Printing PVA Structures

[bapardue 0]

I am working with a Chemical Engineering researcher who is printing ABS structures that are placed in gels and the ABS is dissolved to form flow paths.  Can you print with PVA as the only material so that the printed structure would be water soluble?  I did not know if anyone had tried this?

[gr5 2,234]

Yes!  Absolutely.  Some people actually print just with PVA and never dissolve the part in water.  I don't know what their plan was but yes you can certainly print a part purely in PVA.  You don't need a 2 head printer for that.

 

It's not as nice a material as PLA - PVA doesn't stick to itself when molten the same way PLA and ABS does so you tend to get occasional little bits of PVA scattered about but the quality isn't too bad.  I bet you could dye it as well.  PVA absorbs water well so I'm guessing a water based dye would look fantastic on a PVA part.

[bapardue 0]

Thanks for the response.  My current understanding of the research is that we would print flow paths out of the PVA and then a biogel would be cast around the PVA.  Once the biogel is set up the PVA is dissolved leaving a flow passage in the gel.

[gr5 2,234]

When you soak PVA for a while it gets like a gel.  Not sure if you can get it to completely dissolve.  I guess probably but depending how thin the passages are and how long it could take weeks to dissolve a channel of PVA deep in a gel.

[RogueWave 15]

2 hours ago, gr5 said:

When you soak PVA for a while it gets like a gel.  Not sure if you can get it to completely dissolve.  I guess probably but depending how thin the passages are and how long it could take weeks to dissolve a channel of PVA deep in a gel.

PVA in water temp 125 degrees F for over two hours turned into a gel state and overnight room temp 70F and some dissolved in the water but a glop of gel remained.....Yah, hard stuff to remove.....

[pongo 0]

Depends on the grade of PVA used, but more often than not you should be able to get the PVA to dissolve completely. The higher the temperature and the more agitation the quicker it will dissolve.

[geert_2 558]

Just a question: do the flow channels have a special irregular shape? Or are it just straight channels? If straight channels, maybe another option could be to print them in a very strong material like nylon, cast the gel around it, and then pull-out the nylon strings? But this obviously won't work with irregular channel shapes...

 

The problem with dissolving PVA could be that you need a good flow in the channels, to wash away the dissolved material, and to apply fresh water. I don't know if such a flow is possible, it may depend on the dimensions?