SmarterEd

Aussie Maths & Science Teachers: Save your time with SmarterEd

ENGINEERING, AE 2025 HSC 10 MC

Which mechanical property of a thermosetting polymer increases when the number of cross-links between the polymer chains is increased?

  1. Ductility
  2. Flexibility
  3. Stiffness
  4. Toughness
Show Answers Only

\(C\)

Show Worked Solution
  • Cross-links are covalent bonds between polymer chains — more cross-links restrict chain movement, increasing stiffness.
  • Ductility and flexibility both require chain movement — cross-linking reduces these properties.
  • Toughness requires energy absorption through deformation — heavily cross-linked polymers become brittle, not tough.

\(\Rightarrow C\)

ENGINEERING, AE 2023 HSC 25a

Describe the process of compression moulding when used to manufacture aircraft components.   (3 marks)

 

Show Answers Only

  • The process of compression moulding of aircraft components requires a polymer to be fed into an open, heated mould cavity.
  • Once the polymer is soft, the mould is then closed and compressed.
  • Compression allows the material to fill the mould entirely. The charge cures within the heated mould.
  • When the piece is cured it is removed and the mould can be reused.

Show Worked Solution

  • The process of compression moulding of aircraft components requires a polymer to be fed into an open, heated mould cavity.
  • Once the polymer is soft, the mould is then closed and compressed.
  • Compression allows the material to fill the mould entirely. The charge cures within the heated mould.
  • When the piece is cured it is removed and the mould can be reused.
♦ Mean mark 50%.

ENGINEERING, AE 2023 HSC 21d

Draw, label and describe the microstructure of a thermosetting polymer.   (3 marks)
 

Show Answers Only

Show Worked Solution

  • Thermosetting polymers have a three-dimensional network structure, where polymer chains are cross-linked by covalent bonds in a network of polymer chains.
     

♦♦ Mean mark 36%.

ENGINEERING, PPT 2018 HSC 26d

The components of the bearing assembly used in the fidget spinner are shown.
 

The retainer can be made from either glass fibre-reinforced nylon or stainless steel.

Compare the in-service properties of these materials for use in the retainer.   (4 marks)

Show Answers Only

Show Worked Solution

ENGINEERING, AE 2019 HSC 25b

Some materials have properties that allow them to be used in the manufacture of both modern racing yachts and aircraft. These materials include Kevlar® aramid fibre, carbon fibre epoxy composites and aluminium alloys.

Complete the table by providing a property which makes each of these materials suitable for the manufacture of both yachts and aircraft.   (3 marks)
 

Show Answers Only

Include one of the properties in the second column:

Show Worked Solution

Include one of the properties in the second column: