Composition, Properties and Uses of Polymer Questions in English

(D) Terylene,also known as $Dacron$,is a polyester fiber.
It is widely used in the textile industry for making fabrics (like $Terycot$ and $Terywool$).
It is also used in the manufacture of safety items like seat belts and ropes due to its high tensile strength and durability.
It is often blended with natural fibers like cotton or wool to produce synthetic silks and other clothing materials.
Therefore,all the given options are correct applications of Terylene.

(C) Nylon threads are made up of polyamide.
Some common examples are nylon $6$ and nylon $6,6$.
Polyamides are polymers which contain repeating amide,$-CONH-$ linkages.

(A) Nylon-$66$ is a polyamide prepared by the condensation polymerization of hexamethylenediamine $(H_2N-(CH_2)_6-NH_2)$ and adipic acid $(HOOC-(CH_2)_4-COOH)$.
The repeating unit is $(-CO-(CH_2)_4-CO-NH-(CH_2)_6-NH-)_n$.

(D) $Nylon-6,6$ is a high-strength synthetic polyamide fiber. Due to its high tensile strength,elasticity,and thermal stability,it is widely used in the manufacturing of tyre cords,ropes,and fabrics.

(A) $S$ (Sulphur) or $S_2Cl_2$ is used in the vulcanization of rubber.
Vulcanization involves heating raw rubber with sulphur to introduce cross-linking between polymer chains.
This process makes the rubber harder,more durable,and resistant to heat and cold.

(D) $PVC$ (Polyvinyl chloride) is a widely used thermoplastic polymer.
It is primarily used in the manufacture of plastic pipes,plumbing components,cable coatings,medical devices,and automotive parts.
It is also used for flooring,siding,raincoats,and various household items.

(A) The given structure represents a segment of polyisobutylene (or polyisobutene).
By observing the repeating unit $-[CH_2-C(CH_3)_2]-$,we can identify the monomer by introducing a double bond between the carbon atoms to satisfy valency.
Thus,the monomer is isobutylene ($2$-methylpropene),which is $CH_2=C(CH_3)_2$.
Therefore,the correct option is $A$.

(D) Thermosetting plastics are polymers that become hard and rigid upon heating and cannot be remolded.
They possess a highly cross-linked structure,which makes them inelastic,brittle,and strong.
Due to this extensive cross-linking,they are insoluble in common organic solvents.

(B) Cellulose is a natural polymer consisting of a linear chain of several hundred to many thousands of $\beta(1 \rightarrow 4)$ linked $D$-glucose units.
Its molecular weight typically ranges from $20,000$ to $500,000$ $u$.

(B) Cellulose is a polymer consisting of repeating glucose units with the general formula $[C_6H_7O_2(OH)_3]_n$.
Each glucose unit in cellulose contains $3$ hydroxyl $(-OH)$ groups.
Trinitrocellulose is formed by the complete nitration of these $3$ hydroxyl groups,where the hydrogen atoms of the $-OH$ groups are replaced by nitro $(-NO_2)$ groups.
Therefore,in the original glucose unit of cellulose,there are $3$ $-OH$ groups.

(B) In elastomers,the polymer chains are held together by weak intermolecular forces.
These weak forces allow the polymer to be stretched easily.
$e.g.$,Vulcanised rubber.

(C) . Terylene (also known as Dacron) has an ester linkage.
It is a polyester formed by the condensation polymerization of ethylene glycol and terephthalic acid.
The structure is:
$[-OCH_2CH_2-O-CO-C_6H_4-CO-]_n$
It is widely used in the textile industry.

(B) . Acrilan is the trade name for polyacrylonitrile $(PAN)$.
It is a synthetic polymer produced from the monomer acrylonitrile $(CH_2=CH-CN)$.
Its structure is represented as $(-CH_2-CH(CN)-)_n$.
It is known for being hard,horny,and having a high melting point.

(B) The correct answer is $(B)$.
Nylon-$66$ is a synthetic polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid.
It contains amide linkages $(-CONH-)$ in its backbone,which classifies it as a polyamide.

(B) Teflon (polytetrafluoroethylene) is a fully fluorinated polymer. Its monomer is tetrafluoroethylene,$F_2C = CF_2$.
Neoprene is made from the monomer chloroprene ($2$-chlorobuta-$1,3$-diene). The structure of Neoprene is $[ -CH_2-C(Cl)=CH-CH_2 -]_n$.
Thiokol is an organic polysulfide polymer.
$PVC$ (polyvinyl chloride) is made from the monomer vinyl chloride. The structure of $PVC$ is $[ -CH_2-CH(Cl) -]_n$.

(B) Thermosetting plastics have three-dimensional cross-linked structures. Such polymers are prepared in two steps. The first step is the formation of long-chain molecules which are capable of further reaction with each other. The second step is the application of heat,which causes a reaction to occur between the chains,thus producing a complex cross-linked polymer.

(A) is the correct answer.
Guttapercha is a naturally occurring polymer that consists of $trans-1, 4$-polyisoprene.
It is a hard,horny,and inelastic material compared to the $cis$-form,which is natural rubber.

(C) The fibre of terylene is highly crease-resistant,durable,and has low moisture content.
It is also not damaged by pests like moths and mildew.
It is therefore used for the manufacture of wash and wear fabrics.
It is also blended with cotton (\text{Terycot}) and wool (\text{Terywool}) to increase their resistance to wear and tear.

(C) Melamine is a nitrogen-rich heterocyclic compound used in the production of melamine-formaldehyde resins. It exists as a $ \text{white crystalline solid} $ at room temperature.

(D) Glyptal is a polyester formed by the condensation polymerization of ethylene glycol and phthalic acid.
It is a type of alkyd resin used in the manufacture of paints and lacquers.

(C) Glyptal is a polyester resin formed by the condensation of ethylene glycol and phthalic acid. It is not a polyamide. Nylon-$6,6$,Nylon-$6$,and proteins all contain amide linkages $(-CONH-)$ in their structure.

(D) The correct answer is $(D)$.
Raw rubber is plastic in nature,meaning it deforms easily.
It becomes soft at high temperatures and brittle at low temperatures.
It has low durability and a high water-absorption capacity,making it unsuitable for many industrial applications without vulcanization.

(B) $Celanese$ silk is a synthetic fiber made from cellulose acetate.
Therefore,the correct option is $(b)$.

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

(B) $PMMA$ (Polymethyl methacrylate),also known as Plexiglas or Lucite,is commonly used in the manufacturing of bulletproof glass due to its high transparency and impact resistance.

(B) Gun-cotton is a nitrocellulose or cellulose trinitrate,which is used in explosives and as a binder for solid rocket propellant.

(A) Motion picture film consists of a clear plastic base coated with a thin layer of gelatin.
This layer contains an image made from colour dyes,or in black and white film,very small particles of silver.
Cellulose acetate safety film base was used from the $1950$s.
It can be identified by the words,$\text{safety film}$ imprinted on the film edge.

(C) In the viscose process,cellulose is treated with $NaOH$ to form alkali cellulose.
This is then reacted with carbon disulphide $(CS_2)$ to form cellulose xanthate.
Cellulose xanthate is soluble in aqueous $NaOH$ solution,which is then extruded into an acidic coagulation bath to form viscose fibers.
Thus,the solvent system involves $NaOH$ and $CS_2$.

(B) Acrylonitrile $(CH_2=CH-CN)$ undergoes addition polymerization to form polyacrylonitrile,which is commercially known as $Orlon$ or $Acrilan$.

(D) Plastic crockery is made from melamine-formaldehyde resin.
This is a thermosetting polymer formed by the condensation polymerization of melamine and formaldehyde.

(C) Terylene fibers are durable and resistant to weather conditions. They are also resistant to mold and insect damage. Therefore,they are widely used to make wash-and-wear clothes.

(B) The polymerization of hexamethylenediamine and adipic acid is carried out at high temperature $(553 \ K)$,resulting in the formation of a liquid polymer of Nylon-$66$ which is then cast into ribbons or chips.
$n \ H_2N-(CH_2)_6-NH_2 + n \ HOOC-(CH_2)_4-COOH$ $\xrightarrow{553 \ K, \ N_2} [-HN-(CH_2)_6-NH-CO-(CH_2)_4-CO-]_n + 2n \ H_2O$
This reaction produces Nylon-$66$ in a molten (liquid) state.

(C) Nylon is a polyamide polymer,which contains amide linkages $(-CONH-)$ in its structure. These amide groups contain nitrogen atoms.
Polyvinyl chloride $(PVC)$ is a polymer of vinyl chloride $(CH_2=CHCl)$.
Bakelite is a phenol-formaldehyde resin.
Terylene is a polyester,which contains ester linkages $(-COO-)$.

(B) $Nylon-66$ is a fiber,not an elastomer. Elastomers are polymers that have weak intermolecular forces of attraction,whereas fibers have strong intermolecular forces like hydrogen bonding. Therefore,the statement in option $B$ is incorrect.

(C) Polystyrene is a polymer formed by the addition polymerization of styrene monomers.
The chemical structure of styrene is $C_6H_5 - CH = CH_2$ (vinylbenzene).
Therefore,the correct monomer is $C_6H_5 - CH = CH_2$.

(D) $1$. $Nylon-6$ is prepared by heating caprolactam with water at high temperature,so it is the correct monomer.
$2$. Terylene (Dacron) is a condensation polymer of ethylene glycol and terephthalic acid,which is a polyester.
$3$. Bakelite is a cross-linked polymer formed by the condensation reaction of phenol and formaldehyde.
$4$. Natural rubber is a linear polymer of isoprene $(2-methyl-1,3-butadiene)$. Therefore,the statement that butadiene is the monomer of natural rubber is incorrect.

(A) Vulcanization is a process of improving the physical properties of natural rubber by heating it with sulfur.
Sulfur forms cross-links between the polymer chains,which makes the rubber harder,stronger,and more durable.
Therefore,elemental sulfur $(S)$ is the substance used in the vulcanization of rubber.

(D) Teflon is the addition polymer of tetrafluoroethene $(CF_2 = CF_2)$.
It is prepared by heating tetrafluoroethene with a free radical or persulphate catalyst at high pressure.

(C) Teflon is the common name for polytetrafluoroethylene $(PTFE)$.
It is a synthetic fluoropolymer of tetrafluoroethylene which has the chemical formula $(C_2F_4)_n$.
Since all hydrogen atoms in the ethylene monomer are replaced by fluorine atoms,it is considered a completely fluorinated polymer.

(C) The commercial name for Plexiglas is Polymethyl methacrylate $(PMMA)$.
It is used in the manufacture of lenses,light covers,optical devices,and transparent windows.

(D) Orlon is a polymer of $Acrylonitrile$ $(CH_2=CH-CN)$.
It is also known as polyacrylonitrile $(PAN)$.
It is used in the manufacture of clothes,carpets,and blankets.

(D) Polymers are macromolecules formed by the polymerization of monomers.
They possess very high molecular masses,typically ranging from $10^3$ to $10^7 \ u$.
Therefore,the statement that polymers have very low molecular masses is incorrect.

(D) Toluene diisocyanate $(TDI)$ is a key monomer used in the production of polyurethanes.
It reacts with polyols to form the urethane linkage $(-NH-CO-O-)$ which is the characteristic functional group of polyurethanes.
Therefore,the correct option is $D$.

(D) The given structure represents a segment of polyisobutylene,which is formed by the polymerization of isobutylene ($2$-methylpropene). The monomer is $CH_2 = C(CH_3)_2$.

(A) Buna-$N$ is a synthetic rubber formed by the copolymerization of $1,3$-butadiene $(H_2C = CH - CH = CH_2)$ and acrylonitrile $(H_2C = CH - CN)$.
It is also known as nitrile rubber or $NBR$.

(B) The strength of intermolecular forces in polymers depends on their structure:
$1$. $B = \text{Buna-}S$ is an elastomer,which has the weakest intermolecular forces (weak van der Waals forces).
$2$. $C = \text{Polythene}$ is a thermoplastic,which has intermediate intermolecular forces (stronger van der Waals forces than elastomers).
$3$. $A = \text{Nylon-}6,6$ is a fiber,which has the strongest intermolecular forces due to hydrogen bonding.
Therefore,the increasing order of intermolecular forces is $B < C < A$.

(C) Magnetic recording tapes are typically made from polyester films,specifically polyethylene terephthalate,which is commonly known as $Terylene$ or $Dacron$. $Terylene$ is a condensation polymer of ethylene glycol and terephthalic acid. It is widely used in the manufacturing of magnetic recording tapes due to its high tensile strength and durability.

(C) Rayon is a semi-synthetic fiber. It is prepared from naturally occurring polymers,specifically $Cellulose$,which is obtained from wood pulp or cotton linters. The $Cellulose$ is chemically treated to form a viscous solution,which is then extruded through spinnerets to form fibers.

(C) Biodegradable polymers are those that can be broken down by microorganisms.
Option $A$ is Neoprene.
Option $B$ is Buna-$N$.
Option $C$ is $PHBV$ (Poly-$\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate),which is a well-known biodegradable polyester.
Option $D$ is Nylon-$6,6$.
Therefore,the correct answer is $C$.

(C) Nylon-$66$ is a polyamide. Polyamides contain amide linkages $(-CONH-)$ in their backbone,which allow for strong intermolecular hydrogen bonding between the polymer chains.