Hi Bob,
Tg and CTE are not related. CTE measures the expansion of a material as the temperature increases. Tof G or Tg (Glass Transition) is the measurement of strength as the temperature increases. Two completely different things and in the composite industry we have to take both into account. The Tg of polyester is around 110 degrees and this is the point where the resin matrix begins to soften and becomes unstable, I never implied that turns to rubber. Of course you can increase the Tg of a composite laminate by post curing, but in general, the Tg of polyester will never exceed much above 140 even with post curing. A high temperature polyester is available but only to industry as far as I know and even that stuff is only good to 160 with post curing.
We have done plenty of testing of surface temperatures on carbon fiber and we have never seen temperatures even close to 240 degrees and our tests were conducted in the Middle East for a military application. The maximum temperature that was recorded was 197 degrees and I believe the ambient was around 120 degrees and we were fairly close to the Equator.
I feel that this has started to become case of 'one-upmanship' and I don't believe Keith would appreciate it on his Thread, so let's just leave it as you can go do your thing and I'll do mine.

Regards,
Ian