PVA is another plastic material that is available as filament for 3D printers. While every filament has its own advantages, PVA is very unique in that it dissolves quickly in water. Depending on the project and your creativity, PVA filament can be an innovative solution for 3D-printing. It is important to understand how PVA filament is used and stored before using it with your 3D printer.
What is PVA?
PolyVinyl Alcohol (known as PVA, PVOH, or PVAL) is a synthetic polymer. Vinyl acetate is first polymerized to form polyvinylacetate, it is then hydrolyzed to create the PVA filament used for 3D printing. (source: http://botnexus.com)
The main advantage for using PVA filament is because it is water-soluble. This may sound counter-intuitive since you just finished your 3D print, why would you want it to dissolve. But for certain applications it is exactly what you need. For example, printing a support structure for other projects that can easily be dissolved when no longer needed. Or printing casting molds that can be safely removed without damaging the cast.
PVA is also a sustainable alternative 3D printing plastic. Not only is PVA biodegradable and nontoxic, no oil is required to produce it. When printing prototypes or projects that you don't plan on keeping for very long, PVA is a great option.
While PVA's water-solubility makes it a very unique material with many practical uses, it may also be its disadvantage. Depending on the purpose of the structure being printed, PVA filament may not be the right choice. Any exposure to water, moist environments, or weather will increase the risk of the PVA dissolving. Storage is also slightly challenging as moisture can damage the material and cause bubbles in prints.
PVA should also stay away from heated elements and high temperatures. PVA has a low melting point of 190°C and begins to undergo pyrolysis at temperatures higher than 200°C. When printed at 200°C or higher, tar jams will form that are very difficult to remove. Simply increasing the temperature or drive force will not clear the nozzle. A jammed nozzle will require replacement or re-drilling. (source: http://bilbycnc.freshdesk.com)
All that is required to begin the process is to submerge the print into water. PVA objects will start to dissolve in room-temperature water within 20 minutes, and completely dissolve within 24 hours. Using warm water or gently agitation will speed up the process. ( http://bilbycnc.freshdesk.com)
PVA filament should be stored in an airtight container with silica at room temperature with dry conditions. Proper storage will increase the shelf life of the PVA.
Besides 3D filament, PVA is commonly found in water-soluble packaging, like for laundry detergent tabs. Freshwater fishermen also use small PVA bait bags to spread dry bait around the hook to lure in a bigger catch. Scientists are finding many uses for PVA and it is even being used in the bio-engineering field. PVA is also used in hydrographics (water transfer printing).
- PVA filament sizes: 1.75mm or 3mm
- Glass transition temperature - 85° C
- Extrusion temperature for printer: 160° C to 190° C
- Heated bed temperature, if applicable: 55 °C to 60 °C
- Specific heat - 0.4 cal/gC