This set of Polymer Engineering Questions and Answers for Campus interviews focuses on “Fluoropolymers”.
1. What is the melting point of polymer formed by polymerization of tetrafluoroethylene?
a) 100 ᵒC
b) 156 ᵒC
c) 327 ᵒC
d) 533 ᵒC
View Answer
Explanation: The melting point of polytetrafluoroethylene is around 327 ᵒC. Polytetrafluoroethylene is a highly temperature stable polymer.
2. What is the nature of the fluoro polymer polytetrafluoroethylene, regarding its crystallinity?
a) highly crystalline
b) highly amorphous
c) cannot be determined
d) atactic
View Answer
Explanation: Polytetrafluoroethylene is a highly crystalline polymer with high density, due to its regular chain structure present in the polymer.
3. How is the final product of polymerization of tetrafluoroethylene obtained in the form of?
a) granular
b) granular or aqueous dispersion
c) granular or homogeneous solution
d) suspension
View Answer
Explanation: The final polymer product of polymerization of the tetrafluoroethylene, i.e. PTFE is obtained in the form of granules or in the form of aqueous dispersion.
4. Which of the following solvent can dissolve the polymer PTFE at room temperature?
a) propane
b) carbon tetrachloride
c) hexane
d) none of the mentioned
View Answer
Explanation: The polymer polytetrafluoroethylene is completely in insoluble in almost all the hydrocarbon solvents. There is no such solvent for PTFE at room temperature.
5. Which of the following is false about the properties of polytetrafluoroethylene?
a) low friction coefficient
b) low dissipation factor
c) high crystallinity
d) low chemical inertness
View Answer
Explanation: PTFE has high crystallinity due to its regular chain structure and extremely low dielectric constant and friction coefficient due to its waxy feel. It has an outstanding chemical inertness and is also unaffected by water.
6. Which of the following form of polytetrafluoroethylene can be used for casting films?
a) dispersion form
b) granular form
c) powder form
d) none of the mentioned
View Answer
Explanation: The dispersion form of the polytetrafluoroethylene can be used for casting films, dip coating, etc.
7. Which of the following fluoro polymer film is sold under the name of Tedlar by DuPont?
a) polytetrafluoroethylene
b) polyvinyl fluoride
c) polyvinylidene fluoride
d) hexafluoropropylene
View Answer
Explanation: Polyvinyl fluoride, with high crystallinity, is available as a tough and flexible film and is sold by the name of Tedlar by DuPont.
8. Polymer A, also available as copolymer with trifluoroethylene, is a crystalline polymer with a melting point greater than 160 ᵒC and is used in coatings and insulation materials. What is the name of polymer A?
a) polyvinyl fluoride
b) polytetrafluoroethylene
c) polyvinylidene fluoride
d) polyvinyl chloride
View Answer
Explanation: Polyvinylidene fluoride is a crystalline polymer having melting point of about 176 ᵒC. It is also available as a copolymer with trifluoroethylene which have much higher crystallinity and is used in coatings and insulation on electrical wires and cables.
9. A polymer ‘A’ is formed by the polymerization of monomer B. Monomer B is formed by the pyrolysis of monochlorodifluoromethane in contact with platinum at 700 ᵒC. Monomer is a highly crystalline polymer with excellent insulation properties. What is the name of monomer B?
a) tetrafluoroethylene
b) vinylidene chloride
c) vinylidene fluoride
d) vinyl fluoride
View Answer
Explanation: The monomer B is tetrafluoroethylene which polymerizes to give polytetrafluoroethylene which is a highly crystalline polymer with outstanding insulation properties and chemical inertness. Tetrafluoroethylene is formed by the pyrolysis of monochlorodifluoromethane in contact with platinum at 700 ᵒC.
2CHClF2 → CF2═CF2 + 2HCl.
10. What is the approximate density of the polymer polytetrafluoroethylene?
a) 1.8 g/cm3
b) 2.2 g/cm3
c) 0.6 g/cm3
d) 1.5 g/cm3
View Answer
Explanation: PTFE h\is a high density polymer with a density of about 2.2 g/cm3 . Its properties depend on its particle size and molecular weight.
Sanfoundry Global Education & Learning Series – Polymer Engineering.
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