1. materials (plastics)

Question 1

What are plastics?

Answer 1

they are made of polymers and are mostly refined from oil

Question 2

What are most polymers?

Answer 2

synthetic (man-made by chemical engineers)

Question 3

What are the two categories of polymers?

Answer 3

• thermoset
• thermoplastic

Question 4

What are thermosetting polymers?

Answer 4

• A polymer, that once set, cannot be reheated or remoulded
• this is because they undergo a chemical change when they set

Question 5

What are thermoplastic polymers?

Answer 5

A polymer that can be heated and shaped multiple times

Question 6

What is a polymer?

Answer 6

a plastic

Question 7

What is plastic memory?

Answer 7

when a polymer is heated and they return to their original shape

Question 8

What are the characteristics of thermoplastic polymers?

Answer 8

• soft when heated, harden once cooled
• they can be recycled as they can be reheated many times
• plastic memory

Question 9

What are 3 examples of thermoplastics?

Answer 9

• acrylic
• polypropylene (PP)
• high impact polystyrene (HIPS)

Question 10

What are the properties of acrylic?

Answer 10

• hard wearing
• will not shatter
• can be coloured

Question 11

What are 3 examples of thermosetting plastics?

Answer 11

• urea formaldehyde
• melamine formaldehyde
• epoxy resin

Question 12

What are the uses for acrylic?

Answer 12

• bathtubs
• school projects
• display signs

Question 13

What are the properties of polypropylene?

Answer 13

• high impact strength
• softens at 150 degrees celcius
• can be flexed many times without breaking

Question 14

What are the uses of polypropylene?

Answer 14

• school chairs
• crates

Question 15

What are the properties of high impact polystyrene? (HIPS)

Answer 15

• light but strong
• widely available in sheets

Question 16

What are the uses of high impact polystyrene? (HIPS)

Answer 16

casings of electronic products

Question 17

What are the properties of polythene (LDPE)?

Answer 17

• weaker and softer than HPDE
• lightweight

Question 18

What are the uses for polythene (LDPE)?

Answer 18

• carrier bags
• squeezy bottles

Question 19

What are the properties of polythene (HDPE)?

Answer 19

• stiff, strong plastic
• used for pipes and bowls

Question 20

What are the uses for polythene (HDPE)?

Answer 20

buckets

Question 21

What are the properties of urea formaldehyde?

Answer 21

• colourless plastic
• can be coloured

Question 22

What are the uses of urea formaldehyde?

Answer 22

• door and cupboard handles
• electrical fittings

Question 23

What are the steps for injection moulding?

Answer 23

1. Clamping
2. Injection can begin after the two plates of the mould are clamped together
3. Dwelling - the melted plastic fills the entire mould
4. Cooling
5. Mold opening
6. Ejection

Question 24

What are the steps for blow moulding?

Answer 24

1. parison ready
2. Mould closes over parison
3. Parison inflated to fill mould. Extruder forming new parison
4. Bottle removed and trimmed

Question 25

What are the steps for vacuum forming?

Answer 25

1. Mould is made from MDF or expanded polystyrene 2. The mould is placed in the bottom of the vacuum former 3. The sheet of plastic is placed above the mould and clamped in place 4. The electric element (heater) is turned on and begins to warm the plastic sheet 5. The thermoplastic becomes flexible as it is heated. The mould is moved up to the plastic using the handle 6. The pump is turned on and the air is removed from under the plastic, sucking the plastic over the mould

Question 26

What are the types of manufacturing processes for plastics?

Answer 26

- Vacuum forming - Injection moulding - Blow moulding