Polymers Flashcards
1
Q
Define
polymer.
A
a substance that has a molecular structure built up from a large number of similar units (monomers) bonded together
2
Q
Define
monomer.
A
a molecule that can be bonded to other identical molecules to form a polymer
3
Q
Define
synthetic.
A
a manufactured substace that imitates a natural product
4
Q
What are two examples of
natural polymers?
A
rubber and cellulose
5
Q
What are the positives of
synthetic polymers?
(3)
A
- easy to process
- cost-effective
- available in a wide range of properties
6
Q
What are some general properties of
polymers?
(5)
A
- lightweight
- waterproof
- tough
- electrical and/or thermal insulator
- resistant to atmospheric degradation (don’t rust or rot)
7
Q
What are the uses of
PET?
(1) and what is its recycling code number?
A
bottles
e.g. for soft drinks, mineral water, fruit juice, cooking oil
1 - PET
8
Q
What are the uses of
HDPE?
(5) and what is its recycling code number?
A
- crates
- bottles
- pipes
- buckets
- bowls
2 - HDPE
9
Q
What are the uses of
PVC?
(4) and what is its recycling code number?
A
- pipes
- guttering
- roofing sheets
- window frames
3 - PVC
10
Q
What are the uses of
LDPE?
(3) and what is its recycling code number?
A
- squeezy bottles
- bin liners
- carrier bags
4 - LDPE
11
Q
What are the uses of
PolyPropylene?
(4) and what is its recycling code number?
A
- syringes
- crates
- rope
- containers with built in hinges
5 - PP
12
Q
What are the uses of
PolyStyrene?
(2) and what is its recycling code number?
A
- disposable plates
- food containers
6 - PS
13
Q
What are the uses of
Expanded PolyStyrene?
(2) and what is its recycling code number?
A
- sound and heat insulation
- protective packaging
6 - PS
14
Q
What are the uses of
nylon?
(3) and what is its recycling code number?
A
- clothing
- combs
- hinges
7 - other
15
Q
What are the uses of
acrylic?
(3) and what is its recycling code number?
A
- illuminated signs
- car rear-light clusters
- baths
7 - other
16
Q
What are the uses of
ThermoPlastic Elastomers?
(3) and what is its recycling code number?
A
- watch straps
- scuba diving masks
- remote control buttons
7 - other
17
Q
What are the uses of
ABS?
(4) and what is its recycling code number?
A
- safety helmets
- car parts
- food mixers
- toys
7 - other
18
Q
What are the properties of
PET?
(4) and what type of polymer is this?
A
- clear
- tough
- shatter-resistant
- good moisture and gas barrier properties
thermopolymer
19
Q
What are the properties of
HDPE?
(5) and what type of polymer is this?
A
- range of colours
- hard
- stiff
- good chemical resistance
- high impact
thermopolymer
20
Q
What are the properties of
PVC?
(6) and what type of polymer is this?
A
- stiff
- hard
- tough
- good chemical resistance
- good weather resistance
- good sunlight resistance
thermopolymer
21
Q
What are the properties of
LDPE?
(5) and what type of polymer is this?
A
- range of colours
- tough
- flexible
- good electrical insulator
- good chemical resistance
thermopolymer
22
Q
What are the properties of
PolyPropylene?
(7) and what type of polymer is this?
A
- hard
- lightweight
- good chemical resistance
- can be sterilised
- good impact
- easily welded together
- good work fatigue resistance
thermopolymer
23
Q
What are the properties of
PolyPropylene?
(6) and what type of polymer is this?
A
- stiff
- hard
- tough
- good chemical resistance
- good weather resistance
- good sunlight resistance
thermopolymer
24
Q
What are the properties of
PolyStyrene?
(6) and what type of polymer is this?
A
- range of colours
- stiff
- hard
- lightweight
- food safe
- good water resistance
thermopolymer
25
# What are the properties of
Expanded PolyStyrene?
| (4) and what type of polymer is this?
- lightweight
- absorbs shock
- good sound insulator
- good heat insulator
| thermopolymer
26
# What are the properties of
nylon?
| (6) and what type of polymer is this?
- hard
- tough
- resilient to wear
- self-lubricating
- good chemical resistance
- good resistance to high temperatures
| thermopolymer
27
# What are the properties of
acrylic?
| (9) and what type of polymer is this?
- stiff
- hard
- clear
- durable outdoors
- easily machined
- easily polished
- good range of colours
- excellent impact resistance
- scratches easily
| thermopolymer
28
# What are the properties of
TPE?
| (3) and what type of polymer is this?
- flexible
- tough
- will return to original shape after stretching and bending
| thermopolymer
29
# What are the properties of
ABS?
| (7) and what type of polymer is this?
- tough
- high impact strength
- lightweight
- scratch-resistant
- good chemical resistance
- excellent appearance
- excellent finish
| thermopolymer
30
# What are the uses of
urea-formaldehyde?
| (2) and what type of polymer is this?
- white electrical fittings
- wood glue
| thermosetting polymer
31
# What are the uses of
melamine-formaldehyde?
| (3) and what type of polymer is this?
- tableware
- decorative laminates for work surfaces
- electrical insulation
| thermosetting polymer
32
# What are the uses of
phenol-formaldehyde?
| (2) and what type of polymer is this?
- dark electrical fittings
- saucepan and kettle handles
| thermosetting polymer
33
# What are the uses of
epoxy resin?
| (1) and what type of polymer is this?
adhesives used to bond different materials
(such as wood, metal, porcelain)
| thermosetting polymer
34
# What are the uses of
polyester resin?
| (3) and what type of polymer is this?
- boats
- car shells
- car bodies
| thermosetting polymer
35
# What are the properties of
urea-formaldehyde?
| (6)
- stiff
- hard
- brittle
- heat resistant
- good electrical insulator
- range of colours
36
# What are the properties of
melamine-formaldehyde?
| (7)
- stiff
- hard
- strong
- range of colours
- scratch resistant
- stain resistant
- odourless
37
# What are the properties of
phenol-formaldehyde?
| (4)
- stiff
- hard
- strong
- heat resistant
38
# What are the properties of
epoxy resin?
| (4)
- good chemical resistance
- good wear resistance
- heat resistant (up to 250°C)
- electrical insulator
39
# What are the properties of
polyester resin?
| (4)
- tough when laminated
- hard
- strong
- brittle without reinforcement
40
# What are the uses of
silicone?
| (2) and what type of polymer is this?
- flexible baking trays
- bathroom sealant
| elastomer
41
# What are the uses of
neoprene?
| (2) and what type of polymer is this?
- wetsuits
- knee and elbow pads
| elastomer
42
# What are the uses of
butadiene rubber?
| (2) and what type of polymer is this?
- tyres
- golf ball cores
| elastomer
43
# What are the uses of
fluoroelastomer?
| (1) and what type of polymer is this?
apple watch sport straps
| elastomer
44
# What are the properties of
silicone?
| (2)
- excellent heat resistance
- excellent oil resistance
45
# What are the properties of
silicone?
| (2)
- excellent heat resistance
- excellent oil resistance
46
# What are the properties of
neoprene?
| (2)
- weather resistant
- flame retardant
47
# What are the properties of
butadiene rubber?
| (2)
- resistant to abrasion
- resistant to cracking
48
# What are the properties of
fluoroelastomer?
| (2)
- durable
- resistant to chemicals
49
# What are some
sources of natural polymers?
| (3)
- animals' horns and hooves
- resin from rubber trees
- resin from bugs
50
# Define
synthesised.
made by combining parts of
| e.g. combining different carbon compounds
51
They are made of chemicals which are synthesised from carbon compounds.
| These compounds are largely obtained from crude oil.
## Footnote
The crude oil is first fractionally distilled and then some of the products are processed further to produce a chemical.
52
# Define
catalysts.
chemicals that cause a reaction to happen
53
# Define
polymerisation.
the process of joining small molecules to form polymers
54
# Define
additives.
substances added to polymers to improve their mechanical properties
55
# What are some examples of
additives?
| (6)
- plasticisers
- pigments
- stabilisers
- fillers
- catalysts
- antioxidants
56
# What do
plasticisers do?
they improve the flow properties of polymers for moulding
57
# What do
stabilisers do?
they help prevent damage from UV light, which can cause several polymers to become brittle
58
# What do
fillers do?
they bulk up polymers and reduce costs
they can also improve strength by reducing brittleness and increasing resistance to impact
59
# What do
catalysts do?
| and what is an example of this?
they speed up the synthesis of polymers
| epoxy resin
60
# What do
antioxidants do?
prevent oxidation
61
# What are some
safety concerns surrounding polymers?
| (examples of accidents and effects of theses)
Producing plastics can be hazardous to workers. Serious accidents have included:
- explosion
- chemical fires
- chemical spills
- clouds of toxic vapour
## Footnote
These kinds of occurences have caused:
- deaths
- injuries
- evacuations
- major property damage
62
# What are the
health effects of plasticisers?
they are capable of causing cancer
63
# What are the
environmental effects of polymers waste products?
They end up in landfill. This damages marine ecosystems. For example:
- animals can ingest plastic matter
- animals can become entangled in plastic matter
- floating plastic items can transport microbes, algae and invertebrates into non-native regions
64
# What is the
average time taken for a simple PET bottleto degrade?
at least 450 years
65
# What are some
positives of recycling?
| (2)
- reduces the amount of energy and natural resources needed to create new plastic
- reduces the amount of material dumped in landfill
66
# Define
downcycling.
recycling into a lower-quality product
67
# What are some
negatives of recycling polymers?
| (2)
- uses a lot of energy
- waste polymer needs to be sorted, cleaned and chipped before being melted down into useable granules
68
# What is an example of a product that has
reduced the amount of polymer material being used?
the new Nestle Eco-Shape bottle uses 30% less plastic and a thinner label than the previous version
69
# What is the
waste hierarchy?
a set of principles for the efficient use of resources
70
# Define
biobased.
a product made from a renewable resource
71
# Define
biodegradable.
the ability of a substance or object to break down naturally in the environment through the action of micro-organisms
72
# What is
PLA?
| and what are some uses of this?
polylactic acid - a biobased polymer derived from cornstarch that breaks down into harmless chemicals when composted
| used to make disposable items such as cups, cutlery and food containers
73
# What are three examples of how
laws encourage manufacturers and consumers to consider the environment?
| (when buying or disposing of products)
- electrical items have a label with their energy rating
- consumers are encouraged to take their old devices to collection points, from which manufacturers arrange collection
- new vehicles do not use toxic materials and have all polymer parts labelled to help with recycling
74
# Define
stock form.
commonly available forms of polymer that can be bought
75
# What are some examples of
stock forms of polymer?
| (8)
- sheets
- granules
- rods
- extruded sections
- tubes
- foamed plastics
- powdered
- reels
76
# Define
standardised component.
an individual part or component, manufactured in thousands or millions, to the same specificatino
77
# What are some
standardised components that are commonly manufactured from polymers?
| (5 examples with brief detail)
- **nuts and bolts** - usually made from nylon
- **washers** - used to secure fittings
- **wall plugs** - used to provide anchors for screws in walls
- **end caps** - used to hide the heads of screws or to close pipes/tubing
- **plastic gear wheels** - used in various toys and mechanical devices
78
# Define
wastage.
cutting away material to leave a desired shape
79
# What are some different ways of
marking out a polymer?
| (so that the design can be cut) (2.5)
## Footnote
and what are the advantages and drawbacks of these?
- a **chinagraph pencil** - can be wiped of easily but line can sometimes be too thick to follow effectively
- a **non-permanent marker** - lines can be smudged easily
## Footnote
a **permanent marker** can be used on quick early models where progress is more important than a high-quality finish
80
# What are some different items used to
cut a polymer?
| (4)
- **scissors** can be used on thin foam sheetd and 0.5mm HIPS
- **craft knives** can be used to cut thicker sheets of HIPS
- **coping saws** can be used to to cut curves in thin plastic sheet
- a **laser cutter** can be used to cut any 2D shape out of acrylic sheet
81
# Define
CNC.
a computer-controlled machine used in industry
82
# What are some ways of
joining polymers together?
| (2)
- adhesion
- heat welding
83
# Define
welding.
a fusion of metals caused by intense heat
84
# Define
line bending.
bending a polymer sheet after softening a narrow strip
85
# How does
line bending work?
| (3) and what is this used for?
1. The sheet material is heated along a line using a strip heater.
2. Once the material has softened the heater can be removed and the sheet bent to the desired angle using a former or bending jig.
3. It must then be held in place until the polymer has cooled and become hard again.
| it used to create simple bends in polymers sheet
86
# How does
drape forming work?
| (3) and what is this used for?
1. The polymer sheet is heatd in an oven (to ensure that the whole piece is heated evenly).
2. Once softened, it is draped over a former and a piece of cloth is pulled tightly across it to hold it in shape until the polymer has cooled.
| it used when a large curve or bend is required
87
# Define
press moulding.
forming a hollow shape from a softened polymer sheet
88
# How does
press moulding work?
| (4) and what is this used for?
1. The polymer sheet is heated in an oven (to ensure it is heated evenly).
2. It is then positioned over the plug and and pushed down over it using the yoke.
3. These are then clamped together until the material has cooled.
4. Once the piece has cooled you can remove the excess plastic
| it used to produce more complex shapes
## Footnote
it is important that the plug has angled sides and rounded edges so that the finished piece can be easiy removed from it
89
# Define
vacuum forming.
producing thin hollow items over a shaped model
90
# How does
vacuum forming work?
| (4) and what is this used for?
1. A sheet of suitable polymers (usually HIPS) is fixed across the top of the machine by clamping. This must form an airtight seal.
2. The plastic sheet is heated evenly until soft.
3. The heater is moved out of the way, the mould is raised and the air between the mould and the plastic sheet is evacuated by an air pump.
4. The air pressure on the outside of the sheet then presses the plastic into close contact with the mould
## Footnote
it used in the packaging industry where it is used to form clear plastic into shaped that allow a product to be viewed
the shape of the mould must be carefully designed to allow the plastic sheet to be easily removed and moul reused
the sides must be slightly tapered to produce a draft angle and corners should be radiused
91
# Define
92
# What are the characteristics of
thermosetting polymers?
hard but brittle
## Footnote
this can be made stronger and tougher by using other materials to reinforce it
93
# What is
GRP?
glass-reinforced plastic - the reinforcement of polyester resin using strands of glass fibre
94
# What are the properties of
glass-reinforced plastic?
| (5)
- high tensile strength
- high compressive strength
- light
- hard-wearing surface
- excellent corrosion resistance
95
# Define
reinforce.
to strengthen or support an object or substance with additional material
96
# Define
UV degradation.
the weakening of polymers when exposed to the UV light in sunlight
97
# Define
stabiliser.
an additive added to polymers to help them withstand UV degradation
98
# Why are
sheet materials excellent for developing initial ideas?
- quick to work
- easy to work
- not too expensive
99
# Define
iterative modelling.
repeated modelling to develop an idea
100
# Define
dichloromethane.
a solvent used to join polymer pieces together
101
# What are some materials for
making iterative models?
- acrylic sheets
- styrene sheets
- foam sheets
- sticky-bakced vinyl
- foam board
- polystyrene foam
102
# Define
block models.
an informal model that captures the form of an idea
| this tends to have no moving parts
103
# Why are
polymers so good for iterative modelling?
they can be manipulated quickly and easily and can be used for a wide variety of iterative modelling
104
# Define
self-finishing.
a material that requires no further coatings or finishin processes
105
# Define
co-injection moulding.
an injection-moulding process that uses two different polymers
106
# Define
gate.
the entry point for molten plastic to flow into a mould
107
# Define
flash.
excess material formed between the joint of a mould
108
# What are some examples of
finishing processes for polymers?
| (4)
- degating
- deflashing
- cleaning
- decorating
109
# What is
degating?
the process of removing the excess material from injection moulding
110
# What is
deflashing?
the removal of excess material from moulding
| this is often using a knife or other cutting utensil
111
# What is
cleaning?
spraying or dipping parts in a mild detergent solution then rinsing and drying
| this is in order to remove residue, grease and dirt from the machine
112
# What are some examples of
decorating a polymer?
- plating
- vacuum metalising
- printing
- painting
113
# Define
rapid prototyping.
the process of making a 3D shape from a digital file
114
# Define
CAM
computer-aided manufacture
115
# What are some examples of
CAM?
| (4)
- stereo lithography
- laser sintering
- fused deposition modelling
- 3D printing
116
# What are the steps of
stereo lithography?
| (intro + 4 steps)
The component is built up in layers on the platform. The liquid is a photopolymer.
1. When the liquid is exposed to UV light from the laser beam, it cures or solidifies.
2. The platform moves downwards, and the sweeper passes over the newly formed layer, breaking the surface tension and ensuring that a flat surface is produced for the next layer.
3. Subsequent layers are laid down, and bind together.
4. The part is then removed from the vat.
117
# What are the steps of
laser sintering?
The material is a polymer filament.
The polymer is passed through a heating element, melted and extruded.
## Footnote
Each slice of the model is drawn from a continuous length of the molten filament.
118
# What are the steps of
3D printing?
| (2)
1. A thin layer of material (typically plaster-or-starch-based) is gradually glued together by a print head that can also colour the material using regular printer ink.
2. The final product is removed from the powder, cleaned and the outer surface strengthened by dipping in Superglue.
119
# Define
CAD.
computer-aided design
120
# Define
CAE.
computer-aided engineering
121
# Define
FEA.
finite element analysis
122
# What are some uses of
CAD?
| (3)
- create and explore ideas
- quickly visualise ideas
- create fully realised products
123
# What are some
benefits of CAD?
| (4)
- quickly make alterations to components
- incorporate commonly used components from a built-in online library
- collaborate on designs with other professionals from aroun the world
- render product designs in a variety of different colours and materials
124
# What is an example of a use for
FEA?
testing a model product in a virtual environment for weaknesses
125
# What are important considerations when deciding the
scale of production?
- form
- budget
- time
- material
126
# Define
one-off production.
| and state what this is used for.
making only one or a small number of products
| this is usually used for epcialist products
127
# Define
fabricating.
making parts by gluing, turning, carving or welding
128
# What is
CNC machining?
an example of subtractive manufacturing, which means that the material is cut away from a block
## Footnote
the shape of the parts possible is limited as internal structures are difficult to create
129
# Define
batch production.
making a set number of identical products
130
# Give a brief overview of
vacuum forming.
| (4 key points)
- sheets of plastic are warmed and sucked onto a mould
- there is no need for pressure or high temperatures
- mould can be made from cheap amterials
- the shape is quite limited
131
# Give a brief overview of
casting.
| (3 key points)
- liquid plastic in the form of a resin is poured into a mould and then solidifies
- moulds are cheap but cannot be reused a number of times
- parts tend to be quite smalle but can be solid/thick
132
# What are the steps of
rotational moulding?
| (3) and what is this used to make?
1. A mould containing plastic paste or powder is heated
2. As the plastic melts and the mould rotates, the plastic coats the surface of the mould cavity with an even layer of plastic.
3. The mould is then cooled before opening.
| it is used to make barrels, tanks, large hollow toys
133
# Define
mass/high volume production.
producing very large numbers of products
134
# Tell me about
compression moulding.
| (2 key points)
## Footnote
and give some typical objects made in this way. (4)
- often used for shaping thermosetting plastics
- the plastic is heated and compressed into shape
## Footnote
typical objects include:
- children's tableware
- electric plugs
- sockets
- light switches
135
# Tell me about
injection moulding.
## Footnote
and give some typical objects made in this way. (7)
molten plastic is injected into a mould via an injection screw or ram, cooled and the object is then ejected
## Footnote
typical objects include:
- model kits
- bottle crates
- buckets
- car bumpers
- phone cases
- plastic chairs
- washing-up bowls
136
# Tell me about
extrusion blow moulding.
## Footnote
and give some typical objects made in this way. (2)
a short tube of melted plastic is extruded and trapped in a mould, then air is blow in so that the plastic take the shape of the mould cavity
## Footnote
typical objects include:
- bottles
- drums
137
# Tell me about
thermoforming.
| (2 key points)
## Footnote
and give some typical objects made in this way. (6)
- a process used for vacuum forming for mass production
- an extruded sheet of plastic is heated and then shaped by pressure and/or vacuum
## Footnote
typical objects include:
- chocolate box trays
- packaging trays
- vending cups
- groups of yoghurt pots
- baths
- acrylic sinks
138
# Tell me about
extrusion.
## Footnote
and give some typical objects made in this way. (8)
molten plastic is pushed continuously through a shaped hole (die) before being cooled
## Footnote
typical objects include:
- drain pipes
- garden hose
- guttering
- rods
- rulers
- sheets
- tubes and pipes
- window frames
139
# Tell me about
calendering.
## Footnote
and give some typical objects made in this way. (1)
suitable thermoplastic compositions are passed through heated metal rollers with progressively smalle gaps to produce continuous film and precision thin sheet
## Footnote
typical objects include:
- foil
140
# Tell me about
blown film extrusion.
## Footnote
and give some typical objects made in this way. (2)
it is the process whereby extruded plastic is expanded into a sheath and then wound on to reels
## Footnote
typical objects include:
- packaging films
- 'plastic' bags
141
# Define
viability.
the ability to work successflly
142
# Define
stakeholder.
a person with an interest in the success of a product
143
# Define
tolerance.
an allowable amount of variation of a specified quantity
| especialy in three dimensions of a part
144
# Define
lean manufacturing?
a systematic method for the elimination of waste within a manufacturing system
145
# What are some ways to
reduce the mount of waste in design?
- **designing parts correctly** - this will avoid quality issues further down the line that would take more time to correct
- **minimising material** - e.g. judging the correct wall thickness
- **reducing the cycle time** - investing time in advanced mould design that is able to cool and eject parts faster
- **reusing waste material** - excess material from processing can be fed back into the moulding machines
