Not a damn bit, but it sure is good for engine parts and gears!
Jon (hell, no, I can't afford it!) FP 73
On Thu, 27 Jul 2000 17:01:00 EDT "Otto Crosser" <ottocrosser@hotmail.com>
writes:
> Ok, Heat cycling helps. What about Cryogenically freezing them?
>
> Otto Crosser
>
>
> >From: Alan Pozner <AlanP@identicard.com>
> >Reply-To: Alan Pozner <AlanP@identicard.com>
> >To: "'autox@autox.team.net'" <autox@autox.team.net>
> >CC: "'kevin_stevens@hotmail.com'" <kevin_stevens@hotmail.com>
> >Subject: Re: Heat cycle for the DOT Race tires, needed or not?
> >Date: Thu, 27 Jul 2000 15:02:16 -0400
> >
> >Kevin wrote in part:
> > >Allow 24-48 hours mininum time before using or don't bother
> > >heatcycling at all.
> >
> > >>One aspect of heat-cycling I've never understood is the above.
> If the
> >tires
> >aren't good to go as soon as they cool, then there must be some
> bonding
> >transitions still going on - that's clear. What's not clear is
> how. Once
> >they have cooled any chemical reactions are going to be happening
> at a
> >glacial rate compared to what goes on when they're heated up.<<
> >
> >First off plenty of chemical reactions occur at room temp. The
> difference
> >between 130 deg Fahrenheit and 70 degrees Fahrenheit is really
> small when
> >referenced to absolute zero ( -273.15 deg Celsius ).
> >
> >Second what is it that really takes place? My understanding is that
> the
> >long
> >chains of molecules in the rubber compound are unaligned and of
> various
> >sizes before the first heat cycle. After heating the molecular
> chains are
> >shorter and unattached. By letting them cool gradually they can
> align and
> >form similar length long chains making the compound stronger. Did
> you ever
> >do the "grow a purple or blue crystal experiment" in school? Where
> you heat
> >some salt in water with a string dangling from a popsicle stick.
> The
> >crystal
> >starts growing as the mixture cools but continues to grow for
> several
> >hours/days after the liquid is back to room temp. I suspect that
> the rubber
> >is going through an analogous process. The chains continue to grow
> for a
> >period after cooling. Experience has shown that most of the growth
> has
> >stopped in 24 - 48 hours hence the waiting period. If you heat the
> tire up
> >before the 24 hours is up you break the chains. After the 24 hours
> the
> >chains are stronger and longer and better resist heat cycle
> breakdown.
> >
> >Regards,
> >Alan "yes, I do have a Chemistry degree, among others" Pozner
>
>
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