Polyethylene terephtalate facts for kids
- The animals can be found under pet
| PET | |
|---|---|
| Density | 1370 kg/m3 |
| Young modulus(E) | 2800–3100 MPa |
| Tensile strength(σt) | 55–75 MPa |
| Elongation @ break | 50–150% |
| notch test | 3.6 kJ/m2 |
| Glass temperature | 75 °C |
| melting point | 260 °C |
| Vicat B | 170 °C |
| Thermal conductivity | 0.24 W/m.K |
| linear expansion coefficient (α) | 7×10−5/K |
| Specific heat (c) | 1.0 kJ/kg.K |
| Water absorption (ASTM) | 0.16 |
| Price | 0.5–1.25 €/kg |
| source: A.K. van der Vegt & L.E. Govaert, Polymeren, van keten tot kunstof, ISBN 90-407-2388-5 | |
Polyethylene terephthalate (aka PET, PETE or the obsolete PETP or PET-P) is a thermoplastic polymer resin of the polyester family. The chemical industry makes it. It is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination with glass fiber. It is one of the most important raw materials used in man-made fibers. It is also used as the dielectric in multi-purpose capacitors (K73-16 series).
Depending on its processing and thermal history, it may exist both as an amorphous (transparent) and as a semi-crystalline (opaque and white) material. Its monomer can be synthesized by the esterification reaction between terephthalic acid and ethylene glycol with water as a byproduct or the transesterification reaction between ethylene glycol and dimethyl terephthalate with methanol as a byproduct. Polymerization is through a polycondensation reaction of the monomers (done immediately after esterification/transesterification) with ethylene glycol as the byproduct (the ethylene glycol is recycled in production).
The majority of the world's PET production is for man-made fibers (in excess of 60%) with bottle-making accounting for around 30% of global demand. In discussing cloth uses, PET is generally referred to as simply "polyester" while "PET" is used most often to refer to packaging applications.
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A PET bottle (containing mineral water)
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sails are often made of PET-fibers.
Uses
Plastic bottles made from PET are widely used for soft drinks (see carbonation). For certain specialty bottles, such as those designated for beer containment, PET sandwiches an additional polyvinyl alcohol (PVOH) layer to further reduce its oxygen permeability.
Biaxially oriented PET film (often known by one of its trade names, "Mylar") can be aluminized by evaporating a thin film of metal onto it to reduce its permeability, and to make it reflective and opaque (MPET). These properties are useful in many applications, including flexible food packaging and thermal insulation (such as space blankets). Because of its high mechanical strength, PET film is often used in tape applications, such as the carrier for magnetic tape or backing for pressure-sensitive adhesive tapes.
Non-oriented PET sheet can be thermoformed to make packaging trays and blister packs. If crystallizable PET is used, the trays can be used for frozen dinners, since they withstand both freezing and oven baking temperatures. Both amorphous PET and BoPET are transparent to the naked eye. Color-conferring dyes can easily be formulated into PET sheet.
When filled with glass particles or fibres, it becomes significantly stiffer and more durable.
PET is also used as a substrate in thin film solar cells.
Terylene (a trademark formed by inversion of (polyeth)ylene ter(ephthalate)) is also spliced into bell rope tops to help prevent wear on the ropes as they pass through the ceiling.
PET is used since late 2014 as liner material in type IV composite high pressure gas cylinders. PET works as a much better barrier to oxygen than earlier used (LD)PE.
PET is used as a 3D printing filament, as well as in the 3D printing plastic PETG.
Images for kids
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Sailcloth is typically made from PET fibers also known as polyester or under the brand name Dacron; colorful lightweight spinnakers are usually made of nylon.
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Replacing terephthalic acid (right) with isophthalic acid (center) creates a kink in the PET chain, interfering with crystallization and lowering the polymer's melting point.
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A finished PET drink bottle compared to the preform from which it is made. Worldwide, 480 billion plastic drinking bottles were made in 2016 (and less than half were recycled).
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PET preform for injection stretch blow moulding of a bottle
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A finished PET bottle
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A PET bottle which has been heated by a candle and has recrystallized, making it opaque.
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PET clamshell packaging, used to sell fruit, hardware, etc.
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Polyester yarn
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Microfiber towels and cleaning cloths
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Aluminized Mylar balloons filled with helium
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See also
In Spanish: Tereftalato de polietileno para niños
