This set of Polymer Engineering Interview Questions and Answers for Experienced people focuses on “Synthetic Rubber-II”.
1. Which of the following resistances is provided by the presence of chlorine in CR molecules?
a) resistance to flex cracking
b) ozone resistance
c) flame resistance
d) resistance to oxidative aging
Explanation: CR compounds exhibit some inherent flame resistance due to the presence of chlorine in the molecules.
2. Which one of the following conditions does not resemble to hot nitrile rubbers?
a) high temperature 25-50 C
b) high gel content
c) little gel content
d) branched units
Explanation: Hot nitrile rubbers are formed by copolymerization at around 25-50 C which have characteristic toughness due to the presence of gels and branch units in polymer chains.
3. Which property of NBR-PVC blends mends its way to be used in footwear soling?
a) good weathering resistance
b) good abrasion resistance
c) good flame resistance
d) solvent resistance
Explanation: Good abrasion resistance had led to the use of NBR-PVC blends in footwear soling.
4. What is the polymerization temperature of isobutylene to give high molecular weight polyisobutylene?
a) 80 C
b) -80 C
c) 25 C
d) -25 C
Explanation: Isobutylene can be commercially polymerizaed to high molecular weight polyisobutylene using cationic catalysts such as boron trifluoride at a temperature of -80 C.
5. What is the monomer composition of IIR polymer or Butyl Rubber?
c) isoprene and isobutylene
d) isoprene, isobutylene and chloroprene
Explanation: Butyl rubber or isobutylene-isoprene rubber (IIR) is formed by the copolymerization of isoprene and isobutylene monomers.
6. Which of the following properties does not correspond to butyl rubbers?
a) poor resilience
b) low heat build-up
c) high internal viscosity
d) good flexibility even below -40 C
Explanation: Butyl rubber retains its flexibility even below -40 C by not crystallizing at lower temperatures. The methyl side groups of butyl rubber hinder elastic movements, thus giving rise to high internal viscosity and consequently, high heat build-up and poor resilience.
7. Butyl Rubber usually exhibits high gas permeability. State true or false.
Explanation: The densely packed structure of the linear hydrocarbon chains makes butyl rubber exhibit unusually low gas permeability.
8. Polyisobutylene rubbers can be vulcanized easily using conventional curing systems. State true or false.
Explanation: Polyisobutylene is rubbery in nature but it cannot be vulcanized easily using conventional curing systems because of the absence of unsaturation in the chain molecules.
9. Which of the following is used for vulcanization of butyl rubber to produce vulcanizates with improved heat resistance and aging characteristics?
b) oxime and red lead
c) phenol-formaldehyde resins
d) carbon black
Explanation: Vulcanization with phenol-formaldehyde resins produces the vulcanizates with improved heat resistance and aging characteristics as compared to other vulcanizing agents.
10. How can the curing of halobutyl rubbers be done conveniently?
a) sulphur cure
b) amine cure
c) quininoid cure
d) all of the mentioned
Explanation: Curing of chlorobutyl or bromobutyl rubbers can be conveniently done following conventional sulphur cure or quininoid cure, resin cure, amine cure or simply metal oxide cure.
11. What approx proportion of third diene monomer is added to produce EPDM rubber?
Explanation: EPDM ruuber is a terpolymer formed by the copolymerization of a non-conjugated diene as a third monomer in small proportions, upto 5%, along with ethylene and propylene.
12. Which of the following does not resemble to EPDM rubbers?
a) high density
b) moderate tear strength
c) good heat stability
d) good storage stability
Explanation: EPDM rubbers have low density around 0.85 gram per cubic centimeters.
13. Which of the following is used as curing agent for acrylate rubbers?
b) zinc oxide and stearic acid
c) aliphatic amines and polyamines
d) metal peroxides
Explanation: Acrylate rubbers are readily cured using aliphatic linear amined and polyamines.
14. What is the monomer composition of polymer named Vamac?
a) methyl acrylate, ethylene, curing site monomer
b) propylene, ethylene, ethyl acrylate
c) ethyl acrylate, ethylene
d) ethyl acrylate, ethylene, cure site monomer
Explanation: A terpolymer of methyl acrylate, ethylene and a cure site monomer is known as Vamac in the trade.
15. Which monomer pairs copolymerize to give nitroso rubber?
a) trifluoronitrosomethane and tetrafluoroethylene
b) tetrafluoronitrosomethane and trifluoroethylene
c) trifluoronitrosomethane and trifluoroethylene
d) tetrafluoronitrosomethane and tetrafluoroethylene
Explanation: Nitroso Rubber is an alternating copolymer of trifluoronitrosomethane and tetrafluoroethylene of high molecular weight.
Sanfoundry Global Education & Learning Series – Polymer Engineering.
To practice all areas of Polymer Engineering for Interviews, here is complete set of 1000+ Multiple Choice Questions and Answers.