Polymers

Question 1

what are thermoplastics and what properties do they have?

Answer 1

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

Question 2

what is the thermoplastic cycle? [4]

Answer 2

heated
softened and moulded
cools
hardens

Question 3

what is LDPE and its triangle number?

Answer 3

Low density polyethylene [4]

Question 4

what are LDPE properties and uses?

Answer 4

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

Question 5

what is HDPE and its triangle number?

Answer 5

High density Polyethylene [2]

Question 6

what are HDPE properties and uses?

Answer 6

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

Question 7

what is PP and its triangle symbol?

Answer 7

Polypropylene [5]

Question 8

what are PP properties and uses?

Answer 8

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

Question 9

what is plastic fatigue resistance?

Answer 9

resistance to deformation after dynamic stress

-stops cracks appearing after constant use

Question 10

what is HIPS and its triangle symbol?

Answer 10

High impact polystyrene [6-PS]

Question 11

what are HIPS properties and uses?

Answer 11

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

Question 12

what is ABS and its triangle number?

Answer 12

Acrylonitrile Butadiene styrene [7-other]

Question 13

what are ABS properties and uses?

Answer 13

• 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

Question 14

what is PMMA and its triangle number?

Answer 14

Polymethyl methacrylate or Acrylic [7]

Question 15

what are PMMA properties and uses?

Answer 15

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

Question 16

what is nylon and its triangle number?

Answer 16

thermoplastic polymer [7]

Question 17

what are Nylons properties and uses?

Answer 17

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

Question 18

how is PVC made to be flexible?

Answer 18

plasticisers are added to decrease its viscosity

Question 19

what are flexible PVC properties and uses?

Answer 19

• water resistant
• chemical resistant
• hose pipes, electrical insulation, clothing

Question 20

what is rigid PVC and its triangle number?

Answer 20

polyvinyl chloride [3-v or 3- pvc]

Question 21

what are rigid PVC properties and uses?

Answer 21

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

Question 22

what is PET and its triangle number?

Answer 22

Polyethylene terephthalate [1]

Question 23

what are PET properties and uses?

Answer 23

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

Question 24

How do thermosets differ to thermoplastics?

Answer 24

more brittle and suited for stiffer mouldings

Question 25

how do you thermoset plastics?

Answer 25

- condensation polymerisation [1 water molecule produced]

Question 26

what is the structure of thermosets?

Answer 26

- long chain molecules - rigid molecular structure when cured - endothermic reaction

Question 27

what is the thermoset cycle? [5]

Answer 27

``` heated softened + moulded baked hardens [burns if heated] ```

Question 28

what are the properties of thermosets?

Answer 28

- hard - waterproof when solid - difficult to mould - can't be reheated or reshaped - retain shape well at high temperatures - used as adhesives

Question 29

what is UF and its properties?

Answer 29

Urea Formaldehyde - hard - opaque - organic compound - good resistance to deformation by heat - high tensile strength

Question 30

UF uses?

Answer 30

- adhesives - electrical casings - sockets and switches

Question 31

what is MF and its properties?

Answer 31

Melamine Formaldehyde - hard - scratch resistant - opaque - heat and chemical resistant

Question 32

Melamine Formaldehyde uses?

Answer 32

- surface coatings - decorative laminates - toilet seats - kitchen utensils

Question 33

what is Polyester resin and its properties?

Answer 33

- most common resin in marine industry - water resistant - heat resistant - chemical resistant - needs to be mixed with catalyst to cure

Question 34

Polyester resin uses?

Answer 34

- used in glass reinforced plastic - boat hulls - bath tubs - chair seats

Question 35

what is epoxy resin and its properties?

Answer 35

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

Question 36

Epoxy resin uses?

Answer 36

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