Hi, I was wondering if anyone could help me here. I noticed that a pMMA plastic that I have is experiencing cloudy swirling patterns at its interface with an aqueous terpene solution. I was wondering if anyone could help me understand what is going on.
Based on what I know about terpenes, I don't think this is a chemical reaction. If it is a chemical reaction, I would think chain scission would be the most likely cause. However, I don't really see how this could be happening.
My other thought is that this is a solvent effect. The terpene is low MW, and with a backbone, I could see some solvent migrating into the polymer's amorphous structure. This would create areas with different refractive indexes and hence the cloudy appearance on the polymer. I think this is what is happening, but I can't find any research to back it up and wonder if anyone else has any ideas.
Thank you,
Hi , you change the crystallization surface to another one who diffracts rays in a different manner, here cloud
Materials tend always to go to a lower level entropy state
My best guess is that your second thought might be the correct one.
Based on:
1) Terpenes and terpenoids are good solvents for PS, "because" they share similar Hildebrand Solubility Parameters (HSP):
Chapter Recycling of Expanded Polystyrene Using Natural Solvents
2) PMMA also ranges in HSP similar to that of PS. Although I did not find a thorough solubility study about PMMA and terpenes: "Terpene resins will be effective as solid solvents for an elastomer when their Hildebrand solubility parameters are close to the Hildebrand solubility parameters of the respective polymer. [...] Further, terpene phenol resins are suitable tackifiers forpoly(vinyl acetate), poly(methyl methacrylate), andpoly(ethylene terephthalate)."
Chapter Terpene Resins
In summary, I suggest that:
The aqueous terpene solution is partially able to absorb PMMA at the interface (hence, the cloudy swirling patterns), because (some) terpenes (may be) good solvents for PMMA (unlike water, of course).
Best regards
Hi;
Please check the link below:
https://www.sciencedirect.com/topics/engineering/hildebrand-solubility-parameter
My regards
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