Topic: [Recycled ABS] - Sabic MG94 regrind by Ggalisky
Ggalisky was so gracious as to granulate some of my failed prints. This was 100% natural Sabic MG94 ABS, extruded once on a Filastruder at ~185C, printed at 230-260C, granulated, and reextruded on a Filastruder.
Extruder type: Hybrid Experimental Filastruder with overdrilled (+0.2mm bore) 1.75mm melt filter, full barrrel insulation, horizontal, overvolted motor, roughly 1800 hours of use so far.
Printer type: SD3, E3D v6, Glass bed.
Extrusion temperature: 192°C
Extrusion rate without colorant: 24-30inches per minute.
Average diameter of filament: 1.69mm
Tolerances: +/- 0.05mm (same as observed with virgin MG94 ABS)
Photos:
Here's what it looked like when I got it back from Ggalisky. As a note, he was very quick to granulate and return - I on the other hand let it sit on a shelf for a week before finding time to run it.
It extruded just fine, nothing exciting to see. It fed without problems, I was actually very impressed with how uniform in size the granulate was - this is far better than what I've seen out of Filabot/Filamaker shredders.
Here's a comparison between filament made from 100% virgin natural MG94, and 100% regrind natural MG94. You can see the latter is darker and more grey, I believe this to be due to carbonization since it has gone through a few heat cycles.
Strength testing:
Sabic MG94 ABS has a UTS (tensile strength) of 35 MPa.
I hung weights from a piece of filament made from 100% virgin, and a piece of filament made from 100% recycled. In both cases, the piece of filament supported 7kg of weight, and failed at 8kg of weight. This works out to failing somewhere between 32.7MPa and 37.4MPa, with the predicted strength from Sabic falling right between those numbers. This means that at worst, the recycled filament has 90% of the strength of virgin ABS, but could be closer to 100%.
Other material properties:
100% recycled ABS seems to be just as flexible (not brittle) as virgin ABS. This is very promising.
Printing:
Unfortunately, i could not get the 100% recycled plastic to have the same inter-layer strength as virgin plastic, resulting in severe delamination. I would estimate less than a third of the layer bonding of virgin material. This makes sense, as everything I've read states that 100% recycled plastic is not the same mechanically - it turns out the tensile strength is similar, but the layer bonding is not even close.
I would recommend no more than 1/3rd recycled plastic at this time, at least with ABS.