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Questions and Answers
What is the primary method of conducting addition polymerization?
What is the primary method of conducting addition polymerization?
How is control of molecular weight achieved in addition polymerization?
How is control of molecular weight achieved in addition polymerization?
Which type of reaction involves the addition of monomer to successive radicals in chain growth polymerization?
Which type of reaction involves the addition of monomer to successive radicals in chain growth polymerization?
How is each successive propagation reaction characterized in chain growth or propagation reaction?
How is each successive propagation reaction characterized in chain growth or propagation reaction?
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What expression represents all successive propagation steps in chain growth polymerization?
What expression represents all successive propagation steps in chain growth polymerization?
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In chain-growth polymerization, what is used to achieve control of molecular weight under specific conditions?
In chain-growth polymerization, what is used to achieve control of molecular weight under specific conditions?
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Which type of polymerization proceeds by an equilibrium step reaction mechanism?
Which type of polymerization proceeds by an equilibrium step reaction mechanism?
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In which type of polymerization does the growth process involve intermolecular condensation reactions between related functional groups?
In which type of polymerization does the growth process involve intermolecular condensation reactions between related functional groups?
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Which type of polymerization has a slower step process compared to addition or chain polymerization?
Which type of polymerization has a slower step process compared to addition or chain polymerization?
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In which type of polymerization can any two species of any size, including monomers, react and contribute to the growth process?
In which type of polymerization can any two species of any size, including monomers, react and contribute to the growth process?
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Which type of polymerization sees the monomer disappear much faster in the early stages of the process?
Which type of polymerization sees the monomer disappear much faster in the early stages of the process?
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Which type of polymerization allows for the isolation of molecular species in the intermediate stages of growth?
Which type of polymerization allows for the isolation of molecular species in the intermediate stages of growth?
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What is the main characteristic of addition polymerization?
What is the main characteristic of addition polymerization?
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Which type of monomers readily undergo addition polymerization?
Which type of monomers readily undergo addition polymerization?
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What initiates the chain polymerization process?
What initiates the chain polymerization process?
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Which step in chain-growth polymerization involves the actual growth of the polymer chain?
Which step in chain-growth polymerization involves the actual growth of the polymer chain?
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How can chain polymerization be characterized?
How can chain polymerization be characterized?
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What term is used to describe the mechanism of addition polymerization?
What term is used to describe the mechanism of addition polymerization?
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Study Notes
Addition Polymerization
- Addition polymerization is usually done in gas phase, liquid bulk monomer, or under melt condition, or by solution, suspension, or emulsion techniques.
- Control of molecular weight is achieved by selecting appropriate initiator and monomer concentrations and temperature of polymerization.
- Chain transfer agents can be used to control molecular weight.
Chain Growth or Propagation Reaction
- The chain growth or propagation reaction involves the addition of monomer M to RM and to the successive radicals.
- Each successive propagation reaction is characterized by the rate constant of propagation kp.
- The radical reactivity is independent of chain length as long as the end structural segment is the same.
Characteristics of Addition Polymerization
- Addition polymerization is a process by which unsaturated monomers are converted to polymers of high molecular weight.
- It exhibits the characteristics of a typical chain reaction.
- Many different classes of unsaturated monomers, such as ethylene, olefins, vinyl compounds, and conjugated diolefins, undergo this type of polymerization.
Stages of Addition Polymerization
- Initiation of the chain process is triggered by heat, light, high energy radiations, or chemical additives (initiators or catalysts).
- Propagation of the chain or the chain growth process is the second stage.
- Cessation of the chain growth, i.e. the chain termination process, is the final stage.
Comparison with Condensation Polymerization
- Chain-growth polymerization is a fast reaction, whereas step-growth polymerization is a slower process.
- Monomers bearing functional groups undergo condensation polymerization.
- The growth process in condensation polymerization is characterized by relatively slow intermolecular condensation reactions.
- Any two species of any size, including monomers, may react and contribute to the growth process in condensation polymerization.
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Description
Explore the differences between addition/chain-growth polymerization and condensation/step-growth polymerization, including the techniques used and factors affecting molecular weight control. Table 3.1 provides further insight into these processes.
