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Experiment results: at what temperature will a CGC holder deform?

Started by Joseph Ragno,

166 posts in this topic

selegue

selegue

Posted
Posted
Very graphic (and expensive) experiment!

 

Old thread about CGC holder thermal properties

 

"Barex (polyacrylonitrile copolymers -- I don't know which one of many commerical products like Barex 210, 214, 218 is used in "slabs" -- anyone know?) about 200 to 210 deg C (392 to 410 deg F)"

 

I still don't know which Barex is used in the CGC inner holder (anyone know?):

 

You clearly hit the melting point of the outer holder, made of SAN Styrene Acrylonitrile Copolymer, which melts at 239 °F.

The melting temperature is not the appropriate temperature upon which to base the performance of the holder. Rather, the more pertinent temperature is the glass transition temperature, which is lower (often much lower) than the melting temperature. This is the temperature which when reached, molecular bonds are significantly weakened such that deformation mechanisms such as creep come into play. Time, stresses, and temperature all have a role in the amount of deformation that can occur, and they usually have a non-linear behavior. It may be that leaving the slab in the 200 F oven for a much longer time could have similar effects.

 

 

OK, strictly speaking you're right, but it looked to me like the holder melted.

 

Do you know the glass transition temperature of SAN? I couldn't find in on a quick search.

 

Even 200 °F is well above the "maximum UTILZATION [sic] TEMPERATURE" of 185 °F.

 

DEFLECTION TEMPERATURE (deg. F)

- @ 66 psi: 209

- @ 264 psi: 195

 

UTILZATION TEMPERATURE (deg. F)

- min: -94

- max: 185

 

Jack

From this paper, Tg for SAN is around 374 to 380 K (215 to 225 F), depending on what flavor of SAN is being tested.

 

Well searched! Acta Chimica Slovenica 1999 -- how could I have missed it in such an obvious place? :D

 

Looks like the conclusion's the same either way (Tg or melting point). OK at 200 °F, no good at 250 °F. Not that I'd recommend storing slabbed funnybooks at 200 °F.

 

Thanks,

Jack

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comicparadox

comicparadox

Posted
Posted
Forgive me if this has been covered on a previous thread, but I decided to do an experiment on a very important topic: are my CGC graded comics safe in my fire safe?

 

increased the temp in the oven to 250 degrees for 5 minutes. Here are the results:

 

vdzfrp.jpg

 

Farenheit 451, eh? It appears from the photo that the CGC slab is uncracked. It's clear, therefore, that your comics in CGC slabs are safe even at 250 degrees. If, however, there had been a crack in the case, that temperature would potentially be a problem since you can't guarantee the integrity of the comic once the slab has been cracked. I suppose for that reason only, I wouldn't recommend storing one's CGC comics in an oven.

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armydoc

armydoc

Posted
Posted
Sell on ebay as CGC variant??

 

:signfunny:

 

 

 

Anyone know if slabs will crack at low temps? The reason I ask is that I left a bunch of books in a footlocker in my garage while home on mid-tour and forgot to move it inside prior to leaving. The garage isn't climate controlled and will probably get down to freezing temps this winter. I guess I should have my wife move them inside just to be safe, but I knocked her up and don't want her lifting anything. (thumbs u

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szelim

szelim

Posted
Posted
Sell on ebay as CGC variant??

 

:signfunny:

 

 

 

Anyone know if slabs will crack at low temps? The reason I ask is that I left a bunch of books in a footlocker in my garage while home on mid-tour and forgot to move it inside prior to leaving. The garage isn't climate controlled and will probably get down to freezing temps this winter. I guess I should have my wife move them inside just to be safe, but I knocked her up and don't want her lifting anything. (thumbs u

Oooh! Brittle fracture and ductility talk ...

 

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DrWatson

DrWatson

Posted
Posted
Sell on ebay as CGC variant??

 

:signfunny:

 

 

 

Anyone know if slabs will crack at low temps? The reason I ask is that I left a bunch of books in a footlocker in my garage while home on mid-tour and forgot to move it inside prior to leaving. The garage isn't climate controlled and will probably get down to freezing temps this winter. I guess I should have my wife move them inside just to be safe, but I knocked her up and don't want her lifting anything. (thumbs u

Oooh! Brittle fracture and ductility talk ...

 

You guys are nerds among nerds. lol

 

Squared. lol

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szelim

szelim

Posted
Posted
Well, if any of you "chemistry geeks" wants one of these before I throw it out, let me know. No charge except for the postage of your choice. --Joe

Before you toss them, can you determine whether either the outer or inner container melted, or did they just deform?

 

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Joseph Ragno

Joseph Ragno

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Before you toss them, can you determine whether either the outer or inner container melted, or did they just deform?

The inner lining melted too at 250 for 5 minutes. At 200 for 5 minutes, I didn't see a problem.

 

If I ever do this again, I might try 125 degrees for 1 hour. I may also try styrofoam around one (is styrofoam flammable at these temps?).

 

I have a fire safe rated at 350 for 1 hour. So far, the only change I think I'm going to do is put my most valuable books in the middle of the stack. Who knows, maybe there's an insulating effect. Hmm... another experiment.

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Fan4Fan

Fan4Fan

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I guess I would have started the oven with the books inside (rather than pre-heating), and then continued from there.

 

Some materials will do better if they are acclimated to higher temps rather than "shock" exposures. So, even if little visible damage was done at 200 by your method, the case may have been shocked more than if it had had a slower exposure.

 

On the other hand, slow exposure to heat could ensure a uniform distribution of heat and cause earlier warpage.

 

I think you need to retry this with more valuable books... :baiting:

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Transplant

Transplant

Posted
Posted

Regardless of the temperature inside, you may not want to store your books in a firesafe anyway. There's a thread here on the fact that some firesafes will cause very quick rusting of the staples. Too lazy to link it.

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mica

mica

Posted
Posted
Wow. I was curious too, except I used electricity. Same results though: BCS (baked comic syndrome)

 

Volts.jpg

 

Same book too! What are the odds? :insane::kidaround:

lol:applause:

 

Now send it to someone marked "DO NOT BEND".

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