3D-manufacturing with biomaterials


#21

Here’s a picture of the fully dried object from the last experiment:

A small clip illustrating the hardness:

And a clip with a 170cm drop test:


#22

Nice results @TomV ! Those last pieces look really strong. I can imagine the material being useful for pots and vases, similar to ceramics. Or perhaps for protection for electrical wires and light switches? You should put some high voltages on it to test ;-D

Did you end up trying any naturally occurring binders?


#23

Thanks!

I see this applicable where you’d normally use either wood or plastic for structural or volumetric purposes. Ceramics would certainly be cool too. I’ll try sanding it one of these days!

Regarding the binders:
I’ve greatly reduced the amount of binder, which made think wether I need it at all. That will be one of the next tests.

I’ve also coated one piece by dusting it with starch. This stuck very well (see the one image with one large and two small samples, the white-ish one). I’ll try using starch with fresh material, as previous batches now have traces of methylcellulose.

I have pieces drying, so updates soon!

One a side note:
I’m experiencing a lot more Kahm-yeast contaminations in the tea lately, even after thorough cleaning. Anyone with ideas to prevent that as it stunts the growth of the scoby?


#24

I’ve looked into some papers and found more evidence that binders may not be necessary at all. Here’s what I’ve learned, but feel free to correct.

Nanocellulose fibers tend to irriversibly agglomerate and form additional hydrogen bonds with neighbouring fibers when drying, resulting in plastic-like material (hornification) but with less/no elastic properties.

This might be the reason why bacterial leather cracks and becomes so brittle over time or when exposed to sun (and thus dry). The agglomeration is something that is probably less desireable when the goal is to mix the fibers into composites. However, the hardening of the material may be desireable when you use it as the main material where ceramic materials are used or where elasticity and impact absorption are not really important.

I could conclude that a first drying step may not be necessary, unless for storing it to accumulate a large stock of raw but less qualitative material. This means that for small objects, a SCOBY-smoothie or semi-dried SCOBY would work even better.

Nanocellulose is also very hydrophillic, which explains why it tends to dry at a rather slow rate.

I found most of these insights referenced here, though still looking to read the original sources:

https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpsredir=1&article=1171&context=honors


#25