How can the same material have different glass transition temperatures?!

How can one compound appear to have different Tg values? That's crazy! Surely there should be only one, true value? Well, you'd think so but in reality the way the glass is made AND the way Tg is measured will all affect the Tg value determined. But why? What is it about formation that changes Tg? And why do different analytical techniques give different Tg values? All will become clear in this handy explainer video!
There are two sets of data in the video from the literature. The original sources are;
Dielectric Tg data, Gainaru et al, www.pnas.org/cgi/doi/10.1073/pnas.1411620111
DMA Tg data, Akil & Zamri, doi.org/10.153...
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Or you could watch the series on Mastering DSC, the first video of which is here;
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