Chemistry

Polymers and Plastics

1,228 Questions

Polymers and plastics questions explore the properties, synthesis, and applications of various synthetic and natural polymers. Key topics include biodegradable plastics, vulcanization, and polymer nanocomposites. These concepts are frequently tested in science and engineering competitive exams.

Biodegradable plasticsPolymer nanocompositesVulcanization of rubberPolymer molecular weightAsphalt binders

Polymers and Plastics Questions

Multiple choice chemistry synthetic fibres and plastics environmental impact: plastics plastic plastic plastic waste garbage in, garbage out

Statement: Plastics which get deformed easily on heating and can be bent easily are known as thermoplastics.


State whether the given statement is true or false.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Plastics are categorized into thermosoftening/thermoplastic and thermosetting/thermoset plastics.


In thermosoftening/thermoplastic, the forces between the polymer chains are weak, so they can easily be remoulded into new shapes. 

This makes it possible to recycle this type of plastic. whereas in thermosetting plastics there are strong covalent bonds forming cross-links between the polymer chains, making these plastics hard and rigid. Once set into its original shape, a thermosetting plastic can't be softened and remoulded. 

The strong bonds between polymers also mean that thermosetting plastics are much more heat resistant than thermosoftening ones.

Hence, the given statement is $\text{true}$

Multiple choice chemistry synthetic fibres and plastics environmental impact: plastics plastic plastic plastic waste garbage in, garbage out

Plastics are capable of molding and casting into various shapes and size plastic.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Plastics are categorized into thermosoftening and thermosetting plastics.
In thermosoftening plastics, the forces between the polymer chains are weak, so they can easily be remoulded into new shapes. This makes it possible to recycle this type of plastic. whereas in thermosetting plastics there are strong covalent bonds forming cross-links between the polymer chains, making these plastics hard and rigid. Once set into its original shape, a thermosetting plastic can't be softened and remoulded. The strong bonds between polymers also mean that thermosetting plastics are much more heat resistant than thermosoftening ones.
Example: Melamine is an example of a thermosetting plastic and polythene is a thermosoftening plastic.
Option A is correct

Multiple choice chemistry synthetic fibres and plastics environmental impact: plastics plastic plastic plastic waste garbage in, garbage out

State whether true or false :

Bakelite is the first synthetic thermosetting plastics.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bakelite is prepared in laboratories by controlling the pressure and temperature applied to phenol and formaldehyde. 


Baekeland produced a hard moldable material which he named "Bakelite". 

It was the first synthetic thermosetting plastic ever produced.

Therefore, option A is correct

Multiple choice chemistry polymer polymers of commercial importance some commercially important polymers condensation polymers

The commercial name of polyacrylonitrile is:

  1. dacron

  2. orlon (acrilan)

  3. PVC

  4. bakelite
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The commercial name of polyacrylonitrile is orlon or acrilan,

The addition polymerisation of acrylonitrile in presence of a peroxide catalyst leads to the formation of polyacrylonitrile. Polyacrylonitrile is used as a substitute for wool in making commercial fibers.

Multiple choice chemistry polymer polymers of commercial importance some commercially important polymers condensation polymers

Few polymers are matched with their uses. Point out the wrong match.

  1. Polyester - Fabric, tyre cords, safety belts

  2. Nylon 6 - Ropes, tyre cords, fabrics

  3. Bakelite - Packaging industry, lubricant

  4. Teflon - Oil seals, gaskets, non-stick utensils
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Uses of bakelite:

  • For making combs, phonograph records, electrical switches,
  • For making handles of various utensils,
  • Paints

So the incorrect option is [C}.

Multiple choice chemistry polymer polymers of commercial importance some commercially important polymers condensation polymers

Novolac on heating with formaldehyde undergoes _______ to form an infusible solid mass called _______.

  1. polymerization, melamine

  2. vulcanization, resin

  3. cross-liking, bakelite

  4. condensation, polystyrene
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On heating with formaldehyde undergoes crosslinking and form a thermosetting polymer named as$bakalite$.

These are obtained by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst. The reaction starts with the initial formation of $o-and/or p-hydroxymethylphenol$ derivatives, which further react with phenol to form compounds having rings joined to each other through –CH2 groups. The initial product could be a linear product – Novolac used in paints.
The correct option is [C].

Multiple choice chemistry polymer polymers of commercial importance some commercially important polymers condensation polymers

$C{F} _{2} = C{F} _{2}$ is a monomer of:

  1. Teflon

  2. Orlon

  3. Polythene

  4. Nylon-6
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Tetrafluorothylene $C{F} _{2} = C{F} _{2}$ is a monomer of Teflon $ { \left( -C{ F } _{ 2 }-C{ F } _{ 2 }- \right)  } _{ n }$.


             $n  C{ F } _{ 2 } = C{ F } _{ 2 }   \rightarrow   { \left( -C{ F } _{ 2 }-C{ F } _{ 2 }- \right)  } _{ n }$

Multiple choice chemistry polymer polymers of commercial importance some commercially important polymers condensation polymers

Teflon is an example of polymer which is a/an

  1. polyamide

  2. addition Ploymer

  3. polyster

  4. formaldehyderesin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

TEFLON  -  It is an addition polymer prepared by heating tetrafluoroetane with a free radical.
      $n CF _{2} = CF _{2}  \xrightarrow[High  pressure]{Catalyst} -[CF _{2}-CF _{2}-] _{n}$
   Tetrafluoroetane                                   Teflon
POLYAMIDE  -  These are polymers possessing amide linkage and Teflon doesn't contain any amide linkage.
POLYSTER -  These are polycondensation products of dicarboxylic acids and diols.
FORMALDEHYDE  RESIN - It can refer to many formaldehyde polymers such as melamine formaldehyde, urea formaldehyde, phenol formaldehyde.

Multiple choice chemistry polymer polymers of commercial importance some commercially important polymers condensation polymers

Which of the following polymers shows a sharp melting point?

  1. Butyl rubber

  2. Polystyrene

  3. Bakelite

  4. Nylon-6,6
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Crystalline polymers exhibit sharp melting points because their chains are arranged in an ordered structure. Polystyrene, specifically isotactic polystyrene, can show crystalline properties, whereas rubbers and cross-linked polymers like Bakelite are amorphous or thermoset.