Polymers Flashcards

1
Q

what are thermoplastics and what properties do they have?

A
  • most commonly used plastic
  • long chain molecules with no fixed structure or pattern
  • soft
  • flexible
  • some shape memory
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2
Q

what is the thermoplastic cycle? [4]

A

heated
softened and moulded
cools
hardens

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3
Q

what is LDPE and its triangle number?

A

Low density polyethylene [4]

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4
Q

what are LDPE properties and uses?

A
  • flexible
  • tough
  • translucent or opaque
  • chemical resistant
  • carrier bags, squeezy bottles, toys
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5
Q

what is HDPE and its triangle number?

A

High density Polyethylene [2]

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6
Q

what are HDPE properties and uses?

A
  • tough
  • high strength to weight ratio
  • chemical resistant
  • bleach bottles, buckets, bins
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7
Q

what is PP and its triangle symbol?

A

Polypropylene [5]

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8
Q

what are PP properties and uses?

A
  • tough
  • flexible
  • fatigue resistant
  • chemical and solvent resistant
  • clear or transparent
  • boat rope, Tupperware, medical equipment
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9
Q

what is plastic fatigue resistance?

A

resistance to deformation after dynamic stress

-stops cracks appearing after constant use

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10
Q

what is HIPS and its triangle symbol?

A

High impact polystyrene [6-PS]

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11
Q

what are HIPS properties and uses?

A
  • rigid
  • lightweight
  • high impact strength
  • retains heat without deforming
  • glossy
  • food safe
  • plastic cutlery, yoghurt pots salad bowls
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12
Q

what is ABS and its triangle number?

A

Acrylonitrile Butadiene styrene [7-other]

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13
Q

what are ABS properties and uses?

A
  • hard and tough
  • good impact strength
  • resistant to oils, acids, alkalis and grease
  • easily moulded
  • high quality surface finish
  • used for appliance casings, safety helmets and car bumpers
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14
Q

what is PMMA and its triangle number?

A

Polymethyl methacrylate or Acrylic [7]

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15
Q

what are PMMA properties and uses?

A
  • tough
  • lightweight
  • shatter resistant
  • clear or opaque
  • poor chemical resistance
  • baths, glasses, shower trays
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16
Q

what is nylon and its triangle number?

A

thermoplastic polymer [7]

17
Q

what are Nylons properties and uses?

A
  • abrasion resistant
  • heat resistant
  • durable
  • low coefficient of friction
  • used for seat belts, rope, parachutes, carpets
18
Q

how is PVC made to be flexible?

A

plasticisers are added to decrease its viscosity

19
Q

what are flexible PVC properties and uses?

A
  • water resistant
  • chemical resistant
  • hose pipes, electrical insulation, clothing
20
Q

what is rigid PVC and its triangle number?

A

polyvinyl chloride [3-v or 3- pvc]

21
Q

what are rigid PVC properties and uses?

A
  • tough
  • hard
  • fire retardant
  • good chemical and weather resistant
  • gutters, pipes, window frames
22
Q

what is PET and its triangle number?

A

Polyethylene terephthalate [1]

23
Q

what are PET properties and uses?

A
  • strong
  • rigid
  • chemical resistant
  • water resistant
  • drink packaging [juice and water]
24
Q

How do thermosets differ to thermoplastics?

A

more brittle and suited for stiffer mouldings

25
Q

how do you thermoset plastics?

A
  • condensation polymerisation [1 water molecule produced]
26
Q

what is the structure of thermosets?

A
  • long chain molecules
  • rigid molecular structure when cured
  • endothermic reaction
27
Q

what is the thermoset cycle? [5]

A
heated 
softened + moulded
baked
hardens 
[burns if heated]
28
Q

what are the properties of thermosets?

A
  • hard
  • waterproof when solid
  • difficult to mould
  • can’t be reheated or reshaped
  • retain shape well at high temperatures
  • used as adhesives
29
Q

what is UF and its properties?

A

Urea Formaldehyde

  • hard
  • opaque
  • organic compound
  • good resistance to deformation by heat
  • high tensile strength
30
Q

UF uses?

A
  • adhesives
  • electrical casings
  • sockets and switches
31
Q

what is MF and its properties?

A

Melamine Formaldehyde

  • hard
  • scratch resistant
  • opaque
  • heat and chemical resistant
32
Q

Melamine Formaldehyde uses?

A
  • surface coatings
  • decorative laminates
  • toilet seats
  • kitchen utensils
33
Q

what is Polyester resin and its properties?

A
  • most common resin in marine industry
  • water resistant
  • heat resistant
  • chemical resistant
  • needs to be mixed with catalyst to cure
34
Q

Polyester resin uses?

A
  • used in glass reinforced plastic
  • boat hulls
  • bath tubs
  • chair seats
35
Q

what is epoxy resin and its properties?

A
  • clear resin that needs to be mixed with a catalyst to cure
  • hard
  • tough
  • maintains structure at high temperatures
  • good chemical resistance
36
Q

Epoxy resin uses?

A
  • adhesive for disimilar materials
  • surface coatings
  • encapsulating electrical components [LEDs]