1.3 Polymers

Question 1

What is a thermoplastic?

Answer 1

Can be heated and shaped many times
Soften when heated and can be shaped when hot
Harden when cooled, but can be reshaped because there are no links between the polymer chains

Question 2

List the properties and uses of PET (Polyethylene Terephthalate)

Answer 2

Properties
- Excellent barrier against atmospheric gases
- Does not flavor the contents
- ‘Crystal clear’ appearance
- Very tough
- Lightweight – low density

Uses
- Fizzy drink bottles
- Food packaging
- Food trays

Question 3

List the properties and uses of HDPE (High-Density Polyethylene)

Answer 3

Properties
- High resistance to chemicals
- Good barrier to water
- Tough and hard-wearing
- Can be colored
- Lightweight – can float
- Rigid

Uses
- Unbreakable bottles
- Very thin packaging sheets

Question 4

List the properties and uses of PVC (Polyvinyl Chloride)

Answer 4

Properties
- Weather resistant
- Chemical resistant
- Gas impermeable
- Strong – abrasion resistant
- Rigid or flexible

Uses
- Packaging for toiletries,
food, drink and
confectionaries

Question 5

List the properties and uses of LDPE (Low-Density Polyethylene)

Answer 5

Properties
- Good resistance to chemicals
- Good barrier to water, but not chemicals
- Tough and hard wearing
- Can be coloured
- Very light – floats on water
- Very flexible

Uses
- Cling film
- Milk carton coating

Question 6

List the properties and uses of PP (Polypropylene)

Answer 6

Properties
- Lightweight
- Rigid
- Excellent chemical resistance
- Stiff or flexible
- Low moisture absorption
- Good impact resistance

Uses
- Food packaging
- Yoghurt pots
- Snack wrappers

Question 7

List the properties and uses of Acrylic

Answer 7

Properties
- Stiff, hard but scratches easily
- Durable
- Brittle in small sections
- Good electrical insulator
- Machines and polishes well.

Uses
- Signs
- Covers of storage boxes
- Aircraft canopies and windows
- Covers for car lights
- Wash basins and baths

Question 8

List the properties and uses of ABS (Acrylonitrile Butadiene Styrene)

Answer 8

Properties
- Impact resistance and toughness.
- Pigments can also be added, as the raw material original colour is translucent ivory to white
- Resistant to aqueous acids and alkalis
- Can be recycled, although it is not accepted by all recycling facilities
- Light weight
- Can be injection moulded and extruded

Uses
- Drain pipes
- Musical instruments
- Protective headgear
- Lego bricks
- Electrical socket

Question 9

What is a thermosetting plastic?

Answer 9

Can only be heated and shaped once
If re-heated they cannot soften as polymer chains are
interlinked
- Separate polymers are joined in order to form a huge polymer

Question 10

List the properties and uses of Epoxy Resins (ER)

Answer 10

Properties
- Good electrical insulator
- Hard but brittle unless reinforced
- Resists chemicals well

Uses
- Casting and
encapsulation
- Adhesives
- Printed circuit boards (PCB’s)
- Surface coatings

Question 11

List the properties and uses of Urea Formaldehyde

Answer 11

Properties
- Stiff, hard, strong but brittle
- Good electrical insulator

Uses
- Electrical fittings
- Handles and control knobs
- Adhesives

Question 12

List the properties and uses of Polyester Resin (PR)

Answer 12

Properties
- Stiff, hard but brittle unless laminated
- Good electrical insulator
- Resists chemicals well

Uses
- Casting and encapsulation
- Bonding of other materials
- Car bodies and boats