--- Horace Heffner <[EMAIL PROTECTED]> wrote:
> It is surprising that lead is a powerful electron donor, as powerful
> as "cat fur":
>
> http://www.school-for-champions.com/science/static_materials.htm
>
> Also noted as a weak donor is aluminum.
>
> This seems somewhat consistent with the electron affinity table:
>
> http://en.wikipedia.org/wiki/Electron_affinity
>
> because lead is 35 and Al is 42, but the *extreme* donating ability
> of lead is surprising. The problem remaining then is to find a good
> transport molecule for interacting with lead.
>
> Odd there was no mention of zinc.
>
> Lead is the metal also at the top of the Wikipedia list at
>
> http://en.wikipedia.org/wiki/Triboelectric_effect
>
> and is listed just above cat fur.
>
> Though not a metal, silicon is listed as better than gold or platinum
> as an electron acceptor. If doped silicon works as well in that role
> as silicon then it might be worth considering. It may also be
> possible to add materials to ebonite or silicone rubber to make them
> sufficiently conducting to work, but neither would be good for high
> temperatures, nor would lead.
>
> Either CO2 or nitrogen must be a good transport molecule, I'm not
> sure which:
>
> http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=10120574
>
> I guess it would be CO2 that transports because CO2 could then
> neutralize the coal by acting as a quasi conductor. The other
> interpretation might be that nitrogen is a contact transporter that
> charges coal in the first place. Neither would necessarily be
> inconsistent with the dry pile operation. I bet on CO2 as the
> transporter because dry nitrogen is a terrific insulating gas.
>
> Horace Heffner
> http://www.mtaonline.net/~hheffner/
I am always amused by triboelectric series tables. The people who put
these out usually have absolutely no idea what they are talking about.
The position of lead on this table is complete nonsense. Other gross
errors include acrylic, polyester and styrene on the negative side.
The vast majority of acrylics, and there are thousands, tend to go
positive when rubbed with almost anything, including cat fur and rabbit
fur. Styrene is interesting because in can go either way depending on the
conditions, however, it usually goes positive. Styrofoam tends to go
negative whereas crystal styrene almost always tends positive, even though
they are chemically identical.
Glass is interesting. Most modern glasses are difficult to charge. One of
the best ways to charge glass is to use aluminum foil, much better than
those materials listed on the negative side of Wikipedia's series. Of
course you have to keep the glass against a conductive surface, wood, Formica,
metal, etc., while you are rubbing the glass so that the charge is kept at
low voltage. You then pick up the sheet of glass and it hisses its
positive charge into the nearest grounded object.
That's clear glass. Frosted, ground, or sandblasted glass tends to go
negative. The only reason I bring all this up is that the conventional
ideas as to what constitutes electron sources are not necessarily valid.
Several metals and other substances dutifully listed on triboelectric
series are in their positions based on assumptions, hearsay, and errors.
So goes the rest of science and most other human endeavors.
"There is someting fascinating about science. One gets such wholesale
returns of conjecture out of such a trifling investment of fact."
--Mark Twain
M.
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