Polyethene terephthalate (PET) is one of the most used plastics in the world due to its known cost-effectiveness, durability, and lightweight properties. PET was first developed in the 1940s by British chemists John Rex Whinfield and James Tennant Dickson. Initially used for packaging, PET gained prominence in the textile industry with the invention of polyester in the early 1950s.
While PET has transformed industries with its practicality and affordability, producing plastic and its disposal creates significant environmental challenges. Low production costs have driven a surge in demand for inexpensive packaging and textiles, contributing to increased waste and environmental issues.
Over half of all PET plastic is used to produce synthetic fibres like polyester. Polyester is a type of polymer, a chain-like molecule made through chemical polymerization. The process involves a chemical reaction between purified terephthalic acid (PTA) or dimethyl terephthalate (DMT) and monoethylene glycol (MEG). This chemical process connects small molecules called monomers to form long chains, creating a polymer which can then be moulded into a desired plastic shape. For polyester, the small plastic parts are melted into a liquid and then forced through a spinneret with tiny holes, forming continuous filaments. The process can also involve incorporating matting agents, colour pigments, and flame retardant additives to modify the properties of the polymer blend. The filaments from the spinneret are then cooled and solidified into polyester fibres.
rPET is recycled polyester made from existing water bottles where no virgin material is needed. It’s like “de-polymerizing” the plastic to its basic building blocks before reassembling them into polyester fibres. After removing the caps and sterilization, the plastic is dried and shredded into small flakes.
Flakes are melted and extruded (squeezed) into filament(yarn). Then, the yarn is spun into thread and woven into fabric.
However, during this recycling process, some toxic chemicals, including antimony trioxide, can drift away from polyester to saliva and sweat, even at low temperatures, and could be carcinogenic. About 24% of chemicals used to make plastics/polyester are known to harm humans and the environment.
Challenges & Environmental Impact
PET originates from crude oil(a non-renewable resource) and uses energy-intensive production methods involving fossil fuels, leading to the emission of greenhouse gases and other pollutants that affect the climate and air quality.
To produce PET, we use chemicals that can be harmful to health. Although PET material is considered safe for normal use, exposure to certain additives or by-products during production can harm workers and neighbouring communities.
The rise of PET recycling can create a false sense of security around plastic use. Many consumers believe that if they recycle, plastic use is not problematic, diminishing incentives to reduce plastic consumption and promote plastic reuse or alternatives.
Textiles from PET also release microfibers into waterways. When PET products break down, primarily through mechanical abrasion or UV exposure, they can form tiny particles called microplastics. These microplastics can be dispersed in ecosystems and taken up by animals, affecting the entire food chain.
We also don’t know how long PET materials take to break down in nature, as they have existed for only 70 years. We can use technologies to recycle, but it seems like this material will continue to exist for an uncertain period into the future and, therefore, not a material that brings forth circularity.
So, why use plastic bottles instead of discarded polyester to recycle polyester?
There are no straightforward solutions yet for recycling polyester fabric into new polyester fibre. Polyester is often mixed with other materials, and it isn’t easy to separate the individual materials, as they all have different properties. The added dye is also challenging to remove and will limit the recycled potential colours. On the other hand, plastic bottles are a pure, clear and high-quality form of PET and can be recycled several times. When PET bottles are used to create textiles(polyester) instead of recycling them into new ones, it takes them out of a relatively closed-loop system, creating a one-way and dead end of the material.
There is currently no technology scaled up enough to take these fabrics and return them to virgin quality polyester so we can use them again. So, the value of the material is bonded to the clothing. Once it has reached its end-of-life, it will either be down-cycled or end up in a landfill.
Sources
Britannica – PET fiber 
Science Direct – Polyethylene terephthalate (PET) recycling: A review
Science Direct – Fabrics made from recycled PET bottles
Science Direct – Safety of recycled plastics and textiles
The Circular Laboratory – Recycled polyester and the plastic bottle dilemma
November 2024, RETHINK
