Styrofoam cup in pressure cooker

[Oomph!]

Hello.
If you give a styrofoam cup to pressure cooker, it expand first, but than it extremely reduce. It reduce because the high pressure of the water vapor within the pressure cooker compresses or squeezes the tiny air pockets within the styrofoam cup and reduces the size of the cup, ok.
But why it expand first? And why it will melt, if you leave it in the pressure cooker too long?

Thank you very much.

 

[voko]

What happens with the air in the tiny air pockets as its temperature rises? What happens with the stuff in which the tiny air pockets exist along that way?

 

[davenn]

And why it will melt, if you leave it in the pressure cooker too long?

its really hot in the pressure cooker and Styrofoam has a very low melting point

Dave

 

[Oomph!]

The air in air pockets have bigger pressure, so it can make cup expand. But why it reduce than?

 

[davenn]

The air in air pockets have bigger pressure, so it can make cup expand. But why it reduce than?

so what do you think happens when the air pocket bubbles burst ?



Dave

 

[Oomph!]

So, the cup will be reduce. Buw why the air bubless burst?

 

[davenn]

So, the cup will be reduce. Buw why the air bubless burst?

think about what is happening to the air in the bubbles as it heats up

when you answer that question you will have the answer to the bursting bubbles


Dave

 

[Oomph!]

The bubble has bigger pressure and if it can, it expand. But in one while it can not expand. So, it burst? It is like a soap bubble? And where will go the air from the bursted bubbles? To the cooker?

 

[davenn]

yes, will mix into the air in the cooker
so lots of bubbles expanding and bursting release their little bits of air and the remaining Styrofoam collapses and its area decreases in size

Dave