Comments on: Thermal Decomposition of Sucrose http://gaussling.wordpress.com/2008/10/04/thermal-decomposition-of-sucrose/ Editorials of a Scientist Political Mon, 16 Nov 2009 16:03:33 +0000 http://wordpress.com/ hourly 1 By: gaussling http://gaussling.wordpress.com/2008/10/04/thermal-decomposition-of-sucrose/#comment-14565 gaussling Mon, 01 Jun 2009 14:41:13 +0000 http://gaussling.wordpress.com/?p=1417#comment-14565 Hi Jason, A TGA experiment is fairly simple minded- it's just a platinum balance pan in a furnace. The temperature ramp can have an effect on the onset temperature and the slope of the mass loss- that's why one typically chooses a favorite heating rate for an experimental series. The low sample mass has the effect of offering minimal thermal inertia. Decomp is likely to occur substantially at the surface at least for some period of time. If decomposition renders the surface impermeable, then conceivably other processes within the bulk material may be favored owing to higher temperature within. The question about the use of isotopes to monitor how the carbon is chemically bound sounds like a good experiment. It might be more useful to use 13C since it is NMR active and characteristic chemical shifts can be obtained. Hi Jason,

A TGA experiment is fairly simple minded- it’s just a platinum balance pan in a furnace. The temperature ramp can have an effect on the onset temperature and the slope of the mass loss- that’s why one typically chooses a favorite heating rate for an experimental series. The low sample mass has the effect of offering minimal thermal inertia.

Decomp is likely to occur substantially at the surface at least for some period of time. If decomposition renders the surface impermeable, then conceivably other processes within the bulk material may be favored owing to higher temperature within.

The question about the use of isotopes to monitor how the carbon is chemically bound sounds like a good experiment. It might be more useful to use 13C since it is NMR active and characteristic chemical shifts can be obtained.

]]> By: Jason Kennerly http://gaussling.wordpress.com/2008/10/04/thermal-decomposition-of-sucrose/#comment-14564 Jason Kennerly Sun, 31 May 2009 22:37:09 +0000 http://gaussling.wordpress.com/?p=1417#comment-14564 So.. if we make the assumption that whats left at the end is very nearly all carbon, it looks like roughly half of the original carbon remains. Does this percentage change substantially if the furnace ramp speed is changed - instead of 50 minutes, if you set the unit up to proceed across a timespan of 200, 100, or 25 minutes, is the amount of carbon present at the end different? Also, can radioactive labels determine the likelyhood that any given carbon in the sucrose matrix is going to end up a part of the charcoal goop or a part of the vapors? So.. if we make the assumption that whats left at the end is very nearly all carbon, it looks like roughly half of the original carbon remains.

Does this percentage change substantially if the furnace ramp speed is changed – instead of 50 minutes, if you set the unit up to proceed across a timespan of 200, 100, or 25 minutes, is the amount of carbon present at the end different?

Also, can radioactive labels determine the likelyhood that any given carbon in the sucrose matrix is going to end up a part of the charcoal goop or a part of the vapors?

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