polymers and smart materials

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what is a thermoplastic?
a material that can be repeatedly reheated and reshaped allowing it to be recycled after its initial use
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what is the structure of a thermoplastic?
thermoplastics have long linear chain molecules held together by van der walls forces
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what is a thermosetting polymer?
a material which once heated undergoes a chemical change where molecules form rigid cross links. these plastics cannot be reshaped even at a very high temperature
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what is an elastomer?
a material that at room temperature can be deformed under pressure and once released it will return to its original shape
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what is the structure of an elastomer?
elastomers have weak bonds which allow them to stretch easily
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name some thermoplastics
Low / high density polyethylene (LDPE)/ (HDPE), polypropylene (PP), high impact polystyrene (HIPS), polyethylene terephthalate (PET), polyvinyl chloride (PVC)
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name some thermosetting polymers
urea formaldehyde (UF), melamine formaldehyde (MF), polyester resin, epoxy resin
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name some elastomers
natural rubber, neoprene silicone
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give an example of a polymer and why it is suitable for a certain product
e.g. PET is suitable for a drinks bottle because.... its is a thermo plastic so it can be recycled, this is important for a single use product: it is tough so if the user dropps the bottle it will not crack/ split so the contents will not be released
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describe the process of vacuum forming
see page 48 of the textbook
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describe the process of thermoforming
see page 48-49 of the textbook
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describe the process of calendering
see page 49 of the textbook
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describe the process of line bending
see page 49 of the textbook
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describe the process of injection moulding
see page 50 of the textbook
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describe the process of blow moulding
see page 51 of the textbook
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describe the process of rotational moulding
see page 51-52 of the textbook
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describe the process of extrusion
see page 52-53 of the textbook
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describe the process of compression moulding
see page 53 of the textbook
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what is the international symbol for PET
01
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what is the international symbol for HDPE
02
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what is the international symbol for PVC
03
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what is the international symbol for LDPE
04
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what is the international symbol for PP
05
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what is the international symbol for PS
06
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what is the international symbol for all other plastics
07
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what is the international symbol for ABS
ABS
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what are some positives of blow moulding
once set up it produces hollow objects rapidly, can produce a variety of bottle shapes
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what are some negatives of blow moulding
moulds expensive so setup costs are high, difficult to produce triangular bottles, bottle shape must allow extraction from mould
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what are some positives of rotational moulding
can produce one piece mouldings, produces rigid tough shapes, large range of sizes, can apply surface textures/ stickers to the mould so they become part of the product, no high pressure so production is cheaper
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what are some negatives of rotational moulding
can only produce hollow shapes
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what are some positives of injection moulding
good for complex 3D shapes, good consistent quality, can insert metal into mould
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what are some negatives of injection moulding
moulds are expensive so setup costs are high
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what are some positives of extrusion
lower cost process because it is a simple die
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what are some negatives of extrusion
can only produce a continuous cross sectional shape
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what are some negatives of compression moulding
the slug must be manufactured, cant be used to create complex shapes
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what are some positives of compression moulding
moulds are less expensive than those in injection moulding, little waste material
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what is a smart material?
a material whos physical properties change in-response to an input from the environment
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what is sma?
shape memory alloy, eg nitinol
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give an example of where a phosphorescent pigment may be used
emergency exit sign
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give an example of where a thermochromic pigment may be used
thermomiters
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what is a ph-sensative polymer
pH-sensitive polymers are materials that change in volume when the pH of the surrounding medium changes
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give examples of some smart materials and what they are used for
e.g. Electroluminescent materials give out light when an electric current is applied to them. Among many possible applications are safety signs and clothing for use at night.
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Other cards in this set

Card 2

Front

what is the structure of a thermoplastic?

Back

thermoplastics have long linear chain molecules held together by van der walls forces

Card 3

Front

what is a thermosetting polymer?

Back

Preview of the front of card 3

Card 4

Front

what is an elastomer?

Back

Preview of the front of card 4

Card 5

Front

what is the structure of an elastomer?

Back

Preview of the front of card 5
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