AQA · A-Level · Chemistry
Course version: 7405 · Version from Sept 2016
Typical uses of poly(chloroethene), commonly known as PVC, and how its…
Full specification wording
Addition polymers: Typical uses of poly(chloroethene), commonly known as PVC, and how its properties can be modified using a plasticiser.
Poly(chloroethene) carries a chlorine atom on every second carbon.
Checked against the AQA 7405 specification (opens in a new tab) on .
- Point 6 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Poly(chloroethene) carries a chlorine atom on every second carbon. The C–Cl bond is polar, so chains attract each other by permanent dipole–dipole forces as well as van der Waals forces, and the material is hard and rigid: window frames, drainpipes, guttering. A plasticiser is a small molecule added between the chains. It pushes the chains further apart, so the intermolecular forces between them act over a greater distance and are weaker, and the chains can then slide past one another. The same polymer becomes flexible, giving cable insulation, flooring and blood bags. Nothing is bonded to the chain and no covalent bond is broken; the plasticiser simply changes how strongly one chain is held to the next.
What earns the marks
- One use of rigid poly(chloroethene) and one use of the plasticised form.
- Saying plasticiser molecules get between the polymer chains.
- Saying the chains are forced further apart so the forces between them are weaker.
- The consequence that the chains slide over each other, making the polymer flexible.
Common mistakes and how to put them right
Saying the plasticiser breaks covalent bonds in the polymer chain.
Saying the plasticiser reacts with the polymer rather than sitting between the chains.
Claiming poly(chloroethene) chains are held together by hydrogen bonds.
Describing the plasticiser as a lubricant without mentioning intermolecular forces at all.
Exam tips
- Use the full chain of reasoning: between the chains, further apart, weaker forces, chains slide, more flexible.
- Give a use that clearly matches each form, rigid and flexible, rather than a general use of plastic.
- Name the force as permanent dipole–dipole, since the C–Cl bond is polar.
Try the lesson
The start of the Addition polymers: Typical uses of poly(chloroethene), commonly known as PVC, and how its properties can be modified using a plasticiser. lesson, made from checked teaching notes for this specification point.
Have a go first
Which of the following is a typical use of unplasticised poly(chloroethene)?
Listen
Poly(chloroethene) carries a chlorine atom on every second carbon. The C–Cl bond is polar, so chains attract each other by permanent dipole–dipole forces as well as van der Waals forces, and the material is hard and rigid: window frames, drainpipes, guttering. A plasticiser is a small molecule added between the chains. It pushes the chains further apart, so the intermolecular forces between them act over a greater distance and are weaker, and the chains can then slide past one another. The same polymer becomes flexible, giving cable insulation, flooring and blood bags. Nothing is bonded to the chain and no covalent bond is broken; the plasticiser simply changes how strongly one chain is held to the next. A strong answer earns marks for these points. one use of rigid poly(chloroethene) and one use of the plasticised form. saying plasticiser molecules get between the polymer chains. saying the chains are forced further apart so the forces between them are weaker. the consequence that the chains slide over each other, making the polymer flexible. Exam tip: Use the full chain of reasoning: between the chains, further apart, weaker forces, chains slide, more flexible.
Key words
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poly(chloroethene)
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permanent dipole–dipole forces
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plasticiser between chains
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chains slide
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See every definition
- poly(chloroethene)
- A polymer that carries a chlorine atom on every second carbon, commonly known as PVC.
- permanent dipole–dipole forces
- Forces by which chains attract each other because the C–Cl bond is polar, acting as well as van der Waals forces.
- plasticiser between chains
- A small molecule added between the chains that pushes them further apart, so the intermolecular forces act over a greater distance and are weaker.
- chains slide
- What the chains can then do past one another, making the same polymer flexible.
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