Let's take a closer look at the lifecycle of polyester fibers.
PET is the most common plastic in the world, but despite its popularity, its production process and life cycle remain a mystery to most of us… but this is about to change! This article answers the most common questions about the composition and origins of PET and rPET plastics.
How to recognize PET plastic?
There are many different types of plastics, but the good news is that plastic-based products are marked with numbers that come in handy when trying to identify the type (you will find it inside a triangle made of arrows, usually on the bottom or side of a bottle, container or any other object). The categories, also known as ASTM International Resin Identification Coding System, range from 1 to 7 and will help you easily identify the type of plastic in your hand!
PET plastic comes with the number 1.
But… what exactly is PET plastic?
PET stands for polyethylene terephthalate. Other acronyms used for this polymer are PETE, PETP, and PET-P, and in textiles, PET is commonly referred to as polyester.
PET plastics are extremely popular and not without reason! They come with many advantages over other materials. But what are their properties and what made PET plastics so widely used nowadays?
PET is very strong and at the same time lightweight, which makes it easy and efficient to transport. This type of plastic is also temperature resistant (-60°C to 130°C!), doesn’t break or fracture, and acts as an effective barrier to moisture and gas. It can be formed in nearly any shape or colour, including transparent applications. PET’s physical properties and chemical structure made health agencies worldwide approve PET plastic as a material safe for contact with food and drinks. As such, PET plastics’ popularity skyrocketed.
From food and beverage containers to clothing, fashion, cosmetics containers, electronics, and automotive components - PET plastics are all around us! Did you know that polyester, widely used in clothing and textiles, is also a form of PET plastic?
What is PET plastic made of and how is it produced?
PET plastic comes from the polymerization of purified terephthalic acid (TPA, also referred to as PTA) and ethylene glycol (EG, also known as MEG), raw materials that are derived from crude oil. By 2050, it is expected that 20% of all global oil will be used to produce plastic.
PTA and EG are heated together (with a catalyst, under low vacuum pressure) to, at high temperature, create polymer chains - that is the recipe for molten virgin PET! Next, strands are turned into pellets that later are used to produce PET products of many shapes.
Interesting fact: PET plastic was invented as the result of a study of phthalic acid that began in 1939 in the Calico Printers Association lab in the United Kingdom by JT Dickson and Rex Whinfield. PET plastic was patented in 1941.
What is rPET plastic?
Have you ever heard of rPET plastic? We sincerely hope so, because that means the PET resin used to create the plastic bottle in your hand (or any other PET-based product, of course!) comes from… you got it right - from recycled materials!
With rPET, the PTA and EG monomers used to produce it are not sourced from Earth’s natural resources but from PET plastic waste. Chemical recycling technologies like DePoly convert PET waste back into virgin-quality PTA and MEG, with chemical structures identical to PTA and MEG sourced from crude oil.
PET plastics are originally produced from oil and the truth is, most of them end up as single-use products – landing in landfills, where it takes roughly 450 years to decompose, or being incinerated.
But PET plastics can be 100% recycled (and they can be sustainable!). Depending on the technology used, PET waste can be recycled a few times (as with traditional methods that break down PET plastic mechanically, causing its degradation with every cycle) or infinitely, like with our chemical process that recycles PET back to its pure raw materials, PTA and MEG. Those components can be used to produce virgin-quality rPET plastics, creating a truly circular economy for PET plastics.
See also: Sustainability of polyester fibers.