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CIVE40007 – Materials > Polymers/plastics > Flashcards

Polymers/plastics Flashcards

1
Q

What are plastics?

A
  • Are carbon-based
  • Range of organic materials
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2
Q

What are plastics building blocks?

A

Monomers

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3
Q

What turns monomers into polymers?

A

Polymerization

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4
Q

How are plastics manufactured?

A

From crude oil

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5
Q

Whats the first synthetic material made?

A

Bakelite

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6
Q

What bakelite and example of?

A

Thermosetting plastic

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7
Q

What is electro-negativity?

A

The electron attracting potential of an element

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8
Q

What are the elements in organic polymers?

A

C, H, N, O, P and S

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9
Q

What does difference in electro-negativity determine?

A

Bond type

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10
Q

What does a big difference in electro-negativity show?

A

It is an ionic bond

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11
Q

What does a small difference in electro-negativity show?

A

It is a covalent bond

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12
Q

How is ethane denoted?

A

C_2H_6

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13
Q

What organic molecule is the start of a homologous series?

A

CH_4

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14
Q

Whats the source of all plastics?

A
  • Crude oil
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15
Q

What does crude oil consist of?

A
  • Consists predominantly of hydrocarbons
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16
Q

What percentage of the hydrocarbons in crude oil are aliphatic?

A

25%

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17
Q

What percentage of hydrocarbons in crude oil are aromatic?

A

17%

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18
Q

What percentage of hydrocarbons in crude oil are naphthenes?

A

50 %

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19
Q

What does increasing the number of carbons do?

A

Increases the boiling point in a systematic way

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20
Q

What is the basis of oil refining?

A

Separating in different fractions

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21
Q

What colour is crude oil?

A

Viscous, dark colored

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22
Q

What kind of boiling points do small molecules have?

A

low

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23
Q

What is an example of aromatics?

A

Benzene

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24
Q

Example of cycloalkanes?

A

Methyl

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25
Q

Example of Alkynes?

A

Acetylene

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26
Q

What is the biggest contributor to petrochemical feedstock?

A

Gasoline

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27
Q

What is petrochemical feedstock?

A

Petrochemical feedstock is used for manufacturing polymers
accounts for 2.7% of crude oil

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28
Q

What is the polymerisation of ethylene?

A

Polyethylene

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29
Q

What uses, heat, pressure and catalyst?

A

Polymerization

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30
Q

What causes the distribution of chain lengths and thus molecular weights?

A

Formation of macromolecules during polymerization

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31
Q

How is molecular weight determined?

A

Molecular weight determined by polymerization conditions

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32
Q

What has a lower molecular weight?

A

The increased amount of polymer

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33
Q

What are the two types polymers?

A

They can be crystalline or amorphous

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34
Q

What are thermoplastics?

A
  • Become soft and melt when heated and can be moulded into a new shape that is retained on cooling
  • Thermo-plastics can be reheated and remoulded many times
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35
Q

What are the thermosetting plastics?

A
  • Thermosetting plastics cannot be remolded
  • If reheated it will not soften
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36
Q

When do thermosetting plastics set?

A

When first cooled

37
Q

What will happen to thermosetting plastics when reheated?

A

Will not soften

38
Q

What polymers are included in thermoplastics?

A

Polyethylene, polystyrene, nylon

39
Q

How are thermoplastics bond?

A

Weak intermolecular bonding

40
Q

What kind of density do straight chained materials have?

A

High density material

41
Q

How are straight chains and branched chains different?

A

Branched chains cannot come close together

42
Q

What is the effect of side chains?-

A
  • Side chains increase distance between the main C-C chain
  • Reduced packing and reduced intermolecular attraction
43
Q

What cannot happen to thermoplastics?

A

Cannot be reprocessed

44
Q

What do thermosetting plastic polymers undergo?

A

A chemical reaction that locks the monomer chains

45
Q

What are examples of polymers in thermosetting plastics?

A

Includes phenolics, various epoxy resins

46
Q

What are co-polymers?

A

Many commercial polymers are prepared from more than one
monomer

47
Q

What are the 4 most common co-polymers?

A
  • Random
  • Alternating
  • Block
  • Graft
48
Q

What is the arrangement of normal polystyrene?

A

Normal polystyrene is atactic → rings are randomly arranged, irregular

49
Q

What is syndiotactic?

A

Syndiotactic is more crystalline than atactic → rings on different sides, regular alternating pattern around the hydrocarbon backbone chain

50
Q

What are some properties of polymers?

A
  • Low melting point
  • Variable molecule size
  • Low compressive strength
  • Low stiffness
  • Low density
  • High toughness
51
Q

What is the area under a stress strain graph?

A

Absorbed energy

52
Q

How much plastic produced annually world wide?

A

300 million tonnes per year

53
Q

How much is consumption growing by in Western Europe?

A

4% per year in western Europe

54
Q

How much of plastics is used in construction?

A

1/4

55
Q

How can use of plastics have environmental benefits?

A
  • Use in vehicles resulting in fuel savings
  • Foam insulation
56
Q

What are examples of high volume plastics?

A
  • Polyethylene (PE)
  • Polyethylene terephthalate (PET)
  • Polyvinylchloride (PVC)
57
Q

What is PVC used for?

A
  • Window frames
  • Pipes
58
Q

What is PET used for?

A
  • Bottles
  • Food packaging
59
Q

How much of plastics is used in the transport sector?

A

8%

60
Q

What do plasticisers do?

A

Makes plastic mouldable at particular temps

61
Q

What are some additives to polymers?

A
  • Plasticisers
  • Fillers
  • Pigments
  • Antioxidants
62
Q

What type of polymers are ideal for application?

A

hard and tough

63
Q

How does extrusion work?

A
  • Granules go into extruder → plastic melt
  • Barrel heated so it melts and then extruded through a nozzle
64
Q

What two quantities help to generate shear heat in an extruder?

A

Combination of pressure and compression

65
Q

How does injection moulding work?

A
  • Load plastic pellets in the machine hopper
  • Using a RAM inject melted plastic into mould
  • Open the mold and eject the solidified plastic part
66
Q

How does processing by compression moulding work?

A
  • Lump of plastic and squeeze it in a mould using a plunger
67
Q

What is plastic is mainly used in construction?

A

PVC

68
Q

How much of plastic used in construction goes towards making pipes and ducts?

A

1/2

69
Q

Where is HDPE used?

A

The lining system in a landfill will have a high-density polyethylene to stop leaching getting into the environment

70
Q

What does HDPE stand for?

A

High-density polyethylene

71
Q

What are characteristics of HDPE lining in landfills?

A
  • Flexible membrane liners
  • It is a thermoplastic so they are heat-sealed together
72
Q

What is used for the cover of landfills?

A

LDPE

73
Q

Why do they use LDPE as the cover in landfills?

A

Needs to be more flexible because waste is contracting due to degradation. There is subsidence

74
Q

Where is bitumen used?

A

Coat roads in it and is the binder

75
Q

What can be mixed into bitumen?

A

Aggregates

76
Q

What is bitumen produced from?

A

Bitumen is produced from crude oil during fractional distillation

77
Q

What are the features of bitumen?

A

Viscous liquid or solid consisting of polycyclic aromatic hydrocarbons

78
Q

Bitumen is the ? oil fraction.

A

Heaviest

79
Q

What is bitumens boiling point?

A

> 370˚C

80
Q

What does bitumen do when heated

A

Softens when heated and non-volatile

81
Q

What are advantages of bitumens properties?

A

Bitumen has excellent waterproofing and adhesive properties

82
Q

How much bitumen is produced annually in Europe?

A

16 million tonnes per year

83
Q

How much carbon and hydrogen does bitumen contain?

A

82-88%
8-11%

84
Q

How trace metals exist as in bitumen?

A

Trace metals present as inorganic salts

85
Q

What does the exact composition of bitumen depend on?

A

Exact composition depends on the crude oil and the distillation process

86
Q

What are the main chemical groups in bitumen?

A

Asphaltenes and Maltenes

87
Q

How can Maltese’s be subdivided?

A

Resins, aromatics, and saturates.

88
Q

What is the optimum amount of filling in asphalt?

A

Bitumen fills the voids. Both the stone skeleton and bitumen contribute to the properties of the mix

89
Q

What is the suboptimal filling in asphalt?

A

Too much or too little bitumen so either stone skeleton or properties dominate

CIVE40007 – Materials (16 decks)

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