Why didn't flash freezing make the polycaprolactone plastic brittle?

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The discussion centers on a science fair project exploring the mobility of polymer chains in relation to temperature and pressure. The project involves flash freezing polycaprolactone (Instamorph) to demonstrate its brittleness. The user created a cooling bath using dry ice and isopropyl alcohol, aiming for a temperature lower than the polymer's glass transition temperature of -60 Celsius. After submerging the plastic for 30 seconds, it did not exhibit brittleness when tested. The key takeaway is that reaching the glass transition temperature does not automatically result in brittleness; further understanding of the material's properties and behavior at low temperatures is necessary to achieve the desired effect.
R_Lee
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Hello, I am working on a science fair project with my son. His project is about the mobility of polymer chains depending on temperature and pressure. As part of his project we want to flash freeze a piece of plastic to show how brittle it becomes. We bought instamorph, which is polycaprolactone. It has a glass transition temperature of -60 celcius. Next, I bought some dry ice, put it in a plastic bottle and poured 99 percent isopropyl alcohol into it to create a cooling bath. This cooling bath should be about -77 celcius right? Lower than the glass transition temperature. So then I dipped the piece of plastic into the bath, held it there for about 30 seconds and pulled it out. I tried to smash it to test the brittleness but it didnt break. It felt the same, but just cold. Why is that? And how can I make it brittle?
 
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"Glass transition" does not mean that a material becomes "brittle."
 

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