Polymers

Question 1

Where do most plastics come from?

Answer 1

They are mostly made from crude oil. After refining, chemical reactions produce a large number of identical molecules called monomers which are then combined together to form long strands called polymers. All plastics are a form of polymers.

Question 2

What are thermoforming polymers?

Answer 2

Thermoforming polymers are plastics that can be re-heated and therefore shaped in various ways. They become mouldable after reheating as they di not undergo any significant chemical change. These types of plastics can be recycled.

Question 3

List the pros and cons of thermoforming polymers

Answer 3

Pros:
- Highly recycable
- Asthetically superior
- Remoulding/reshaping capabilities
- Chemical resistant
- Eco friendly manufacturing

Cons:
- Generally more expensive than thermoset
- can melt if heated

Question 4

Name some thermoforming polymers

Answer 4

• High impast polystyrene (HIPS)
• High density Polythene (HDPE)
• Polethylene Terephate (PET)
• Acrylic (PMMA)
• Polypropylene (PP)
• Polyvinyl Chloride (PVC)

Question 5

What is a Thermosetting Polymer?

Answer 5

Plactics that once ‘set’ these plastics cannot be reheated to soften, shape and mould. This is because of losse polymer chains.

Question 6

Name some thermosetting polymers

Answer 6

• Urea Formaldehyde (UF)
• Poltester resin
• Epoxy Resin
• Melamine Formaldehyde (MF)
• Phenol Formaldehyde (PF)

Question 7

What do polymer additives do?

Answer 7

They further enhance the properties of polymers through the introduction of additives.

Question 8

Name some polymer additives and what they do

Answer 8

• Plasticisers: soft and flexible (often PVC)
• Pigments: changes colour
• Stabilisers: withstand UV light damage (outdoor products)
• Fillers: increase the bulk, improve its impact resistance.

Question 9

What are Bioplastics

Answer 9

Plastics can be also made from plant oils in other words from renewable materials but they are still quite rare.

Question 10

Properties of High impact Polystyrene and Uses

Answer 10

• Hig impact strength/impact resistant
• good machinability
• easy to glue, paint and print
• flexible
• lightweight
• can be food safe
• outstanding thermoforming characteristics

Uses:
-yoghurt pots, vacuume formed products

Question 11

Properties and uses of high-density polythene

Answer 11

Properties:
- lightweight, rip and chemical rsistant, weatherproof, low cost, good low temp toughness

Uses:
- milk bottles, pipes, crates, wheelie bins

Question 12

Properties and uses of polythene terephate (PET)

Answer 12

Properties:
- blow moulded, chemically resistant and fully recycable
Uses:
- drink bottles, food containers, yarn

Question 13

Properties and uses of acrylic (PMMA)

Answer 13

Properties:
- tough but brittle when thin
- easily scratched, formed and bonded
- wuperior weather properties

Uses:
- car lights
- alternate to glass
- modern baths
- clothing
- acrylic nails
- paint

Question 14

Properties and uses of Polypropeline (PP)

Answer 14

Properties:
- flexible
- tough
- lightweigh
- food safe
- good ftigue resistance

Uses:
- kitchen
- medical products
- rope
- food packaging etc

Question 15

Properties and uses for polyvinyl chloride (PVC)

Answer 15

Properties:
- flexible
- easily extruded
- tough
- resistant to chemicals

Uses:
- raincoats
- pipes
- electrical tape
- blood storage bags

Question 16

Properties and uses of polyester resin (PR)

Answer 16

Properties:
- good electrical insulator
- hard
- becomes tough when mixed with glass strands to form glass reinforced plastic (GRP)
- water and many chemical resistant

Uses:
- encapsulation
- boat hulls as GRP

Question 17

Properties and uses of Urea formaldehyde (UF)

Answer 17

Properties:
- high tensile strength
- heat resistant
- good electrical insulator
- hard
- brittle
- easily injection moulded

Uses:
- adhesives for bonding particle boards
- decorative laminates
- electrical casings

Question 18

Properties and uses of phenol formaldehyde (PF)

Answer 18

Properties:
- Heat resistant and a good electrical insulator

Uses:
- heat resistant handles
- electrical components
- snooker balls

Question 19

Properties and uses of melamine formaldehyde (MF)

Answer 19

Properties:
- lightweight
- hard but not brittle

Uses:
- worktops
- surfaces
- some kitchenware

Question 20

Explain why thermosetting polymers are more difficult to recycle than thermoforming polymers?

Answer 20

The molecular structure of thermosets is more rigid, making them difficult to reform once set. When thermosets are reheated they often tend to burn rather than melt.

Question 21

Properties and uses of epoxy resin (ER)

Answer 21

Properties:
- good strength to weight ratio
- good electrical insulator
- heat resistant

Uses:
- bonding waterproof coatings
- electronic curcuit boards
- adhesive purposes

Question 22

What are Stock Forms

Answer 22

Stock forms are the standard shapes and sizes in which a material is available. You buy polymers and textiles in stock forms.

Question 23

Name some polymer additives and what they do

Answer 23

Polymer additives enhance different properties of polymers:
- Plasticisers - soft and flexible (often PVC)
- Pigments - changes colour
- stabilisers - withstand UV light damage
- fillers - increases the bulk, improves impact resistancex

Question 24

Give the number used to identify different thermoforming plastics

Answer 24

Polyethylene terephthalate: 1
High density polythene: 2
Polyvinyl chloride: 3
Low density polythene: 4
Polypropylene: 5
Polyestyrene: 6
Other: 7