10. Polymer-based materials are increasingly substituted for metals in transport
ID: 542023 • Letter: 1
Question
10. Polymer-based materials are increasingly substituted for metals in transportation applications, because polymers typically: a. are stronger, b. are stable to much higher temperatures; c. have a lower density; d. are better electrical conductors; e. none of the above. 11. Below its glass transition temperature, a typical thermoplastic polymer: a. is ductile; b. is brittle; C. can flow easily: d. can undergo a large elastic (recoverable) deformation; e. none of the above. 12. A gel is: a. b. c. d. e. a thermoplastic polymer that can be easily recycled when heated; a highly crosslinked polymer that repels water and other solvents; a lightly crosslinked polymer that swells when immersed in a solvent like water; an example of a block copolymer none of the above. ,Explanation / Answer
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5. Polymer-based materials are increasingly substituted for metals in transportation applications, because polymers typically
Ans: c. Have a low density
Explanation: Due to low density , the overall weight of transportation reduces resulting in saving the operating energy.
Also the energy requirements for the production of a unit of polymers are only one tenth to one half that of metals.
6.Below its glass transition temperature, a typical thermoplastic polymer
Ans: b. is brittle
Explanation: As the temperature of a polymer drops below transition temperature, it behaves in an increasingly brittle manner. As the temperature rises above the transition temperature, the polymer becomes more rubber-like. Thus, knowledge of Tg is essential in the selection of materials for various applications. In general, values of Tg well below room temperature define the domain of elastomers and values above room temperature define rigid, structural polymers.
7. A gel is;
Ans : c. a lightly cross-linked polymer that swells when immersed in a solvent like water;
Explanation: Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state. It consists of 90% of solvent (water).
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