How Lego perfected the recycled plastic brick

Brick also needs to not only hold its shape and hold that clutch, but do so over entire generations of play, as Brooks says these materials slide and change shape over time. Standard Lego bricks are tested using high and low temperatures, butter and even false saliva to ensure they retain their integrity for decades of use.

With its new PET brick, however, Lego has cracked it. Well almost. “Now we need to work on how to tighten the clutch slightly and add color to the brick,” says Brooks. “When we do that, we’ll go through shape by shape and determine how many ABS bricks can be replaced with PET. “

The key here is that of the 3,500 or so different shapes produced by Lego, the 2×4 brick is one of the most popular. If the company can replace such a component with a recycled plastic version, it will have a significant impact on Lego’s environmental goal of using fully sustainable materials in its products by 2030. “We have what we call it. “high runners”, ”says Brooks. For example, we know most sets will have a 2 x 4, we certainly know roughly all the set will have a 1×1 dot. This is by far the most common brick we make. “

“ABS is incredibly stiff. Very stiff, very precise, very hard. PET is less stiff, less hard and less precise, which is why we have to use an impact modifier with PET. That’s what’s different here. We use a different grade of PET with an additional “secret sauce” for which we have a patent pending. So you are considering a PET that we are modifying to make it efficient like ABS. “

Gregg Beckham of the National Renewable Energy Laboratory of the US Department of Energy, who in 2018, along with John McGeehan of the University of Portsmouth, designed an enzyme that digests PET, is impressed with Lego’s progress.

“ABS is an incredible material. It’s extremely versatile, because you can change the ratio between A, B, and S. And depending on how you phrase it, there are a huge number of versions of ABS plastic that you can make. We literally touch it every day, ”says Beckham. “PET, on the other hand, is difficult to formulate in a way that exhibits the same material properties as ABS, as you’ll find in the Lego brick. It’s an exceptional scientific challenge for polymer science, that’s for sure. It’s super exciting.

As to why it took so many decades of plastic production to get to this, Beckham says that while it would be nice if we could wave a magic wand and make it happen, in many cases the task is deceptively difficult. “This is a fundamental materials science and engineering that has to figure out how to meet the same types of material properties with raw materials that are either made from recycled plastic or themselves become recyclable,” he said. “In the case of ABS bricks, they are neither made from recycled plastics nor recycled at the end of their life. This could potentially address both of these challenges simultaneously. “

Another advantage of the new PET brick prototype is that it has a 70% reduction in carbon compared to the brick made of virgin ABS material.

But, interestingly, as the development of new environmentally friendly plastics is underway, the real environmental benefits may well come from developing ways to recycle things that we currently can’t. Stuff like ABS. “Laboratory research today envisions using advanced recycling approaches capable of breaking down polymers, these long chains of molecules, into their building blocks,” Beckham explains. “Then purify them and put them back in the same plastic they were in the same grade of virgin type plastic or to recycle them in open loop and turn them into something else that has an even higher value. . “


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