ORGLIST:Oleic acid and paraffin wax

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From: walker$##$netcon.net.au
Date: Thu May 13 2004 - 19:14:26 EDT


I have been working with a mixture of oleic acid and paraffin wax as a
binder. The oleic acid is in the mix as a rheology modifier. I have
noticed something strange about the physical properties of the material and
I hope someone can explain it to me. I am not an organic chemist.

I use a low melting (around 50 deg C) paraffin wax which is a mixture of C20
to C35 alkanes, mostly C23 - C26. I use lab grade (99.9%) oleic acid.

I melt the wax at 100 deg C and mix in the oleic acid very thoroughly then
cool it to solidify.

I have tried 2 weight percent oleic acid and 5 weight percent oleic acid.

The strange effect is that the physical properties of the resulting solid
material changes over time. The low oleic acid mix becomes more brittle in
2 - 5 days and the high oleic acid becomes stronger and tougher in 2 - 5
days.

Why is this? Is there some sort of cross-linking reacion with the double
bond? Can the oleic acid oxidise a little after a few days exposed to air?

Any comments?

Thanks

Alan Walker
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