A very interesting new 3D printing company has emerged from MIT, but there may be more going on here than first appears.
Atlas Building Composites is an MIT spinout developing a system for producing structural building components from recycled plastic. The company envisions distributed “micro-factories” that would take locally available plastic waste and turn it into foundations, trusses and other construction components using large-format additive manufacturing.
That sounds interesting enough, but large-format 3D printing with recycled polymers isn’t new. Several companies already do this.
The really interesting question is: what kind of recycled plastic?
That’s important because plastic recycling has a near financially-fatal problem. You simply cannot scoop up an arbitrary pile of plastic garbage, melt it together and expect usable material to come out the other end.
Different polymers don’t necessarily mix properly. Is that piece of trash made of ABS and that other one made of PET? There can also be labels, adhesives, food residue, moisture, dirt and other contaminants.
Up to now all manufacturers of recycled 3D print materials require known, sorted and reasonably clean input materials. Typically that’s done by partnering with some industrial process where uniform scraps are regularly collected.
Contaminants can make a part made from a material less strong. Imagine chunks of cardboard interspersed with your polymer. That issue becomes even more critical when the parts printed are expected to be a structural component in a building.
Atlas, however, seems to be suggesting something quite different.
The Atlas system apparently shreds single-use bottles and other objects, melts them, and combines them with glass fiber. More intriguingly, Atlas describes its approach as “waterless recycling”, and says it can process low-grade plastic that otherwise might not be particularly desirable.
If that actually means what it sounds like, this could be the most interesting part of their process: cleaning waste material.
There’s some history here.
Atlas co-founder AJ Perez previously worked on the MIT HAUS project, which investigated large-scale additive manufacturing of structural building components. A recently published paper describes the production of eight-foot floor trusses using recycled PET reinforced with 30% glass fiber, which sounds a lot like the Atlas process.
The 13 lb trusses were each printed in around 13 minutes, and a complete test floor eventually failed at a load of 4,480 lb.
But here’s the catch.
The material used in those experiments was Airtech Dahltram T-100GF, a commercially prepared recycled copolyester containing 30% glass fiber. In other words, the researchers weren’t dumping sticky pop bottles into the printer. They were using a known, clean, engineered material.
In February, Perez described the material used for the truss experiments as the “crème de la crème of recycled feedstocks.” It came from factory-discarded material. At that point, the team was still experimenting with genuinely dirty material such as used soda bottles containing liquid residue.
The research paper itself points in the same direction. It says the cost of the trusses remained high because of the material, and proposed developing a tailored recycling stream using commodity rPET and short glass fiber. The researchers estimated this could cut material costs by three to five times.
Now, only months later, Atlas says its process can take single-use plastic, shred it, combine it with fiberglass and produce building components — without requiring the conventional water-intensive recycling process.
Something apparently happened between those two points.
Unfortunately, Atlas doesn’t explain exactly what.
We don’t yet know how tolerant the process is of contamination, whether the input must still be PET-only, whether caps and labels must be removed, how moisture is handled, or whether the material is filtered, compounded or chemically modified before reaching the printer.
The 3D printing portion isn’t especially mysterious. Industrial pellet extrusion systems have been doing this sort of thing for years. But the potentially revolutionary technology is before the printing happens.
If Atlas has actually found an economical way to take genuinely messy post-consumer plastic garbage and turn it into a predictable structural composite material, then they may have solved one of the problems that has frustrated plastic recycling for decades.
Via MIT, U Texas and Atlas Building Composites
