Plastics

Question 1

What are plastics?

Answer 1

• A group of materials made up of long chains of molecules.
• Many of them are known as hydrocarbons because the long-chain molecules consist of hydrogen and carbon atoms in various combinations with other atoms.
• Some plastics have been created from natural sources.

Question 2

What is the correct name for plastic materials?

Answer 2

Polymers

Question 3

Why are plastics so popular?

Answer 3

They have several advantages over many more traditional materials:

• lightweight
• self-coloured
• electrical insulator
• thermal insulator
• ability to be formed into complex shapes
• good strength to weight ratio
• good atmospheric and chemical corrosion resistance

Question 4

What are the main sources of raw materials used in manufacturing plastics?

Answer 4

• Animal and vegetable by-products are used in semi-synthetic polymers eg. cellulose (from plant fibres) is mixed with acetic acid to produce cellulose acetate.
• Coal, oil and gas, through a process called thermal cracking, are the source for synthetic plastics. This accounts for the majority of modern plastics.

Question 5

What are the three groups of plastics and their main properties?

Answer 5

• Thermoplastics - These materials can be repeatedly reheated and remoulded.
• Thermosets - These undergo a chemical change resulting in them becoming permanently rigid. They cannot be reheated and reshaped.
• Elastomers - Polymers that have good elasticity. They can be distorted under pressure but will return to their original shape when the pressure is removed.

Question 6

Draw the structure of a Thermoplastic.

Answer 6

Thermoplastic

Question 7

Draw the structure of a Thermosetting plastic.

Answer 7

Thermosetting Plastic

Question 8

Draw the structure of an Elastomer.

Answer 8

Elastomer

Question 9

Additives are a way of improving the properties of plastics. Name five additives.

Answer 9

• Fillers
• Flame-retardants
• Anti-static agents
• Plasticiser
• Stabilisers

Question 10

What do fillers do when added to plastics?

Answer 10

• Fillers reduce the bulk of the plastic.
• Fillers are cheap and therefore reduce the cost of the plastic.
• Some fillers can increase strength and hardness by removing brittleness.
• Examples of fillers include saqwdust, crushed quartz and limestone.

Question 11

What does a flame retardant reduce the risk of, when added to plastic? How does it actually work?

Answer 11

• Flame retardants reduce the risk of combustion and therefore fire.
• The retardant produces a chemical reaction that slows and stifles combustion.
• A good example of the use of flame retardants is in foam filled cushions.

Question 12

Name a product made from synthetic materials that would benefit from anti-static agents being added to it.

Answer 12

Carpets made from nylon and polyester.

Question 13

How does an additive that is a plasticiser improve plastic manufacturing processes?

Answer 13

• Plasticisers improve the flow properties of plastics when being moulded.
• Plasticisers also reduce the softening temperature.

Question 14

In what types of plastic products are stabilisers used in and why?

Answer 14

• Products such as window frames, doors and conservatories use stabilisers.
• Stabilisers reduce the effect of ultraviolet light by making the plastic more resistant to being “broken down” by sunlight.
• Stabilisers are important for the aesthetic and structural integrity of the product.

Question 15

What are biodegradeable plastics?

Answer 15

Biodegradable plastics are designed to degrade (break down) under biologically and enviromentally rich conditions (such as rain and sun) unlike conventional plastics which clog up landfill sites.

Question 16

What are the majority of biodegradeable plastics produced from?

Answer 16

Renewable raw materials

Question 17

What are renewable materials?

Answer 17

Renewable materials are from managed and sustainable sources.

Question 18

Give examples of renewable materials.

Answer 18

• Starch based polymers from wheat, corn and potatoes are used for medicine capsules
• Polylactides (PLA) are a type of polyester derived from corn starch that is used for clear bottles, bags and gardening containers

Question 19

List as many thermoplastics as you can.

Answer 19

Thermoplastics:

• ABS, Cellulose Acetate, Nylon (Polyamide), Acrylic, Polypropylene (PP), High Impact Polystyrene (HIPS), Polystyrene (PS), Expanded Polystyrene, Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Unplasticised Polyvinyl Chloride (uPVC), Polyethylene Terephthalate (PET), Polycarbonate (PC)

Question 20

List as many thermosetss as you can.

Answer 20

Thermosets:

• Epoxy Resins, Melamine Formaldehyde, Polyester resins, Urea Formaldehyde

Question 21

What are the properties of ABS (Acrylonitrile Butadiene Styrene) and what is it commonly used for?

Answer 21

ABS Properties: High impact strength, scratch resistant, lightweight durable

Uses: Kitchen products, mobile phone cases, safety helmets, toys, some car parts

Question 22

What are the properties of Cellulose Acetate and what is it commonly used for?

Answer 22

Cellulose Acetate Properties: Tough and rigid, lightweight, transparent, non-flammable

Uses: Photographic film, handles for cutlery, frames for glasses

Question 23

What are the properties of nylon (polyamide) and what is it commonly used for?

Answer 23

Nylon properties: Hard, tough, resistant to wear, low friction coefficient

Uses: Bearings, gears,clothing, curtain rail fittings

Question 24

What are the properties of** acrylic** and what is it commonly used for?

Answer 24

Acrylic properties: Food-safe, tough, hard, durable, easily machined

Uses: Light units, illuminated signs, lenses for car lights

Question 25

What are the properties of** polypropylene** and what is it commonly used for?

Answer 25

Polypropylene properties: Lightweight, food-safe, good impact resistance even at low temperature, good chemical resistance Uses: Kitchen products, food containers, medical equipment, string and rope

Question 26

What are the properties of** high impact polystyrene **and what is it commonly used for?

Answer 26

High Impact Polystyrene properties: Good impact resistance, good strength and stiffness, lightweight Uses: Toys, refrigerator linings

Question 27

What are the properties of** expanded polystyrene **and what is it commonly used for?

Answer 27

Expanded Polystyrene properties: Floats, good sound and heat insulator, lightweight, low strength Uses: packaging, disposable cups, sound and heat insulation

Question 28

What are the properties of** polystyrene **and what is it commonly used for?

Answer 28

Polystyrene properties: Lightweight, rigid, colourless, low impact strength Uses: packaging, disposable plates, cups and food containers

Question 29

What are the properties of** low density polyethylene **and what is it commonly used for?

Answer 29

Low density polyethylene properties: Low density (lightweight), low stiffness, good chemical resistance Uses: detergent bottles, toys, carrier bags

Question 30

What are the properties of** high density polyethylene **and what is it commonly used for?

Answer 30

High density polyethylene properties: High density, good stiffness, good chemical resistance Uses: crates, bottles, buckets and bowls

Question 31

What are the properties of** polyvinyl chloride (PVC)** and what is it commonly used for?

Answer 31

Polyvinyl Chloride properties: Good chemical resistance, good resistance to weathering, rigid, hard, tough, lightweight, can be coloured Uses: Flexible hose, hose pipes, cable insulation

Question 32

What are the properties of** unplasticised polyvinyl chloride (uPVC)** and what is it commonly used for?

Answer 32

Unplasticised Polyvinyl Chloride properties: Good chemical resistance, good resistance to weathering, rigid, hard, tough, lightweight, can be coloured Uses: pipes, guttering, bottles and window frames

Question 33

What are the properties of** Polyethylene Terephthalate (PET)** and what is it commonly used for?

Answer 33

Polyethylene Terephthalate (PET properties: Moderate chemical resistance Uses: Fibres used in clothing, blow moulded bottles for beer and soft drinks, electrical plugs and sockets, insulation tape

Question 34

What are the properties of** polycarbonate** and what is it commonly used for?

Answer 34

Polycarbonate properties: Good chemical resistance, extremely tough Uses: Used for protective shields, safety glasses, vandal proof covers, hairdryer cases

Question 35

What are the properties of** epoxy resin **and what is it commonly used for?

Answer 35

Epoxy resin properties: Good chemical and wear resistance, high strength when reinforced with fibre (eg GRP) Uses: Surface coating, encapsulation of electronic components, adhesives

Question 36

What are the properties of** polyester resins** and what is it commonly used for?

Answer 36

Polyester resins properties: Rigid, brittle, good heat and chemical resistance Uses: Casting, used in glass re-inforced plastics for boat hulls etc

Question 37

What are the properties of** melamine formaldehyde **and what is it commonly used for?

Answer 37

Melamine formaldehyde properties: Rigid, good strength and hardness, scratch resistant, can be coloured Uses: Tableware, decorative laminate surfaces

Question 38

What are the properties of** urea formaldehyde **and what is it commonly used for?

Answer 38

Urea formaldehyde properties: Rigid, hard, good strength, brittle, heat resistant, good electrical insulator Uses: electrical fittings, adhesives