Vitrification and Devitrification of Rigid Amorphous Fractionduring Quasi-isothermal Cooling and Heating

摘要

Poly(butylene terephthalate), PBT, and Poly(ethylene terephthalate), PET, werestudied by quasi-isothermal (QI) Temperature Modulated Differential ScanningCalorimetry (TMDSC). For the first time, temperature dependent crystalline a fraction andrigid amorphous fraction (RAF) were analyzed during quasi-isothermal cooling andheating. In both materials, heat capacity measurements show most RAF vitrifies step-by- bystepduring the quasi-isothermal cooling after completion of crystallization. Uponstep subsequent QI heating, RAF devitrifies also step-by-step and almost completely devitrifiesbefore start of melting.