A glass may have different entropy characteristics

A concept closely related to the variable non-equilibrium entropy trapped in the glass is adlcdfragility. It is important to realise at the outset that this particular 

However, the concept was later extended to relate to the residual entropy (and so the non-equihbrium thermodynamic properties) trapped in the glass during the supercooHng process. At this stage it was applied to polymers above, through, and very sHghtly below the glass transition temperature. 

The fact that plastics are frozen in a non-equilibrium state has consequences for all the physical properties that depend on density and also for the long term dimensional stability. Because the supercooled state is thermodynamically metastable, the polymer molecules move slowly in an attempt to reach equilibrium. These very slow molecular motions, even in the glassy state, are extensions of the processes which are observed in shorter times above the 

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