Densely cross-linked, glassy polymers

This situation is well known for linear polymeric glasses, but for densely cross-linked networks the experimental data are very limited. However, it is not yet clear whether the densely crosslinked polymer networks in the glassy state exhibit, in general, the same mechanical behaviour as linear polymeric glasses. The results given in this Section allow us to answer this question concerning some important mechanical properties. 

Expression a for densely cross-linked polymers in glassy state is analogos to the same, derived for densely cross-linked polymers in hyperelastic state, but in the formula is used thermal expansion s coefOcient of glassy state... 

One view of a gel is as a modified mbber. The properties of amorphous polymers change dramatically above the glass transition point where the chains become mobile. Since polymer chains are mobile in solution and we think of a simple gel as a cross-linked solution, we can regard a single phase gel as a dilute rubber. Dense polyacrylamide, for instance, is a glassy polymer. We do not want to compare the gel properties with this state but with the same polymer as a cross-linked mbber above its glass transition. 

---