AQA · A-Level · Chemistry
Course version: 7405 · Version from Sept 2016
Condensation polymers (A-level only): Typical uses of these polymers.
Properties follow from the links and the forces between chains, and uses follow from the properties.
Checked against the AQA 7405 specification (opens in a new tab) on .
- Point 3 of 4
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Properties follow from the links and the forces between chains, and uses follow from the properties. Terylene can be drawn into a fine fibre that resists stretching and does not crease easily, so it is used in clothing, and the same polymer moulded rather than spun becomes the drinks bottle. Nylon 6,6 has an N-H on every amide link, so its chains hydrogen bond to one another strongly; it is tough and resists abrasion, which suits ropes, carpets, parachutes and clothing. Kevlar's chains are aromatic and rigid, and they hydrogen bond into flat sheets that stack, giving a tensile strength greater than steel for the same mass, hence body armour and protective gloves. All three hydrolyse slowly, so they eventually degrade.
What earns the marks
- A named use matched to the named polymer.
- Linking that use to a property such as tensile strength, flexibility or resistance to abrasion.
- Tracing that property back to hydrogen bonding between the chains.
- Naming a drawback, such as slow degradation in landfill.
Common mistakes and how to put them right
Giving a use with no property to justify it, so there is nothing for the explanation mark.
Attributing Kevlar's strength to covalent cross-links between separate chains.
Saying the chains in a polymer are joined to each other by covalent bonds.
Claiming polyesters and polyamides do not degrade at all.
Exam tips
- Answer 'suggest a use' questions in three steps: structure, then property, then use.
- Hydrogen bonding needs an N-H or an O-H. Polyamides have one; polyesters do not, which is why they differ in strength.
Try the lesson
The start of the Condensation polymers (A-level only): Typical uses of these polymers. lesson, made from checked teaching notes for this specification point.
Have a go first
Which polymer is commonly used to make clothing fibres because of its strength and resistance to stretching?
Listen
Properties follow from the links and the forces between chains, and uses follow from the properties. Terylene can be drawn into a fine fibre that resists stretching and does not crease easily, so it is used in clothing, and the same polymer moulded rather than spun becomes the drinks bottle. Nylon 6,6 has an N-H on every amide link, so its chains hydrogen bond to one another strongly; it is tough and resists abrasion, which suits ropes, carpets, parachutes and clothing. Kevlar's chains are aromatic and rigid, and they hydrogen bond into flat sheets that stack, giving a tensile strength greater than steel for the same mass, hence body armour and protective gloves. All three hydrolyse slowly, so they eventually degrade. A strong answer earns marks for these points. a named use matched to the named polymer. linking that use to a property such as tensile strength, flexibility or resistance to abrasion. tracing that property back to hydrogen bonding between the chains. naming a drawback, such as slow degradation in landfill. Exam tip: Answer 'suggest a use' questions in three steps: structure, then property, then use.
Key words
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hydrogen bonding between chains
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tensile strength
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fibres and mouldings
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durability and disposal
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See every definition
- hydrogen bonding between chains
- Nylon 6,6 has an N-H on every amide link, so its chains hydrogen bond to one another strongly.
- tensile strength
- Kevlar's chains are aromatic and rigid, and they hydrogen bond into flat sheets that stack, giving a tensile strength greater than steel for the same mass.
- fibres and mouldings
- Terylene can be drawn into a fine fibre that resists stretching and does not crease easily, and the same polymer moulded rather than spun becomes the drinks bottle.
- durability and disposal
- All three hydrolyse slowly, so they eventually degrade.
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