PVA (Polyvinyl alcohol) the plastic that’s afraid of water

Today we are going to be starting a multipart series looking at some non-standard materials that are printed using Fused Deposition Modeling (FDM).

PVA (Polyvinyl alcohol)

This type of polymer dissolves in water!! FDM printers which have two nozzles can print in PVA and usually ABS simultaneously. When the print is done the model can be submerged in water. The PVA will dissolve leaving the ABS portion of the model intact. The advantages are the ability to print models with overhangs. This method can also be used to print floating or movable parts.

This cube was printed in gray ABS and off-white PVA by thingiverse user Tony Buser.

dissolvable-support-gearbox5

After printing it was submerged in water.

dissolvable-support-gearbox6

The PVA dissolved and the ABS remained. This allowed the Hilbert cube containing many overhangs to be printed.

dissolvable-support-gearbox4

How it’s made

PVA is produced through multiple chemical reactions. However, the starting compound is ethylene gas. So, where does ethylene gas come from? Well it is actually produced by some plants when their fruit ripens. It can also be produced from ethanol. These methods are just too expensive for commercial production. So, it’s made from you guessed it oil. However, it is able to be broken down by some types of bacteria making it biodegradable.

Material Properties:

Type of 3D printing which utilizes material: FDM (Fused deposition Modeling)

Usually printed with dual extrusion as a support material.

Most printers utilize 1.7mm filament, some use 3mm filament

Strength:  Weak and water soluble. Used as structural support for other materials.

Post Processing:  PVA support material can be removed by submersing the model in water. This allows the PVA to dissovlve.

Suggested Printing Temperature:  160-175 °C DO NOT EXTRUDE AT HIGHER TEMPERATURES!

The accuracy at which temperature is controlled is dependent on the printer.

Special Considerations: PVA starts to absorb water from the air as soon as it is opened. For those of you in humid environments the effect will be greatly increased. I suggest resealing the PVA in a bag using a vacuum sealer when not in use. This will allow it to last much longer.

Biodegradable: Yes

Renewable Resource: No

Starting material= oil

Cost: $88 -$90 a kg

Favorite Source:  Ultimachine both 1.7mm and 3mm filament available in many sizes.

Color: PVA is usually only available in it’s natural color off white.

PVA_Natural_2

Example: This ABS gear mechanism was produced in one print with PVA as the support material. It has moving parts!

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Posted on June 3, 2013, in 3D Printing and tagged , , , , , , , , , . Bookmark the permalink. 4 Comments.

  1. Although most any discussion of the use of PVA material for 3D printing suggest using it for support material, the main print software for use with the MakerBot Replicator 2X printer (which has the ability to print with two different materials in one session), MakerWare, does not allow choosing the second extruder to create the support structure. I’ve questioned why this is, as if MakerWare can automatically generate the code to build the support, why can’t it also specify using the second extruder to build it? There are complicated schemes to generate negative spaces in objects, and then fill those spaces perfectly with other objects so that two different materials can be used. How much easier it would be to just have one more box to check before printing that specifies the second extruder for PVA as support.

    • In reply to my ancient post of July 29, MakerBot MakerWare 2.3.0 now allows you to specify the material used to create the support material. Exactly what I asked for. I have PVA on order, and look forward to giving it a try. So far the only solution I’ve seen from 3D Systems is to use PLA for the support material, and then have you put the part in an ultrasonic cleaner (they sell one for $1300) with sodium hydroxide solution (drain cleaner). No thank you.

  2. I’ve actually found PVA will print much better with PLA, rather than ABS. ABS has trouble sticking onto PVA for some reason -maybe the larger temperature difference.

  1. Pingback: 3D Printering: Alternative Filaments

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