Polymers/plastics Flashcards
(89 cards)
1
Q
What are plastics?
A
- Are carbon-based
- Range of organic materials
2
Q
What are plastics building blocks?
A
Monomers
3
Q
What turns monomers into polymers?
A
Polymerization
4
Q
How are plastics manufactured?
A
From crude oil
5
Q
Whats the first synthetic material made?
A
Bakelite
6
Q
What bakelite and example of?
A
Thermosetting plastic
7
Q
What is electro-negativity?
A
The electron attracting potential of an element
8
Q
What are the elements in organic polymers?
A
C, H, N, O, P and S
9
Q
What does difference in electro-negativity determine?
A
Bond type
10
Q
What does a big difference in electro-negativity show?
A
It is an ionic bond
11
Q
What does a small difference in electro-negativity show?
A
It is a covalent bond
12
Q
How is ethane denoted?
A
C_2H_6
13
Q
What organic molecule is the start of a homologous series?
A
CH_4
14
Q
Whats the source of all plastics?
A
- Crude oil
15
Q
What does crude oil consist of?
A
- Consists predominantly of hydrocarbons
16
Q
What percentage of the hydrocarbons in crude oil are aliphatic?
A
25%
17
Q
What percentage of hydrocarbons in crude oil are aromatic?
A
17%
18
Q
What percentage of hydrocarbons in crude oil are naphthenes?
A
50 %
19
Q
What does increasing the number of carbons do?
A
Increases the boiling point in a systematic way
20
Q
What is the basis of oil refining?
A
Separating in different fractions
21
Q
What colour is crude oil?
A
Viscous, dark colored
22
Q
What kind of boiling points do small molecules have?
A
low
23
Q
What is an example of aromatics?
A
Benzene
24
Q
Example of cycloalkanes?
A
Methyl
25
Example of Alkynes?
Acetylene
26
What is the biggest contributor to petrochemical feedstock?
Gasoline
27
What is petrochemical feedstock?
Petrochemical feedstock is used for manufacturing polymers
accounts for 2.7% of crude oil
28
What is the polymerisation of ethylene?
Polyethylene
29
What uses, heat, pressure and catalyst?
Polymerization
30
What causes the distribution of chain lengths and thus molecular weights?
Formation of macromolecules during polymerization
31
How is molecular weight determined?
Molecular weight determined by polymerization conditions
32
What has a lower molecular weight?
The increased amount of polymer
33
What are the two types polymers?
They can be crystalline or amorphous
34
What are thermoplastics?
- 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
35
What are the thermosetting plastics?
- Thermosetting plastics cannot be remolded
- If reheated it will not soften
36
When do thermosetting plastics set?
When first cooled
37
What will happen to thermosetting plastics when reheated?
Will not soften
38
What polymers are included in thermoplastics?
Polyethylene, polystyrene, nylon
39
How are thermoplastics bond?
Weak intermolecular bonding
40
What kind of density do straight chained materials have?
High density material
41
How are straight chains and branched chains different?
Branched chains cannot come close together
42
What is the effect of side chains?-
- Side chains increase distance between the main C-C chain
- Reduced packing and reduced intermolecular attraction
43
What cannot happen to thermoplastics?
Cannot be reprocessed
44
What do thermosetting plastic polymers undergo?
A chemical reaction that locks the monomer chains
45
What are examples of polymers in thermosetting plastics?
Includes phenolics, various epoxy resins
46
What are co-polymers?
Many commercial polymers are prepared from more than one
monomer
47
What are the 4 most common co-polymers?
- Random
- Alternating
- Block
- Graft
48
What is the arrangement of normal polystyrene?
Normal polystyrene is atactic → rings are randomly arranged, irregular
49
What is syndiotactic?
Syndiotactic is more crystalline than atactic → rings on different sides, regular alternating pattern around the hydrocarbon backbone chain
50
What are some properties of polymers?
- Low melting point
- Variable molecule size
- Low compressive strength
- Low stiffness
- Low density
- High toughness
51
What is the area under a stress strain graph?
Absorbed energy
52
How much plastic produced annually world wide?
300 million tonnes per year
53
How much is consumption growing by in Western Europe?
4% per year in western Europe
54
How much of plastics is used in construction?
1/4
55
How can use of plastics have environmental benefits?
- Use in vehicles resulting in fuel savings
- Foam insulation
56
What are examples of high volume plastics?
- Polyethylene (PE)
- Polyethylene terephthalate (PET)
- Polyvinylchloride (PVC)
57
What is PVC used for?
- Window frames
- Pipes
58
What is PET used for?
- Bottles
- Food packaging
59
How much of plastics is used in the transport sector?
8%
60
What do plasticisers do?
Makes plastic mouldable at particular temps
61
What are some additives to polymers?
- Plasticisers
- Fillers
- Pigments
- Antioxidants
62
What type of polymers are ideal for application?
hard and tough
63
How does extrusion work?
- Granules go into extruder → plastic melt
- Barrel heated so it melts and then extruded through a nozzle
64
What two quantities help to generate shear heat in an extruder?
Combination of pressure and compression
65
How does injection moulding work?
- 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
How does processing by compression moulding work?
- Lump of plastic and squeeze it in a mould using a plunger
67
What is plastic is mainly used in construction?
PVC
68
How much of plastic used in construction goes towards making pipes and ducts?
1/2
69
Where is HDPE used?
The lining system in a landfill will have a high-density polyethylene to stop leaching getting into the environment
70
What does HDPE stand for?
High-density polyethylene
71
What are characteristics of HDPE lining in landfills?
- Flexible membrane liners
- It is a thermoplastic so they are heat-sealed together
72
What is used for the cover of landfills?
LDPE
73
Why do they use LDPE as the cover in landfills?
Needs to be more flexible because waste is contracting due to degradation. There is subsidence
74
Where is bitumen used?
Coat roads in it and is the binder
75
What can be mixed into bitumen?
Aggregates
76
What is bitumen produced from?
Bitumen is produced from crude oil during fractional distillation
77
What are the features of bitumen?
Viscous liquid or solid consisting of polycyclic aromatic hydrocarbons
78
Bitumen is the ? oil fraction.
Heaviest
79
What is bitumens boiling point?
>370˚C
80
What does bitumen do when heated
Softens when heated and non-volatile
81
What are advantages of bitumens properties?
Bitumen has excellent waterproofing and adhesive properties
82
How much bitumen is produced annually in Europe?
16 million tonnes per year
83
How much carbon and hydrogen does bitumen contain?
82-88%
8-11%
84
How trace metals exist as in bitumen?
Trace metals present as inorganic salts
85
What does the exact composition of bitumen depend on?
Exact composition depends on the crude oil and the distillation process
86
What are the main chemical groups in bitumen?
Asphaltenes and Maltenes
87
How can Maltese's be subdivided?
Resins, aromatics, and saturates.
88
What is the optimum amount of filling in asphalt?
Bitumen fills the voids. Both the stone skeleton and bitumen contribute to the properties of the mix
89
What is the suboptimal filling in asphalt?
Too much or too little bitumen so either stone skeleton or properties dominate
