C2 Revision - Polymers

Overview

• Ploymers = Plastic
• Strong covalent bonds hold the atoms togethor in long chains.
• The bonds between the different molecule chains that determine the properties of the plastic.

Weak Forces

• Individual tangled chains of polymers, held togethor by weak intermolecular forces and are free to slide over each other.

Thermosoftening Polymers

• Dont have cross linking chains.
• Forces are easy to overcome so its easy to melt.
• When it cools, the polymer hardens and forms a new shape.
• You can repeat the melting and forming as much as you like.

Strong Forces

• These plastics have stronger intermolecular forces between the polymer chains called crosslinks (these hold the chains firmly togethor).

Thermosetting Plastic

• Have crosslinks that hold the soild structure togethor.
• Doesn't soften when heated.
• They are tough,strong,hard and rigid.

• The starting materials and reaction conditions affect the properties of a polymer.

Two types of polythene can be made using different conditions.

Low density polythene is made by heating ethene to about 200 degrees under high pressure. Its flexible so its good for bags and bottles.

High density polythene is made at a lower temperature and pressure but uses a catalyst. MOre rigid and is used for drain pipes.