High‐pressure dependence of structural evolution in polyamide 11 during annealing

This work focuses on the pressure dependence of some microstructure changes like the secondary crystallization induced by annealing above the glass transition temperature. Polyamide 11 samples were annealed under a hydrostatic argon pressure ranging from the ambient up to 4000 bars. Structural evolutions were investigated by differential scanning calorimetry (DSC) and compared with similar experiments performed under atmospheric pressure. Pressure results in a strong shift of the endothermic peak observed in DSC traces toward lower temperatures, with a change of kinetics. The pressure sensitivity is clearly nonlinear. It decreases with increasing pressure levels until saturating above about 3000 bars.