Glossary
30 terms on PET, preforms and blowing in plain words. Start typing to filter the list.
- Acetaldehyde
- A substance formed during PET melt processing that can give water an off-taste.
- Amorphous PET
- PET with randomly arranged chains. It is clear, which is how it should be in a preform.
- Barrier preform
- A preform with an additive or layer that slows oxygen ingress.
- Blow moulder
- A machine that heats preforms, stretches them with a rod and blows them into bottles.
- Conditioning
- Keeping preforms in the shop so they reach room temperature before blowing.
- Crystallisation
- Ordering of PET molecules when overheated. The material turns white and brittle.
- Flash
- Thin excess plastic along the mould parting line. On the thread it interferes with capping.
- Gate
- The point in the centre of the preform base where the melt entered the mould.
- Glass transition (Tg)
- A temperature of about 70-80 °C above which PET turns from rigid to rubbery.
- Hot fill
- Filling a hot product. It needs heat-set preforms and heat-set blowing.
- Infrared oven
- The section of a blow moulder where lamps heat the preform body zone by zone.
- Intrinsic viscosity (IV)
- A measure of PET chain length. Bottle grades are about 0.8 dL/g.
- Masterbatch
- A colour concentrate added to PET to make blue, brown or other tinted preforms.
- Neck (finish)
- The top of the preform with the cap thread. It does not change during blowing.
- Oriented PET
- PET whose molecules lined up during stretching. It is stronger and holds gas better.
- PCO 1810
- The classic 28 mm neck standard, about 21 mm tall.
- PCO 1881
- A 28 mm neck standard about 17 mm tall. About 1.3 g lighter than PCO 1810.
- PET
- Polyethylene terephthalate, a clear and strong polyester used for drink bottles.
- Petaloid base
- A five-foot base for carbonated drink bottles. It holds pressure.
- Polariscope check
- Viewing a preform between polarisers: colour bands show stress in the wall.
- Pre-blow
- The first low-pressure air shot that starts shaping the bottle.
- Preform
- An injection-moulded blank of a PET bottle with a finished neck. A blow moulder turns it into a bottle.
- Recycled PET (rPET)
- PET made by recycling used bottles.
- Resin code 1
- The PET mark on packaging: a triangle with the number 1.
- Stretch ratio
- How many times the material was stretched in length and around the circumference.
- Stretch rod
- A rod that pulls the heated preform down before blowing.
- Support ring
- The ring below the neck by which the blow moulder holds and carries the preform.
- Tamper band
- A ring on the cap that breaks on first opening and shows the bottle has not been opened.
- Two-stage process
- Preforms are moulded in one place and bottles are blown in another, usually at the bottling plant.
- Virgin PET
- Raw material that has not been used before. It gives consistent colour and clarity.
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