Testing for Ethylene Glycol Layer on PMMA Experiment

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Discussion Overview

The discussion revolves around an experiment involving the creation of a mold from poly methyl methacrylate (PMMA) using a resin that contains epichlorohydrin and ethylene oxide. Participants explore the possibility of ethylene oxide reacting with absorbed water in PMMA to form a layer of ethylene glycol, and seek methods to test for the presence of ethylene glycol in the experiment.

Discussion Character

  • Exploratory
  • Technical explanation
  • Experimental/applied

Main Points Raised

  • One participant questions whether the absorption of water by PMMA could lead to a reaction with ethylene oxide, potentially forming a glycol layer.
  • Another participant provides a method to test for the presence of epichlorohydrin by using a copper wire and observing the flame color, suggesting that a green flame indicates chlorine presence.
  • The original poster clarifies that there was no intentional addition of water to the resin, but notes the presence of an oily substance on the cured resin, speculating it may be glycol.
  • The original poster expresses concern about the small size of bubbles in the oily substance, which may hinder the ability to perform the flame test effectively.
  • A later reply reassures that the flame test is sensitive enough to detect the presence of the substance.

Areas of Agreement / Disagreement

Participants have not reached a consensus on whether the oily substance is indeed ethylene glycol, and there are differing views on the potential for water absorption and its effects on the reaction.

Contextual Notes

The discussion does not clarify the specific conditions under which the reactions may occur, nor does it address the implications of the resin's composition on the outcomes of the experiment.

dacruick
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Hi

I am doing an experiment right now trying to make a mould out of a poly methyl methacrylate (PMMA) using a resin containing Epichlorohydrin and ethylene oxide.

I do not know very much about chemistry but through some research I see that ethylene oxide can react with water to produce glycol. I also hear that PMMA can absorb water.

Is it possible that there was enough water absorbed into the PMMA that the ethylene oxide reacted with it and formed a layer of glycol at the top?

And my big question is, is there any easy way to test if the layer is ethylene glycol?

Thanks a bunch

dacruick
 
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Ethylene glycol is soluble in water in all proportions. Epichlorohydrin is slightly soluble.

If you have a copper wire, pass it through a hot flame (blue flame from bunsen burner) and when cool, dip it into the liquid. Put that back into the flame and look for green. Green signifies chlorine and means that you have at least some epi in that sample. http://www.sha.org/research_resources/conservation_faqs/documents/beilstei.pdf"
 
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I will try that. But to clarify, I do not have any water (or at least no water that I meant to have), in the resin. It was simply the resin and the acrylic only.

originally I had the ethylene oxide and the epichlorohydrin, then I mixed in Triethylenetetramine which is the hardener for the resin. It has now completely cured and is a solid block of this resin, but with an oily substance on the top.

bubbles have formed of this oily substance and if I had to guess, I would guess it is glycol.

Thank you for your help, and in advance for any future help:).

Oh P.S

The bubbles are very small, I am concerned that I won't be able to scavenge enough of it to create a flame that is green.
 
Don't worry, it's a very sensitive test.
 

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