The endothermic "annealing peak" of poly(phenylene sulphide) and poly(ethylene terephthalate)

The appearance of an endothermic annealing peak in semicrystalline poly(phe nylene sulphide) and semicrystalline poly(ethylene terephthalate) after ann ealing at or above the cold-crystallization temperature is investigated by temperature-modulated differential scanning calorimetry, thermomechanical a nalysis and dynamic-mechanical analysis. The results indicate relaxation pr ocesses in the interlamellar amorphous phase, which is in a strongly constr ained state after cold crystallization. During the annealing treatments rea rranging processes take place. These processes result in a separation of th e amorphous phase into an interlamellar relaxed and a "pseudo-crystalline" phase.