarrow I$.
Glyptal is a condensation polymer of phthalic acid and ethylene glycol. Thus,$C \rightarrow IV$.
Nylon $2$-Nylon $6$ is a condensation polymer of glycine and aminocaproic acid. Thus,$D \rightarrow II$.
Therefore,the correct matching is $A-III, B-I, C-IV, D-II$.

(A) Glyptal is a condensation polymer of ethylene glycol and phthalic acid.
Bakelite is a thermosetting polymer that is used in making electrical switches and other electrical appliances.
Nylon-$2$-nylon-$6$ is a biodegradable polymer.
Thus,all the statements are correct.

(A) The reaction sequence shows the conversion of $p$-nitrotoluene to terephthalic acid $(R)$.
$R$ is terephthalic acid $(C_6H_4(COOH)_2)$.
Terephthalic acid and ethylene glycol $(HOCH_2CH_2OH)$ are the monomers used for the synthesis of the polymer Dacron (also known as Terylene or Polyethylene terephthalate).

(C) $A-III, B-I, C-IV, D-II$.
$A$. Natural rubber is chemically $cis-1,4-polyisoprene$.
$B$. $PVC$ ($Polyvinyl$ $chloride$) is typically formed via free radical addition polymerisation.
$C$. Terylene $(Dacron)$ is a polyester formed by the condensation polymerisation of ethylene glycol and terephthalic acid.
$D$. Syndiotactic polymers are those in which the side groups (substituents) alternate on opposite sides of the polymer chain.

(C) Synthetic rubbers are polymers that exhibit rubber-like properties and are prepared artificially.
$(i)$ Terylene is a polyester fiber.
$(ii)$ Buna$-S$ is a copolymer of $1,3$-butadiene and styrene,which is a synthetic rubber.
$(iii)$ Buna$-N$ is a copolymer of $1,3$-butadiene and acrylonitrile,which is a synthetic rubber.
$(iv)$ Neoprene is a polymer of chloroprene ($2$-chloro-$1,3$-butadiene),which is a synthetic rubber.
$(v)$ Polyacrylonitrile is a synthetic fiber (Orlon).
Therefore,$(ii)$,$(iii)$,and $(iv)$ are synthetic rubbers.
Hence,the correct option is $(c)$.

(C) The monomer units of nylon-$6, 6$ are hexamethylene diamine,$H_2N(CH_2)_6NH_2$ and adipic acid,$HO_2C(CH_2)_4CO_2H$.
The monomer units of nylon-$2$-nylon-$6$ are glycine,$H_2NCH_2COOH$ and aminocaproic acid,$H_2N(CH_2)_5COOH$.
Therefore,the correct option is $C$.

(C) $Glyptal (X):$ Ethylene glycol and phthalic acid.
$Dacron (Y):$ Ethylene glycol and terephthalic acid.
$Nylon 2-nylon 6 (Z):$ Glycine and aminocaproic acid.

(A-II, B-I, C-IV, D-III) The correct matches are as follows:
$A$. Natural rubber is a polymer of isoprene ($2$-methyl-$1,3$-butadiene). Thus,$A \rightarrow ii$.
$B$. Cellulose is a polysaccharide consisting of a linear chain of $\beta(1-4)$ linked $\beta$-$D$-glucose units. Thus,$B \rightarrow i$.
$C$. The monomer unit of Nylon-$6$ is caprolactam. Thus,$C \rightarrow iv$.
$D$. Teflon is formed by the polymerization of tetrafluoroethylene monomer units: $n(CF_2=CF_2) \rightarrow -(CF_2-CF_2)_n-$. Thus,$D \rightarrow iii$.
The correct matching is $A-ii, B-i, C-iv, D-iii$.