Polymers

Polymers

1. Forces between molecules determine the properties of plastics

   • Strong covalent bonds hold the atoms together in long chains
   • The bonds between the different molecule chains determine the properties of the plastic
   • Whatever the plastic, its always a polymer

2. Weak forces

   • Individual tangled chains of polymers, held together by weak intermolecular forces, they are free to slide over eachother
   • Thermosoftening Polymers don't have cross linking between chains
     • Forces between chains are easy to overcome so its dead easy to melt the plastic
       • When it cools, the polymer hardens into a new shape, these can be melted and remoulded as many times as you like
   • Thermosoftening

3. Strong forces

   • Thermosetting
   • Some plastics have stronger intermolecular forces between the polymer chains called crosslinks
     • Thermosetting polymers have crosslinks that hold the chains together in a solid structure
       • The polymer dosen't soften when heated
         • Soft hard and rigid
   • Crosslinks hold the chain firmly together
     • Think of it as a brick wall

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