Okay, so we're heading towards the 2 year anniversary of Perpetual Plastic Project. By now we have done over 40 events all over Europe to show people the possibilities of 3D printing with plastic waste. But what plastic waste is suitable for the PPP process of recycling and 3D printing? For most materials there is no documentation available for recycling for 3D printing, according to the PPP team the best way to find out is to try it out! We collected different kinds of plastic waste, put them through our washing tower, shredder, extruder and finally into the 3D printer. Today we'll provide you with a list of the materials we have put to the test during the events and the time in between, the ones that were recycled successful but also those who did not make it yet.
We've started out with the familiar PLA at Lowlands festival 2012 in The Netherlands. PLA is today a common material for festival disposables and a common material for FDM, the perfect match to kick-off the Perpetual Plastic Project. PLA works great for both extruding as 3D printing.
Since we were completely into drinking cups since the Lowlands festival we were eager to try out the other common disposable material Polystyrene (PS). We did the first successful recycling of a plastic PS cup into the familiar PPP ring at the Open Day of the Martini Hospital in Groningen (NL).
The third material added to the PPP portfolio was another familiar disposable; plastic bags. Plastic bags are made of low density poly-ethylene (LDPE). We took a bunch of broken plastic bags form the Albert Heijn, a supermarket chain in the Netherlands with a iconic blue color, and put the material to the test. Since our PPP shredder was designed for drinking cups it did not work properly with the plastic bags. Instead we had to cut them into pieces by hand. A lot of work but the end result was a succes. The LDPE material results in a somewhat flexible end product, like the input material; the bags.
Not only plastic bags but also bottle caps are usually made from LDPE. We went to our local supermarket and got an hour to get as many caps at the bottle recycling point. Here is the result;
Next up is polyamide (PA). We got a batch of PA powder from Shapeways, This powder is the waste material from their SLS 3D printing machines. With the PPP machine we have been able to use the waste powder from SLS printing as input for FDM 3D printing. So a second step of 3D printing with the same material. Although the 3D printing with PA needs some tweaking we have been able to make a proper PPP ring. The material works great for extruding but the powder requires a different extruder design to handle the powder.
I almost wanted to write polypropylene (PP) under the section of materials that we have not been able to successfully recycle with the PPP installation. We did some tests before with a broken IKEA box but the material was not good for extruding so we ended up with just some small pieces of filament. Turns out that even these bad pieces of filament were extremely good for 3D printing. Even with our basic PLA print settings we got a great result. Here's a picture of todays result:
The materials that did not (yet) make it.
So you just saw the materials we have successfully recycled with the PPP installation. Now we'll show you some materials that did not make it yet.
Polyethylene terephthalate (PET) is a very common plastic and one of the most recycled plastics in the world. In order to recycle PET in a high quality it needs special treatment compared to other plastics. PET is a semi-crystalline plastic, this means it appears in two phases, amorf and crystalline. Check wiki for the details. As a result we get a mixture of crystallised PET and amorf PET which leads to an inhomogenous end result. The pellets should be dried and crystallised before going to the extruding process to end up with a high quality end result. So fas we haven't managed to get this right. To be continued...!
We working on recycling more plastics for 3D printing as we speak. Next to that we're looking into combinations of plastics that could work together for 3D printing. Successful combinations could lead to the elimination of the complicated and expensive separation the plastic for recycling.
If you have a material and you are curious if it is possible to use it for recycling for 3D printing? Please let us know, we love to try out new materials! Send us a batch, we'll put it through the machine and see what happens. Contact: firstname.lastname@example.org