These properties are useful in many applications, including flexible food packaging and thermal insulation (such as space blankets).īOPET is used in the backsheet of photovoltaic modules. : 104 Flexible packaging īiaxially oriented PET (BOPET) 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). PET is permeable to oxygen and carbon dioxide and this imposes shelf life limitations of contents packaged in PET. Color-conferring dyes can easily be formulated into PET sheet. : 1378 Both amorphous PET and BoPET are transparent to the naked eye. Crystallizable PET withstands freezing and oven baking temperatures. Non-oriented PET sheet can be thermoformed to make packaging trays and blister packs. PET sandwiches an additional polyvinyl alcohol (PVOH) or polyamide (PA) layer to further reduce its oxygen permeability. For beverages that are degraded by oxygen, such as beer, a multilayer structure is used. Plastic bottles made from PET are widely used for soft drinks, both still and sparkling. Polyester fibres are used in fashion apparel often blended with cotton, as heat insulation layers in thermal wear, sportswear and workwear and automotive upholstery. As of 2022, there are many brands around the world, mostly Asian. It was first commercialized in the 1940s by ICI, under the brand 'Terylene'. The invention of the polyester fibre is attributed to J.

Polyester fibres are widely used in the textile industry. Polymerization is through a polycondensation reaction of the monomers (done immediately after esterification/transesterification) with water as the byproduct. One process for making PET uses bis(2-hydroxyethyl) terephthalate, which can be synthesized by the esterification reaction between terephthalic acid and ethylene glycol with water as a byproduct (this is also known as a condensation reaction), or by transesterification reaction between ethylene glycol and dimethyl terephthalate (DMT) with methanol as a byproduct. The semicrystalline material might appear transparent (particle size less than 500 nm) or opaque and white (particle size up to a few micrometers) depending on its crystal structure and particle size. The National Association for PET Container Resources (NAPCOR) defines PET as: 'Polyethylene terephthalate items referenced are derived from terephthalic acid (or dimethyl terephthalate) and mono ethylene glycol, wherein the sum of terephthalic acid (or dimethyl terephthalate) and mono ethylene glycol reacted constitutes at least 90 percent of the mass of monomer reacted to form the polymer, and must exhibit a melting peak temperature between 225 ☌ and 255 ☌, as identified during the second thermal scan in procedure 10.1 in ASTM D3418, when heating the sample at a rate of 10 ☌/minute.' ĭepending on its processing and thermal history, polyethylene terephthalate may exist both as an amorphous (transparent) and as a semi-crystalline polymer. PET is commonly recycled, and has the digit 1 (♳) as its resin identification code (RIC). PET consists of repeating (C 10H 8O 4) units. Polyester makes up about 18% of world polymer production and is the fourth-most-produced polymer after polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).

In the context of textile applications, PET is referred to by its common name, polyester, whereas the acronym PET is generally used in relation to packaging. The biggest application is in fibres (in excess of 60%), with bottle production accounting for about 30% of global demand. In 2016, annual production of PET was 56 million tons. Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins.

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