1. Home
  2. ⚗ Polymers Forum
  3. Epoxy Etching from Alkaline Solution

Epoxy Etching from Alkaline Solution

I have client that uses the light from a LED with a clear epoxy end and a phototransistor, housed in a similar clear epoxy package, to measure the clarity of a soap solution. He is worried that in time the clear surfaces of the devices will become cloudy during years of being immersed in a strong soap solution. He wants to conduct a year-long test, to determine if the solution etches the epoxy. Couldn't a stronger hot alkaline solution, such as potassium hydroxide, be used to accelerate his testing? Do you think his concerns are justified? What other materials would be better than epoxy?

David A. Johnson, P.E. --- Consulting Engineer

formatting link
formatting link
Home of the Imagineering on-line magazine. Also,
formatting link
A collection of over 7,000 schematics.

Reply to
David A. Johnson
Loading thread data ...

I would wory that the potassium hyroxide would not be a good mimic of the soap. The reaction(s) would be too different.

You are right about heating the solution to accelerate the test. Unfortunately you don't know how much faster a given temperature will be. The standard rule of thumb in chemistry is that a 10 degree C increase in temperature double the reaction rate. This corresponds to a fairly low activation energy ~ 13 kcal/mole, making the estimates fairly conservative.

John

Reply to
John Spevacek

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.