16 Questions
What is the main difference between thermoplastics and elastomers?
Thermoplastics can be reheated and reformed, while elastomers cannot be reformed by reheating.
What are the advantages of plastics mentioned in the text?
Wide range of properties and good insulation.
In polymerization, what is the functionality of a monomer?
The number of active bonds in a monomer.
What is the process involved in chain growth polymerization?
Formation of long chains by covalent bonds from small molecules (monomers).
What is the range of degree of polymerization (DP) mentioned in the text?
3500-25000
What is the defining characteristic of thermosetting plastics?
They cannot be reformed by reheating; they are set by a chemical reaction.
What is the process of extending a polymer chain by the addition of monomers called?
Propagation
Which type of polymerization involves the chemical reaction taking place in more than two reaction sites, forming a 3D network?
Network Polymerization
What is the average molecular weight determined by in materials science and engineering?
Special physical and chemical techniques
In the sample problem example, what is the degree of polymerization if a particular type of polyethylene has a molecular mass of 150,000 g/mol?
$5357 (mers/mol)$
What is needed for initiation in chain polymerization?
A radical
What occurs during termination in chain polymerization?
Combining of two chains
What happens in stepwise polymerization?
Formation of linear polymers and small byproducts
What does the degree of polymerization represent?
$\frac{molecular ext{ mass ext{ }(g/mol)}}{mass ext{ of a mer }(g/mer)}$
What is the role of a termination free radical in chain polymerization?
To combine two chains
How is the energy of the system affected during chain polymerization?
Energy decreases due to polymerization
Test your knowledge of the properties and types of polymers and plastics with this quiz based on the content from Chapter 6 of 'Foundations of Materials Science and Engineering, 5th Edn.' by Smith and Hashemi.
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