Re: 1991 ranger brake problem - CO2 & O3

"Clare Snyder"  wrote in message news:vcadjjta7qb14jlee2r76lk1394hrvncji@4ax.com...
The carbonyl [C=O] end groups which are formed are usually aldehydes or
ketones, which can oxidise further to carboxylic acids. The net result
is a high concentration of elemental oxygen on the crack surfaces,
which can be detected using energy-dispersive X-ray spectroscopy in
the environmental SEM, or ESEM. The spectrum at left shows the high
oxygen peak compared with a constant sulfur peak.
---------------------------------
That's slightly wrong like much of Wiki. Aldehyde implies an oxygen at the end but a ketone has oxygen hanging off in the middle. Chemistry is too complex for simple explanations. My 4 year degree in it qualified me only to understand further education which the Vietnam draft prevented, though the knowledge of matter, energy and quantum mechanics gave me a boost into other fields like semiconductor physics.
Sulfur is mixed into raw rubber to react with the C=C sites, but with different consequences, being less aggressive than its cousin oxygen it hardens and stabilizes, "vulcanizes", the rubber instead of enabling further degradation. It's the reason burning rubber smells bad.
Linseed and other "unsaturated" (double-bonded, -C=C-) plant-based oils cross-link and harden in air by a similar process. The fire hazard from a covered waste can of oily rags was caused by the feedback loop of oxidation releases heat and heat speeds further oxidation. The mineral oils that replaced them in machining have fewer double bonds and don't heat up. "Paraffin" is from Latin "parum affinitas" and means low reactivity.