Thread: Dust!!!!
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Old 23rd April 2018
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Re: Dust!!!!

Quote:
Originally Posted by Ricoh View Post
I read some advice to get fresh Eclipse; apparently over time the alcohol degrades the plastic bottle potentially resulting in desolved plastic in solution. When the alcohol evaporates the plastic stuff remains leaving a white film on whatever it is you clean, lens or sensor.
How true I'm not sure. I'm not a chemist.
I'd not heard that. A quick bit of Googling reveals little, although I did find an abstract of some research in using methanol to de-polymerise PET (which is the most commonly-used plastic for bottles). This is what it said:

Quote:
The degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated with the aim of developing a process for chemical recycling of waste plastics. A batch reactor was used at temperatures of 573–623 K under an estimated pressure of 20 MPa for a reaction time of 2–120 min. PET was decomposed to its monomers, dimethyl terephthalate and ethylene glycol, by methanolysis in supercritical methanol. The reaction products were analysed using size-exclusion chromatography, gas chromatography–mass spectrometry, and reversed-phase liquid chromatography. The molecular weight distribution of the products was obtained as a function of reaction time. The yields of monomer components of the decomposition products including by-products were measured. Continuous kinetics analysis was performed on the experimental data.
But - that's a reaction at 20,000 atmospheres of pressure and 300 degrees C!

I doubt there's much in the claim that PET will dissolve in methanol at STP.
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The Following 3 Users Say Thank You to pdk42 For This Useful Post:
OM USer (23rd April 2018), Ricoh (23rd April 2018), RobEW (23rd April 2018)