Fast scanning chip calorimetry (FSC) experiments were carried out in a wide range of rates of temperature for semi-crystalline polymers (i.e poly(butylene terephthalate (PBT), polyphenylene sulfide, and isotactic polypropylene) to investigate the kinetics of non-isothermal crystallization, isothermal crystallization, and melting. First, the heat of fusion after cooling was discussed for the quantitative understanding of melt-crystallization on cooling. Despite polymer species, crystallinity decreases with increasing cooling rate. The cooling rate dependence of crystallinity showed two distinctive areas. The scanning rate dependence of enthalpy of melt crystallization, cold crystallization and recrystallization obtained from FSC are quantitatively explained on the basis of Ozawa's method. For isothermal kinetics, FSC allows to obtain the annealing-temperature dependence of crystallization half-time in a wide range of the supercooling without any unwanted nucleation or crystallization during cooling. A bimodal curve with two minima was observed for PBT and PBT with 0.1 wt% talc.
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Keywords:fast scanning calorimetry, differential scanning calorimetry, crystallization, superheating, melting.
Publication Date: 2020-04-25