Plastics

Annotations:

• Synthetic plastics. More widely used than Natural Plastics, which include materials such as amber and latex.

1. Thermoplastics
   1. Formed from long polymer chains joined loosely together
   2. Heating weakens the join and softens plastic (reshapeable)
   3. High density polythene
   4. Low density polythene
   5. Polypropylene
   6. Acrylic
2. Thermosetting plastics
   1. Formed when a polymer is mixed with a catalyst to produce a chemical change
      1. Results in a permanently rigid material
      2. Cannot be reformed, as polymer chains so tightly linked
   2. Epoxy Resin
   3. Melamine Formaldehyde
   4. Extremely strong and durable
3. Reinforced plastic
   1. Thermoplastic and thermosetting plastics can be reinforced by the addition of fibres
      1. Glass fibre
      2. Carbon fibre
4. Produced industrially from carbon-based materials. Polymerisation: monomer molecules created, then joined to form long chains of molecules called monomers.
   1. Most modern plastics are synthetic
   2. Plastics can be defined as thermosetting or thermoplastics
   3. Can be combined with other materials to reinforce structures
   4. Most can be recycled
   5. Mass production: Injection moulding and vacuum forming