Ha!! Love that show. Bob Steve writes: > Direct communications, should anyone with to negotiate the details of their coating's doom, can go to [log in to unmask] . > > Best > > Steve Sent from my iPhone On Nov 12, 2010, at 2:32 PM, [log in to unmask] wrote: > It really has to be tough working in a technical industry with the name > Steve Smith, as a Red Green fan the first thing I thought of was duct > tape... > > Keep your stick on the ice, > - Graham > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman > Sent: Friday, November 12, 2010 2:54 PM > To: [log in to unmask] > Subject: Re: [TN] UV radiation and conformal coating > > Doug, > > I sent your posting to an old college friend who is a physicist with a > great deal if working knowledge on chemical finishes as his company > makes paints and protective coatings for the marine environment. He is > teamed with Bill Rollins at Raytheon Tucson on a grant from the MDA to > develop a whisker-tough conformal coating. > > He replied: > > Bob, > > Thanks for forwarding this to me. I am not subscribed to the list, so > please post this for me. > > All, > > Varnish fails on wood of boats in one or a few years, due to the > ultraviolet of the sunlight eventually getting thru the varnish [even > with UV absorbers] and breaking down the cellulose of the wood below. > Cellulose has a lot of carbon-carbon and carbon-oxygen bonds. > > Indeed; the loss of gloss of varnish is due to surface-oxidation by the > solar ultraviolet photons breaking the atomic bonds of the > material at the surface; those surface free radicals react almost > immediately with atmospheric oxygen, and are literally burned away. > > A carbon-carbon bond has an energy of about 348 kilojoules per mole, and > will readily break with a barely-ultraviolet photon. > > A carbon-oxygen bond has an energy of about 360 kilojoules per mole, and > a carbon-hydrogen bond about 413. For more details, see > http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html . > > Ultraviolet and even blue-visible photons have enough energy to break > these bonds. > > Broken atomic bonds create free radicals, and some of these will bond > onto neighboring polymer chains, causing increased modulus, reduced > elongation, and in fact the polymer gets smaller. the reason flakes of > paint curl outwards when they fail is that the outer surface has more > tensile stress than the material below, due to free-radical damage at > the sunlight-exposed surface. So, you see, it's going on all the time > the sun shines. > > Your conformal coating (made of carbon, hydrogen, oxygen and nitrogen > and perhaps other atoms) is doomed; it's only a matter of time. > > Steve Smith > Www.smithandcompany.com > > > > On Nov 11, 2010, at 8:20 AM, Douglas Pauls <[log in to unmask]> > wrote: > >> Good morning all, >> >> Does anyone know of any papers on the effects of UV light on conformal > >> coating? Not talking the cosmic radiation hard space kind. I know it > >> would be wavelength and intensity specific. Got a question from one > of >> our engineers and I, of course, gave the very intelligent answer of > "Beats >> me". But I have this wonderful resourse called Technet............... >> >> Doug Pauls >> >> ______________________________________________________________________ >> This email has been scanned by the MessageLabs Email Security System. >> For more information please contact helpdesk at x2960 or > [log in to unmask] >> ______________________________________________________________________ >> >> --------------------------------------------------- >> Technet Mail List provided as a service by IPC using LISTSERV 15.0 >> To unsubscribe, send a message to [log in to unmask] with following text > in >> the BODY (NOT the subject field): SIGNOFF Technet >> To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) >> To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest >> Search the archives of previous posts at: > http://listserv.ipc.org/archives >> Please visit IPC web site > http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 > ext.2815 >> ----------------------------------------------------- >> > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email Security System. > For more information please contact helpdesk at x2960 or > [log in to unmask] > ______________________________________________________________________ > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > To unsubscribe, send a message to [log in to unmask] with following text > in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: > http://listserv.ipc.org/archives > Please visit IPC web site > http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 > ext.2815 > ----------------------------------------------------- > ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------