About PET

It will stay there, inert, similar to glass. It will not degrade biologically; one of the reasons it is such a good choice for packaging foods is its resistance to attack by microorganisms. It will be crushed flat without fragmenting (no shards) and occupy less space that the more rigid glass. It is resistant to the chemical species found in landfills and will not give rise to any harmful leachates. Indeed, these very properties are utilized in stabilisation of landfills and processed baled PET bottles have been used for stabilisation of the foundations for road works.

Virtually all plastic cola and sparkling mineral water bottles are made from PET. Usually the PET container is marked with an identification symbol in the form of three arrows making a triangular shape, a number 1 in the centre of the triangle and the acronym PET under the base of the triangle. The symbol can be found either printed on the label or moulded on the base or shoulder of the bottle.

PET is the one plastic which has the correct balance of properties ideally suited for packaging carbonated (fizzy) drinks like colas and lemonades. All plastics are porous to some degree and will allow gasses to pass through the structure given sufficient time. PET will retain sufficient carbon dioxide in a beverage bottle to keep the drink fresh within the normal shelf life of the product, which is not true for other widely available plastics. The same property also keeps oxygen outside the container and prevents spoilage from oxidation.

This is a frequent question that is almost impossible to answer. When looking at environmental criteria – unless each effect is categorised, classified, and ranked in order of societal importance – a clear answer cannot be given. For example, which is the most important – reduction of global warming gases, fossil fuel depletion rates, consumption of water, emissions to water courses, air emissions, eutrophication of waterways, reduction of ozone depleting gases, or other parameters?

An answer to this question is that there is no clear consensus on ranking. Even environmental NGOs have no unambiguous priorities. Each parameter is usually ranked differently; there is no solution that is best for every aspect.However, overall reductions in the listed aspects are generally beneficial. PET, because of its lightweight and general toughness, requires less packaging material per unit of packaged product, which, in general, reduces the overall environmental burdens.

Simply comparing manufacture of a glass and a PET bottle is misleading, it is necessary to compare what they are being used for, both are used to deliver drinks or liquids to the consumer and when compared on resources used to deliver one litre of beverage the situation is rather different. In this respect comparative studies show the PET bottle competes very well indeed, especially in the larger sizes and over longer transport distances.The environmental impact analysis over the full life cycle of the various packaging alternatives (LCA) shows that in most uses PET has very favourable results compared to the other options.

When an organic acid is mixed with an organic base it makes something called an ester. PET is made with an organic acid – terephthalic acid – and a base – ethylene glycol. When we make plastics we use a substance called a monomer and when two monomers react with each other they form a poly(mono)mer, or polymer for short. So an ester reacting with an ester becomes known as a polyester. When PET is used for fibre or fabric applications, it is usually referred to as “polyester”. When PET is used for container and packaging applications, it is typically called “PET” or “PET resin.”