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I'm searching for polylactic acid (that used in 3D printing) solvent, that is less toxic. It's used to postprocessing to polish object.

Dichloroethane is toxic, acetone and dichloromethane less, but enough. Tetrahydrofurane and chloroform usage is limited in Russia.

As I know there is D- and L- polylactic acid, I don't know what type is it, but can test using acetone.

Can I use ethylacetate for this purpose? Or there is another solvents?

Sorry about my english

Useful links: https://www.researchgate.net/post/What_is_the_best_solvent_for_polylactic_acid2/amp https://www.researchgate.net/post/Solubility_of_PLA/amp https://groups.google.com/forum/m/#!topic/tvreprapug/1wTmQZJMc9g

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D- and L- polylactic acids come from both enantiomers of the monomeric lactic acids. There will be no difference in solubility between both polymers. Besides, lactic acid is normally produced by fermentation and the L- form is obtained, so the standard PLA used in 3D printing will be L- PLA.

I have tested the solubility of a piece of PLA and it is not soluble in ethylacetate in one hour. It does even not seem to be attacked by it.

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However, when you rub a 3D printed piece with a paper soaked in ethylacetate, some polishing is attained.

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I make basically structural pieces, so I normally do not polish them and therefore I do not know if this is enough for your purpose.

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My experience with PLA and EA is the following:

  • Temperature matters a lot. At room temperature, almost nothing happens. What I tend to do is put a print in a jar with some EA, and hold it under running hot water while shaking it.
  • If this works at all also depends on lot on the 'PLA' used; and this is true of printing materials and solvents generally; producers are
    not in the habit of providing a complete list of ingredients, and
    many filaments have additives that interfere with solvents. Ive tried a bunch of brands and I had by far the best results with PLA/PHA from colorfab.

But at the right temperature and with the right filament, EA works quite well as a smoother; typically done smoothing in about 20 seconds this way.

Also, dryness of your solvent may matter a lot. I used to be very disappointed by the action of acetone on ABS; untill I put a little CaCl in. I dont think EA naturally attracts water as much as acetone but in general the purity of your EA may matter; it might have things in it that compete with the dissolution of PLA, so try to keep those to a minimum.

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  • $\begingroup$ How hot water you suggest? 60C (140F) degrees is maximum for PLA. After it shape degrades rapidly $\endgroup$ – Евгений Новиков May 23 '18 at 7:37
  • $\begingroup$ Ive never measured the temperature of the EA; but vapor pressure goes up considerably so a substantial fraction of its BP. But PLA has low thermal conductivity and high latent heat; having it submerged around hot water tap temperatures for a few seconds isnt going to have any effect but at the surface, even if the internal temperature would go over 60C. But in the end there are so many variables that nothing beats experience I think; just experiment with different temperatures with some scrap pieces. $\endgroup$ – Eelco Hoogendoorn May 23 '18 at 11:11
  • $\begingroup$ Note that the short working times that higher temperatures allow are infact helpful in keeping the same of your part intact. Ive also tried just waiting longer at lower temperatures; and what tends to happen then is that the EA penetrates deep into your part and makes it all rubbery (and delaminate), long before the surface actually smooths. So a short treatment under conditions that would in the long term completely destroy your part is actually pretty much a necessity. $\endgroup$ – Eelco Hoogendoorn May 23 '18 at 11:14

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