Plastics

There are two main types of plastics:
                   Thermo Plastics (chained)
                   Thermosetting plastics (cross linked)


Polymers (plastics)
      ABS     aerylonitrile butadiene styrene
      CA       cellulose acetate
      Nylon   polyamide
      PMMA polymethylmethacrylite
      PP        polypropylene
      HIPS    high impact polystyrene
      PS        polysyrene
      LDPE  low density polyethylene
      HDPE high density polyethylene
      uPVC   polyvynil chloride
      PVC     polyvynil chloride (unplasticisized, flexibe)
      PET     polyethylene terephthalate
      PC       polycarbonate

• good electrical and thermal insulator
• good strength to weight ratio
• good resistance to atmospheric and chemical erosion
• low melting point
• light weight
• wide range of colour and transparency's

Thermoset polymers:
      Epoxy resins
      Melamine Formaldahide
      Polyester resins
      Urea Formaldahide

Moulding Processes:
     Injection Moulding
      plastic granuels are poured into the njection moulder, they are then pushed down through a screw like tube, heating up on the way down, so they're liquid form, then they are injected into a split mould and cooled to set, then the mould is split open and there you have the finished product. The benifits of injection moulding are that its a very quiet, quick process, where there is no waste. There is also the oppetunity to add lots of detail. All deformed materials can be reheated and used again, therefore creating no waste materials.

      Compression Moulding
          this process uses powdered plastic, or sometimes sheet plastic, in the bottom of the heated mould, the hydrolic press then presses down onto the liquid plastic, and compresses into its required shape, the plastic then cools, ceating the shape reqired, this is a more difficuls prosess, as ther is a lot of ecsess materials.