On 9/5/2017 3:13 PM, Jeff Wisnia wrote:


Nancy Young wrote:

I had to replace mine after two shelves emptied themselves spontaneously
all over me.Â* Broken dishes all over, that was fun, too bad I didn't
learn after the first one.Â* I actually had hunted down plastic
replacements.

nancy


All we lost last week was a nice quite heavy clear glass water pitcher.

One of my chemically knowledgeable friends told me that the plasticizer
evaporates out of the plastic over a period of years leaving it more
brittle and subject to cracking. I'm not a chemist, but that sort of
makes sense to me. Most of the plastic shelf brackets in our kitchen,
save for the few I've already replaced have been there since we bought
the home new 34 years ago.

Jeff

I am a retired chemist and it is true that plascitizers can bleed out
but I doubt if they are used in transparent refrigerator shelves.
Plastics usually degrade by oxidation accelerated by heat and sunlight.
Sometimes solvents can cause crazing. You don't put chemical solvents
in your refrigerator but oils and things like alcohol at high levers can
be detrimental. I worked for a while on automotive resins and we tested
samples with all the crap that can fall on a plastic part like oil, gas,
windshield washer fluid, brake fluid etc. Plastics are fine for many
uses but I have seen a lot of badly designed ones.