Composition, Properties and Uses of Polymer Questions in English

(D) $PCTFE$ stands for Polychlorotrifluoroethylene.
The monomer unit of $PCTFE$ is chlorotrifluoroethylene,which is $CFCl = CF_2$.
Therefore,the repeating unit is derived from $CFCl = CF_2$.

(D) Ebonite is a highly vulcanized rubber containing a high percentage of sulfur (usually $20-30 \%$),which makes it hard and brittle.

(B) In elastomers,the polymer chains are held together by weak intermolecular forces.
For example,vulcanized rubber.

(A) The process of heating natural rubber with sulfur at a temperature range of $373 \ K$ to $415 \ K$ is known as $Vulcanization$. This process introduces sulfur bridges between the polymer chains,which improves the mechanical properties of rubber,such as its elasticity and strength.

(D) Natural rubber is a linear polymer of isoprene ($2-$methyl-$1, 3-$butadiene) and has a $cis-$configuration at every double bond. Therefore,the statement that it has a trans configuration is incorrect.

(B) The monomer prop-$2$-enenitrile is commonly known as acrylonitrile $(CH_2=CH-CN)$.
Polymerization of acrylonitrile leads to the formation of polyacrylonitrile $(PAN)$.
Polyacrylonitrile is commercially known as Orlon or Acrilan.

(A) The given polymer structure is:
$(-CH_2-C(CH_3)_2-CH_2-C(CH_3)_2-)_n$
This is the structure of polyisobutylene.
The repeating unit is $-CH_2-C(CH_3)_2-$.
To find the monomer,we introduce a double bond between the carbon atoms that are bonded to each other in the polymer chain.
Thus,the monomer is $CH_2=C(CH_3)_2$,which is isobutylene ($2$-methylpropene).

(C) Thermosetting plastics are polymers that become hard and infusible on heating and cannot be remolded.
$Bakelite$ (phenol-formaldehyde resin) is a classic example of a thermosetting plastic.
$PVC$,$PVA$,and $Perspex$ are thermoplastic polymers that soften upon heating and can be reshaped.

(D) Nylon is a type of synthetic polymer that contains repeating amide linkages $(-CONH-)$ in its backbone. Therefore,it is classified as a polyamide. While it is also a condensation polymer,the most specific and descriptive classification among the given options is polyamide.

(B) Biodegradable polymers are polymers that can be decomposed by bacteria.
Nylon-$2$-nylon-$6$ is a polyamide copolymer of glycine $(H_2N-CH_2-COOH)$ and amino caproic acid $(H_2N-(CH_2)_5-COOH)$.
It is a biodegradable polymer because it contains amide linkages that can be hydrolyzed by enzymes.
$PHBV$ is a polyester,not a polyamide.
Nylon-$6,6$ is a synthetic polyamide but is not biodegradable.
Dextran is a polysaccharide.

(C) $PTFE$ (Polytetrafluoroethylene),commonly known as Teflon,is chemically inert and resistant to attack by corrosive reagents.
It has a low coefficient of friction,making it useful for making non-stick surfaces and as a lubricant.
Due to its high thermal stability and chemical resistance,it is also used as an electrical insulator.

(B) Orlon,also known as polyacrylonitrile $(PAN)$,is a synthetic polymer.
Its monomer is acrylonitrile,which has the chemical formula $CH_2 = CH-CN$.
Therefore,the correct statement is that the monomer of Orlon is $CH_2 = CH-CN$.

(C) Non-stick cookware is coated with $Teflon$,which is the common name for $Polytetrafluoroethene$ $(PTFE)$.
$PTFE$ is a synthetic fluoropolymer of tetrafluoroethene that has numerous applications due to its high thermal stability and chemical inertness.
Therefore,the correct option is $C$.

(D) Natural rubber is an example of an elastomer. Elastomers are polymers held together by the weakest intermolecular forces,such as weak van der Waals forces,which allow the polymer chains to be stretched.

(A) Terylene,also known as $Dacron$,is a condensation polymer formed by the polymerization of $Ethylene \ glycol$ $(HO-CH_2-CH_2-OH)$ and $Terephthalic \ acid$ $(C_6H_4(COOH)_2)$.
This reaction involves the elimination of water molecules to form an ester linkage,classifying it as a polyester.

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

(D) $PHBV$ (Poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate) is a biodegradable,aliphatic polyester.
It is used in orthopedic devices and in controlled drug-release capsules because it undergoes bacterial degradation in the environment.

(A) Polyamides are polymers containing amide linkages $(-CONH-)$ in their backbone.
Nylon-$6,6$ is a condensation polymer formed by the reaction of hexamethylenediamine and adipic acid,which contains amide bonds.
Terylene is a polyester,Teflon is an addition polymer of tetrafluoroethene,and Bakelite is a phenol-formaldehyde resin.

(D) Ebonite is a hard and highly $(20-30\%)$ vulcanized rubber.

(A) The polymer Terylene (also known as Dacron) is formed by the condensation polymerization of ethylene glycol $(HO-CH_2-CH_2-OH)$ and terephthalic acid $(HOOC-C_6H_4-COOH)$.
Its structure is represented as $(-O-CH_2-CH_2-OOC-C_6H_4-CO-)_n$.
Therefore,option $A$ is the correct answer.

(C) Teflon is a polymer of tetrafluoroethene $(CF_2=CF_2)$.
Its chemical structure is represented as $[CF_2-CF_2]_n$.
Therefore,the correct option is $C$.

(C) Terylene (also known as Dacron) is a polyester fiber.
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 involves the elimination of water molecules to form an ester linkage $(-COO-)$ between the monomer units.

(C) $PHBV$ (poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate),$PGA$ (polyglycolic acid),and $PCL$ (polycaprolactone) are well-known biodegradable polymers.
$PMMA$ (polymethyl methacrylate) is a synthetic,non-biodegradable polymer commonly used as a shatterproof substitute for glass.

(D) Nylon-$6, 6$ is formed by the condensation polymerization of hexamethylenediamine and adipic acid.
It contains amide linkages $(-CONH-)$,so it is a polyamide.
Since it is formed by the elimination of small molecules like water,it is a condensation polymer.
It is not a polyester because it does not contain ester linkages $(-COO-)$.

(D) The correct classifications are as follows:
$A$. Neoprene is a synthetic rubber (polychloroprene).
$B$. Nylon-$6,6$ is a polyamide.
$C$. Terylene (Dacron) is a polyester.
$D$. Polystyrene is a vinyl polymer,not a polyether. Therefore,the pair $D$ is incorrectly matched.

(C) $PVC$ is very hard. To make it soft (rubber-like),a plasticizer such as di-$n$-butyl phthalate is added to it.

(C) Natural rubber is a linear polymer of $isoprene$ $(2-methyl-1,3-butadiene)$.
It is also known as $cis-1,4-polyisoprene$.
Therefore,the correct option is $C$.

(B) Lexan is a polycarbonate polymer known for its high impact resistance and optical clarity,making it suitable for use in bulletproof glass.

(B) Perlon is another name for Nylon-$6$.
It is a polyamide polymer formed by the polymerization of caprolactam.

(A) 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 $(C_6H_4(COOH)_2)$.
Since it is formed from two different monomers with the elimination of small molecules like water,it is a condensation copolymer.
Buna-$S$ and Buna-$N$ are addition copolymers,and Neoprene is an addition homopolymer.

(A) In the process of vulcanization,natural rubber is heated with sulfur ($4$ to $5\ \%$) and an appropriate additive to accelerate the reaction between rubber and sulfur.
This process creates cross-links between the polymer chains,which improves the elasticity and wear resistance of the rubber.

(D) Terylene is a polyester fiber formed by the condensation polymerization of ethylene glycol and terephthalic acid.
It is a thermoplastic polymer,not a thermosetting plastic.
Thermosetting plastics are cross-linked polymers that do not melt upon heating,whereas Terylene softens and melts when heated.

(A) The polymer used is Polymethyl methacrylate,commonly known as $PMMA$.
It is transparent and possesses excellent light transmission properties.
Due to its superior optical clarity compared to glass,it is widely used in the manufacturing of contact lenses.

(B) Buna-$S$ is a synthetic rubber formed by the copolymerization of $1,3$-butadiene and styrene in the presence of a peroxide catalyst.
The name 'Buna' is derived from 'Bu' for butadiene and 'na' for sodium (which was used as a catalyst in early processes),while '$S$' stands for styrene.

(B) Nylon is a synthetic fiber that belongs to the class of polymers known as polyamides. It is formed by the condensation polymerization of diamines and dicarboxylic acids,which results in the formation of amide linkages $(-CONH-)$ in the polymer chain. Therefore,nylon threads are made from polyamides.

(C) Bakelite is a thermosetting phenol-formaldehyde resin. It is formed by the condensation polymerization of phenol and formaldehyde. Therefore,it is classified as a resin.

(C) Terylene (also known as Dacron) is a polyester fiber.
It is prepared by the condensation polymerization of ethylene glycol and terephthalic acid.
Since it is formed by the elimination of small molecules like $H_2O$,it is a condensation polymer,not an addition polymer.
Therefore,the statement that it is an addition polymer is incorrect.

(D) Nylon-$6,6$ is a polyamide polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid. Due to its high tensile strength,elasticity,and durability,it is widely used in the manufacture of tyre cords,ropes,and fabrics.

(C) Nylon is a generic designation for a family of synthetic polymers known as aliphatic polyamides. It is formed by the condensation polymerization of diamines with dicarboxylic acids or by the ring-opening polymerization of lactams. Therefore,nylon thread is made of polyamide.

(D) Carbon fibers are high-strength,lightweight materials known for their exceptional mechanical properties.
They are widely used in medical applications such as $Bone \ plates$ due to their biocompatibility and strength.
They are also used in automotive and aerospace industries for $Brake \ pads$ because of their high heat resistance and durability.
Additionally,due to their high tensile strength,they are used in the manufacturing of $Bulletproof \ jackets$.
Therefore,all the given options are correct applications of carbon fibers.

(D) - Nylon $-66$ is a polyamide polymer,which contains nitrogen atoms in its structure.
Its repeating unit is represented as: $[ -NH-(CH_2)_6-NH-CO-(CH_2)_4-CO- ]_n$.

(B) Ethylene-propylene rubber $(EPR)$ lacks sufficient unsaturation in its polymer backbone for effective vulcanization with sulphur.
Therefore,it is typically vulcanized using peroxides,which generate free radicals to form cross-links between the polymer chains.

(A) Buna-$S$ is a copolymer formed by the polymerization of $1,3$-butadiene and styrene in the presence of a catalyst.
It is also known as $SBR$ (styrene-butadiene rubber).
The reaction is:
$nCH_2=CH-CH=CH_2 + nC_6H_5CH=CH_2 \xrightarrow{Na} (-CH_2-CH=CH-CH_2-CH(C_6H_5)-CH_2-)_n$

(A) Orlon is polyacrylonitrile $(PAN)$,which is a synthetic polymer.
Its monomer unit is vinyl cyanide,also known as acrylonitrile $(CH_2=CH-CN)$.

(A) The correct answer is $A$.
$(-CF_2-CF_2-)_n$ is known as Teflon (Polytetrafluoroethene).
It is a highly stable polymer due to the strong $C-F$ bonds and is resistant to heat and fire,making it non-flammable.

(D) Artificial silk,commonly known as rayon,is a regenerated cellulose fiber. Cellulose is a natural polymer made up of glucose units,which is a type of polysaccharide.

(C) Natural rubber is a linear polymer of isoprene $(2-methyl-1,3-butadiene)$.
In natural rubber,the double bonds are present in the $cis-$ configuration,which means the bulky groups are on the same side of the double bond.
This $cis-$ configuration gives natural rubber its elastic properties.
Therefore,natural rubber has an all $cis-$ configuration.

(C) Nylon-$2$-nylon-$6$ is a biodegradable polyamide copolymer.
It is formed by the condensation polymerization of glycine $(H_2N-CH_2-COOH)$ and aminocaproic acid $(H_2N-(CH_2)_5-COOH)$.
The reaction is: $n(H_2N-CH_2-COOH) + n(H_2N-(CH_2)_5-COOH) \rightarrow [NH-CH_2-CO-NH-(CH_2)_5-CO]_n + 2nH_2O$.

(D) Bakelite is a thermosetting polymer. These polymers are cross-linked or heavily branched molecules,which on heating undergo extensive cross-linking in moulds and become infusible. They cannot be reused.
Option $(A)$ is Neoprene (elastomer),$(B)$ is $PVC$ (thermoplastic),and $(C)$ is Nylon $6,6$ (fiber).