Plastics Flashcards
What are plastics?
Materials made up of long chains of molecules.
What are the general properties of plastics?
- Good electrical and thermal insulators
- Good strength to weight ration
- Good atmospheric and chemical corrosion resistance
- Lightweight
- Self finished.
What are thermoplastics?
Plastics that can be reheated and reshaped.
What are thermosetting plastics?
Plastics that become permanently rigid when heated and cannot be reshaped multiple times.
What are elastomers?
Plastics that have good elasticity and deform under pressure but return to the original shape when the pressure is removed.
What is used to improve the properties of plastics?
Additives
What are 5 examples of additives?
- Fillers
- Flame-retardants
- Anti-static agents
- Plasticisers
- Stabilisers
What are fillers and what are they used for?
Fillers include sawdust, wood flour, crushed quartz and limestone. Fillers are used to reduce the amount of plastic used. They are often cheaper than plastic but are sometimes used to add strength and hardness.
What are flame-retardants and what are they used for?
Flame-retardants are chemicals that reduce the chance of combustion taking place by releasing agents to stifle combustion. An example of where they are used is in the foam of sofas.
What are anti-static agents?
They reduce the effects of static charges that could build up on items like carpets.
What are plasticisers?
They are molecules that are added to plastics in order to increase flexibility and reduce the brittleness of materials.
what are stabilisers?
They are used to increase resistance to UV.
What are some applications of biodegradable plastics?
- Shopping bags
- Food trays
- soft drink bottles
- Disposable pots
- Gardening products
- medical and sanitary products
How is PHA produced?
A bacteria is modified to produce it.
How is PLA Produced?
It is made using starch.
