Getting down to the molecule level with circular polymers

Author: Lena Barner-Rasmussen

Getting down to the molecule level with circular polymers

Efficient chemical recycling of plastics could make all the difference in enabling reuse of plastics waste. But there are a lot of misconceptions when it comes to the process of recycling. A chat with Walki's Category Manager Gunilla Laakso sets the record straight.

What happens to the plastic garbage we sort in a separate bin at home?
Post-consumer mixed plastics waste typically end up in a landfill, or then it is incinerated, which is in no way optimal. If the plastic waste is less contaminated and thoroughly sorted, it is usually mechanically recycled. That means that the plastic material is being grinded, washed, separated and dried, and then again made into granules that can in turn be used again. For example, many plastic bags you nowadays can choose to carry your groceries in, may contain such recycled plastics.

All is good then?
Not really, because the problem is that the plastics recycled in a mechanical way leave impurities in it, hence the grey colour and the odd smell. This means that you cannot use mechanically recycled plastics for food packaging. Also other properties in the plastics are poorer compared to virgin polymers. So mechanical recycling limits the ways for reusing the plastic. Also, there is a limitation as to how many times it can be recycled.

But in the near future, we will see more of chemical recycling, or what we refer to as 'circular polymers'.

How does circular polymers differ from mechanical recycling?
When you do circular polymers, you break down the plastic garbage using a procedure called pyrolysis. This means that you thermally decompose the plastic in a high temperature in an inert atmosphere. This pyrolysis oil is thereafter upgraded to be suitable for further processing in crackers.

What are the benefits of using circular polymers?
The big upside is that there are no impurities left in the recycled plastic when it's recycled through pyrolysis, so the recycled plastic can be reused as food packaging, as it is exactly as clean as virgin plastic. This is important, because for certain food stuff, plastic is the best way to package it.

Another big benefit is that we can recycle used food packaging. When you eat your salad and throw the package in the bin, some leftover food always remains in the packaging. That means that the plastic is not optimal for mechanical recycling because the food components decay in the recycled plastic. Using pyrolysis, the leftover food is eliminated. So with circular polymers we can efficiently reuse old food packaging.

How many times can you run plastics through pyrolysis?
Basically forever. Using mechanical processes, the quality of the plastics will deteriorate for every time it's processed because the polymers become weaker. With circular polymers using pyrolysis, however, you can use the molecules over and over again without compromising the quality. The circular polymers have the same quality as virgin polymers.

So from being the bad polluter, the reputation of plastics can be restored?
Plastic are in a lot of ways an excellent material. What we need is efficient and circular ways to recycle it.

Does this mean that we can go on using fossil plastics?
Oil is still a perishable resource. As we need to insert virgin material in the plastics circular loop, we should increase the use of renewable polymers, which are made out of plant-based material such as tall oil, a side product from pulp production. That's why we at Walki focus a lot on polymers from renewable sources that are not ethically contradictory with food sources and/or farmland.

Can renewable, plant-based polymers be used for circular polymers?
Yes, pyrolysis works in the same way for both fossil and non-fossil plastics.

How will the transformation towards circular polymers happen?
As a first step, we believe in a so-called mass-balance principle. It’s an approach to account for materials entering and leaving a system: we cannot say what the exact mix of plastic waste-based cracker feedstock we get is and what the ratio is between it and fossil-based materials. This will change once the world is ready to process bigger volumes. We are now in a transition and using the mass-balance system is a good stepping stone towards 100% bio-based materials.

So what is needed for circular polymers to really take off on a larger scale?
Investment in supporting collection systems and in pyrolysis facilities, as well as in facilities for upgrading pyrolysis oil. But we have taken the first steps with petrochemical manufacturer Sabic, a long-time partner of ours, in a market foundation stage for introducing circular polymers on the market. Hence, we are amongst the pioneers regarding this ground-breaking sustainable solution.

How do you see Walki’s role in a circular economy?
Brand owners and retailers are of course in a key role, but they cannot transform packaging unless the right materials are available. Sabic is in an important role as producer of circular polymers. At Walki, we see ourselves as the enabler of a circular economy and a zero waste future. We understand the specific requirements brand owners have for their product packaging, and can provide the ultimate material mix. In Walki, we target to have 100 % renewable and recyclable materials by 2030.

Please watch our Zero Waste Future animation about circular polymers

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