This set of Manufacturing Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Introduction To Plastics”.
1. The polymerization of two or more chemically similar monomers forming a long molecular chain is termed as ____________
a) addition polymerization
b) copolymerization
c) condensation polymerization
d) step-growth polymerization
View Answer
Explanation: Addition polymerization (also called as chain-growth polymerization) involves addition of two or more ‘similar’ monomers to form a long chain molecule. In, addition polymerization, empirical formula is the same as that of monomer. Polyolefins are formed through addition polymerization.
2. The polymerization of two or more chemically different monomers forming a long molecular chain is termed as ____________
a) addition polymerization
b) copolymerization
c) condensation polymerization
d) chain growth polymerization
View Answer
Explanation: Copolymerization involves polymerization of two or more different monomers to form a long chain molecule. A well-known ‘Nylon 66’ is a copolymer of hexamethylenediamine and adipic acid.
3. The polymerization of two or more chemically different monomers forming a cross link polymer along with a by-product (can be either water or ammonia) is termed as ____________
a) addition polymerization
b) copolymerization
c) condensation polymerization
d) chain-growth polymerization
View Answer
Explanation: Condensation polymerization (also called as step-growth polymerization) involves condensation (losing small molecules as by-products, usually such as water, methanol and ammonia) of different monomers to form a cross linked polymer. In, condensation polymerization, empirical formula is different as that of monomer. Polymers like polyamides, polyacetals and proteins are formed through condensation polymerization.
4. Which of the following additive is used as an initiator in polymerization reaction?
a) Benzoyl peroxide
b) Mica
c) Glass powder
d) Hydrogen peroxide
View Answer
Explanation: Addition polymerization involves three steps for form an addition polymer, known as initiation, propagation and termination. In the initiation step, an initiator like hydrogen peroxide, easily split to form two species with a free electron attached to each.
5. Thermosetting plastics have ____________
a) 1-Degree bond
b) 2-Degree bond
c) 3-Degree bond
d) 0-Degree bond
View Answer
Explanation: A thermosetting plastic is a polymer which gets irreversibly hardened when heated. They have a three-dimensional network of ‘1-degree’ primary bond. A well-known example of this kind are bakelite, polyester and epoxy resin, etc.
6. Which of the following is a primary bond network of thermosetting plastics?
a) 1-Dimensional
b) 3-Dimensional
c) 2-Dimensional
d) 0-Dimensional
View Answer
Explanation: Thermosetting plastics have a three-dimensional network of ‘1-degree’ primary bond.
7. Thermoplastics have _____________
a) 1-Degree bond
b) 2-Degree bond
c) 3-Degree bond
d) 0-Degree bond
View Answer
Explanation: A thermoplastic is a polymer which gets softened when heated. They have a one-dimensional network of ‘2-degree’ secondary bond. A well-known example of this kind are PET (polyethylene terephthalate), PVC (polyvinyl chloride), and PP (polypropylene) etc.
8. Which of the following is a secondary bond network of thermoplastics?
a) 1-Dimensional
b) 3-Dimensional
c) 2-Dimensional
d) 0-Dimensional
View Answer
Explanation: Thermoplastics have a one-dimensional network of ‘2-degree’ secondary bond.
9. Thermoplastics become softer upon heating.
a) True
b) False
View Answer
Explanation: Thermoplastics have 1-dimensional secondary bond structure, due to this, when heated, their individual polymer chains can slide one over other, thus making them softer.
10. Thermosetting plastics become softer upon heating.
a) True
b) False
View Answer
Explanation: Thermosetting plastics have 2-dimensioanl primary bond structure (strong covalent cross links), thus making them stronger upon heating.
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