Engineering Questions with Answers - Multiple Choice Questions

Polymer Engineering MCQ’s – Inhibition and Retardation

1 - Question

he substance that reduces the rate and degree of polymerization, without halting the propagation process, is called a___________
a) retarder
b) inhibitor
c) modifier
d) regulator
View Answer Answer: a
Explanation: Inhibitors consume the radicals and completely suppress the polymerization and brings the rate of polymerization to a zero value.

2 - Question

Which of the following has the highest practical utility as an inhibitor?
a) benzoquinone
b) t-butyl catechol
c) nitro benzene
View Answer Answer: d
Explanation: DPPH (diphenylpicrylhydrazyl) is too stable toact as free radical but it has great potential to react with chain radicals to completely terminate them.

3 - Question

What is the order of inhibitor consumption in an inhibition process?
a) first
b) second
c) zero
d) none of the mentioned
View Answer Answer: c
Explanation: In an ideal inhibition process, the consumption rate is independent of inhibitor concentration and depends on the rate of generation of radicals, by any means. The radical generation is however independent of the inhibitor, thus the inhibitor consumption is of zero order.

4 - Question

The inhibition period is proportional to the monomer concentration in the system. State true or false.
a) true
b) false
View Answer Answer: b
Explanation: The inhibition period does not depend on monomer concentration; instead, it is proportional to the initial concentration of the inhibitor.

5 - Question

What does the stoichiometric ratio and nature of products formed depends on, when the reaction of inhibitor radicals and chain radicals leads to copolymerization?
a) nature of monomer
b) initiator
c) solvent
d) all of the mentioned
View Answer Answer: d
Explanation: The nature of non-radical products formed through reaction of inhibitor radicals and chain radicals, which may even lead to copolymerization, and the stoichiometric ratio, may not follow a uniform pattern which largely depends on the nature of monomer and overall polymerization environment including initiator, solvents, etc.

6 - Question

Where has the role of aromatic nitro compounds as an inhibitor or retarder been unsuccessful?
a) styrene polymerization
b) vinyl acetate polymerization
c) acrylate polymerization
d) vinyl chloride polymerization
View Answer Answer: c
Explanation: These compounds have been unsuccessful or ineffective in any of retardation and inhibition, for acrylate polymerization.

7 - Question

What happens to the rate of polymerization at the end of inhibition period as compared to the rate for uninhibited monomer, when oxygen is used as an inhibitor?
a) recedes
b) exceeds
c) remains same
d) none of the mentioned
View Answer Answer: b
Explanation: The rate of polymerization usually observed at the end of inhibition period due to oxygen often exceeds that for the uninhibited monomer under otherwise comparable conditions.

8 - Question

What is the necessary condition for hydroquinone to be used as inhibitors?
a) presence of α-hydrogen
b) presence of oxygen
c) presence of ring
d) none of the mentioned
View Answer Answer: b
Explanation: The inhibitory action of hydroquinone is noticeable only in the presence of oxygen, as it become effective due to its oxidation to quinones.

9 - Question

What role does nitrobenzene play for the polymerization of methyl acrylate?
a) inhibitor
b) retarder
c) chain transfer agent
d) none of the mentioned
View Answer Answer: c
Explanation: The value of inhibitor constants for a particular substrate widely depends on the reactivity of chain radicals. Nitrobenzene acts as a strong chain transfer agent for polymerization of methyl acrylate due to the less reactivity of methyl acrylate radicals.

Get weekly updates about new MCQs and other posts by joining 18000+ community of active learners