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Polymer Engineering > Basic Types Of Polymerization > Flashcards

Basic Types Of Polymerization Flashcards

1
Q

A process through which a large number of monomer molecules react together to form a polymer.

A

Polymerization

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2
Q

IUPAC Definition: A chain reaction in which the growth of a polymer chain proceeds exclusively by reactions between monomer and reactive site on the polymer chain with regeneration of the reactive sites at the end of each growth step.

A

Chain-growth Polymerization or Addition Polymerization

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3
Q

Chain-growth polymerization involves the addition of ____________ molecules to a rapidly growing chain.

A

Unsaturated

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4
Q

Enumeration.
Three fundamental steps of Chain-growth Polymerization.

A
  1. Initiation
  2. Propagation
  3. Termination
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5
Q

Enumeration:
Classification of Chain-growth Polymerization.

A
  1. Free radical Polymerization
  2. Cationic Polymerization
  3. Anionic Polymerization
  4. Coordination or Stereoregular Polymerization
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6
Q

IUPAC Definition: A chain polymerization in which the kinetic-chain carriers are free radicals.

A

Free Radical Polymerization

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7
Q

Most frequently, initiation of free radical polymerization is brought about by the addition of small quantities of compounds called __________.

A

Initiators

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8
Q

Usually a weak organic compound that can be decomposed thermally or by irradiation to produce free radicals, which are molecules containing atoms with unpaired electrons.

A

Initiators

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9
Q

Enumeration.
Initiation in a free-radical polymerization consists of two-steps.

A
  1. Dissociation
  2. Addition
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10
Q

It involves the dissociation of a radical initiator molecule which is easily dissociated by heat or light into two free radicals.

A

Chain Initiation.

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11
Q

Involves the linear growth of the polymer chain by the sequential addition of monomer units to this active growing chain molecule.

A

Propagation

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12
Q

IUPAC Definition: A reaction of an active center on the growing polymer molecule, which adds one monomer molecule to form a new polymer molecule one repeat unit longer.

A

Chain Propagation

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13
Q

The sequence of propagation reactions is terminated at some point due to annihilation of the radical center of the propagating chain.

A

Termination

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14
Q

Enumeration.
Two termination step that involves the reaction of any two free radicals with each other.

A
  1. Combination
  2. Disproportionation
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15
Q

Two propagating chains are terminated when two radicals combine to form an electron-pair (covalent) bond

A

Combination (Coupling)

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16
Q

The reaction of the unpaired electrons of two chains to form a covalent bond between them.

A

Combination

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17
Q

This termination step involves two growing molecules that react to from two “dead chains”.

A

Disproportionation

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18
Q

The transfer of a hydrogen atom from one chain to the other so that the two product chain molecules are unchanged in length but are no longer free radicals.

A

Disproportionation

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19
Q

A growing polymer chain is deactivated or terminated by transferring its growth activity to a previously inactive species.

A

Chain Transfer

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20
Q

Involve chain carriers or reactive centers that are organic ions or charged organic groups.

A

Ionic Polymerization

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21
Q

IUPAC Definition: An ionic polymerization in which the kinetic-chain carriers are cations.

A

Cationic Polymerization

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22
Q

A type of chain growth polymerization in which a cationic initiator transfers charge to a monomer, which then becomes reactive.

A

Cationic Polymerization

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23
Q

The catalysts generally require the presence of a Lewis base such as water, alcohol, or acetic acid

A

Cocatalyst

24
Q

IUPAC Definition: An ionic polymerization in which the kinetic-chain carriers are anion.

A

Anionic Polymerization

25
Q

A form of chain-growth polymerization or addition polymerization that involves polymerization of monomers initiated with anions.

A

Anionic Polymerization

26
Q

Enumeration.
Commonly used initiator systems for anionic polymerization.

A
  1. Alkali Metals and Alkali Metal Complexes
  2. Organometallic Compounds
  3. Lewis Bases
  4. High-energy Radiation
27
Q

Initiate polymerization by transfer of an electron to the double bond of the monomer.

A

Alkali Metals and Alkali Metal Complexes

28
Q

Initiation by _________ and __________ occurs by a direct attack of these compounds on the double bond of the monomer molecule.

A

Organometallic Compounds, Lewis Bases

29
Q

Complexing of the monomer to the initiator frequently precedes the insertion process and this polymerization is therefore often called _______________.

A

Coordination Polymerization

30
Q

The range of type of this catalysts was subsequently extended to produce polymers exhibiting a wide range of stereoregular structures including those derived from dienes and cycloalkenes.

A

Ziegler-Natta Catalysts

31
Q

It refers to a type of polymerization mechanism which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers.

A

Step-growth Polymerization

32
Q

It refers to the molecule’s interlinking capacity or the number of sites it has available for bonding with other molecules under the specific polymerization conditions.

A

Functionality

33
Q

In step-growth polymerization, the stepwise reaction occurs between pairs of chemically ____________ on the reacting molecules.

A

Reactive or Functional Groups

34
Q

Enumeration.
Categories of Step-growth Polymerization.

A
  1. Polycondensation
  2. Polyaddition
35
Q

Small molecule is eliminated at each step.

A

Polycondensation

36
Q

Monomers react without the elimination of a small molecule.

A

Polyaddition

37
Q

It is used as film (mylar) and in bottle applications.

A

Polyester

38
Q

Special class of polyesters derived from carbonic acid.

A

Polycarbonates

39
Q

Characterized by the presence of amide linkages (-CONH-) on the polymer main chain.

A

Polyamides

40
Q

Condensation polymers obtained from the reaction of dianhydrides with diamines.

A

Polyimides

41
Q

Families of synthetic heterocycles with a wide range of applications due to their physical and chemical properties.

A

Polybenzimidazoles and Polybenzoxazoles

42
Q

A type of polymer that consists of repeating units connected by aromatic linkers, such as benzene rings.

A

Aromatic Ladder Polymers, Ladder Polymers or Linker Polymers

43
Q

Employed in the production of aminoplasts and phenoplasts, which are two different but related classes of thermoset polymers.

A

Formaldehyde Resins

44
Q

Polymers consisting of monomers joined together by ether linkages (two carbon atoms bonded to an oxygen atom).

A

Polyethers

45
Q

Closely related to polyethers in structure and properties and is typically used as electrical insulators and structural parts in the building of engines and vehicles.

A

Polysulfides

46
Q

Another family of linear aromatic polymers that are tough, high temperature-resistant engineering thermoplastics.

A

Polysulfones

47
Q

True or False.
1. In step-growth, monomers bearing functional groups such as -OH, -COOH, -NH2, -NCO, etc. undergo step polymerization.
2. In chain-growth, monomers with carbon-carbon unsaturation undergo polymerization when an active center is formed.

A

Both statements are true.

48
Q

True or False.
1. In step-growth, the growth of polymer molecules proceeds by a stepwise intermolecular reaction, normally with the elimination of small molecules as by-products of condensation. The molecule never stops growing during polymerization.
2. In chain-growth, each polymer molecule/chain increases in size at a rapid rate once it growth has been started by formation of an active center. When the macromolecules stop growing, it can generally not react with more monomers.

A

Both statements are true.

49
Q

True or False.
1. In step-growth, any two molecular species present can react.
2. In chain-growth, only growth reaction adds repeating unit two at a time of the chain.

A

Statement 1 is true.
Statement 2 is false. “Two” -> “One”

50
Q

True or False.
1. Step-growth: Monomer units can react with each other or with polymers of any size. Growth occurs in a series of fits and starts as the reactive species of a monomer or polymer encounters other species with which it can form a link.
2. Chain-growth: Growth of a polymer molecule is caused by a kinetic chain of reactions involving rapid addition of monomer to an active center that may be a free radical, ion, or polymer-catalyst bond.

A

Both statements are true.

51
Q

True or False.
1. Step-growth: This can occur even in the absence of an added catalyst.
2. Chain-growth: The active center is produced by some external source (energy, highly reactive compound, or catalyst)

A

Both statements are true.

52
Q

True or False.
1. Step-growth: The average size increases with conversion.
2. Chain-growth: Consists of growing chains of intermediate sizes.

A

Both statements are true.

53
Q

True or False.
1. Step-growth: Backbone polymer chains contains heteroatoms such as N, O, S, etc. at a regular intervals due to condensed interunit links.
2. Chain-growth: Usually the backbone of polymer chains consists of -C-C- linkages and other kinds of atoms such as O, N, S, etc. may appear in the side groups.

A

Both statements are true.

54
Q

IUPAC Definition: A polymerization in which a cyclic monomer yields a monomeric unit which is acyclic or contains fewer cycles than the monomer.

A

Ring-opening Polymerization

55
Q

A form of chain-growth polymerization in which the terminus of a polymer chain attacks cyclic monomers to form a longer polymer. The reactive center can be radical, anionic, or cationic.

A

Ring-opening Polymerization

Polymer Engineering (6 decks)

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