Polymers

Polymers

1. Weak forces: individual tangled chains of polymers, held together by weak intermolecular forces are free to side over each other.

   • Thermosoftening Polymers: don't have cross-linking between chains. The forces between the chains are really easy to overcome so, it's easy to melt the plastic.
     • When it cools, the polymers hardens into a new shape. You can melt these plastics and remould them as many times as you like.

2. Strong Forces: some plastics have stronger intermolecular forces between the polymer chains, called crosslinks, that hold the chains firmly together.

   • Thermosetting Polymers: have crosslinks. These hold the chains together in a solid structure. The polymer doesn't soften when it's heated/
     • Thermosetting polymers are tough. They're strong hard and rigid.

3. The starting materials and reaction conditions will affect the properties of the polymer.

   • Polythene
     • High Density polythene is made at a lower temperature and pressure (with a catalyst). It's more rigid and is used for water tanks and drain pipes.
     • Low Density polythene is made by heating ethane to about 200oC under high pressure. It's flexible and is used for bags and bottles.