3D Printing Recycled PE/PP & PLA
Earlier we introduced to you the ReMake Plastics project.
In this post we will elaborate on some of our first recycled plastic tests.
ECO-oh! supplied us with recycled PE/PP blend in various qualities, the mixtures are made of recycled household waste! With the material consisting of 75% PE & 25% PP it was challenging to find the optimal settings. Especially due to melting temperature differences, ranging from 125 to 160 °C.
In the video the plastic is well extruded at the start, however it starts to burst by the end of the video. Hypothetically, fusing the types of plastic together is a slow process. When extruding fast a higher temperature was required for the materials to mix, which was found to exceed the temperature limitations of the PE fraction. Therefore, the printing speed was set low to achieve results.
Since PE & PP are semi-crystalline polymers, the material acts differently during the hardening process. To prevent the material from too much stress while cooling, heated air was applied. The results show good extrusion on the parts where heat was supplied and cracking of the material when the temperature differences during cooling are too large.
Temperature: 170 – 185 °C
Printspeed: 3 mm/s
Printlayer: 5 mm
While printing with recycled PLA we experienced considerable expansion and shrinkage of material. The video gives a good impression of the materials behavior after extrusion. Lowering the extrusion temperature and directly applying cooled airflow improved the results.
In addition the forming of air bubbles amplified the expanding and shrinking process. PLA is known for being hydroscopic, meaning it absorbs water. When heating up the water vaporizes, resulting in the forming of air bubbles. Dry storage and being able to dehydrate the material before use is essential for quality production with PLA.
Temperature: 170 – 180 °C
Printspeed: 20 mm/s
Printlayer: 5 – 8 mm
In these tests the layer height is reduced to 3 – 4 mm, spreading out the material and building it up in thinner layers. During printing various settings are modified. Especially the increase in print speed and reduced temperature after the 5th layer changed the quality of the output. Video can be found here.
Temperature: 165 – 190 °C
Printspeed: 7 – 20 mm/s
Printlayer: 4 mm
With the installment of couplers and nozzles the quality of the output greatly improved. Since recycled plastics from household waste are used we are excited about the first results!
Temperature: 195 – 205 °C
Printspeed: 11 mm/s
Printlayer: 4 mm
Nozzle Diameter: 5 mm
Thanks for the awesome post. I am looking forward to make one pp extruder by myself in the future.
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