Polarization Phenomena in Rheomolded Polymers

Differential scanning calorimetry has shown that the metastability of polymers is strongly modified by Rheomolding®. The thermally stimulated current technique has been applied to the characterization of conformational states in the amorphous phase. The corresponding enthalpic relaxations have been studied independently from the volumetric ones. Around the glass transition, Rheomolding has been found to enlarge the distribution function of the order parameter. Above the glass transition, the liquid-liquid transition is shifted towards lower temperatures. This modification is due to a spectacular decrease of the critical temperature from 40 to -22°C. This variation explains the observed improvement of impact strength in Rheomolded polystyrene.