Polyethene

• Low-density Polyethene conditions needed:

  • high pressures
  • oxygen present
• Low-density Polyethene properties:

  • not closely packed
  • lower softening temp
  • very flexible
• High-density polyethene conditions needed:

  • normal pressure
  • catalyst at 50C
• High-density polyethene properties:

  • packed closer together
  • stronger
  • high softening temp
  • slightly flexible
• • Thermosoftening - plastics which will soften when heated and can be reshaped. Weak intermolecular forces
• Thermosetting - plastics do not soften on heating. They are used when resistance to heat is important. Strong covalent bonds