For an upcoming research project I am trying to mix PLA pellets with bone substitute materials such as Beta TCP and Bioglass to produce 3D printable bio-ceramic filaments
What is the best way to get a homogenous mixture of the PLA pellets and the powder?
if you are using FDM, well you can just grind your PLA and mix it with your fillers (Thermal conductive polymers and BG) via filament extrusion machine. Probably you need to regrind it and extrude it again and repeat it probably 10x until the filament is homogeneous. But of course it depends on your FDM specification.
You will likely want to grind PLA pellets into fine powder. Alternatively, you can source PLA powder with particle size that corresponds to that of your ceramic fillers. Combine the powders at a desired ratio and rotate in a baffled tumbler until a fairly homogeneous blend is obtained.
Dear Lukas, I have done that in my PhD and will write down some opinions
Grinding the material it is a good option for improving mixing, however, PLA is quite sensitive to shear. In my case, I did it very slowly using N2, still, I have a decrease in 10% of molar mass. I also tested 2 different grades of PLA, the content of D or L also can impact a little PLA degradation. (take a look at a paper of mine "Analysis of the degradation during melt processing of PLA/Biosilicate® composites ".
I also developed filaments for FDM by using a twin-screw extrusion setup and it worked quite well, (single screw is easier to control, but has lower mixing capacity). The original idea was to use Biosilicate (look above the article), it is also a bioglass, but made in my former university, It however induced severe degradation and compromised the fabrication. Take a look at the reference below from Professor Aldo Bocaccini, their group was able to make the composite filaments, but the degradation levels are right, and also the processing conditions are low because the materials seem quite degraded during processing.
Article Polymer-Bioactive Glass Composite Filaments for 3D Scaffold ...
Another alternative is to use hot syringe /3D plotting, then you can mix your materials previously using solvents.
Fell free for further questions
Best regards
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