Problematic polyester: Post-consumer recycled vs. virgin polyester

Every piece of polyester (polyethylene terephthalate, PET) that has ever been created still exists on this earth today, and the problem is growing by around 200 million pieces of clothing every day.

The material is a non-biodegradable polluting plastic created from petrochemicals (crude oil) in a process called polymerization, and it’s currently in over half of all our clothing – a figure which is expected to double by 2030, Greenpeace predicts.

Polyester fibers can take up to 500 years to degrade, yet every year around 75 billion more pieces of virgin polyester clothing items are created.

Most will come to a shapeless end in landfills, or will be incinerated for energy, but an estimated 15% will be donated – with 11% of that fraction recycled in some capacity.

Recycling unwanted polyester into new fabric was hailed as the earth-saving answer to all our clothing waste problems when it first became popular commercially in 2010, but how does the material really compare to its virgin counterpart?

The problem with virgin polyester (PET)

Firstly, here’s why we desperately need to stop creating more virgin polyester:

• A shocking 40% of the fashion industry’s total emissions are released creating virgin polyester.
• Virgin polyester relies on petroleum (crude oil) as a raw material – a finite and dwindling resource that releases vast amounts of CO2e into the atmosphere.
• The process of creating virgin polyester is incredibly energy intensive, using more than double the energy of cotton, wool, or viscose.
• One virgin polyester t-shirt has double the carbon footprint of a cotton shirt, releasing 5.5kg of CO2e compared with 2.1kg.

The limitations of recycled polyester (rPET)

There’s a satisfying feel-good feeling when you drop your old clothes into the recycling bin to ‘do your bit’ for the world. But unfortunately, recycling does very little to offset the damage already done by the garments.

Looking on the bright side, it’s true that recycled polyester – known as rPET (recycled polyethylene terephthalate) – is one of the best uses for discarded polyester and PET plastic bottles that would otherwise go to landfill.

It takes about 50 PET plastic bottles to make one fleece, so that’s 50 plastic bottles fewer bobbing about in the ocean.

Another positive is that recycling polyester requires 59% less energy than producing the material new and also contributes 79% fewer carbon emissions than its virgin equivalent during production.

So far, so good.

However, there is a catch. Recycling polyester into rPET using the standard mechanical method can only be done a few times before the fibers degrade and become low quality.

To explain further; there are two methods that can be used to recycle polyester (PET), mechanical or chemical recycling.

Currently, mechanical recycling is the only method considered commercially viable.

Mechanical recycling is done by breaking down PET plastic, such as water bottles, fishing nets, or old clothes, into chips which are then heated to 270C and squeezed into artificial fiber shapes.

Each time the rPET is heated and manipulated into a new item the fibers weaken and break, meaning it has to be ‘down-cycled’ into a lesser quality product – before eventually becoming useless.

In order to combat weakened fibers sometimes virgin polyester is mixed in with rPET.

Although this helps to strengthen the material it also means that the material will take even longer to decompose when it inevitably does end up in a landfill.

The mix of old and new fibers also means that the rPET can’t easily be recycled again so it is more likely to find its way onto the trash heap.

Whilst it is possible to recycle existing polyester clothes using mechanical recycling it is much simpler to start with PET clear plastic bottles as the feedstock as they are a uniform starting block.

You wouldn’t think it from the amount of littering the planet’s beaches but surprisingly clear PET bottles are in high demand.

With the drinks industry now facing pressure to produce recycled bottles for its own products the competition for used PET bottles is high.

Despite the world making an estimated 20,000 plastic bottles every second, used bottles can be difficult for manufacturers to get hold of due to poor collection rates.

There is some discussion about whether recycling old PET plastic bottles into clothes is an efficient use of the resource.

If PET bottles are recycled into more bottles they can stay in the system being repeatedly recycled for much longer than if turned into rPET fabric.

Another negative that comes with mechanical recycling of PET for material is the inconsistency of the product produced.

Even the chopped up chips from clear PET plastic bottles can vary in color from white to yellow. Toxic chlorine bleach is used to turn them white before the dyeing process begins, with high water, energy and chemical usage.

Additionally, the mechanical process requires 100% PET to work and is not able to separate materials before chopping it into ‘chips’ to be melted.

Many polyester ‘athleisure’ clothes are mixed with elastane and nylon (for stretch), and are therefore unsuitable for recycling in this manner.

So what is chemical recycling, and why don’t we use it?

Chemical recycling is a lot more forgiving and works on mixed materials by depolymerizing the PET to its base-chemical molecules and reforming it into polymers.

These can then be used to create polyester using the same machinery that produces virgin polyester, the end result is a material identical to virgin polyester.

Despite its effectiveness, the proportionally high cost of chemical recycling means it doesn’t make financial sense for companies to source their polyester or rPET this way.

This could be set to change with biochemical companies like Carbios, in central France, leading innovation with a PET eating enzyme, which would create a ‘closed-loop’ circular economy in plastics by allowing plastics to be recycled indefinitely.

In the meantime, mechanical recycling still gets the job done by preventing polyester from entering landfill, as well as reducing the demand for virgin polyester.

But let’s not kid ourselves, after that old polyester fleece has been recycled several times it will inevitably end up in landfill.

How does rPET compare to virgin polyester?

Overall rPET can be regarded as the lesser of two evils, but it is far from perfect.

With today’s technology newly recycled polyester, rPET, can be used to make the same products as virgin polyester, so in that sense they are almost identical.

However, rPET remains a more expensive material than virgin polyester due to the lower rate of rPET production and low cost of crude oil. This leaves little incentive for fast fashion brands to choose the less polluting option (rPET).

Additionally, rPET avoids the issue of relying on crude oil as raw material, but it still shares two other substantial lifecycle problems with virgin polyester.

The materials are both likely to end up in a landfill at the end of their life, and they both release the same amount of tiny fibers called ‘microplastics’ into the water when put in a washing machine.

The average item of polyester clothing releases between 700 thousand to 6 million ocean polluting ‘microplastics’ when washed.

The fibres are so small (less than 5 millimeters in size) they often pass through water filtration systems and end up in the sea, where they are accidentally consumed by fish that later end up on our plates.

Research has found that humans are consuming over 100,000 microplastics particles each per year.

At the current rate it is predicted that there will be more plastic in the ocean than fish by 2050.

Are there any pros to using a synthetic fiber?

Steering away from synthetic fabric altogether is the best thing you can do for the environment, however the lifecycle of polyester and its recycled counterpart have several ‘pros’ that some argue make it more environmentally friendly than cotton – although we don’t agree.

The fact that man-made polyester doesn’t require agricultural land to grow can be seen as a major benefit. Instead it is made in a chemical reaction that uses petroleum, air, and water.

At its current rate, the fashion industry is predicted to take up 35% more land (115 million hectares) to grow fibers by 2030.

The more land that is converted to grow monocrops for fibers such as conventional cotton (non-organic) the less land and water there is available to grow food for the growing populations in those developing countries.

Growing conventional cotton slowly decreases biodiversity in the area, due to the agrochemicals that decimate ecosystems and destroy the soil structure allowing polluted water to run into the water supply.

The absence of pesticides in the rPET process is a definite benefit, along with the reuse of existing plastic to prevent further natural landscapes being ravaged for their petrochemicals.

So in conclusion, recycling is a bit of a messy answer to a problem we’d be better off solving at the route – by stopping the production of virgin polyester altogether.

You can play your part by avoiding synthetic fibers including polyester, nylon and acrylic.

There is no denying that these fibers contribute to the world’s plastic pollution, whether you recycle them or not.