PLA
Contents
PLA
Polylactic acid (PLA) is a bio-degradable polymer that can be produced from lactic acid, which can be fermented from crops such as maize. This makes it an ideal candidate for use in certain energy rich, cash poor areas of the world.
It is harder then PTFE and melts at a lower temperature (around 170°C to 210°C), so is potentially a very useful material. It does exhibit higher friction than PTFE however which can make it difficult to extrude and more susceptible to extruder jams.
For more details, see the Wikipedia entry on Polylactic acid
Usage
PLA is the ideal material for a Mendel RepRap. It is dimensionally stable, so there is no need for a heated bed. It is relatively inexpensive, and is not hard to source in filament form.
It does require some torque to move PLA through an extruder because of its higher coefficient of friction (relative to ABS), so it is recommended that you use a Geared_Nema17_Extruder or Geared_Nema17_Extruder_Driver vs the stock mendel extruder.
Heater Settings
Depending on which material you use, you should adjust your heat accordingly.
4042D should extrude at 190
4032D requires higher temperatures and may need to be set as high as 230
Extrusion width
There has been some evidence that pigment may affect extrusion width. If you are switching plastics a lot, it is a good idea to measure the extrusion before going through the toolpath process.
Build Surface
PLA bonds very very firmly to Acrylic, and it is not recommended to print directly on an Acrylic build surface.
It does stick well and is removed easily from BlueTape
It can also be printed on Polyimide(Kapton) that is pre-heated, but will be hard to remove until both the part and the surface are cooled.
Availability
New Zealand
Contact VikOlliver through his email or IRC for PLA 4042D in NZ
He has natural and black as well as some standard colors (blue, yellow, green). If you want a custom color, and can meet a minimum order, he can source it locally.
USA
Several resellers have popped up and are supplying two different varieties of PLA
Ultimachine - http://ultimachine.com/ Green, Black, Natural 4042D in 5lb coils
Makerbot - http://store.makerbot.com/ Natural 4032D in 5 coils.
Makergear - http://makergear.com/ Green, Black, Natural 4032D and 4042D in 5 lb coils and lb packs
Synthesis
A crude form of PLA can be produced by simply heating powdered lactic acid with powdered stannous chloride - commonly used in pottery glazes - in a test tube. Extracting it from the test tube afterwards is left as an excercise for the diligent student.
See papers in footnote for further details.
Papers etc
- [[File:PLA-kim-23-2-6-98033.pdf: Synthesis, Characterization and in Vitro Degradation of Poly(DL-Lactide)/Poly(DL-Lactide-co-Glycolide) Films.|thumb]]
- [[File:PLA-v30 327 334.pdf: Synthesis and Characterization of Poly(L-lactide-co-ε-caprolactone) Copolymers: Effects of Stannous Octoate Initiator and Diethylene Glycol Coinitiator Concentrations|thumb]]
- [[File:PLA-DiscreteYttriumComplexesasLactidePolymerizationCatalysts.pdf: Discrete Yttrium(III) Complexes as Lactide Polymerization Catalysts|thumb]]
- Stereoselective Ring-Opening Polymerization of meso-Lactide: Synthesis of Syndiotactic Poly(lactic acid) [[
, Page 2, Addendum|thumb]]
- Plastics from Renewable Materials A Royal Society of Chemistry educational document giving details of how to synthesise many polymers, including PLA.
