
3D printing with cellulose - udfalkso
http://news.mit.edu/2017/3-d-printing-cellulose-0303
======
Tepix
This claim is pretty incredible:

“After we 3-D print, we restore the hydrogen bonding network through a sodium
hydroxide treatment,” Pattinson says. “We find that the strength and toughness
of the parts we get … are greater than many commonly used materials” for 3-D
printing, including acrylonitrile butadiene styrene (ABS) and polylactic acid
(PLA).

~~~
robert_foss
Maybe a bit too incredible.

How do thick-walled materials have their hydrogen bonds restored? This process
seems rather more involved than regular 3D printing.

~~~
lsaferite
Sounds like they soak the print in a NaOH solution. I imagine if the material
is porous enough to evaporate acetone, it's also porous enough to absorb a
NaOH solution.

~~~
digi_owl
Just in case someone else gets bogged down in chemistry, NaOH is better known
as lye or caustic soda.

~~~
lsaferite
They called it Sodium Hydroxide in the article as well. :)

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acd
If you scale it up you could 3d print houses from Cellulose. Since 3d printing
is inexpensive and the material abundant you can 3d print an outer isolation
layer of a honey comb structure, bio inspired from bees. If the outer
isolation layer becomes degraded from years of contact with wind and rain you
can simply print a new one.

~~~
adrianratnapala
Is 3d printing really the most efficient way to make such a structure? Could
you not pack straws together and then squish them? Could you not make a
corrugated sheets like cardboard?

~~~
simonh
Mass 3D printing an item that can already be manufactured through e.g.
injection moulding or assembling standardised parts is never going to be
efficient at scale. That's not what it's for. Where 3D printing excels is at
producing one-offs or short runs, immediate production (no time consuming
buildout phase manufacturing moulds and setting up production lines), on-site
or mobile manufacturing, or making designs that are not amenable to
traditional manufacturing processes such as objects with complex geometries or
internal voids.

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fudged71
This is fantastic. If the properties and aesthetics are good, I can see a lot
of demand driving the filament manufacturers to adopt this material. Paste-
like extruders for open-source machines exist on the market today for
chocolate and clay.

Only concern for me is it sounds like post-processing is required.

~~~
yetihehe
From the article:

> As the acetone quickly evaporates, the cellulose acetate solidifies in
> place. A subsequent _optional_ treatment replaces the acetate groups and
> increases the strength of the printed parts.

~~~
digi_owl
Effectively, dipping the thing in lye.

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contingencies
I've been researching thermoforming polymer materials for the last few weeks,
and there is a well established category of materials known as PLA.

 _Polylactides (PLA) or polylactic acids represent a relatively new group of
thermoplastics for packaging applications obtained from renewable resources.
In extensive tests the functional and thermoforming properties of PLA are
compared with those of other polymers. They are a biodegradable /compostable
polyester manufactured from plant based resources. At 60°C and relative air
humidity of 80% PLA will degrade completely after 60 days.

PLA's properties make it suitable for various thermoforming applications,
particularly cups for cold bevarages and trays for fruit and vegetables. To
produce high-molecular PLA, a process is used that is sustainable, solvent-
free, and environmentally friendly.

PLA can be obtained from cassava, corn, maize, sugar beet, sugar cane, wheat,
or agricultural byproducts containing natural plant sugars.

Although PLA has been known for more than a century, it has only been of
commercial interest in recent years, in light of its biodegradability.

While PLA is one of the most promising bio-basedplastics, its main
disadvantages are high price and unsatisfactory mechanical properties._

My understanding is that thermoforming is however only really utilized for
sheet-based PLA material with essentially non-convex configurations. Also, it
tends to degrade over 60 degrees celsius.

I wonder how this process and its output differs step-wise, limitation wise,
and in terms of resulting material's mechanical properties. From the sounds of
it, it's essentially a layering process and too early to judge limitations,
though a small temperature range could perhaps be expected.

~~~
Jack000
maybe I'm missing something, but PLA is just 3d printer filament. There's only
two plastics commonly used for extruder-style 3d printers, and they're ABS and
PLA.

~~~
obsurveyor
This is a bit out of date. Nylon, PETG, TPE/TPU and polycarbonate are quite
common for home 3D printing now as well as a number of hybrid materials.

~~~
jononor
Polypropylene is coming in too. PVA for water-soluble (mostly as support
material).

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jszymborski
Looks like the website is under heavy load.

Here's a mirror: [https://archive.fo/eoohY](https://archive.fo/eoohY)

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slurple
Sounds promising for both 3D printing applications and the need for non-
petroleum based plastic-like materials.

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aruggirello
Just a funny coincidence but, did you see "TreeMaker" origami software just
below this thread? :-)

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agumonkey
For the last few months I was wondering if there were a way to implement logic
in cellulose ..

~~~
jacquesm
What application do you have in mind?

Cellulose absent water is extremely inert, so inert that we use it as long
term information storage, it is also an extremely good insulator.

You'd be more likely looking at using the cellulose as a non-conducting
carrier than as part of the logic itself.

~~~
Mtinie
Are there an any advantages to using hydrodynamic vs. electrodynamic forces
for carrying signals? Hollow cellulose nanotube structures could be printed to
carry fluid to different areas of a three dimensional circuit.

Would you be able to sacrifice some of the raw "speed" you gain from using
electrical current to carry the signals in a traditional PCB if it meant you
could work with significantly reduced heat? Or is my rudimentary understanding
of the physics here betraying me? Friction is going to exist, so it's quite
possible that these types of organic fluid logic gates would be useful for
other reasons, but not in the ways I've imagined.

Without some(all?) of the electromagnetic changes associated with the
continued reduction of die size for traditional electrical circuits, can you
build significantly denser (and eventually more powerful) mechanical circuits
with fluid-filled cellulose nanotubes?

~~~
jacquesm
It's prone to rotting in the presence of fluid, if you make it wet I think
that would be a quick and messy ending.

~~~
Mtinie
Good point. Would an oil-based transport fluid mitigate that to some degree,
or is the organic nature of cellulose going to be a liability to hurdle to
making a durable component regardless of the fluid used?

~~~
jacquesm
The problems are size and shape change as it saturates and losing structural
integrity (soggy...). Capacitors are a nice example, they're always wrapped in
something else both to contain the fluid and to keep things in one place.

Any kind of acidity would also be taboo. It would be very hard I think to make
something like this but I'm more than willing to admit that none of these are
'dealbreakers'. That's why I asked about the application, after all, if that's
the only way to do it and the application is valuable enough then maybe there
is a reason to invest a large amount of $ for R&D.

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jlebrech
so it's practically paper?

~~~
stagbeetle
No, it's similar to hard plastic.

~~~
jlebrech
I thought it was plant based

~~~
maxerickson
Cellulose acetate was one of the first materials used for many of the things
we use petroleum based plastics for now. Early Lego were cellulose acetate.

It's still used for lots of things.

~~~
logfromblammo
Cellulose is a very useful chemical. It was generally replaced by
petrochemical synthetic polymers for many of its original applications because
the latter may be more stable at higher temperatures, under UV light, in
contact with certain common chemicals (like water), etc. And most of the
petro-plastics are cheaper to manufacture.

Cellulosic thermoplastics often appear in products where you don't want the
plastic component to last forever, particularly textile fibers.

[https://en.wikipedia.org/wiki/Cellulose_acetate](https://en.wikipedia.org/wiki/Cellulose_acetate)

[https://en.wikipedia.org/wiki/Cellulose_triacetate](https://en.wikipedia.org/wiki/Cellulose_triacetate)

[https://en.wikipedia.org/wiki/Rayon](https://en.wikipedia.org/wiki/Rayon)

[https://en.wikipedia.org/wiki/Cellophane](https://en.wikipedia.org/wiki/Cellophane)

[https://en.wikipedia.org/wiki/Lyocell](https://en.wikipedia.org/wiki/Lyocell)

This 3D printing application seems similar to processes used to produce rayon
and cellophane, but instead of producing the more universally useful fiber and
sheet forms as a commodity, it forms an end-product directly and then
stabilizes it chemically.

