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Glossary of plastics

Supplier: Pro-Pac Packaging
30 November, 2011

Glossary of terms used in plastics manufacturing.


  • Stands for High Density Polyethylene (also known as polythene).
  • HDPE is the most common plastic in packaging. It is found in plastic milk bottles and most shampoo bottles. Because it is used so frequently it is relatively cheap.
  • HDPE has good chemical resistance to most common products, though it is slightly porous and volatile components may pass through the container walls.
  • HDPE is commonly supplied in 2 colours, White and Natural (without pigmentation). Natural HDPE is translucent but not clear.
  • HDPE can be coloured to match any colour of the PMS book.
  • LDPE (Low Density Polyethylene)is very similar to HDPE. It is softer and more pliable.

PET (Polyethylene Triphthalate)

  • It is the most recyclable of our plastics. This is the plastic of soft drink bottles, and is marked 1 in the recycle triangle.
  • PET has the clarity of glass but does not break.
  • PET tooling is very expensive, hence there has been a limited range of product available. This is slowly changing.
  • Coloured PET can not be recycled as it will contaminate the clear product, hence there is very little coloured PET product available.
  • PET does not like acetone.
  • PET cannot be filled at a temperature greater than 75°c or it will lose its shape and collapse.

PVC (Poly Vinyl Chloride)

  • PVC has the same clarity as PET, but not the same gloss. It is very good at withstanding dilute acids, alkalis, and oils.


  • Is mainly used for jars and vials.
  • It has a very good clarity but is very brittle. If you drop a Styrene jar it will shatter into sharp splinters.
  • Styrene is suitable for most cosmetic creams or water based paints but cannot withstand Methyl Salicylate (the smelly stuff in most sports rubs) or acetone.


  • Abbreviated to PP, it is a good all round plastic which looks like HDPE, ie it is milky in its natural state.
  • PP is often used in jars because it is stiff but not brittle like Styrene.
  • PP has good chemical resistance properties but is not commonly made into bottles because of its cost.
  • Most caps are made of PP. Normally the cap material should be different to the bottle material or else the cap will bind as you put it on the container.


  • Is extremely tough, very clear and very expensive. It is not normally used for bottles because of price.