plastics and polymers Flashcards

1
Q

list 4 polymers

A

nylon, polyethylene, polyester, Teflon

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2
Q

what are mechanical properties

A

mechanical properties are the characteristics a material displays when subject to an external force

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3
Q

list 4 mechanical properties

A

toughness
flexibility
elasticity
mouldability

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4
Q

what is toughness

A

a polymers ability to absorb energy and deform plastically without cracking by dissipating it.
e.g bike helmets

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5
Q

what is elasticity

A

is a materials resistance to distortion and the ability to return to its original shape
e.g balloons

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6
Q

what is flexibility and folding

A

the ability of a material to be bent or folded without breaking whilst stiffness is a measure of how rigid the material is.

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7
Q

mouldability

A

a polymers ability to be shaped into a form or mould will dictate the type of product it is used for.

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8
Q

what two examples of moulding plastics

A

thermoplastics and thermosets

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9
Q

what is the difference between thermoplastics and thermosets

A

thermoplastics are usually moulded in a hot or molten state under mechanical pressure.

thermosets are usually moulded in could liquid form and cured using a catalyst.

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10
Q

what are 7 physical properties

A

Insulation
Self finishing
UV resistant
Melting points
Transparency and translucency
Resistance to chemicals and liquids
Ability to be combined with other polymers and additives

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11
Q

what is the purpose of additives

A

additives are sometimes used to make polymers easier and more efficient to process

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12
Q

what are class the two types of polymers

A

thermosets and thermoplastics

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13
Q

what are synthetic polymers

A

synthetic polymers are produced from finite recourses such as coal, gas and oil

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14
Q

what are natural polymers

A

natural polymers come from a variety of sources such as rubber and amber, which both come from trees

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15
Q

what is the process of getting synthetic polymers

A

fractional distillation (different polymers are from different fuels)

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16
Q

what is polymerisation (4 marks)

A

-molecules of single compounds known as monomers join together
-these atoms join end to end to form long chains
- the long chains of molecules are called polymers

16
Q

why cant we use large hydrocarbon molecules for polymers

A

large molecules do not flow very well and aren’t suitable to be made into plastics

16
Q

what happens in cracking with polymers

A

breaks down large polymers down into smaller more useful ones

17
Q

describe the structure of thermoplastics

A

-have long chains of molecules, tangled together with no fixed structure of pattern
-generally soft and flexible with some shape memory

18
Q

what is LDPE

A

low density polyethylene, quite flexible but also tough and is chemical resistant
e.g squeezy bottles or snap lids

19
Q

what is HDPE

A

high density polyethene, is tough and has higher strength to weight ratio than LDPE and ahs good chemical resistance
e.g rigid plastic toys or buckets

20
Q

what is PP

A

polypropylene is a tough, flexible polymer with excellent fatigue resistance and resistant to chemicals and solvents
e.g medical equipment or moulded furniture

21
Q

what is HIPS

A

high impact polystyrene is a rigid lightweight polymer with high impact strength and ability to retain heat
e.g yoghurt pots or plastic cutlery

22
Q

what is ABS

A

acrylonitrile butadiene styrene is a hard and tough with excellent impact strength and chemical resistance
e.g builders helmets or car bumpers

23
what is PMMA
polymethyl methacrylate is a lightweight tough material relatively poor chemical resistance compared to other polymers e.g baths or lenses in glasses
24
what is nylon
nylon is the first commercially successful thermoplastic polymer it is durable and resistant to abrasion e.g tents or seat belts
25
what is rigid PVC
polyvinyl chloride is one of the most widely used polymers and can be both rigid and flexible it has good chemical and weather resistance e.g plumbing or external doors
26
what is flexible PVC
plasticisers are added to PVC to increase flexibility it is water and chemical resistant e.g inflatable products or alternative leather
27
describe thermosets
thermosets are more brittle than thermoplastics and are best suited to stiffer mouldings , cant be reheated or reshaped
28
what are stock forms
the standard shapes and sizes in which a material is available
29
list 6 stock forms
- sheet - film - granules - rod and other extruded forms - foam - powder
30
what are elastomers
elastomers are polymers that are highly elastics and capable of recovering their original shape after being stretched most elastomers are thermosets
31
name some examples of elastomers
thermoplastic elastomers stretching elastomer grip based elastomers texture based elastomers
32
what is vulcanisation
vulcanisation is a process used to cure rubber making it harder, more durable and heat resistant
33