Re: phase diagrams wanted

[brian whatcott <inet@INTELLISYS.NET>]

At 13:52 1/31/99 -0500, Chuck Britton wrote:
> At 3:24 PM -0700 1/28/99, Daniel Schroeder wrote:
> > > > Does anyone know where to find phase diagrams for some common
> > > > everyday two-component systems, like antifreeze (water + ethylene glycol)
> ...

> I'll recommend a Dover reprint of 'Phase Rule' by A. Findlay, revised and
> enlarged ninth edition by Campbell and Smith. 1951 copyright by Dover.
> ...
> Chuck Britton

I too tried a search for diagrams. It seems that (poly)ethylene glycol has
the unusual and useful property of being soluble in water over a range of
molecular weights, though its melting point rises with each polymeric
length increment, in a wax-like manner, as follows

MW     Melting point.

 62    -13C  (boils 197C)   monomer ??
300    -10C  (boils 245C)
400     -6C
600     22C
900 abt 34C
1000    29C
1500    45C
3400    55C
8000    62C
10000   63C
(Data from Aldrich cat)

 Apparently, the commercial anti-freeze ingredient has a mix of lengths,
and so it would be impolitic to attempt a definitive phase diagram.
I gather that the modal length of the commerce form is the diethylene -mer.
 At the low temperature end, it appears the mixture provides a sludge
which is mechanically much preferable to an expanding solid plug.

 According to Hampel & Hawley, other ingredients may include corrosion
inhibitors like borates, phosphates, nitrites, arsenites, molybdates or
sulphonated oils to form a protective film of some kind on metal surfaces;
defoamers such as silicones or organic phosphates etc.; and antileak or
leak stoppers like small polystyrene particles or powdered ginger root to
counter the mixture's searching tendency.

Brian
brian whatcott <inet@intellisys.net>
Altus OK