Glass Transition
Glass Transition
(OP)
I have got a slope for finding glass transition of polymer. Does anyone have suggestions of finding exact temperature for the glass transition. If so could you please how to find that in excel...if you can direct me to any link then also its fine.....your help is highly appreciated





RE: Glass Transition
If you have a DSC you can easily know Tg.
If you are looking for data, Handbook is your friend. For example PvC Handbook
Cheers
RE: Glass Transition
RE: Glass Transition
RE: Glass Transition
RE: Glass Transition
Regards
Pat
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RE: Glass Transition
RE: Glass Transition
What is Tg? It is the temperature at which 10-15 polymer segments can move together giving some flexibility to the polymer. If you test quickly the temperature needed for 10-15 units to move is much higher than if you test slowly because during a slow test the units have more time to move. Another definition is the temperature at which the free volume of the system is around 2.5 volume % (this can be measured by positron annihilation).
Sorry for the details. Did my PhD in polymer science so I have had this drilled into me. In the real world, Tg is irrelevant except as it pertains to how the material behaves in your application.
Chris DeArmitt - PhD FRSC CChem
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RE: Glass Transition
I can tell you the pipeline coating guys (Fusion Bond Epoxy/FBE) would dispute your assertion about Tg being irrelevant in the real world. Tg by DSC is the gold standard for determining whether the FBE has achieved cure or not.
RE: Glass Transition
If you're not careful Tg will change as you are heating the sample to measure it. For examples, epoxies will cure until Tg = Tcure. At that point the chains can't move and cure any further. So your end Tg will be the same as the cure temperature. When you heat it past that Tg by DSC the epoxy will start curing again(because the chains are mobile again) and Tg changes.
Another way to measure extent of cure by DSC is to ramp the temperature and measure the cure that takes place. That extra cure due to heating (exotherm) shows the reactive groups that remained when your original cure was complete. That's used as standard to give an indication of cure extent.
Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
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RE: Glass Transition
RE: Glass Transition
Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com
RE: Glass Transition
RE: Glass Transition
Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com