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Information:-
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Making a PET bottle starts from
the raw material: ethylene and paraxylene. These two substances'
derivatives (ethylene glycol and terephthalic acid) are made to
react to obtain the PET resin. The resin, in the shape of small
cylinders called pellets, is melt and injected into a mould to
make a preform. The preform, a sort of test tube shorter than
what the bottle will be but with thicker walls, is then blow-moulded.
During the blow-moulding phase, high-pressure air is blown into
the preform allowing it to take the exact shape of the mould it
is set into. The final product is a transparent, strong and
lightweight bottle. |
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It is the strength of the
material that contibutes to make PET the success it is. Indeed,
carbonated soft drinks can generate pressure inside the bottle
reaching up to 6 bar. Such high pressure however, thanks to the
alignment of macromolecules (cristallisation) occurring both
during the resin spinning process and the blow-moulding process,
is not capable of deforming the bottle nor can it make the
bottle explode. |
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Throughout the years, the PET
industry has increasingly taken on environmental concerns,
significantly decreasing the quantity of raw material needed for
the manufacture of bottles. Nowadays, a 1.5 liter PET container
is manufactured with just 35 grams of raw material |
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Another striking feature of PET on
the environmental side is that it is fully recyclable. It was in
1977 that the first PET bottle was recycled and was turned into
a bottle basecup. Soon however, the fiber industry discovered
the "new" material source and started using it for making
textiles, carpets and non-woven. Today, even though the "bottle
to bottle" recycling process is growing, the fiber market is
still the major outlet for recovered PET. |
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