Aluminum oxide on plastic problem
Aluminum oxide on plastic problem
(OP)
I have a several black plastic parts as part of a product that is placed in a large aluminum housing that is outdoors. The aluminum housing is painted on the outside, and the plastic is all exposed to the sun and weather. After several months, one particular plastic part becomes sort of "chalked over" with a loose film that is very reflective and looks white in the sun. The other plastic parts, made from a different material, are unaffected.
A chemist told me that the loose film is either aluminum or aluminum oxide from the environment that seems to stick to the surface of this particular plastic due to small fissures on the surface. Where could it be coming from? The aluminum sign should be covered in oxide that would be very stable I think. Does aluminum shed some amount of oxide in the outdoors?
Thank you,
Jeff
A chemist told me that the loose film is either aluminum or aluminum oxide from the environment that seems to stick to the surface of this particular plastic due to small fissures on the surface. Where could it be coming from? The aluminum sign should be covered in oxide that would be very stable I think. Does aluminum shed some amount of oxide in the outdoors?
Thank you,
Jeff





RE: Aluminum oxide on plastic problem
Come back with the type Al you have.
If your plastic has cracks or fissues, surface degradation, you need to have the compunding formula changed to include more UV blockers.
RE: Aluminum oxide on plastic problem
Whatever you find out changing the additve in the plastic will be required to stop the environmental changes.
RE: Aluminum oxide on plastic problem
The plastic that is "good" and does not turn white is a UL F1 material. Turns out the "bad" plastic is not an outdoor grade. I was able to order the parts with the outdoor UV resistant grade, so maybe I have solved the problem.
Now I would like to devise a test to see if I really fixed the problem. I was thinking of buying some 1-2 micron aluminum oxide powder and seeing if it is "trapped" by the old and new parts after some UV exposure. Although that is starting to sound like a lot of work.
Thanks for your replies,
Jeff
RE: Aluminum oxide on plastic problem
I would avoid the UV testing and put that monkey on the part supplier if you really need the test.