Properties & Structure of Polymers
- The polymerisation method can often determine the properties of the resulting polymer
- Reaction condition in the polymerisation can have a big impact on a polymer’s ability to pack neatly
- Altering reaction conditions can lead to high and low density polymers
- Low density polymers are made at high temperatures and pressures
- They contain many side chains, which leads to poor packing arrangements and disorder within the polymer
- However, high density polymers are made at lower temperatures, pressures and in the presence of a catalyst
- This higher level of control leads to a much better packed and stronger resulting polymer
Thermoplastic polymers
- These polymers are also known as thermosoftening polymers
- They can be melted and formed into a new shape
- For example low density polyethylene is a thermosoftening plastic
- It can be melted and formed into a newly shaped object
Thermosetting polymers
- Thermosetting polymers differ in the fact that once they ‘set’ their shape cannot be altered
- They have many applications where heat resistant materials are required
- Once the polymer is applied to a surface, cross links start to form between the polymer chains
- This sets the polymer and prevent being moulded for an alternate use