Водорастовримый пластик PVA (Poly-vinyl alcohol) от MAKERBOT

Описание

Постепенно буду переводить.

Poly-vinyl alcohol (PVA) is a low temperature thermoplastic with the interesting property of being soluble in water. With a melting point below that of PLA and a texture and compression profile similar to ABS it is relatively easy to extrude. However, because of PVA's sensitivity to water, even mild humidity can ruin an unsealed spool of filament.

PVA vs PVA

This item is  Polyvinyl Alcohol (PVAl). In many other uses PVA stands for  Polyvinyl Acetate (PVAc). PVAc is used as the main ingredient in white glue.

Using PVA

Recommended uses

3D Printing water soluble objects!
Taking advantage of PVA's ability to dissolve in water allows for many interesting designs, such as insertable and removable support items or devices that respond to submersion.

Dissolving PVA

PVA dissolves rapidly with simple submersion. A 10cm cube printed with no one surface at 20% infill and submerged in one cup of room-temperature water will begin to break apart within 20 minutes, and entirely within 24 hours. To speed up the dissolution, gentle stirring can be applied. Warm water may also enhance the process.
The water will quickly become an opaque white, and take on the appearance and consistency of wood glue.

Cautions

Humidity

It is highly recommended that PVA be stored in a cool, dry location.

Resealable plastic bags with desiccant are a good solution for cool climates, but in warm humid weather (such as summer at MakerBot's Brookyln headquarters), extreme caution must be employed. A spool of PVA left out in humid air will become extremely flexible, and can be hard to drive through an extruder. The water boiling out of the plastic in the nozzle will also introduce bubbles to the extruded filament; it will also be extremely prone to jamming in this state.

See below for instructions about drying out waterlogged PVA.

Temperature Sensitivity

PVA has a low melt point, and will flow at only 190?C. While this means that while driving the plastic into the nozzle is easy, PVA is also very sensitive to higher temperatures, and begins to undergo  pyrolysis at higher than 200?C.
Printing at higher than 200?C is probably possible, but should be avoided.

Important:If PVA is left to sit at temperatures higher than 200?C for extended periods of time, it will form tar jams that are extremely difficult to remove. Unlike PLA and ABS, you cannot remove a PVA jam by increasing temperature or drive force.
A jammed nozzle will often need to be replaced.

Dissolved PVA

Please do not drink dissolved PVA. While non-toxic and not a known carcinogen, it has no known nutritional value to humans, and will probably make you ill trying (and failing) to digest it.

MakerBot Water Soluble PVA Technical Information

Product Characteristics	Formulated polyvinyl alcohol
Melt flow index (190 oC, 2.16kg)	1.5- 3.5g/ 10min
Melting point	160- 170 oC
Glass Transition Temperature	45 — 55 oC
Specific Heat	0.4 cal / g oC
Density	1.25 — 1.35 g/ cm3
Solubility into water	soluble into cold water
Form supplied	Pellet

Processing

MakerBot Water Soluble PVA can be used on 3MM filament extruders for the processing of thermoplastic poly olefins. The material absorbs moisture once the packaging is opened and should be therefore processed only from unopened original bag. Otherwise bubbles may occur in the molding.

PVA filament will be very difficult to print with if it has soaked up humidity from the air; this problem will be worse with 1.75 mm filament.

Damp material can be dried at 60 — 80° C for 6 — 8 hours in a circulated air dryer. PVA extrudes best between 180 and 200 oC. It can be extruded at 225 oC, the default temperature for ABS, but at decreased quality.

Storage

MakerBot Water Soluble PVA remains stable for at least 12 months in its original container provided if it is stored correctly, i.e. indoors at room temperature and dry condition. Like all thermoplastics, MakerBot Water Soluble PVA must be stored in a cool place.

Keep MakerBot Water Soluble PVA sealed in an airtight container when not in use.