Explore topic-wise InterviewSolutions in .

(i), (iv)

(i) Teflon

(iv) Polystyrene

(i), (iii)

(i) Heavily branched cross linked polymers.

(iii) Become infusible on moulding so cannot be reused.

Thermosetting polymers are cross linked or heavily branched molecules which on heating undergo extensive cross linking in moulds and again become infusible. Some examples of thermosetting plastics are bakelite, urea-formaldehyde resins, etc.

Thermoplastic polymers are the linear or slightly branched chain molecules capable of repeatedly softening on heating and hardening on cooling. Some examples of thermoplastics are polythene, polystyrene, polyvinyl, etc.

Fibers are the thread forming solids which possess high tensile strength and high modulus. These polymers possess strong intermolecular forces.Thus leading to close packing of chains and imparting crystalline nature. e.g., polyamides( nylon 6,6) and polyesters( terylene), etc.

Synthetic rubber is any vulcanisable rubber like polymer, which is capable of getting stretched twice its length. However, it returns to its original shape and size as soon as the external stretching force is released.

Polytetrafluoroethene (Teflon) is manufactured by heating tetrafluroethene with a free radical or persulphate catalyst at high temperature. It is chemically inert in nature. It is used for making oil seals and gaskets and also used for non-stick surface coated utensils. 

There are three different types of structural polymers: 

(1) Linear polymers: These polymers consist of long and straight chains.

e.g. polythene, polyvinyl chloride, etc.

(2) Branched chain polymers: These polymers contain linear chains having some branches. 

e.g. low density polythene.

(3) Cross linked polymers (network polymers): These are usually formed from bi-functional and tri-functional monomers and contain strong covalent bonds between various linear polymer chains.

e.g. bakelite, melamine etc

Pure monomers are required because even the traces of impurities may act is initiators which leads to the formation of polymers of small chain lengths.

It is because even the traces of certain impurities, which can act as chain transfer agent (or inhibitor) can interfere with the original polymerisation chain reaction. Hence, monomers should be free from all impurities, particularly, inhibitors (or chain transfer agents) like CCl₄, CBr₄, amines, phenols, quinones​ ​​​​​​etc.

(i), (iv)

(i) Nylon

(iv) Polyesters

(i), (iv)

(i) more elastic

(iv) more stiff

Thermosetting polymers: These polymers are cross linked or  heavily branched molecules, which on heating undergo extensive cross linking in moulds and again become  infusible. These cannot be reused. Some common examples are bakelite, urea-formaldelyde resins, etc.