This set of Polymer Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Radical Chain Polymerization”.
1. Which of the following can activate chain initiation?
a) heat
b) light or radiation
c) catalysts
d) all of the mentioned
View Answer
Explanation: The chain initiation can be induced by heat, light or energy radiations or with the help of initiators or catalysts.
2. Which of the following monomers cannot undergo chain growth polymerization?
a) CH2═ CH2
b) CH2═CHCN
c) CH2═CHCOOR
d) COOH−CH2−COOH
View Answer
Explanation: Dicarboxylic acid undergoes condensation polymerization.
3. Why is addition polymerization also known as vinyl polymerization?
a) monomers are unsaturated compounds
b) its a chain reaction
c) most monomers contain (CH2═CH─) group
d) all of the mentioned
View Answer
Explanation: Most of the monomers involves in chain polymerization contains (CH2═CH─) group, which is commonly known as vinyl group.
4. Which of the following cannot initiate the chain reaction in polymerization of acrylo-nitrile?
a) anion
b) cation
c) free radical
d) coordination
View Answer
Explanation: Acrylonitrile contains ─CN group which is an electron withdrawing group and cannot adopt a cationic pathway. Anion, free radical and coordination complex can polymerize it to high molecular weight polymer.
5. What does chain initiation step of free radical polymerization consists of?
a) decomposition of initiator
b) addition of free radical to monomer
c) all of the mentioned
d) none of the mentioned
View Answer
Explanation: The first step in chain initiation is decomposition of initiator to free radicals and the second step is addition of free radical to the monomer unit.
6. Which is the rate determining step of chain initiation step?
a) initiator decomposition
b) chain initiation of monomer
c) chain propagation
d) none of the mentioned
View Answer
Explanation: Initiator decomposition step is the rate determining step of chain initiation step as it is the slowest of two.
7. Which mode in the chain termination step is accompanied by a transfer of hydrogen molecule?
a) combination
b) disproportionation
c) propagation
d) all of the mentioned
View Answer
Explanation: The disproportionation mode of termination is accomplished by a hydrogen transfer from one radical molecule to other, which is given by-
R~~~ CH2−∙CHX + XH∙C−CH2 ~~~~~R → R ~~~ CH2− CH2X + R~~~ CH═CHX.
8. The substance that is so effective, which can suppress the rate as well as degree of polymerization is a ___________
a) retarder
b) inhibitor
c) promoter
d) none of the mentioned
View Answer
Explanation: If an inhibitor is added to a monomer, then it may reduce the rate of reaction and may even suppress degree of polymerization.
9. Which of the following mechanism can occur for the termination step to take place?
a) combination
b) disproportionation
c) all of the mentioned
d) none of the mentioned
View Answer
Explanation: Combination and disproportionation both are the modes of termination step of free radical polymerization.
10. Which of the following factors does termination mechanism depend on?
a) type of active centre
b) nature of monomer
c) reaction conditions
d) all of the mentioned
View Answer
Explanation: The convenient mechanism for chain termination largely depends on all the above factors.
Sanfoundry Global Education & Learning Series – Polymer Engineering.
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