1. 1
   A recycling plant sorts plastic waste into two bins, one for thermosoftening polymers and one for thermosetting polymers, before processing them differently.

   (a)

   A recycling plant heats a sample of thermosoftening polymer. What happens to it?

   [1 mark]

   • AIt melts and can be reshaped
   • BIt chars and does not melt
   • CIt explodes
   • DIt turns into a gas immediately without melting

   (b)

   What happens when a thermosetting polymer sample is strongly heated?

   [1 mark]

   • AIt melts easily and can be reshaped
   • BIt does not melt; it chars or decomposes instead
   • CIt dissolves in water
   • DIt becomes a liquid at room temperature

   (c)

   Describe the structural difference between thermosoftening polymers and thermosetting polymers.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An engineer is choosing suitable polymers for two different products: a recyclable food container and a heat-resistant electrical socket casing.

   (a)

   An engineer is designing a plastic container that must be melted down and reshaped many times for recycling. Which type of polymer should be used?

   [1 mark]

   • AA thermosetting polymer
   • BNeither type can ever be melted
   • CEither type works equally well
   • DA thermosoftening polymer

   (b)

   The engineer instead needs a polymer for an electrical socket casing that must not melt or deform even at high temperatures. Which structural feature makes thermosetting polymers suitable for this?

   [1 mark]

   • ATheir chains are completely straight with no branching
   • BThey contain only single, individual, tangled chains
   • CTheir chains are joined together by cross-links
   • DThey are made from very short monomer units only

   (c)

   Explain why thermosetting polymers do not melt when heated.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A materials science student investigates how two different types of polymer behave when heated to a very high temperature, to understand their suitability for different products.

   (a)

   A student heats two polymer samples, one thermosoftening and one thermosetting, to a high temperature. Explain, in terms of their structure, why the thermosoftening sample melts but the thermosetting sample does not.

   [3 marks]

   (b)

   Explain the behaviour of thermosoftening polymers when heated, in terms of the intermolecular forces between the polymer chains.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A product design team must choose between thermosoftening and thermosetting polymers for a range of new products, and needs a clear explanation of how each type behaves when heated and why.

   (a)

   Explain the differences between thermosoftening polymers and thermosetting polymers in terms of their structure and their properties when heated.

   [6 marks]

   (b)

   Explain thermosoftening polymer behaviour in terms of intermolecular forces between polymer chains, and discuss why this makes thermosoftening polymers suitable for products that need to be reshaped or recycled.

   [6 marks]

   Total for question 4: 12 marks

End of questions