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Characterization Techniques
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stox
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Quote stox Replybullet Topic: How to characterize a Gel
    Posted: 13 March 2006 at 9:10am

Hi all, wanted to ask you.... how is a gel conveniently charachterized?

I'm diong so far viscosity measurements, turbidimetry (assorbance), shrinkage (volume loss). Are there other measurements to do? I've read about DTA and TGA.... what information does this analisys give?

I'm having problems in SEM and TEM analysis in order to see the particles in the gel... do someone know about convenient preparation of gel samples to put under eletronic microscopy?

 

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suresh
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Quote suresh Replybullet Posted: 04 April 2006 at 4:25am

hai friend

DTA/TGa give wight loss..reg to sample i will post u soon....i too have the proble after sol preparation

reg

suresh

suresh kumar.p
Thin Film Division

EMAIL: sureshinphy@yahoo.com
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gabonino
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Quote gabonino Replybullet Posted: 04 April 2006 at 10:54am
Hey stox,

ok, there are several measurements you can do on your gel. Here only a few I know of:

BET Area: Can get you the porosity of the gel, hence the structure.

TGA-DTA: These analysis help you find out somehow the possible structure of the gel. There you can see if, at some temperatures, there are changes such as combustions or phase transitions. Of course, you have to get info about the gel concerning your research first, to check out your results aswell.

X Ray Diffraction: Phase of your gel. NMR helps also on that matter, but I have never worked on it...

Have you tried adding the normal coat for samples on SEM?

Greets
Oscar Gabriel Niño A.
Chemical Engineer
Universidad Nacional de Colombia
M. Sc. Process and Energy Engineering
Technische Universität Berlin
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stox
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Quote stox Replybullet Posted: 05 April 2006 at 8:46am

thnx again gab!

I will run immidiatly to the SEM to make spectographs of the dried samples and will begin to make BET areas, have read a lot of interesting things about it.

 

Thnx a lot!

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gabonino
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Quote gabonino Replybullet Posted: 06 April 2006 at 8:52am
stox,

just another question: What kind of gel are you particularly interested on? Infrared spectrum could be another option too...anyway, if you have any questions, let me know, my email is also on my profile

greets
Oscar Gabriel Niño A.
Chemical Engineer
Universidad Nacional de Colombia
M. Sc. Process and Energy Engineering
Technische Universität Berlin
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hels
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Quote hels Replybullet Posted: 18 April 2006 at 2:42pm
Guys hi there. I have a link that contains very usefull informaitons abouth this topic. So if anybodu nedds to read something more see it :

http://support007.com/find.php?value=How+to+characterize+a+Gel

best regards
hels
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Fanfan
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Quote Fanfan Replybullet Posted: 24 July 2006 at 9:06am

I'd like to share with you some of my experiments.

the dried gels are hard to phase by XRD. I use citrate route, and before further heat treatment, they are amorphous and hard to be characterized.

TGA-DTA is a powerful tool. you can predict the possible physical and chemical changes according to the TGA-DTA results.

I photoed some pictures of dried gel powders by SEM, they are porous, but I don't think SEM is a useful tool here.

At present, I want to do some observation of the gelation before dried under optical microscopes. I don't know if any of you have such experience to share.

Best wishes.

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sagebob
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Quote sagebob Replybullet Posted: 19 August 2006 at 12:21pm

howdy Stox,

There may not be any particles in your gel (besides contamination).  The pure gels have polymerization going on but this leads to an increase in molecular size and shape.  Not exactly a "particle" unless it get really, really big.  there is a company in California, name starts with a W that has an instrument for measuring molecular size in solutions.  There are other solutions that are designed around a suspension of particles of a specific size.  These are easily measured with a conventional particle counter from PMS or somebody.

For quality monitoring in a production environment, I have found viscosity and solids content to be pretty good.  If you have a solution that goes bad due to absorption of water, titration with a water solution is useful.

-bob

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