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Polymers
• Starter: What do the following substances have in common? How are they different?–Plastic kettle–Plastic soldiers–A light plastic bottle–A heavy plastic pipe
• Extension: What is a polymer? How are they made?
Similarities Differences
Learning outcomes
• State that the properties of polymers depend on what they are made from and the conditions under which they are made.
• Describe how thermosoftening plastics are different from thermohardening.
HT Only: Explain the properties of thermosoftening polymers in terms of intermolecular forces.
Key words
• Thermosetting • Thermosoftening• Cross linking• Intermolecular forces• Low density poly(ethene)LDPE• High density poly(ethene)HDPE
• _______________ polymers melt when heated.
• _____________ polymers do not melt when they are heated.
Copy and complete the sentences below with either the words
‘thermosoftening’ or ‘thermosetting’
Thermosoftening
Thermosetting
So, are these plastics thermosoftening or thermosetting?
Plastic kettle Melted plastic army men
Thermosoftening Thermosetting
• __________________ polymers consist of individual, tangled polymer chains.
• _______________ polymers consist of polymer chains with cross-links between them so that they do not melt when they are heated.
Copy and complete the sentences below with either the words
‘thermosoftening’ or ‘thermosetting’
Thermosoftening
Thermosetting
Thermoplastics in art and technology
Watch this video and listen to see what kind of plastic the artist uses:
Design & Technology - Thermoplastics - BBC Learninghttp://www.youtube.com/watch?v=VDHWNNRXiXo
Why do you think she uses this kind of plastic?
• The bottles on the left are made of Low Density Polyethelene (LDPE), which is lighter but less strong.
• The pipe on the right is made of High Density Polyethelene (HDPE), which is heavier and stronger.
Diagrams from:http://www.steinwall.com/ART-polyethylene.html
Task
Draw labelled diagrams showing:
1. thermosoftening plastics
2. thermosetting plastics
3. LDPE (low density polyethene)
4. HDPE (high density polyethene)
GCSE Bitesize diagrams can be found on:http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/bonding/structure_propertiesrev3.shtml